endo journal dec 08

ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY


Editorial

Original Research

4

A Comparison of the Relative Efficacies of Hand and RotaryInstruments in the Removal of Guttapercha from the Root Canalduring Retreatment using Stereomicroscope - An In-Vitro Study

“To Analyze the Distribution of Root Canal Stresses after SimulatedCanal Preparation of Different Canal Taper in Mandibular FirstPremolar by Finite Element Study – An In Vitro Study.”

A Comparative Evaluation of Cyclic Fatigue Resistance of Two RotaryNickel - Titanium Endodontic Systems - An In Vitro Study

Coronal Microleakage of Four Restorative Materials Used inEndodontically Treated Teeth as A Coronal Barrier - An In Vitro Study

In Vitro Evaluation of the Efficacy of Five Apex Locators

A Three-Dimensional Evaluation of Density and Homogeneity of RootCanal Obturation with Guttaflow® using Backfilling Technique inComparison with Conventional Lateral Compaction Technique usingSpiral Computed Tomography - An In Vitro Study

Comparative Evaluation of Radiopacity of Three Root Canal SealersUsing Conventional and Digital Radiographic Technique: An InvitroStudy

The Effect of File Sizes in the Presence of Sodium Hypochlorite andBlood on the Accuracy of Root Zx Apex Locator in Enlarged RootCanals - an In Vitro Study

Sealing Ability of Four Materials in the Orifice of Root Canal SystemsObturated With Gutta-Percha

Current Endodontics Literature

Dhanya Kumar N. M. 5-11Praveen GokulVasundhara Shivanna

Dhanya Kumar N. M. 12-21Abhishek SinghaniaVasundhara Shivanna

Dr. Gaurav Garg 22-26Dr. Sanjay MiglaniDr. Seema YadavDr. Sangeeta Talwar

Mithra N. Hegde 27-35Deepali S.

Niranjan A. Vatkar 36-42Sucheta SatheVivek Hegde

P. Senthil Kumar 43-50A. R. Vivekananda PaiKundabala M.

Swetha H. B. 51-56Shashikala K.

Paluvary Sharath Kumar 57-64Vasundhara Shivanna

Abhishek Parolia 65-70Kundabala M.Shashi Rasmi AcharyaVidya SaraswathiVasudev BallalMandakini Mohan

Sowmya Shetty 71-74

Volume: 20 Issue 2 December 2008 1-76

C O N T E N T S Page


ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYINDIAN ENDODONTIC SOCIETY(Estd. 1988)

FORM IVRULE 8

1. Place of Publication : Mangalore

2. Periodicity of publication : Biannual

3. Printer’s name, nationality and address : Srinivas Prabhu at IndianM/s. Sunline EnterprisesLower Car StreetMangalore - 575 001

4. Publisher’s name, nationality, and address : Dr. Anil Kohli IndianIndian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048

5. Editor’s name, nationality and Address : Dr. B. Sureshchandra IndianDepartment of Conservative Dentistry / EndodonticsA. J. Institute of Dental SciencesN. H.-17, Kuntikana, Mangalore - 575 004, Karnataka.

6. Name and address of the owner of the newspaper : Indian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048

Mangalore Signature of publisher.

Sd/-Dr. K. S. BangaSecretary General

Date: 15/6/2005 Indian Endodontic SocietyE-601, Greater Kailas - IIDelhi - 110 048

2

President:Dr. A. P. Tikku

Secretary General:Dr. K. S. Banga

Joint Secretary:Dr. J. Dhillon

Treasurer:Dr. S. H. Kulkarni

President elect:Dr. Ravi Kapur

Imm Past President:Dr. K. K. Wadhwani

Vice President:Dr. Sukesh KumarDr. S. BalagopalDr. S. Ramchandran

Executive committeePermanent members:

Dr.R.C.Kakkar Dr.Anil Kohli

Dr. Shenoy Kundabala Dr. Sharad KamatDr. Pradeep Jain Dr. Kapil LoombaDr. J. S. Baath Dr. Mithra N. Hegde

Members:

Dr. Roopa Nadig Dr. Moksha NayakDr. Arathi Ganesh Dr. Ida De AtaideDr. Gopi Krishna Dr. Ashwini Dobhal

Editor:Dr. B. Sureshchandra

ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY

Editor:

Dr. B. Sureshchandra

Scientific Advisory Committee

Dr. Govila C. P. (India)

Dr. Gulabivala (U. K.)

Dr. Gutmann James L. (U.S.A.)

Editorial OfficeDepartment of Conservative Dentistry / EndodonticsA. J. Institute of Dental SciencesN.H.-17, Kuntikana, Mangalore - 575 004, Karnataka.Ph: 0824-2224938.Telefax: 0824-2224968.Clinic: 0824-2444041.E-mail: [email protected]

A publication of Indian Endodontic society

Editorial Board

Dr. Banga K. S.

Dr. Choudhary M.

Dr. Gopikrishna

Dr. Indira R.

Dr. Kandaswamy D.

Dr. Kohli Anil

Dr. Laxminarayanan L.

Dr. Mithra N. Hegde

Dr. Naseem Shah

Dr. Shenoy Kundabala

Dr. Shivanna V.

Dr. Tikku A. P.

Dr. Usha H. L.

Dr. Wadhvani K. K.

Abstracts

Dr. Sowmya Shetty

Endodontology is indexed in IndMED, the database of Indian Biomedical Journals, maintained by NationalInformatics Centre, Ministry of Information Technology, Govt. of India.

“Bibliographic details of the journal available in ICMR-NIC Centre’s IndMED database(http:// indmed.nic.in). Full text of articles, from 2000 onwards, being made available in MedlND database(http://medind.nic.in ).”

The journal is aIso listed with Indian National Scientific Documentation Centre (INSDOC), QutabInstitutional Area, New Delhi-110016 and English Serial Division, National Library, Kolkata.

3


Editorial

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Dr. Spangberg is a household name among endodontists who are interested in pulp biologyglobally for his thoughts on PULPBIOLOGY. He belongs to that generation of endodontists who areconcerned about their speciality in the future and not only the present.

This is exactly what he has expressed quite frankly. I have for you a few glimpses of his gem ofan editorial.

An endodontist is supposed to be an expert on diseases thereof. Presently, however, the mostcommon therapy for the exposed and/or diseased pulp is a total amputation. This crude therapy isunfortunate, because today there are restorative materials that rarely require post retention for largerestorations, i.e., the root canal could still harbor a vital pulp if treated properly.

Pulp capping, in the way it is commonly practiced, has a low rate of success. This is despite thefact that past research has clearly outlined how it should optimally be done to result in a high rate of success. This performanceproblem can often be tracked back to lack of basic training in pulp biology and insufficient treatment experience in dentalschool.

Superficial pulp surgery on permanent teeth, although an endodontic procedure, is most frequently done in a generalpractice setting. Much research still remains to be done with this therapy to achieve a high level of success and predictability.This treatment appears to be of little interest, however, to endodontic organizations on any continent. The InternationalAssociation for Dental Research Pulp Biology group has also shown little interest in the clinical application of their basic scienceresearch efforts. This leaves an important form of therapy without any active and progressive interest group behind it. This is apity, because the tooth is probably better off with a functioning pulp that is healed by hard tissues rather than a root canalimplant.

During the last couple of years, much endodontic research has focused on implants and pulpal stem cells. A substantialamount of money is spent on these projects with little visible return for the endodontic patient with a diseased or injuredendodontium.

Endodontists are today infatuated by implants, and an undeserving amount of effort has been diverted from biologicendodontic research. We have been led to believe by implant proponents that the success rate of implants greatly surpasses thesuccess of endodontic treatment. That has without doubt jolted the profession. Recent available literature does not support thatconclusion, however. We often tend to compare the retention rate of implants with endodontic treatment success. This iscomparing apples to oranges. Success for implant procedures is vaguely defined. Therefore, the term “retention” is commonlyused when outcome is discussed. Implant retention does not exclude disease conditions. Recent studies clearly show that manyretained implants experience progressive bone loss, inflammation, and infection. Retention rate for time periods beyond 5 yearsnever exceed 92%. Comparable endodontic data of retained teeth can be gleaned from insurance data showing an endodonticretention rate of 96%-97% after 8 years, which is substantially better than implant data. In my opinion, the endodontists needsto be well informed about these issues and assure him/herself that the endodontic treatment provided is optimal and offers betteroutcome than implant replacement of restorable teeth. In addition, the endodontists needs to be less concerned about implants,which have their role in prosthodontics. Instead, they should broaden their role in pulpal diagnosis and the treatment of thedentin and the dental pulp. This would lead to new enhanced treatment options for the vital pulp beyond organ amputation.The intellectual component of endodontic practice would also be significantly improved by such changes.

Stem cell research and scaffolding are now buzzwords in basic science pulp research. What is more important to remember,however, is the fact that in most cases where endodontic procedures are done after pulp exposure, a fully developed pulpalready exists. Instead of amputating the organ and then rebuilding it, a better idea would be to treat and heal the diseased pulpthat is already established.

The endodontic community needs to enhance its clinical understanding of the vital pulp and dentin and embrace itstreatment. Endodontic postgraduate students need vastly more education in this area to support their future practices and tofunction as future leaders of pulp biology in their dental communities. This field of endodontology needs drastically moresupport both in specialist knowledge and research grant support. This is an area the American Association of EndodontistsFoundation ought to focus on as high priority. It may be exciting to attempt to build connective tissue inside the root canal butit is exceedingly more valuable to the patient to preserve a real pulp, which is already there.

In my personal opinion quite a few endodontists have become over night implantologists since they probably find endodonticsless financially viable. I would love to have the feed back on this editorial. You may send your opinions on [email protected]

Dr. B. Sureshchandra

Extract EDITORIAL; Who Cares About The Dental Pulp Triple ‘O’, Vol. 104, No. 5, Nov. 2007. LARZ S.W. SPANGBERG, SECTON EDITOR, ENDODONTOLOGY


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A Comparison of the Relative Efficacies of Hand andRotary Instruments in the Removal of Guttapercha fromthe Root Canal during Retreatment using Stereomicroscope- An In-Vitro Study

DHANYA KUMAR N. M *#PRAVEEN GOKUL **#VASUNDHARA SHIVANNA ***#

* PROFESSOR, ** POST- GRADUATE STUDENT, *** PROFESSOR AND HEAD, DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS, COLLEGE OF DENTALSCIENCES (C.O.D.S.), DAVANGERE – 577004, KARNATAKA.

INTRODUCTIONNonsurgical endodontic retreatment consists

of cleaning, shaping, and three-dimensional

obturation of previously obturated root canals. It

is the treatment of choice for the management of

endodontic failures when access to the root canals

is feasible10. To successfully accomplish

retreatment, all of the obstructions - preventing a

direct straight line access to the root canals have

to be removed.

The major factors associated with endodontic

failure are the persistence of microbial infection in

the root canal system and/or the periradicular area.

The clinician is often misled by the notion that

procedural errors such as broken instruments,

ABSTRACT:The purpose of this study was to determine the efficiency of Greater Taper, ProTaper & RaCe rotary instrumentscompared with Hedstrom files for removal of guttapercha from root canal during retreatment following anendodontic failure.

60 mandibular premolars were divided into 4 groups, each group consisting of 15 teeth. Group 1: Hedstromfiles; Group 2: Greater Taper rotary (GT); Group 3: ProTaper; Group 4: with Reamer with alternate cutting edges(Race). The teeth were instrumented with K- type files and filled using lateral condensation technique withguttapercha and AH plus sealer. After repreparation with Gates Glidden drills and the test instruments the teethwere cleared. The area of remaining guttapercha/sealer on the root canal wall was measured from mesio-distaland bucco-lingual directions.

The RaCe group showed significantly less obturation material than System GT, ProTaper and H-files (p<0.001).There was no significant difference between System GT and ProTaper in removing guttapercha/sealer. RaCe tookthe least time for removing guttapercha/sealer (p<0.05). One ProTaper files and one H-file separated.

The study demonstrated that, RaCe NiTi rotary instruments cleaned the root canals after retreatment more efficientlythan ProTaper, System GT and H-files.

Keywords: Gutta-percha removal, Root canal retreatment, Nickel Titanium files, Rotary instrumentation.


6

perforations, overfillings, underfillings, ledges and

so on are the direct cause of endodontic failure. In

truth, a procedural accident often impedes or makes

it impossible to accomplish appropriate intracanal

procedures5.

Removal of guttapercha can be obtained with

several techniques such as solvents, K-type or

Hedstrom files, Gates Glidden drills, heat pluggers3,

ultrasonic technique6, and lasers2. Additionally,

rotary instruments can also be used, such as the

inflexible XGP drills, the canal finder3, or more

recently flexible rotary nickel-titanium (NiTi) files

in a slow-speed handpiece.

More recently Ni-Ti retreatment rotary files

have been introduced which have proved to be

efficient and require less time when compared to

hand instrumentation1 although complete removal

of guttapercha has not been attained with these

instruments7. Currently, nickel titanium rotary

instruments like Reamer with alternate Cutting

edges (RaCe), ProTaper and Greater Taper (GT)

rotary have an important role in the removal of

guttapercha for their ability to simulate curved

canals & effectively produce well tapered root canal

form requiring less time.

Purpose of this study is to evaluate the

efficacy of H-file versus RaCe, ProTaper and Greater

Taper (GT) NiTi rotary instruments in the removal

of guttapercha from root canals, the time taken for

removal and procedural errors i.e. separated

instruments that occur during retreatment.

METHODOLOGYSelection of teeth: Sixty freshly extracted

human mandibular premolars were collected from

Dept. of Oral and Maxillofacial Surgery, College

of Dental Sciences, Davangere. Soft tissue and

calculus were mechanically removed from root

surfaces.

Access opening was made on each tooth with

high speed round diamond bur no.2 with air- water

spray. Working length was established l mm short

of root apex and the crowns were sectioned so that

working length was standardized to 18 mm. The

canals were prepared using step-down technique.

The cervical and middle-thirds were flared with

Gates Glidden drills 1, 2 and 3 in a telescopic

preparation. Canal instrumentation was completed

using K-type files with a master apical file size of

30. The canals were debrided using sodium

hypochlorite 5.25% and chlorhexidine 2%

irrigants.

The root canal of each tooth was dried with

paper points and obturated using lateral

compaction. A master gutta-percha cone size 30

was selected and tug-back was checked. AH Plus

sealer (Dentsply DeTrey) was mixed according to

the manufacturer’s instructions. The master cone

was coated with sealer and positioned into the

canal. Then accessory cones were laterally

compacted until they could not be introduced more

than 5 mm into the canal. The extension of the

root canal filling was limited to 14 mm from the

apex so that the volume of gutta-percha was nearly

equal for all teeth. The access cavities were filled

with the Cavit G (3M ESPE). All teeth were stored

in a humidor at 37°C for 2 weeks to allow complete

setting of the sealer.

Retreatment TechniqueAll samples were randomly divided into four

groups with 15 specimens each. All roots had 6

mm of obturation material removed from the

cervical part of the canal using Gates Glidden drills

A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDY


7

2 and 3. After using the Gates Glidden drills, a

drop of eucalyptol solvent was intro-duced into

each canal to soften the gutta-percha. Two or three

addi-tional drops of solvent were applied as

required to reach the working length. Sodium

hypochlorite 5% and chlorhexidine 2% irrigations

were used after each instrument. Each root canal

was irrigated with a total of 30 ml sodium

hypochlorite and 30 ml chlorhexidine. System GT,

Pro-Taper and RaCe rotary instruments were driven

with a torque-con-trolled motor (X-Smart, Dentsply,

Maillefer) according to the manufacturer’s

instructions. The teeth were then rendered

transparent by first decalcifying them in 5% Nitric

acid then dehydrating them in 80% alcohol for

12hrs, 90% alcohol for 1hr and 100% alcohol for

3hrs. The teeth were then cleared using

Methylsalicylate.

Teeth were divided into 4 groups, each group

consisting of 15 teeth.

Group 1: (n=15) with Hedstrom files (Mani):ISO size 15 and 20 Hedstrom files were used for

deep penetration until they reached the working

length. The removal of gutta-percha was completed

using size 25 to 35 Hedstrom files in a

circumferential quarter-turn push-pull filing motion.

Group 2: (n=15) with Greater Taper (GT)NiTi rotary instruments (Dentsply Maillefer): GT

rotary instrument sizes 10.30, 08.30, 06.30, 04.30

were used in a crown-down technique according

to manufacturer’s instructions to remove the

guttapercha from the root canals.

Group 3: (n=15) ProTaper NiTi rotaryinstruments (Dentsply Maillefer): As suggested by

the manu-facturer, the gutta-percha was removed

by the following se-quence using light apical

pressure: Finishing files #3 (ISO size 30, taper

O.O9-O.O5), #2 (ISO size 25, taper 0.08-0.055),

and #l (ISO size 20, taper O.O7-O.O55) were used

in a crown-down technique to remove the gutta-

percha until the working length was reached.

Finishing files #2 and #3 were used again to the

working length to complete gutta-percha removal

and cleaning of the canal walls.

Group 4: (n=15) RaCe NiTi rotaryinstruments (FKG Dentaire) RaCe rotary

instruments sizes 10.40, 08.35, and 06.30 were

used in a crown-down approach. Instrument size

04.25 reached working length. RaCe files 02.30

and 02.35 were used for apical enlargement.

One set of instruments was used for

repreparation of five root canals. Files were wiped

regularly using gauze to remove obturation material

and debris. Preparation was deemed complete

when there was no gutta-percha/sealer covering

the instruments. Each root canal was prepared,

filled and retreated by the same operator to reduce

interoperator variability.

EvaluationFor all roots, three types of data were

recorded.

1. Canal Wall CleanlinessThe amount of gutta-percha/ sealer on the

canal walls was imaged in a standardized way in

bucco-lingual and mesiodistal directions and

measured in mm2 using image analyzer software

connected to a stereomicroscope with 6.5 X

magnification via a CCD-sensor. The evaluator was

blinded to group assignment.

DHANYA KUMAR N. M, PRAVEEN GOKUL, VASUNDHARA SHIVANNA


8

2. Time for RetreatmentThe time elapsed from entering the canal with

the first Gates Glidden bur until the completion of

the reinstrumentation was measured with a

stopwatch.

3. Procedural ErrorsThe number and sort of fractured instruments

were recorded

Statistical analysis:Statistical analysis was performed for multiple

group comparisons by means of Kruskal-Wallis

ANOVA test followed by post hoc tests for pair

wise comparisons

RESULTSFrom the present invitro study the following

results were obtained:

1. Remaining obturation material was

observed in all groups. Imaged in a bucco-lingual

and mesio-distal directions, specimens treated with

RaCe showed least amount of remaining

guttapercha/sealer. The Hedstrom group, System

GT group and ProTaper group revealed significantly

larger areas of obturation material than RaCe group

(p<0.05). System GT group did not differ

significantly from ProTaper group (p>0.05) in the

removal of guttapercha/sealer from the root canals.(

Table 1, Graphs 1-4)

2. Regarding the mean time for retreatment

RaCe group took least time while System GT,

ProTaper and H-files required significantly more

time when compared to RaCe group. (Table 1,

Graph 5).

3. One ProTaper file (size F1) and one H-file

(ISO 25) separated during retreatment.

DISCUSSIONThe main goal of retreatment is to regain

access to the constriction by complete removal of

the root canal filling material, thereby facilitating

sufficient cleaning and shaping of the root canal

system and final obturation5, 8. Prognostic studies

have indicated that endodontic surgery or

extraction could be avoided by conventional

retreatment12.

Eucalyptol was used as a solvent in our study

as it has been reported to be a safe and efficient

alternative to chloroform11.

Different methodologies have been reported

during evaluation of remaining filling material

including longitudinal cleavage of teeth which may

displace filling material remnants; association of

longitudinal and transverse cleavage for evaluation

in thirds; and cleavage and photographic

recordings; visual examination through cleavage

and photography in association with radiographic

examination. The pro-blems with sectioning teeth

are that it can disturb the remaining filling material

and it is unpredictable. In the present study, the

roots were cleared to allow the measurement of

the area of residual obturation material because

remaining Gutta Percha or sealer might get lost by

splitting the roots longitudinally4.

In our study, direct visual scoring with the aid

of a stereomicroscope was adopted for the

evaluation of residual gutta-percha and sealer on

the canal walls, as it was considered a simple and

efficient assessment method9.

The results of our study suggest that RaCe NiTi

rotary instruments performed better when

compared to the other instruments. There was no

A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDY


9

significant difference between System GT and

ProTaper in removal of guttapercha when viewed

in a mesio-distal direction. H-files performed poorly

when compared to rotary instruments. Instrument

separation occurred with H-files and ProTaper NiTi

rotary files.

The first two RaCe instruments (size 10.40 and

08.35) are made of stainless steel. Stainless steel

files have a better cutting efficiency than nickel-

titanium file. Probably this fact and the greater

taper of these two files compared to the ProTaper,

System GT and Hedstrom group might be a reason

for the quick and effective gutta-percha removal.

Other advantages of the RaCe instruments could

be the alternating cutting edges which eliminate

the unde-sirable screwing effect and the smooth

surface of the instruments that is caused by the

special chemical surface treatment. It is also

possible that the gutta-percha adhered less to the

flutes so that the file had a better cutting efficiency.

GT instruments with their taper-centric shaping

ability, Radial lands and U-type cross section

cleaned canal walls better and took less time than

H-files but was inferior than RaCe files and there

was not much difference when compared to

ProTaper.

With ProTaper group final apical preparation

diameter was of size 30 (F3) compared to final

apical diameter in the RaCe group which was of

size 35 therefore its cleaning ability was less when

compared to RaCe and there was not much

difference when compared to System GT although

the cleaning ability was better than hand files. Also

ProTaper shaping files proved to be impossible to

penetrate guttapercha without fractures of the files.

CONCLUSIONWithin the limitations of this in-vitro study the

following conclusions can be drawn from the

results of this study:

RaCe rotary system has alternating cutting

edges which efficiently removed debris from the

root canals and showed least remaining obturating

material. During retreatment the risk of instrument

fractures of ProTaper and H-files instruments seems

to be higher than that of RaCe and System GT, the

reason attributed could be that since RaCe files

utilize reduced working torque there was no

fracture of any instrument, and due to its inherent

instrument design wherein cutting efficiency is

increased RaCe took less time than ProTaper,

System GT and H-files.

Mean areas of remaining obturation material imaged in mesio-distal and bucco-lingual direction withstandard deviations (SD,mm2),mean time for retreatment (min) and number of fractured instruments

Method Mesio-distal Bucco-lingual Mean time Fractures

Mean SD Mean SD Mean SD

Hedstrom 5.49 0.37 4.44 0.63 12.29 1.16 1

System GT 3.81 0.58 2.37 0.32 9.31 0.15

ProTaper 3.79 0.24 2.93 0.38 8.23 0.11 1

RaCe 1.48 0.27 0.93 0.27 7.16 0.11



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GRAPHS PHOTOS

FIG 4: STEREOMICROSCOPE READINGS WITH RaCe

BUCCO-LINGUALMESIO-DISTAL

FIG 3: STEREOMICROSCOPE READINGS WITH ProTaperBUCCO-LINGUALMESIO-DISTAL

Fig 2: STEREOMICROSCOPE READINGS WITH SYSTEM GT

BUCCO-LINGUALMESIO-DISTAL

BUCCO-LINGUALMESIO-DISTALFig 1: STEREOMICROSCOPE READINGS WITH H-FILES

A COMPARISON OF THE RELATIVE EFFICACIES OF HAND AND ROTARY INSTRUMENTS IN THE REMOVAL OFGUTTAPERCHA FROM THE ROOT CANAL DURING RETREATMENT USING STEREOMICROSCOPE - AN IN-VITRO STUDYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY


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BIBLIOGRAPHY1. Barrieshi-Nusair KM. Gutta-percha retreatment: effectivenessof nickel-titanium instru-ments versus stainless steel hand files.J Endod 2002; 28:454-6.

2. D.Viducic, S. Jukic, Z. Karlovic, Z. Bozic, I.Miletic & I. Anic.Removal of guttapercha from root canals using an Nd-YAGlaser. Int Endod J 2003;36:670-3

3. Friedman S, Stabholz A, Tamse A. Endodontic retreatment:case se-lection and technique. Part 3: retreatment techniques.J Endod 1990; 16: 543-9.

4. Gergi R, Sabbagh C. Effectiveness of two nickel-titaniumrotary instruments and a hand file for removing gutta-perchain severely curved root canals during retreatment: an ex vivostudy. Int Endod J 2007;40:532-7

5. J.F. Siqueria Jr. Aetiology of root canal treatment failure:why well-treated teeth can fail. Int Endod J 2001; 34:1-10.

6. Krell KV, Neo J. The use of ultrasonic endodonticinstrumentation in the re-treatment of a paste-filled endodontictooth. Oral Surg Oral Med Oral Pathol 1985:60:100-2.

7. Kosti E, Lambrianidis T, Economides N, Neofitou C. Ex vivostudy of the efficacy of H-files and rotary Ni-Ti instruments toremove gutta-percha and four types of sealer. Int Endod J2006;39:48-54

8. Mandel E, Friedman S. Endodontic Retreatment: A RationalApproach to Root Canal Reinstrumentation. J Endod1992;11:565-9

9. Schirrmeister JF, Wrbas KT, Meyer KM, Altenburger MJ,Heiiwig E, Efficacy of differ-ent rotary instruments for gutta-percha removal in root canal retreatment. J Endod2006;32:469-72.

10. Stabholz A, Friedman S. Endodontic retreatment: caseselection and technique. Part 2: treatment planning forretreatment. J Endod 1988; 14:607-14.

11. Tamse A, Unger U, Metzger Z, Rosenberg M. Gutta-perchasolvents: a comparative study. J Endod 1986;12:337-9Tasdemir T, Er K, Yildirim T, Celik D. Efficacy of three rotaryNiTi instruments in removing gutta-percha from root canals.Int Endod J 2007;41:191-6



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“To Analyze the Distribution of Root Canal Stresses afterSimulated Canal Preparation of Different Canal Taper inMandibular First Premolar by Finite Element Study – An InVitro Study.”

DHANYA KUMAR N. M. *ABHISHEK SINGHANIA **VASUNDHARA SHIVANNA ***

* PROFESSOR, ** POST GRADUATE, *** PROFESSOR & HEAD, DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS, COLLEGE OF DENTAL SCIENCES(C.O.D.S.), DAVANGERE – 577004, KARNATAKA.

ABSTRACTWas to Investigate stress distribution patterns in simulated biomechanically prepared mandibular first premolarswith four different tapers at two different compaction forces and an occlusal load with finite element analysis.

Six recently extracted, intact, non-carious, undestroyed mandibular premolars similar in-straight root canals wereselected. Four finite element models were designed on the software varying only in canal taper of mandibularfirst premolars. Gutta-percha was compacted by vertical condensation technique in three separate verticalincrements under two different vertical compaction forces that are 10N and 15N. Finite element meshes weregenerated with this model by using soft ware to know the pattern of distribution of radicular stresses duringobturation. At last access opening will be filled by using simulated restorative material (composite). A masticatoryload of 50N was applied; again Finite element meshes were generated.

The highest circumferential and radial stresses were found during compaction of first gutta percha increment,while an increase in taper reduced the stress level for the same compaction force. During obturation, higherstresses were found at the canal surface, using the smallest taper, in apical third, during the first gutta perchaincrement and gradually decreased along the canal length. Root stresses during occlusal load application generatesthe highest stresses at external root surface and concentrate at cervical third, an increase taper size caused onlyslight lower root stresses.

With increasing taper root stresses decreased during root canal obturation. Root fracture at the apical third islikely initiated during obturation. Root fracture at the cervical third is likely initiated during occlusal load.

KEYWORDS: canal taper, compaction force, finite element analysis, occlusal load, root stresses, verticalcompaction, vertical root fracture.

INTRODUCTIONAfter endodontic therapy, teeth are more prone

to vertical root fracture because of loss of moisture

(9%) and become more brittle when compared to

vital tooth. Vertical root fracture can occur in teeth

during or subsequent to endodontic therapy. The

causative factors for vertical root fractures are the

compaction of gutta percha, placement of intra-

radicular posts, masticatory load, trauma, and

traumatic injuries. Vertical root fractures are more


common during the vertical condensation

technique of obturation and often complicate or

prevent subsequent restorative procedures. These

fractures a count for the most serious complication

of root canal treatment and often result in tooth

extraction because of poor prognosis6.

It is generally accepted that the strength of an

endodontically treated tooth is directly related to

the amount of remaining tooth structure. Several

treatment procedures such as caries removal, access

preparation, instrumentation of root canal, irrigation

of root canal with sodium hypochlorite, and long

term intracanal dressing with calcium hydroxide

lead to loss of tooth structure or weaken the root

dentine. The prevalence of Vertical root fracture is

not equally distributed over the different tooth types.

Maxillary and mandibular premolars have both

recorded a high prevalence6.

Stresses distribution in endodontically treated

teeth can be measured by photoelastic method,

strain gauge and instron testing machine. But the

major disadvantage of all these methods in stresses

can measured at selected sites only and not inside

the root canal7.

Finite element analysis is an engineering

method for the numerical analysis of complex

structures based on their material properties

(Young’s modulus and Poisson ratio) to determine

the distribution of stresses and strain pattern induced

in internal structure of tooth / bone / implants / any

living tissue5.

The purpose of the present study is to

investigate stress distribution patterns in simulated

biomechanically prepared mandibular first

premolars with four different tapers at two different

compaction forces and an occlusal load with finite

element analysis.

METHODOLOGYTwenty four samples have been derived from

six recently extracted, intact, non-carious,

undestroyed mandibular first premolars. Six x-ray

films were used to know the canal curvature of six

mandibular first premolars. Optical scanner was

used to digitalize the external surface morphology

of six extracted mandibular first premolars on

computer software that has been designed for Finite

Element analysis.

GROUPINGFour finite element models were designed on

the software varying only in canal taper of each

mandibular first premolar. Each model carried six

specimens. These models were assigned as: Group

1 with taper 2%, Group 2 with taper 4%, Group 3

with taper 6% and Group 4 with taper 12%.

All other aspects of the models were held

constant including boundary conditions, material

properties, compaction forces during filling and

magnitude / direction of applied occlusal load. The

tooth model was created by digitizing the external

surface of extracted human mandibular first

premolar with an optical scanner in combination

with Finite element analysis computer software

(NISA). A straight root was chosen for this study to

eliminate effects due to canal curvature. Gutta-

percha were compacted by vertical condensation

technique in three separate vertical increments

(apical 1/3, middle 1/3, cervical 1/3) under two

different vertical compaction forces that are 10

Newton and 15 Newton for each increment. 200µm

thick periodontal ligament layer and a surrounding

bone volume to support the root were created on

DHANYA KUMAR N. M., ABHISHEK SINGHANIA, VASUNDHARA SHIVANNA

13


14

finite element model.

Subsequently, a simulated standard access

opening was made in the crown, and root canals

were created that represented 2%, 4%, 6% and

12%. The 4% and 6% tapers were chosen for

clinical relevancy, as these are incorporated into

commonly used nickel–titanium rotary files and are

representative of clinically imparted tapers on the

canal space. The drastic 12% tapered canal

preparation was chosen arbitrarily to simulate the

effects of excessive canal preparation. All models

were created with a final apical preparation of 0.35

mm at the point of constriction, 0.5 mm from what

would be clinically perceived as the radiographic

apex. All canal preparations were straight. Isotropic

properties were applied for the dentine, periodontal

ligament, supporting bone volume, gutta-percha

and restorative composite. The periodontal ligament

was modeled as a soft incompressible connective

layer.

An arbitrary range of friction coefficients (0.10–

0.25) were evaluated to account for the friction

between the gutta-percha and the root canal wall.

The development of radicular stresses was analyzed

during three consecutive filling steps as well as for

an occlusal load after the root filling using finite

element analysis. Warm gutta-percha was

compacted in three separate vertical increments

until the canal was filled. The gutta-percha

temperature at the start of compaction was 60oCo

and was gradually cooled down during the filling

procedure until it reached 37oCo. In this analysis,

two vertical compaction forces were tested at 10

and 15 N for each increment. The forces were

applied by means of a simulated plugger. The

plugger surface had slightly rounded edges and a

tip-diameter that was 0.5 mm smaller than the canal

diameter at each compaction increment.

After complete simulated obturation, the

simulated access space was closed using a simulated

bonded restorative composite. The composite was

filled; a 50 N occlusal load was applied in the

buccolingual plane to the triangular ridge of the

buccal cusp (functional cusp) at an angle of 600 with

the vertical axis. The value of the occlusal force

was chosen to represent a relatively high biting force

and buccal cusp was selected because it is the

functional cusp and lingual cusp is rudimentary in

mandibular first premolar. During the analysis, the

root was supported by the surrounding bone volume

via the soft periodontal ligament layer, which was

given incompressible properties to approximate

fluid behavior.

The mean value, standard deviation and one

way ANOVA was used to evaluate the site of

maximum stress concentration. Statistical analysis

(ANOVA) was used for multiple comparison and

correlation analysis to assess the relationship

between different taper and radicular stresses.

RESULTSFour finite element models were designed on

the software varying only in canal taper as- Group

1 with taper 2%, Group 2 with taper 4%, Group 3

with taper 6% and Group 4 with taper 12%.

In group 1 with taper 2%, the highest mean

value and standard deviation was at apical third

followed by middle and cervical third under

compaction force of 10 newton (Table-1).

From group 1 to group 4, the highest mean

value and standard deviation was at apical third of

“TO ANALYZE THE DISTRIBUTION OF ROOT CANAL STRESSES AFTER SIMULATED CANAL PREPARATION OFDIFFERENT CANAL TAPER IN MANDIBULAR FIRST PREMOLAR BY FINITE ELEMENT STUDY – AN IN VITRO STUDY.”


15

2% taper (group-1) followed by middle and cervical

third of 2% taper under compaction force of 10

Newton (Table-1). Similar results were obtained in

different groups under compaction force of 15

Newton (Table-2).

During occlusion load application (50N) in

different group, highest mean was recorded in group

1 with 2 % taper and least in group 4 with 12%

taper. Highly significant pairs were group 1 & 2,

group 1 & 3 and group 1 & 4 (Table 3).

On comparing the different tapers with each

increment under compaction force of 10N shows

the significant pairs apical third and coronal third

for taper 2% ( P<0.05), apical third and middle

third, apical third and coronal third for taper 6%

and 12% taper (P<0.001) (Table 4).

Also on comparing the different tapers with

each increment under compaction force of 15N

shows the significant pairs apical third and middle

third, apical third and coronal third for taper 4%,

6% and 12% taper (P<0.001) (Table 5)

Results: Highest circumferential and radial

stresses were found during compaction of first gutta

percha increment, while an increase in taper

reduced the stress level for the same compaction

force. During obturation, higher stresses were found

at the canal surface and in apical third with smallest

taper and during the first gutta percha increment

and gradually decreased along the canal length.

Root stresses distribution during occlusal load

application generated the highest stresses at external

root surface that concentrated at the tooth surface

of the cervical third, an increase taper size caused

only slight lower root stresses.

DISCUSSIONThe prognosis of endodontically treated teeth

depends not only on the success of the endodontic

treatment but also on the amount of remaining

dentine tissue, and the nature of final restoration.

Fractures of restored endodontically treated teeth

are a common occurrence in clinical practice and

it is the second most frequent identifiable reason

for loss of endodontically treated teeth4.

The increased susceptibility of fracture in

endodontically treated teeth had been attributed due

to the increased brittleness of dentine, due to loss

of moisture - Helfer et al reported that the moisture

content of dentine from endodontically treated teeth

was about 9% less than teeth with vital pulp.

However, Papa et al emphasized the importance

of conserving the bulk of dentine to maintain the

structural integrity of post-endodontically restored

teeth. Other studies have also emphasized that the

loss of tooth structure is the key reason for the

increase in fracture predilection of endodontically

treated teeth1.

The fracture resistance of the restored

endodontically treated tooth is a function of the

strength of the root (taper of prepared canal) and

remaining coronal tooth structure.34 Tooth fracture

has been described as a major problem in dentistry,

and is the third most common cause of tooth loss

after dental caries and periodontal disease.

Generally, an endodontically treated tooth

undergoes coronal and radicular tissue loss due to

prior pathology, endodontic treatment, and/or

restorative procedures. The loss of dentine tissue

will compromise the mechanical integrity of the

remaining tooth structure1.

Mandibular premolars and maxillary premolars



16

have both recorded a high prevalence of vertical

root fracture in endodontically treated teeth21.

Vertical root fracture seems to be a more common

reason for extraction of endodontically treated

teeth.2

Root canal biomechanical preparation can be

done by a hand file or rotary file. Canal preparation

involves dentin removal and may compromise the

fracture strength of the roots25. The development

of new design features such as varying tapers,

noncutting safety tips and varying length of cutting

blades in combination with the metallurgic

properties of alloy nickel-titanium have resulted

in a new generation of instruments and concepts33.

Although no significant difference in the fracture

load of hand and rotary nickel titanium canal

preparation could be demonstrated3.

Given increasing acceptance of rotary

instrumentation as a technique for cleaning and

shaping the canal space, it is important to examine

the effect of specific tapers imparted by rotary

instrumentation of the canal wall as it relates to

vertical root fracture. The clinician must make a

decision to use instruments which have an

inherently larger or smaller taper based on the

architecture present in a given canal. Choosing a

smaller taper may reduce the risk of procedural

accidents and untoward events during cleaning and

shaping, but it may compromise the cleanliness of

the canal system and placement of filling material.

Choosing too large a taper may increase canal

cleanliness (especially in the coronal and mid-root

areas), but may also increase the potential for strip

perforations, other procedural accidents, and may

predispose the root to vertical fracture if, indeed,

greater reduction of root structure increases stress

in the canal wall.7

Assessment of stress levels patterns in root

canal can be measured by a number of ways that

includes Instron universal machine, photoelastic

method, strain gauges and most recent one is finite

element analysis10. Assessment of stress levels by

measuring deformation patterns inside the root

canal is extremely difficult, leaving investigators

with indirect external observations at best

extremely difficult. Finite element analyses have

been utilized to address these difficulties and gain

insight into internal stress distributions 7,2.

Finite element analysis which is an

engineering method for the numerical analysis of

structure based on their material properties has

been used for stress analysis. Material properties

such as the Young’s modulus and Poisson Ratio

can be utilized by computer generated analyses to

describe the mechanical behavior of a structure5.

CONCLUSIONWith in the limitation of this finite element

analysis, the following conclusions were drawn.

During simulated obturation, root stresses

decreased as the root canal taper increases and

stresses were greatest at the apical third and along

the canal wall. After simulated root canal obturation

was completed and occlusal force was applied, the

generated stresses were greatest at the cervical

portion of the root surface, and decreased as taper

increases. It was likely that vertical root fractures

initiated at the apical third as result of compaction

forces, whereas vertical root fractures initiated

cervically were a manifestation of subsequent

masticatory load on the root canal obturated teeth.

However additional in-vivo and in-vitro tests

and clinical trial are desirable in order to elucidate

the accuracy of finite element analysis.



17

10 NEWTON OF COMPACTION FORCE

Apical 1/3 Middle 1/3 Cervical 1/3

Tapers Mean SD Mean SD Mean SD

2% 0.789 0.087 0.716 0.067 0.669 0.025

4% 0.713 0.041 0.657 0.022 0.587 0.032

6% 0.667 0.025 0.603 0.029 0.608 0.134

12% 0.646 0.015 0.566 0.030 0.484 0.025

Table-1: Compaction Force of 10N on Apical, Middle and Cervical Third in Different Tapers.

15 NEWTON OF COMPACTION FORCE

Apical 1/3 Middle 1/3 Cervical 1/3

Tapers Mean SD Mean SD Mean SD

2% 1.267 0.373 1.135 0.256 0.988 0.012

4% 1.051 0.038 0.972 0.019 0.869 0.051

6% 0.976 0.018 0.893 0.032 0.767 0.059

12% 0.946 0.017 0.847 0.033 0.540 0.110

Table-2: Compaction Force of 15N on Apical, Middle and Cervical Third in Different Tapers.

Tapers Mean

2% 4.782

4% 3.291

6% 3.007

12% 2.510

P* Value, Sig P<0.001 HS

Significant Pairs** I&II, I&III,I&IV

Table-3: Comparision of Mean Occlusion Load of 50N in Different Tapers.

Tapers Apical 1/3 Middle 1/3 Cervical 1/3 P* Value, Sig Significant Pairs**

2% 0.789 0.716 0.669 P<0.05 S At & Ct

4% 0.713 0.657 0.608 P>0.05 NS -

6% 0.667 0.603 0.587 P<0.001 HS At &Mt, At & Ct

12% 0.646 0.566 0.484 P<0.001 HS At &Mt, At & Ct

Table-4: Comparison Of Different Tapers With Each Increment To Evaluate Significant Pair Under CompactionForce Of 10N.



18

Tapers Apical 1/3 Middle 1/3 Cervical 1/3 P* Value, Sig Significant Pairs**

2% 1.267 1.135 0.988 P>0.05 NS -

4% 1.051 0.972 0.869 P<0.001 HS At &Mt, At & Ct

6% 0.976 0.893 0.767 P<0.001 HS At &Mt, At & Ct

12% 0.946 0.847 0.540 P<0.001 HS At &Mt, At & Ct

Table-5: Comparison Of Different Tapers With Each Increment To Evaluate Significant Pair Under CompactionForce Of 15N.

Fig 1 apical third g.p filling on model with taper 2% under compaction forces (10n) fig. 2 (15n). Fig 3.middle third g.p filling on model with taper 2% under compactionforces (10n).fig 4 (15n). Fig 5cervical third g.p filling on model with taper 2% under compaction forces (10n). Fig 6 (15n). Fig 7 occlusal load of 50n applied on model(2%), after filling the access cavity with composite (stress graph ).fig 8 occlusal load of 50n applied on model (2%), after filling the access cavity with composite(displacement graph). Fig 9 apical third g.p filling on model with taper 4% under compaction forces (15n). Fig 10 (10n). Fig 11middle third g.p filling on model with taper4% under compaction forces ( 15n). Fig 12 (10n).


5 6 7 8

9 10 11 12

1 2 3 4


19

Fig 13 cervical third g.p filling on model with taper 4% compaction forces (15n) fig 14 (10n) fig 15 occlusal load of 50n applied on model (4%), after filling the accesscavity with composite(stress graph ) fig 16 (displacement graph) fig 17 apical third g.p filling on model with taper 6% compaction forces ( 15n) fig 18 (10n) fig 19 middlethird g.p filling on model with taper 6% under compaction forces ( 15n). Fig 20 (10n). Fig 21 cervical third g.p filling on model with taper 6% compaction forces (15n) fig22 10 n fig 23 cervical third g.p filling on model with taper 6% compaction forces (10n) occlusal load of 50n applied on model (6%), after fiiling the access cavity withcomposite (stress graph ) fig 24occlusal load of 50n applied on model (6%), after fiiling the access cavity with composite (displacement graph)


13 14 15 16

17 18 19 20

21 22 23 24

25 26 27 28


20

MATERIAL PROPERTIES APPLIED IN THE STRESS ANALYSIS (FEA)Material Elastic Reference Poisson’s Reference

Modulus (GPa) Ratio Reference

Enamel 84 Craig & Powers 0.33 Farah et al. (1989)(principal direction) (2002)

Enamel 42 Craig & Powers 0.31 Farah et al. (1989)(transverse plane) (2002)

Dentine 14.7 Sano et al. (1994) 0.50 Farah et al. (1989)

Periodontal ligament 0.00118 Dyment and Synge 0.30(1935)

Bone 0.49 Moroi et al. (1993) 0.30 Farah et al. (1989)

Gutta-percha Temperature 0.30 (0 C0) 0.35Dependent (30 C0) 0.40 (60 C0)

Restorative composite 14 Willems et al. (1992) 0.24 Craig & Powers0.24 Craig & Powers (2002)(2002)

GRAPHS


Fig 25 apical third g.p filling on model with taper 12% under compaction forces (10n). Fig 26 (15n). Fig 27 middle third g.p filling on model with taper 12% undercompaction forces (10n) fig 28 (15n). Fig 29 cervical third g.p filling on model with taper 12% under compaction forces (10n). Fig 30 (15n). Fig 31 occlusal load of50n applied on model (12 %), after fiiling the access cavity with composite (stress graph ) fig 32 occlusal load of 50n applied on model (12 %), after fiiling the accesscavity with composit e (displacement graph)

29 30 31 32


21

BIBLIOGRAPHY1) Aviad Tamse. Vertical root fractures in endodonticallytreated teeth: diagnostic signs and clinical management.Endodontic Topics 2006;13:84–94.

2) B. D. Rundquist & A. Versluis. How does canal taper affectroot stresses? International Endodontic Journal. 2006;39:226-237.

3) Chankhrit Sathorn, Joseph E.A. Palamara, and Harold H.Messer. Effect of root canal size and external root surfacemorphology on fracture susceptibility and pattern: A FiniteElement Analysis. J Endod 2005;31:288-291.

4) Chankhrit Sathorn, Joseph E.A. Palamara, and Harold H.Messer. A comparison of the effect of two canal preparationtechnique on root fracture susceptibility and pattern, J Endod2005;31:283-287.

5) Linda J.-William, Peter G. Fotos, Vijay K. Goel, James D.Spivey, Eric M. Rivera and Satish C. Khera. A-three–dimensional finite–element stress analysis of an endodonticprepared maxillary central incisor. J Endod 1995; 21:362-367.

6) Tannaz Zandbiglari et al. Influence of instrument taper onthe resistance to fracture of endodontically treated roots. Oralsurg oral med oral path oral radio endo 2006;101:126-31.

7) Yeera Lertchirakarm et al. Finite element analysis and straingauge studies of vertical root fracture.J Endod 2003;29:529-534.



22

A Comparative Evaluation of Cyclic Fatigue Resistance ofTwo Rotary Nickel - Titanium Endodontic Systems - An InVitro Study

DR. GAURAV GARG *DR. SANJAY MIGLANI **DR. SEEMA YADAV ***DR. SANGEETA TALWAR ****

ABSTRACT:The purpose of this study was to compare the fracture resistance of two different rotary Ni Ti instrument systemsdue to cyclic fatigue. The instruments compared were RaCe (FKG, La- Chaux De Fonds, Switzerland) and a newrotary system - Varitaper (Endomax, Equinox, Holland). The cyclic fatigue testing was conducted with the instrumentrotating freely at two different angles of curvature 45Ú & 90Ú with maximum curvature at 5mm from the tip.Total 60 instruments were tested in the two groups for both angles of curvature. The instruments were rotated at350 rpm using the ATR motor (Dentsply, Maillefer) set at maximum torque, until fracture occurred. The timeuntil fracture was recorded in seconds by using a stopwatch, and the number of rotations to fracture was thencalculated and results were statistically analyzed. RaCe (FKG, La- Chaux De Fonds, Switzerland) performedsignificantly better than Varitaper (Endomax, Equinox, Holland) in cyclic fatigue testing.

* PG Student, ** Asst. Professor, *** Assoc.Professor, **** Professor & Head of Department, Department of Conservative dentistry & Endodontics, Maulana Azad Instituteof Dental Sciences ,MAMC Campus, New Delhi - 110002. Correspondence: Dr. Gaurav Garg (e-mail- [email protected])

INTRODUCTIONRoot canal preparation in narrow and curved

canals is a great challenge. Rotary Ni- Ti files can

be used to prepare curved canals as they are 2-3

times more elastic and flexible in bending & torsion

and have Superior resistance to torsional fracture

compared with similar size stainless steel files1.

Despite the advantages of rotary Ni- Ti instruments,

concern has been expressed by many authors and

clinicians about the potential for rotary Ni- Ti

instrument to fracture within the root canal system

during endodontic treatment2-4. Although

instrument fracture may not affect the prognosis

when endodontic treatment can be performed to a

high technical standard, it may present a problem

if microbial control is compromised3 or should

excessive removal of tooth structure be required

to eliminate the fragment4.

Endodontic instrument fracture within canal

is a complex event. Fracture occurs without

warning and without any visible defects of previous

permanent deformation. So Visible inspection is

not reliable for Ni-Ti instruments.Two modes of

fracture of rotary Ni-Ti endodontic instruments have

been identified in the clinical situation: Torsional

fracture and Flexural fracture5. Among these

flexural fatigue is an important factor in a clinical

point of view. An understanding of factors that

contribute to instrument fracture is important in


23

preventing its occurrence. These include the

following: Root canal anatomy both in terms of

radius & Degree of curvature (most Important),

operator proficiency, operational speed and torque,

previous use, sterilization procedures and cross

sectional area and design of the instrument6. Many

different rotary systems are available with difference

in cross sectional shape and design, Taper and total

number of instruments within system. But it is quite

difficult to determine the best one.

RaCe(FKG, La- Chaux De Fonds, Switzerland)

is one of the system that has been used for severely

curved canals with success due to its extreme

flexibility and Good shaping ability with little

transportation7,8.

Varitaper (Endomax, Equinox, Holland)

comprises of six safe ended instruments including

three apical finishers with a gradual increasing taper

of 3-6% and variable helical angles. It has a unique

crosscut design over cutting edge to reduce stress

on instrument and for efficient debris removal.

Like RaCe (FKG, La- Chaux De Fonds,

Switzerland) the cross section design of Varitaper

is triangular but with slightly positive rake angle

for efficient cutting of dentin as per manufacturer’s

specifications.

Fig.1- Armamentarium

The aim of this study was to evaluate &

compare the cyclic flexural fatigue resistance of

RaCe(FKG, La- Chaux De Fonds, Switzerland) and

recently introduced rotary Ni-Ti system;

Varitaper(Endomax, Equinox, Holland).

MATERIALS AND METHODSThe instruments evaluated were RaCe (FKG,

La-Chaux De Fonds, Switzerland) and Varitaper

(Endomax, Equinox, Holland)(fig.1). All files were

of tip size ISO 25 and 25 mm in length, but there

was a difference in the taper among the two (fig.2).

Fig. 2- instruments evaluated-upper-RaCe,lower-Varitaper.

RaCe has a continuous taper of 0.02

throughout and Varitaper has a gradual increasing

taper from 3-6%.

A system was used that allowed fatigue test to

be conducted in a manner similar to that of Youssef

et al (1999)9. It comprises of three cylindrical steel

blocks (one supporting block and two shaping

block) attached on a 6mm thick acrylic sheet which

was held vertically with the help of a vise.

The positions of the shaping blocks was

adjusted in order to get the desired degree of

curvature (45Ú and 90Ú) in the instrument in such

a manner that maximum curvature was at 5mm

from the tip (fig. 3 and fig.4).

The angle of curvature was calculated by

Schneider’s method10, which defined the angle of

curvature by drawing a line parallel to the long

DR. GAURAV GARG, DR. SANJAY MIGLANI, DR. SEEMA YADAV, DR. SANGEETA TALWAR


24

axis of the canal and the outer line from the apical

foramen to intersect with first line at a point wherein

the canal began to leave the long axis of the canal.

Fifteen instruments were tested in each of the

four experimental groups and for both angles of

curvature to give a total of 60 instruments tested

(table 1).

The instruments were rotated at 350 RPM

using the ATR motor (Dentsply, Maillefer).

The time until fracture was recorded in

seconds by using a stopwatch, and the number of

rotations to fracture was than calculated using the

simple formula: No. of rotation to fracture= 350/

60 X time taken to fracture (in sec.).

Because the study was a direct comparison of

fatigue resistance among groups, a separate control

group was not required.

Results of cyclic fatigue test were analyzed

by using Paired t test (SPSS Software) with level of

significance at p< 0.05.

RESULTSThe number of rotations to fracture, when the

instruments were rotated at a 45Ú and 90Úangle

of curvature, are presented in table 2 and mean &

standard deviation is provided in table 3. Pairwise

comparison showed that the number of rotations

to failure for RaCe was significantly greater than

that of VariTaper at both angles of curvature 45Ú

and 90Ú with p-value .004 and .002 respectively.

(Table 4).

Table 1

Experimental groups and no. ofinstruments in each group (n)

Group 1 Group 2 Group 3 Group 4

VariTaper VariTaper RaCe RaCe(45Ú), n=15 (90Ú), n=15 (45Ú), n=15 (90Ú), n=15

A COMPARATIVE EVALUATION OF CYCLIC FATIGUE RESISTANCE OF TWO ROTARY NICKEL -TITANIUM ENDODONTIC SYSTEMS - AN IN VITRO STUDY

Fig.4- Instrument at 90Úcurvature

Fig.3-Instrument at 45Úcurvature


25

Table 2 : Table of number of rotations atfracture at both angles of curvature for bothinstruments

VariTaper RaCe

Samples 45O 90O 45O 90O

1 332 146 350 154

2 340 150 356 150

3 330 142 352 148

4 315 145 349 154

5 351 152 341 152

6 328 148 346 146

7 340 143 343 153

8 345 151 346 158

9 330 147 349 151

10 337 138 341 143

11 324 149 348 150

12 348 146 351 151

13 352 154 342 148

14 339 143 348 152

15 336 149 350 156

Table 3 : Table of means and standarddeviations of number of rotations to fracture

VariTaper RaCe

45O 90O 45O 90O

Mean 336.47 146.87 347.47 151.07

St. D 10.29 4.24 4.32 3.84

Pairs Mean Diff. St. D P -value

Pair 1 Varitaper 11 12.47 0.00445Ú- RaCe 45Ú

Pair 2 Varitaper 4.2 4.33 0.00290Ú- RaCe 90Ú

Table 4: Table of pairwise comparison amonggroups, mean difference, standard deviationand p value

DISCUSSIONThe present study confirmed that the number

of rotation to fracture an instrument largely depends

on the degree of curvature with more incidence of

breakage at greater degree of curvature as

concluded by other studies11, 12.

In endodontic treatment, Biomechanical

preparation is very important as the outcome is

largely depends on proper cleaning and shaping.

A more tapered preparation results in enhanced

cleaning as there is more removal of infected dentin

and also endodontic irrigants can reach more

apically and results in better microbial control and

better debridement and also good quality

obturation13.

Varitaper has more taper (3-6%) as compared

to RaCe (0.002) and theoretically might results in

better apical preparation with gradually increasing

taper. But in severely curved canals the instruments

with greater taper generally fracture earlier as

compared to 0.02 tapered instruments due to

reduced flexibility14. The results of present study

also confirmed this fact.

The cross cut design incorporated in the

Varitaper system might results in less cyclic fatigue

than other instruments of similar taper as some of

the values of Varitaper at 45Ú & 90Úare similar to

as that of RaCe. As this was an in vitro study clinical

trials should be carried out for more appropriate

comparison.

As Varitaper is a new system, further studies

are required to analyze it with other various rotary

systems according to various aspects.

CONCLUSIONUnder the limitations of present study we

DR. GAURAV GARG, DR. SANJAY MIGLANI, DR. SEEMA YADAV, DR. SANGEETA TALWAR


26

concluded that RaCe performed significantly better

than Varitaper at both degree of curvature.

References:1. Walia H, Brantley W A, Gerstein H. An initial investigationof the bending and torsional properties of nitinol root canalfiles. JOE 1988; 14:346-51.

2. Huismann M, Peters OA,Dummer PMH. Mechenicalpreparation of root canals: shaping goals, techniques andmeans. Endod Topics 2005; 10:30-76.

3. Spili P, Parashos P, Messer HH. The impact of instrumentfracture on outcome of endodontic treatment. J Endod 2005;31:845-50.

4. Souter NJ, Messer HH. Complications associated withfractured file removal using an ultrasonic technique. J Endod2005;31:450-2

5. Sattapan B, Nervo GJ, Palmara JEA, Messer HH. Defects inrotary nickel-titanium files after clinical use. J Endod2000;26:161-5.

6. Margot E Anderson, John WH, Peter parashos. Fractureresistance of electropolished rotary nickel titanium endodonticinstruments. J Endod 2007;33:1212-16.

7. Samantha, Renato Cremonse, Susan Bryant, Paul Dummer.Shaping ability of RaCe rotary Nickel-Titanium instruments

in simulated root canals. J Endod 2005;31:460-67.

8. F Paque, U Musch, M Hulsmann. Comparison of root canalpreparation using RaCe and Protaper rotary Ni-Ti instruments.IEJ 2005;38:8-16.

9. Youssef Haikel, Rene Serfaty, Geoff Bateman, BernardSenger, Claud Allemann. Dynamic and cyclic fatigue of enginedriven rotary Nickel-Titanium endodontic instruments. JEndod 1999;25:434-440.

10. Schneider SW. A comparison of canal preparation instraight and curved root canals. Oral Surg 1971;32: 271-5.

11. Gabriela Zelada, P. Varela, B. Martin, Jose G., F.Magan,Saem Ahn. The effect of rotational speed and the curvatureof root canals on the breakage of rotary endodonticinstruments. JOE 2002; Vol.28, No.7.

12. Margot E.Anderson, John W.H. Price, Peter Parashos.Fracture resistance of electropolished rotary Nickel-Titaniumendodontic instruments. JOE 2007; Vol. 33, No. 10: 1212-1216.

13. Najia Usman, J.Craig, J. Gordon. Influence of instrumentsize on root canal debridement. JOE 2004; Vol.30, No.2.

14. Y. Haikel, Rene Serfaty, G. Bateman, B. Senger, C.Allemann. Dynamic and cyclic fatigue of engine driven rotaryNickel-Titanium endodontic instruments. JOE 1999; Vol.25,No. 6: 434-40.

A COMPARATIVE EVALUATION OF CYCLIC FATIGUE RESISTANCE OF TWO ROTARY NICKEL -TITANIUM ENDODONTIC SYSTEMS - AN IN VITRO STUDY


Coronal Microleakage of Four Restorative Materials Usedin Endodontically Treated Teeth as A Coronal Barrier - AnIn Vitro Study

DEEPALI S. *MITHRA N. HEGDE **

* PG Student, ** Head of the Department, Department of Conservative Dentistry & Endodontics, A.B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore.

ABSTRACTThe present in vitro study was undertaken to evaluate sealing ability of access restoration using, four differentdentin adhesives under composite with conventional glass ionomer cement and resin modified glass ionomercement as intracoronal barrier

65 extracted human maxillary premolars were randomly divided into 15 teeth each in 4 experimental groupsand 5 intact teeth each in control group. Following the biomechanical preparation,all teeth were obturated usingProtaper gutta percha points and AH plus sealer. Once the sealer set, about 3mm of gutta-percha was removedfrom canal orifice in all the teeth. The base was placed till canal orifice extending 1mm coronally.

All the specimens were thermocycled for 500 cycles at 50 – 550 c for 30 sec, and then placed in Rhodomine 6Gfluorescent dye for 24 hrs. The coronal leakage was measured under a fluorescent microscope. Data obtainedfrom the study were subjected to statistical analysis using one way Anova Test and Tukey’s HSD test.

RESULTS - It showed statistically significant difference in coronal leakage among all the groups, but with nostatistically significant difference seen between high strength glass ionomer cement (Group I and Group II) andKetac N 100 (group III and Group IV when placed as intraorifice barrier.

CONCLUSION - Under the limitations of the present study the following conclusions were made that, Compositerestoration with Xeno III adhesive and Ketac N 100 as intraorifice barrier showed better coronal sealing ability inaccess cavities.

INTRODUCTIONThe most common cause for failure of root

canal therapy is apical percolation or microleakage

due to an inadequate apical seal. This allows

periapical fluids, proteins, and bacteria access to

the root canal. Through this interchange an

inflammatory reaction is initiated which often

results in radiographic or clinical signs of failure of

root canal therapy. The question arises that if apical

microleakage is a cause of endodontic failure, what

role might coronal microleakage plays in prognosis

of root canal treatment. 1

Endodontic obturation is often thought of only

in terms of an effective apical seal. However, the

coronal seal may be equally important for the

ultimate success of endodontic treatment. The

apical seal may be adversely affected if coronal

seal is lost or becomes defective.2

A three dimensional filling of the root canal

27


28

system will prevent the penetration of

microorganism and toxins from the oral cavity via

the root canal into the periradicular tissues. Weine

has indicated that improper restoration leads to loss

of more endodontically treated teeth than actual

failure of endodontic therapy. Good coronal

restoration resulted in significant healing of

periradicular inflammation as compared to well

obturated root canals.3

Composite resins are the most common

choice for restoring access cavities. They can be

bonded to tooth structure and most restoratives,

and can provide a good match of color and surface

gloss. Bonded composite materials can also

strengthen existing coronal or radicular tooth

structure, at least in the short time. Traditional glass

ionomer cements are self cure and have very little

polymerization shrinkage, although less than

composite resins. Conventional glass ionomer

cement and resin modified glass ionomer materials

are useful for bulk filling access cavities.

Placement of material over the coronal gutta-

percha to act as a barrier to coronal microleakage

would be advantageous. The ideal intraorificebarrier has not been identified yet, or perhaps, not

even developed.4

Hence there is a need to conduct a study to

assess the coronal microleakage with permanent

access restorative materials with an intraorifice

barrier.

METHODOLOGY65, straight two rooted maxillary premolars

with mature root apices and single canal extracted

on periodontal or orthodontic grounds were used.

Teeth with gross caries involving the root, cracks

on the root surface and for exceptionally short and

thin roots were excluded. All teeth were stored in

10% neutral buffered formalin for at least 2 weeks

and then in distilled water until they were tested.

The teeth were thoroughly cleaned with an

ultrasonic scaler. Radiographs were taken to

confirm the presence of two canals.

Coronal access was achieved and working

length for all teeth was determined by subtracting

0.5 mm from the length at which the file tip

extruded apically. All the teeth were prepared using

ProTaper files in a variable tip crown – down

sequence to an apical size of 0.25 mm (master

apical file size .25 mm) at 0.5 mm from the canal

terminus or apical foramen. All the teeth were

instrumented with the ProTaper instruments

according to the manufacturer’s direction.

15% EDTA (Glyde, Dentsply Co.) was used

to coat the ProTaper files while they were used.

The root canals were irrigated in between each file

with 2.5% sodium hypochlorite (Vensons India)

and physiologic saline using a long 27 gauge

needle alternatively. The smear layer was removed

using 3 ml of 17% EDTA followed by a final flush

with 3 ml of 2.5% sodium hypochlorite. Upon

completion of instrumentation, the canals were

dried utilizing absorbent points. Upon completion

of instrumentation, the canals were dried utilizing

absorbent points. A master cone radiograph was

taken and obturated using F2 gutta percha cone

and accessory cones with lateral condensation

using AH Plus root canal sealer.

Access restoration placement –All the 65 prepared teeth were randomly

divided into four experimental groups of 15 teeth

MITHRA N. HEGDE, DEEPALI S.


29

each as I, II, III and IV respectively, and control

group of 5 teeth.

Control group: 5 teeth used were intact teeth

with periapical seal and coated with Nail Varnish

completely

Intra orifice space preparation - After drying

the access, 3mm of gutta percha was removed from

the coronal orifice (cemento-dentinal junction)

using heated endodontic hand plugger of ISO size

# 30. in all the teeth except control group.

Intraorifice Barrier–Group I and Group II: 30 teeth were used in

which 3mm intraorifice space was restored with

High Strength Glass Ionomer Cement extending

1mm coronally.

Group III and Group IV: 30 teeth were used

in which 3 mm intraorifice space was Primed for

15 seconds and then air dried restored with Ketac

N 100 and cured for 10 seconds extending 1 mm

coronally.

Access Restoration:

Group I: 15 teeth used were etched with 37%

phosphoric acid for 15 Seconds, Prime& Bond NT

adhesive was applied and cured for 10 sec.

Group II: In 15 teeth, Clearfil S3 adhesive was

applied and left for 20 seconds, then Light cured

for 10 sec.

Group III: 15 teeth, G Bond was applied and

left for 10 seconds and then light cured for 10 sec.

Group IV: 15 teeth, Xeno III was mixed

according to manufacturer’s Instructions, left

undisturbed for 20 sec and light cured for 10 sec.

All the four groups were then restored with

Filtek Z 350 and cured for 20 seconds. Teeth were

then placed in artificial saliva for 20 days, later

subjected to thermocycling for 500 cycles at 5- 550c

for dwell time 30 seconds. The samples were dried

for 24 hours.

DYE LEAKAGEFor evaluation of the quality of the coronal

seal, the teeth were subjected to dye leakage.

Experimental groups were coated with two layers

of nail varnish except at 2 mm area around access

restoration.

All teeth were then immersed in Rhodomine

6G fluorescent dye which was freshly prepared

(According to the manufacturer’s instruction) for

48 hours. After this time the excess dye were

washed off and varnish gently scraped away from

the coronal surface.

The coronal portion was then sectioned

buccolingually in a longitudinal direction with a

diamond disc under running water.

MICROSCOPIC EVALUATIONColor photographs were taken of the sectioned

samples using Nikon S-10 camera attached to a

fluorescent microscope and later the pictures were

transferred to a personal computer. Digitized

images were analysed using Image analysis

software. The maximum degree of dye penetration

was recorded for each section, the degree of

leakage was determined from the coronal till the

apex and the dye penetration was scored with

scoring criteria.19

SCORING CRITERIA0 = No leakage detected

CORONAL MICROLEAKAGE OF FOUR RESTORATIVE MATERIALS USED IN ENDODONTICALLYTREATED TEETH AS A CORONAL BARRIER - AN IN VITRO STUDY


30

1 = Slight, just reaching the pulp chamber

2 = Moderate, penetrating halfway into pulp

chamber

3 = Extensive, with leakage extending upto

the floor of the pulp chamber

4 = Gross, extending into the root canal and/

or furcation

RESULTSThe data obtained evaluating the coronal seal

was subjected to statistical analysis using Anova

test. The computed value of p is < 0.005, which

indicates statistically significant difference between

the groups under study. All the experimental groups

exhibited maximum leakage in composite while

the least leakage was in glass ionomer to radicular

dentin.

The mean values showed that the highest

leakage in composite was seen in Group IV

followed by Group III, while least was seen in

group I. At the interface between the glass ionomer

cement and interface, the mean value showed

highest leakage in Group III and least was in Group

IV. At the level of intraorifice barrier highest leakage

was observed in Group I and least in Group IV.

Furthermore, the data was subjected to

Tukey’s HSD test to determine the intergroup

comparison. This test was done to compare the

two groups, it was observed that there was no

statistically significant difference when Group I was

compared with Group II (p value = 0.347), and

there was no statistically significant difference when

Group III was compared with Group IV and (p value

= 0.076).

DISCUSSIONThe success of endodontic therapy depends

on a thorough chemomechanical preparation for

removal of necrotic debris and bacteria from the

root canal followed by sealing the root canal to

prevent ingress of bacteria and tissue fluids. Dow

and Ingle stated that failure most commonly occurs

due to inadequate apical seal. Studies have shown

that a good coronal seal is equally important.5

Swarthz et al found that the failure rate was twice

as high in cases without an adequate coronal

restoration compared to cases which were

adequately restored 6

Fractured teeth and leaking or missing

temporary restorations are encountered clinically,

leaving the access to the canals open to the oral

cavity. Thus the potential exists for oral fluids and

bacterial contamination of the root canal space due

to dissolution of the coronal seal23.

There are several methods that might possibly

prevent microleakage through obturated root canals

in the event the coronal restoration becomes

defective or is lost. These include placement or an

additional material such as IRM into the canal

orifices after removal of portion of the gutta percha

and sealer, sealing the entire chamber floor with a

restorative material, or use of a root canal filling

method that provides a seal without the addition

of other sealing materials.

In the present study, Multirooted maxillary

premolar teeth with two root canals were selected

to minimize anatomical variation, allow

standardization and since accessory canals and

lateral canals in furcation area though are not

routinely obturated, may affect the prognosis of



31

endodontically treated tooth due to close proximity

of furcation to gingival sulcus. 10

The use of tracers is one of the oldest and most

common methods of detecting microleakage in

vitro. Fluorescent dyes are found to be useful as

tracers because they are detectable in dilute

concentrations, inexpensive, are easy to

photograph, permit more reproducible results,

contrast sharply with the natural fluorescence of

teeth, permit direct observation of the total marginal

interface during evaluation and scoring of leakage,

and being nontoxic, can be used safely.16

Thermocycling is a standard protocol in

restorative literature when bonded materials are

evaluated, simulating in vivo aging by subjecting

them to cyclic exposures of hot and cold

temperatures. Resin composite restorative materials

and adhesive systems are sensitive to

thermocycling. Thermocycling stress may induce

a significant amount of bond fatigue and

microleakage at the tooth/restoration interface.

Marginal leakage is believed to be result of a

difference in coefficient of thermal expansion

between restorative material and tooth.15.hence in

accordance with study done by Korsali et al the

samples were thermocycled 500 cycles at 50-550C

for 30 seconds.

The ideal properties of an intraorifice barrier

have been proposed by Wolcott et al. to include

the following characteristics: a) easily placed b)

bonds to tooth structure c) seals against

microleakage d) distinguishable from natural tooth

structure and e) does not interfere with final

restoration. Placement of an additional material

such as Glass ionomer cement or amalgam in to

the canal orifices after removal of a portion of the

gutta percha and sealer upto 3mm has several

advantages.

1. The coronal 3mm of the canal is an ideal

small cavity that is surrounded by intact tooth

structure and can be easily sealed.

2. There is no occlusal load in the orifice area.

3. There are no esthetic considerations in this

method, because the material is placed within the

canal. 14

This is more appropriate on posterior teeth;

however on anterior teeth, more care is necessary

because the suggested material can cause

discoloration of teeth or interfere with future

bonding agents that are usually used for the teeth.

Glass ionomer cements are made primarily

of alumina, silica and polyacrylic acid and self

curing materials. They are the only restorative

materials that depend primarily on a chemical bond

to tooth structure. They form an ionic bond to

hydroxyapatite at dentin surface and also obtain

mechanical retention from micro porosities in the

hydroxyapatite.

Glass ionomer cements form lower initial

bond strength to dentin than resins, (3-7Mpa). But

unlike resins they form a “dynamic” bond as the

interface is stressed, bonds are broken, but new

bonds form .this is one factor that allows glass

ionomer cements to succeed clinically, despite

relatively low bond strength. But they could not

overcome the following disadvantages: 1) they set

slowly and must be protected from moisture and

dehydration during the setting reaction which is

not completed for 24 hours, 2) they rely on ionic

bonding to hydroxyapatite, strong acids should be



32

avoided because they totally eliminate mineral

from dentin surface. Hence could be sensitive to

total etch adhesives for bonding.18 The present study

showed no statistical significance difference

between sealing ability of high strength glass

ionmer cement groups.

Nano resin modified glass ionomer cement

contains an acid- degradable glass and aqueous

solutions of polyacid and monomeric ingredients

such as 2-hydroxyethyl methacrylate (HEMA). The

nano resin modified glass ionomer” restorative

further contains a unique combination of two types

of surface treated nanofillers (approximately 5-25

nm) and nanoclusters (approximately 1.0 to 1.6

microns). The setting reaction of the cement starts

immediately upon mixing as an acid –base

reaction. Free radical polymerization of the

monomeric components is then initiated by visible

light irradiation. Each acrylate group can take part

independently in the chain reaction, but the net

effect is the formation of a covently cross-linked

three-dimensional network. The set cement then

consists of interpenetrating networks of, poly

(HEMA) and polyacrylate salts. This photochemical

reaction reduces the early sensitivity to moisture

and dehydration associated with the early stage of

the acid-base setting reactions of GICs. They have

the clinical advantage of extended working time,

increased mechanical strengths by as much as two

or three times compared to GICs. The primer,

contains HEMA modifies the smear layer which

facilitate better penetration of polyacrylic acid

aiding into increase bond strength compared to

conventional GICs.23 The present study evaluated

no statistical significance difference between

sealing ability of Ketac N 100 groups.

Bonding to dentin with resin is more complex

than bonding to enamel. Dentin consists of 50%

inorganic mineral by volume, 30% organic

components and 20% fluid. The wet environment

and relative lack of mineralized surface made it a

challenge to develop materials that bond to dentin.

Microleakage of the restoration is a more important

issue in endodontically treated tooth. None of the

current adhesives systems are capable of preventing

microleakage over long time.

The current study concluded that all the

adhesive system showed microleakage after 20

days, while Xeno III has shown the least leakage

compared to Clearfil S3, Prime&Bond NT, G Bond.

Self etch adhesives system have become

increasingly popular in the last decade the

combination of etchant and primer into one system

is advantageous in that it reduces the application

time and technique –related sensitivity. On the

other hand, there is on going debate regarding the

efficacy of bonding to enamel with self-etch

adhesives systems. While some authors support the

manufactures recommendations that the adjunctive

use of phosphoric acid etching is necessary when

bonding to uncut enamel, while others argue that

the bond strengths of self etch adhesives are equal

to the bond strength of total-etch adhesives to

unground enamel.20,22

Contemporary self etch adhesives systems can

be categorized as mild, moderate and aggressive

depending on the acid dissociation constants acidic

resin monomers used and the concentration of

monomers present in the adhesives.

Van Meerbeek et al attributed least leakage is

due to it being a intermediary self etch adhesive



33

with acidic PH of 1.5. This acidic nature results in

better micromechanical interlocking to dentin

compared to strong self etch adhesives. It is also

suggested that the residual hydroxyappatite at the

hybrid layer base may still allow for chemical

intermolecularinteraction.25

Clearfil S3 shows better seal among the self

etching adhesives but slightly lower than Xeno III

(p>0.05). The reason attributed to this is the

presence of MDP. This functional phosphate

monomer to a large extent, determines its actual

bonding efficiency and stability. MDP has two

hydroxyl groups that may bind to calcium. Yoshida

et al reported that MDP tightly adheres to

hydroxyapatite and that its calcium salt hardly

dissolved in water. Moreover MDP causes minimal

dissolution of smear plugs and limited opening of

tubules, reducing dentin permeability. It also

facilitates penetration, impregnation,

polymerization and entanglement of monomers

with demineralized dentin to form a relatively thick

hybrid layer. So the lower dye penetration observed

in the samples could be attributed to difference in

chemical compositions of self etch adhesives.24

According to the study conducted by Van

Meerbeek et al, at the dentin interface the

phosphoric acid treatment exposes microporus

network of collagen that is totally deprived of

hydroxyappatite, EDAX have confirmed that nearly

all calcium phosphates were removed or at least

became under detection limit. As a result, the

primary bonding mechanism of Etch & rinse

adhesives to dentin is primarily diffusion-based and

depends on hybridization or infiltration of resin

within the exposed collagen fibril scaffold, which

should be as complete as possible. True chemical

bonding is rather unlikely, because the functional

groups of monomers may have only weak affinity

to the “hydroxyappatite – depleted” collagen. Such

challenging monomer- collagen interaction could

be the prime reason for microleakage. This is in

accordance to the present study which concludes

that, Prime & Bond NT showed the maximum

leakage .25

G bond adhesive (HEMA free adhesive)

showed the highest leakage, the reason could be

attributed to the recent study phase where

separation among the adhesives compositions was

confirmed as droplets entrapped during solvent

evaporation from HEMA free adhesives. That

phenomenon could be explained by the

evaporation of solvents such as acetone, which

affected the balance of solvents and resin monomer

and caused water separate from the composition

of the adhesive.17 Spherical blisters within the resin

film may be the outcome of the residual free water

not completely evaporated and entrapped at the

interfacial level. The convergence of small blisters

into large ones tends to produce honeycomb

structures that may jeopardize the bonded

interface.

In the present study, Filtek Z 350 showed

leakage in all the groups it is in accordance with

study done by Korsali et al, the reason was

attributed to the sealing performance of nano

composite which is affected in access cavities by

cavity configuration (6:1), dimensional changes like

polymerization shrinkage or thermal/hydroscopic

expansion and bonding capacity of resin.

Clinically, the quality of an access restoration

cannot be determined. Although experimental

studies cannot exactly reproduce clinical



34


Table IDYE LEAKAGE

Shows comparison of the mean coronal leakage of fivedifferent group’s

BAR GRAPH SHOWS COMPARISON OFMEAN APICAL LEAKAGE OF THE THREEGROUPS BY ANOVA TEST

Table 1: Comparison of the Coronal Leakage of all theExperimental Groups and control Group.

conditions, and the relationship of in vitro leakage

measurements to the in vivo situation has not yet

been established, the most reasonable way of

testing the efficacy of coronal restoration is

extrapolation of the data obtained from in vitro

studies to clinical conditions and long term clinical

evaluation of the results. 13

CONCLUSIONIn the present study microscopic evaluation

was done to analyze the extent of coronal dye

leakage using Rhodamine 6G fluorescent dye of

access restoration in endodontically treated with

a Composite material ( Filtek Z350) using Prime &

Bond NT, Clearfil S3, G bond and Xeno III

adhesives with High strength glass ionomer

cements and Ketac N 100 as an intra orifice barrier.

The following conclusions were drawn,√ The coronal seal is better when Ketac N 100

is used as intraorifice barrier.

√ Maximal coronal sealing is critical for

successful endodontic therapy. In this simulated

clinical setting, composite restoration with Xeno

III as bonding adhesive and Ketac N 100 as

intraorifice barrier offered the highest probability

for achieving a maximal coronal seal. Figure 2: Fluoroscent Microscope.

Figure 3: Fluorescence of the dye showing extent of coronalleakage.

Figure 1: Bar graph shows comparison of mean coronalleakage of the five groups by ANOVA.


References1. Swanson .K, Madison .S: An Evaluation of CoronalMicroleakage in Endodontically Treated Teeth: Part I. timePeriods. J Endod 1987; 13(2):56 – 59.

2. Derkson.G, Pashley.D.H, Derkson.M: Microleakagemeasurement of selected restorative materials: A new in vitromethod. J Prosthet Dent 1986; 56(4):435 – 440.

3. Andersons.R.W, Powell.B, Pashley.D.H: Microleakage ofthree temporary endodontic restorations. J Endod 1988;14(10):497 – 501.

4. Arnold.A.D, Wilcox.L.R: Restoration of endodonticallytreated anterior teeth: An evaluation of coronal microleakageof glass ionomer and composite resin materials. J ProsthetDent 1990; 64:643 – 646.

5. Torabinejad.M, Borasmy.MS, Kettering.J.D: In vitrobacterial penetration of coronally unsealed endodonticallytreated teeth. J Endod 1990; 16(12):566 – 569.

6. Magura.M.E, Kafrawy.A.H, Brown.C.E, Newton.C.W:Human saliva coronal microleakage in obturated root canals:An in vitro study. J Endod 1991; 17(7):324 – 331.

7. Khayat A, Lee S-J, Torabinejad M. Human saliva penetrationof unsealed obturated root canals. J Endo 1991; 17: 324-331.

8. Shetty M. B. Fracture resistance of intact and endodonticallyprepared human mandibular molars restored with threedifferent combinations of restorative materials- An in-vitrostudy. Endo Society Intern Endo Journal.1993.

9. Wolcott.J.F, Hicks.L.M, Himel.V.T. Evaluation of pigmentedintraorifice barrier in endodontically treated teeth. J Endod1999; 25(9):589-592.

10. Tewari.S, Tewari.S. Evaluation of coronal microleakagein endodontically treated multirooted teeth. Endodont 2000;12:18-22.

11. Wolanek.G.A, Loushine.R.J, Weller.N.R, Kimbrough.F.W,Volkmann.K.R. In vitro bacterial penetration of endodonticallytreated teeth coronally sealed with dentin bonding agent. JEndod 2001; 27(5):354-357.

12. Belli.S, Zhang.Y, Pereira P.N.R, Pashley.D.H. Adhesivesealing of pulp chamber. J Endod 2001; 27(8):521-526.

13. Ozturk B, Ozer F, Belli S. An in vitro comparison ofadhesive systems to seal pulp chamber walls. Int Endo J 2004;37:297-306.

14. Scott.M.M, Scott.B, Goodell.G. The effect ofthermocycling on a colored glass ionomer intracoronal barrier.J Endod 2005; 31(7):5266-528

15. Korsali.D, Ziraman.F, Ozyurt.P, Cehrali.B. Microleakageof self etch primer/adhesives in endodontically treated teeth.J Am Dent Assoc 2008; 138(5):634-640

16. Bahareh Fathi, James Bahcall, James S. Maki. An In VitroComparison of Bacterial Leakage of Three CommonRestorative Materials Used as an Intracoronal Barrier. J Endod.2007; 33(7):872-874.

17. Saunders.WP, Saunders.EM: Coronal leakage as a causeof failure in root canal therapy: a review. Endod DentTraumato1994; 10:105-108.

18. Schwartz R.S, Fransman R. Adhesive dentistry andendodontics : materials, clinical strategies and procedures forrestoration of access cavities : a review. J Endo 2005;31:151-165

19. Leinfelder, K. Current Developments in Dentin BondingSystems. JADA 1993; 124: 40-42.

20. Christensen.G. Self-etching primers are here. J Am DentAssoc 2001; 132(7):1041-1043

21. Smith.G. Surface deterioration of glass-ionomer cementduring acid etching: An SEM evaluation. J Op. Dent 1988;13:3-7.

22. Tay.F, Pashley.D.H. Aggressiveness of contemporary selfetching systems. I: depth of penetration beyond dentin smearslayers. Dent Mat 2001; 15:715-718.

23. Darvell.B, Yelamanchili.A. Network competition in resin-modified glass ionomer cement. Dent Mat 2008; 24:1065-1069.

24. Burke.T.F.J. What’s new in dentine bonding self-etchadhesives. Dent update 2004; 12:580-589.

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36

In Vitro Evaluation of the Efficacy of Five Apex Locators

NIRANJAN A. VATKAR *SUCHETA SATHE **VIVEK HEGDE ***

* Second year post graduate student, ** Professor, *** Head of Department, Department of Conservative Dentistry and Endodontics at M. A. Rangoonwala College of DentalSciences and Research Centre, Azam Campus, Pune-1.

ABSTRACTToday in this field of new era with lot many innovations coming up daily, endodontics has taken a new paradigmshift. The earlier root canal technique of ‘biomechanical preparation’ is now changing into ‘chemobiomechanicalpreparation’. Today’s root canal treatment not only depends on proper cleaning and shaping procedures but alsoproper reaching of the irrigant upto the desired working length. Therefore it is absolutely essential to determineexact working length to achieve an optimum cleaning and shaping procedures. From the beginning of endodontics,many modalities and techniques have been devised for the determination of working length. With increasedunderstanding of the relation of oral mucosa and periodontium to physics, the apex locator was invented whichnow is been used frequently. The present study was conducted to evaluate the efficacy of five different apexlocators in determining the working length.

Key words: apex locator, working model

INTRODUCTIONThe ultimate success of any root canal

treatment depends on multiple factors like the

extent of caries, the biomechanical preparation, the

obturation, the remaining tooth structure, etc.

The proper instrumentation upto the apical

constriction or also called as the cemento-dentinal

junction (9) as seen earlier is also one of the vital

factor for a good prognosis. The cemento-dentinal

junction is a histological landmark and in clinical

practice it is impossible to locate it. Therefore the

apical constriction can be regarded as a clinical

landmark on which we can depend upon. The

apical constriction, when present, is the narrowest

part of the root canal with the smallest diameter of

blood supply and preparation to this point results

in a small wound site and optimal healing

conditions (18).

The traditional methods used till today rely

on the apical tug back for the termination of any

root canal instrumentation. Though this method is

effective, it can also be deceptive as the tug back

could also be possible because of any secondary

curvatures present before the apical constriction.

Also in some cases the canal may be sclerosed or

the constriction has been destroyed by

inflammatory resorption (19).

The radiographs are definitely supportive for

the instrumentation upto the apical constriction,

but they can also prove deceptive due to improper

angulation of the cone. Also, the image obtained

is a two-dimensional image of a three dimensional

object.


37

The moisture on the absorbent point method

can also give us false positive results as the draining

above the apical constriction can happen.

Keeping all the above limitations in mind, an

electronic device for the determination of working

length was investigated first in 1918 by Custer et

al. His ideas were later revisited by Suzuki in 1942

(21) and Sunada in 1962 (20) for the invention of

the modern electronic apex locator apex.

The first electronic working length device

measured the working length by calculating the

electrical resistance between the periodontium and

oral mucosa that gave a constant reading of 6 k¿.

Later on many new devices were invented

measuring the frequency, impedance and

capacitance.

The present study was conducted to evaluate

the efficacy of five different apex locators in

determining the working length.

MATERIALS AND METHODS1. Preparation of samples -

Twenty freshly extracted single rooted single

canal human teeth were chosen for the study. The

teeth were stored in sodium hypochlorite for 24

hours to dissolve any tissue on the root surface.

The teeth were then scaled with an ultrasonic scaler

(EMS, Mectron) to remove any hard tissue if present

on the root surface. Proper precautions were taken

while scaling the apical part of all teeth.

An access to the root canal of all teeth was

prepared using a round and cylindrical bur (Mani

Inc.). A 15# K-file (Mani Inc.) was used to negotiate

the canal using sodium hypochlorite and normal

saline.

2. Measurement of actual working length –A 15# K-file (Mani Inc.) was introduced inside

the canal until it became visible at the apical

foramen. The silicone stop was adjusted, the file

was removed and the distance between the base

of silicone stop and file tip was measured using a

vernier caliper. To obtain the actual working length,

0.5 mm was subtracted from this measured length

(1).

3. Working model for electronic workinglength determination –

Two plastic rectangular boxes, 18 cm×3

cm×4 cm in dimension were used for preparing

this model. Alginate was poured in each of this

boxes that acted as an electroconductive medium

(7, 10, 11, 17, 22).

Ten teeth among the selected samples were

mounted vertically upto the cementoenamel

junction. All measurements were made within 2

hours of the model being prepared (15).

4. Electronic working length measurement -Five apex locators were chosen for this study,

Dentaport ZX (Fig. 1; J. Morita Corporation, Japan),

Root ZX (Fig. 2; J. Morita Corporation, Japan),

Raypex 5 (Fig. 3; Roydent Dental Products, Johnson

City, TN), Propex (Fig. 4; Dentsply), and E Magic

Finder (Fig. 5; Densiti). Each tooth among the

twenty samples was subjected to electronic

working length measurement using all five apex

locators. The entire technique was performed and

the measurements were recorded by a single

IN VITRO EVALUATION OF THE EFFICACY OF FIVE APEX LOCATORS


38

operator. Care was taken to see that all the circuits,

batteries and the operating modes of all five apex

locators are fully functional.

At first, canals were irrigated using 5.25%

sodium hypochlorite placed with a syringe, then

the pulp chamber was gently dried with an air

syringe; cotton pellets were used to dry the tooth

surface and eliminate excess irrigating solution.

A 15# K-file with the file clip of the apex

locator to be used, was attached to the file and

inserted inside the canal until the apex locator

showed the “apex” reading. The file was slightly

pulled out until the apex locator showed the “0.5

mm” reading. The silicone stop was adjusted and

the file was removed and the distance between the

base of silicone stop and file tip was measured using

a vernier caliper.

Measurements were considered as valid if they

were stable for at least 5 seconds otherwise the

value was recorded as an unstable measurement

due to inability of the EALs to reveal a constant

reading. The recorded values were tabulated. The

actual length readings were compared to electronic

working length readings.

Statistical analysis of the recorded readings

was done using a Sign test for nonparametric

evaluation of the groups. Statistical readings were

considered significant when p < 0.05.

RESULTS

TABLE 1

TOOTH ACTUAL PROPEX ROOT DENTAPORT E MAGIC RAYPEX 5SAMPLE LENGTH ZX ZX FINDER

1 21 21 20.5 20.5 21 21

2 24 23.5 24 23 23.5 24

3 22 21.5 21.5 23 22 22

4 23 23 23 24 23 23.5

5 22 21.5 22 22 22 22

6 21 20.5 21 20.5 20.5 20.5

7 21.5 21 22 22 21.5 21.5

8 23.5 23 23 23.5 23.5 23.5

9 19 19 19 18.5 19 18.5

10 24 23.5 23.5 23.5 24 23.5

The results obtained were tabulated as follows -

*Length in mm

NIRANJAN A. VATKAR, SUCHETA SATHE, VIVEK HEGDE


39

TABLE 1

TOOTH ACTUAL PROPEX ROOT DENTAPORT E MAGIC RAYPEX 5SAMPLE LENGTH ZX ZX FINDER

11 19.5 19 19 19 19 19.5

12 19.5 19 19 19 19.5 19

13 24.5 23.5 24.5 24.5 24.5 24

14 20.5 20 20 20 20 20

15 21 21 21 20.5 21 20.5

16 20 20 20 20 19.5 20

17 21 21 21 20.5 21 20

18 21 21 21.5 21 21 21

19 22 22 22 21.5 22 22

20 24.5 24.5 24 24 24.5 24

*Length in mm

Accuracy was calculated only on stable

measurements. There was a highly significant

difference (p < 0.05) when the differences between

measurements obtained with the Dentaport ZX,

Raypex 5 and Propex and those obtained with the

actual length readings were compared. The

graphical representation of each apex locator

compared with the actual length readings were are

shown below.

Table 1 and 2 shows that most measurements

were within ±0.5 mm of the actual length. One

tooth each with Propex (tooth sample 13) and

Raypex 5 (tooth sample 17) and three teeth with

Dentaport ZX (tooth samples 2, 3, 4) gave readings

that were beyond ±0.5 mm.

The statistical data was obtained as below. The

dots above the line indicate the samples that the

apex locator measured short of the apex. The dots



40

below the line indicate the sample that the apex

locator measured beyond the apex. The dots on

the line indicate the samples that the apex locator

measured exactly at apex. The ‘p’ value of each

group is also indicated in each of the graph that

was calculated statistically.

DISCUSSIONThe use of electronic devices to determine

working length has gained increasing popularity

in recent years. Modern apex locators are able to

determine an area between the minor and major

apical foramina by measuring the impedance

between the file tip and the canal with different

frequencies and enables tooth length

measurements in the presence of electrical

conductive media in the root canals (12).

As the mean foramen to apical constriction

distance is approximately 0.5–1.0 mm for all teeth

types (4, 8, 13), it was chosen in this study to record

the actual working length by subtracting 0.5 mm

from the measurement when the file appeared at

the foramen.

NIRANJAN A. VATKAR, SUCHETA SATHE, VIVEK HEGDEENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY


41

Some authors have suggested that taking the

instruments slightly long when using EALs and then

retracting them may increase the accuracy of

readings of EALs (5, 14). Thus, to confirm the

measurement, the file was advanced upto the apex

reading and then retracted to obtain the consistent

‘0.5 mm’ reading.

All measurements were made within 2 hours

of the model being prepared in order to ensure the

alginate was kept sufficiently humid [12].

The relative stiffness of the alginate mould

prevented fluid movement inside the canal that is

responsible of premature electronic readings

registered with previous models (2, 3, 6).

APEX LOCATOR ‘P’ VALUE

Root ZX 1.109

E Magic Finder 0.063

Dentaport ZX 0.035

Raypex 5 0.021

Propex 0.001

The results of the present study confirmed that

Root ZX and E Magic Finder can accurately

determine the canal length within ±0.5 mm from

the apical constriction. The measurements obtained

revealed that the EALs were able to measure the

canal length with a precision compared with the

actual length. If the estimated working length, i.e.

actual length ± 0.5 mm is considered to be

clinically acceptable, then the measurements made

with the Root ZX and E Magic Finder were

acceptable in virtually all cases.

One tooth with Propex and one with Raypex

5 and three teeth with Dentaport ZX gave readings

exceeding the apical constriction (0.5 mm) (Table

1 and 2).

CONCLUSIONAll these modern apex locators gave

comparable results in comparison to actual working

length. However Root ZX and E Magic Finder were

the most precise, followed by Dentaport ZX,

Raypex 5 and Propex.

In conclusion, the modern newly advanced

apex locators are gaining popularity because of

their predictability, precision and ease of working.

It helps you to know the apical constriction which

you cannot see. These gadgets have definitely

improved the quality of endodontics. This short

study was performed to confirm the accuracy of

five apex locators.

References1. Kaufman A. Y., Keila S. & Yoshpe M. Accuracy of a newapex locator: an in vitro study. International EndodonticJournal 2002 35:186–192.

2. Czerw RJ, Fulkerson MS, Donnelly JC. An in vitro test of asimplified model to demonstrate the operation of electronicroot-canal measuring devices. Journal of Endodontics 199420:605–6.

3. Czerw RJ, Fulkerson MS, Donnelly JC, Walmann JO. Invitro evaluation of the accuracy of several electronic apexlocators. Journal of Endodontics 1995 21:572–5.

4. Dummer PMH, McGinn JH, Rees DG. The position andtopography of the apical canal constriction and apicalforamen. International Endodontic Journal 1984 17:192–8.

5. Dunlap CA, Remeikis NA, BeGole EA, RauschenbergerCR. An in vivo evaluation of an electronic apex locator thatuses the ratio method in vital and necrotic canals. Journal ofEndodontics 1998 24:48–50.

6. Fouad AF, Reid LC. Effect of using electronic apex locatorson selected endodontic treatment parameters. Journal ofEndodontics 2000 26:364–7.

7. Fuss Z, Assoline LS, Kaufman AY. Determination of rootperforations by electronic apex locators. Oral surgery, Oralmedicine, Oral Pathology and Endodontics 1996 82:324–329.



42

8. Green D. Stereomicroscopic study of 700 root apices ofmaxillary and mandibular posterior teeth. Oral Surgery, OralMedicine and Oral Pathology and Endodontics 1960 13:728–33.

9. Grove CJ The value of the dentinocemental junction inpulp canal surgery. Journal of Dental Research 1931 11:466–8.

10. Kaufman AY. Katz. Reliability of Root ZX apex locatortested by an invitro model. Journal of Endodontics 199319:201.

11. Keila S, Linn H, Katz A Kaufman AY. Morphometricanalysis of working length determined by impedance typeapex locators. Journal of Endodontics 1994 20:196 (Abstract).

12. Kobayashi C. Electronic canal length measurement. OralSurgery, Oral Medicine, Oral Pathology, Oral Radiology andEndodontics 1995 79:226–31.

13. Kuttler Y. Microscopic investigation of root apices. Journalof the American Dental Association 1955 50:544–52.

14. Lee SJ, Nam KC, Kim YJ, Kim DW. Clinical accuracy of anew apex locator with an automatic compensation circuit.Journal of Endodontics 2002 28:706–9.

15. Lucena-Mart³n C, Robles-Gijon V, Ferrer-Luque CM,Navajas- Rodr³guez de Mondelo JM. In vitro evaluation of

the accuracy of three electronic apex locators. Journal ofEndodontics 2004 30:231–3.

16. Nekoofar M. H., Ghandi M. M., Hayes S. J. & Dummer P.M. H. The fundamental operating principles of electronic rootcanal length measurement devices: review. InternationalEndodontic Journal 2006 39:595–609.

17. Neguyen HQ, Kaufman AY, Komorowski R, Friedman S.Electronic length measurement using small and large files inenlarged canals. International Endodontic Journal 199629:359–364.

18. Ricucci D, Langeland K. Apical limit of root canalinstrumentation and obturation, Part II: A histological study.International Endodontic Journal 1998 31:394–409.

19. Stock C. Endodontics-position of the apical seal. BritishDental Journal 1994 176:329.

20. Sunada I. New method for measuring the length of theroot canal. Journal of Dental Research 1962 41:375–87.

21. Suzuki K. Experimental study on iontophoresis. JapaneseJournal of Stomatology 1942 16:411–29.

22. Tinaz AC, Maden M, Aydin C, Turkoz E. The accuracy ofthree different electronic root canal measuring devices: an invitro evaluation. Journal of Oral Science 2002a 44:91–5.

NIRANJAN A. VATKAR, SUCHETA SATHE, VIVEK HEGDE


43

A Three-Dimensional Evaluation of Density andHomogeneity of Root Canal Obturation with Guttaflow®

using Backfilling Technique in Comparison withConventional Lateral Compaction Technique using SpiralComputed Tomography - An In Vitro Study

P. SENTHIL KUMAR *A. R. VIVEKANANDA PAI **KUNDABALA M. ***

* Specialist Resident, ** Professor, ** Professor & Head, Department of Conservative Dentistry & Endodontics, Manipal college of Dental Sciences, Mangalore.

ABSTRACTThe objective of the study was to three dimensionally compare the density and homogeneity of “GuttaFlow®”using backfilling technique with conventional lateral compaction technique using spiral computed tomography.

30 human extracted maxillary central incisors were used for this study. Following access cavity preparation,working length was determined and root canal preparation was carried out using standard step-back technique.Root canal irrigation was performed using 2.5% NaOCl ,saline and final flushing with 17%EDTA and normalsaline.

After root canal preparation, the specimens were randomly divided into 3 groups with 10 teeth in each group.Specimens in Group-I were obturated with GuttaFlow® using backfilling technique, Group-II were obturated bylateral compaction technique using GuttaFlow® as the sealer and Group-III were obturated by lateral compactiontechnique using zinc-oxide and eugenol as the sealer.

The specimens were then analyzed in both horizontal and vertical sections from the apex to the cemento-enameljunction of each specimen with section thickness of 1mm each using Spiral Computed Tomography.

The data obtained was statistically analyzed using one way ANOVA test followed by FISHER’S test and TUKEYSHSD test.

Results showed that specimens of Group -I was denser, more homogenous compared to other groups and wasstatistically significant. In the evaluation of obturation in the apical, middle and coronal third individually, Group-I showed better results than other groups in apical and middle third which was statistically significant, butshowed inferior results in the coronal third though it was not statistically significant. And Group-II and Group-IIIshowed inferior results in the middle third when compared with Group-I and was statistically significant.

From the results of the study it can be concluded that, Obturation done using GuttaFlow® with backfilling techniqueis superior in the apical and middle third but is inferior in the coronal third of the root canal system whencompared to lateral compaction technique.

Spiral computed tomography is a very useful tool fo checking the density of obturation in endodontics.

Key words: Gutta-Flow, Spiral Computed Tomography, Obturation density, Homogeneity.



INTRODUCTIONThe success of endodontic treatment depends

on the complete obturation of the complex root

canal system with an inert material1. To seal this

system, the obturating material must adapt to all

the portions of the root canal2. The Washington

study of endodontic success and failures indicates

that nearly 60% of the failure is apparently caused

by incomplete obturation of the radicular space3.

Several materials and techniques have been

developed for achieving a successful obturation,

Gutta-percha is the most commonly used root canal

obturation material and its physical properties have

made it possible to use it in several different

techniques4.

One of the most recent techniques which uses

cold flowable filling system for obturation of the

root canal system is “GuttaFlow®” which is

combination of sealer and gutta percha powder. It

consists of polydimethylsiloxane matrix highly

filled with finely ground gutta-percha. Several

studies have shown that GuttaFlow® offers excellent

flow and satisfactory physical properties5 according

to ISO standards6.Unlike thermoplasticized gutta-

percha which shows shrinkage on cooling,

GuttaFlow® expands slightly by 0.2% on setting

further enhancing its sealing properties.

Computed Tomography and Micro Computed

Tomography are currently the leading technologies

for endodontic research7. With spiral computed

tomography three dimensional volume analyses are

possible without sectioning the specimen and thus

avoiding the loss of material during sectioning8 and

it is possible to reconstruct overlapping structures

at arbitrary intervals and thus the ability to resolve

small objects is increased 9.

The purpose of the study is to analyze the

three-dimensional sealing ability of cold flowable

gutta percha (GuttaFlow®) and compare it with cold

lateral compaction technique using spiral

computed tomography.

MATERIALS AND METHODSMechanical Preparation of the Teeth

Thirty freshly extracted single rooted human

teeth with type I root canal anatomy were stored

in normal saline. Following access cavity

preparation, working length was determined and

root canal preparation was carried out using

standard step-back technique. Root canal irrigation

was performed using 2ml of 2.5% NaOCl and

normal saline and final flushing using 17%EDTA

and normal saline. The apical portion of the canal

was enlarged to a maximum of size 50. Any tooth

requiring a size larger than #50 file was discarded.

The coronal third of each canal was flared using a

#2 and #3 Gates Glidden drills.

Obturation TechniquesAfter drying the canals with paper points, the

teeth were randomly selected and divided into

three experimental groups of 10 teeth each.

TABLE. 1Experimental Groups

Groups Obturation Number oftechnique teeth

I Obturation using Gutta Flow®

(back filling technique) 10

II Obturation using using 2%ISOgutta percha points and GuttaFlow® as sealer ( lateralcompaction technique) 10

III Obturation using 2% ISO guttapercha points and zinc oxideeugenol sealer.( lateralcompaction technique ) 10

P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.

44


Analysis of the experimental specimens using

Spiral Computed Tomography.

All the experimental specimens were mounted

on a wax block and placed on the couch of the

computed tomography machine. It was moved

longitudinally towards the gantry at the pitch of

“1”and exposure with 120kv and 180mA was done

for one second.

Both vertical and horizontal sections of 1mm

thickness were made which was followed by three

dimensional reconstruction of the sections. The

specimens were further analyzed for variations in

density in 1 to 5mm from apex ( SUBGROUP I), 6to 10mm from the apex(Subgroup-II) and 11 to16mm from the apex (Subgroup-III) individually in

both vertical and horizontal sections.

The specimens were analyzed using Windows

Advantage Work Station software for

Density of the filling material.

Homogeneity and adaptation

to the canal wall.

Voids.

The analysis of all the specimens was done

followed by statistical analysis.

OBSERVATION AND RESULTSThe assessment was done using spiral

computed tomography for variation in the density

TABLE. 2Sub-Groups

SUB-GROUP -I 1 to 5 mm from the apex

SUB-GROUP II 6 to 10 mm from apex

SUB-GROUP III 11 to 16 mm from apex

RESULTSThe Density was measured in HOUNSEFIELDUNITS

TABLE. 3

and homogeneity. The values were recorded in

both horizontal and vertical sections. The results

were tabulated and graphically analyzed.

All the experimental groups were compared

statistically using ONE WAY ANOVA test and the

sub groups were compared using TUKEYS HSD

test.

In all the groups (p>0.05) was considered

statistically significant.

TABLE. 4

TABLE. 5

Analysis of density among experimentalgroups in vertical section

Analysis of density among sub-groups in vertical section

Analysis of density among experimental groups inHorizontal section

A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDY

45


46

TABLE. 6

DISCUSSIONAchieving a complete seal of the root canal

system is of greatest importance in endodontic

therapy, The Washington study has concluded that

nearly 60% of all endodontic failure is due to

incomplete obturation of the root canal10.

The voids and crevices in the obturating mass

can interconnect with each other opening up either

apically or coronally. Further the tissue fluids,

proteins and bacteria can seep into these empty

spaces which act as a reservoir of irritants leading

to failure of endodontic treatment.

In the present study was used GuttaFlow® as

an obturating material. The ingredients include

gutta-percha powder, polydimethylsiloxane matrix,

silicone oil, paraffin oil, platinum catalyst,

zirconium dioxide, nano -silver(preservative) and

coloring agents.GuttaFlow® is obtained by adding

nano silver particles to its initial version Roekoseal

( Coltene / Whaledent) .

The material is cold flowable and sets within

10 minutes. It is supposed to be easily applied using

lentulo spirals or application syringes. The material

flows into the smallest dentinal tubules, because

of the small particle size (< 0.9microns). The

manufacturer claims a better seal and good

adaptation because of increased flowablity and the

fact that material expands slightly by 0.2% on

setting11.

Since GuttaFlow® is a cold flowable material,

there is no need for rise in the temperature of the

material like thermo plasticized materials and as

per manufacturers instructions there is no need for

compaction of the material during obturation and

hence there is no disadvantages like shrinkage on

cooling, vertical fractures due to undue forces and

is relatively easy to use compared to other systems.

However it should be noted that GuttaFlow®

belongs to the category of root canal filling pastes,

which has a high risk of void formation,over filling

or under filling. There fore this material

(GuttaFlow®) was chosen to study the flowablity,

density, homogeneity.

Spiral computed tomography was chosen over

other diagnostic aids for analysis of the specimens

because of its various advantages like Three-

Dimensional volume measurements are possible

without sectioning the specimens and thus avoiding

the loss of material during sectioning8 and three-

dimensional reconstructions9.

Here we chose 30 freshly extracted maxillary

central incisors and divided into three groups with

10 teeth each. This allowed adequate statistical

analysis and comparison with earlier studies. the

canals of all the groups were prepared using a step

back technique such that a continuously tapering

funnel shape from the apical third to the coronal

third was obtained. This facilitated for the ease of

obturation with the two techniques in the study.

In this study alternating solutions of NaOCl

and normal saline were used for canal irrigation.

Analysis of density among sub-groups inHorizontal section



47

The canals were finally irrigated with 17% EDTA

and normal saline to facilitate removal of dentin

debris and smear layer from the root canal12.

The specimens were then mounted on a wax

block and subjected for analysis using Spiral

Computed Tomography. Each section was

analyzed for variations in the density in the

obturation in Hounsefield Units (HU), and for voids

if any.

It was observed that the Hounsefield units

increase from the apex to the cementoenamel

junction in vertical sections. This could be

attributed to the increase in the obturation mass

from the apex to the CEJ. Similarly there was a

decrease in the Hounsefield units from the centre

towards the periphery in horizontal sections. This

could be due to due to the decrease in the

obturation mass towards the periphery. These

findings were observed in all the samples. However

there were no voids in any of the specimens.

According to the result of the present study,

Group - I showed the best results among the

experimental groups with denser and more

homogeneous obturation in both vertical and

horizontal sections which was statistically

significant. This can be attributed to Highly filled

homogeneous matrix, good flow, 0.2% expansion

on setting ,ability to penetrate into the dentinal

tubules due to small particle size of the fillers and

apart from fluid and injectable nature of

GuttaFlow®, use of a master cone could also be the

reason for the denser obturation. This finding is

supported by studies done earlier by MarthaG 13

and Taranu R 14.

Group-II and Group-III showed inferior results

than Group-I which was statistically very highly

significant in the horizontal section and statistically

significant in the vertical section.

This could be attributed to the studies done

earlier by Torabinajed15 and others reported that

“a pattern of voids was frequently noticed in the

case of lateral compaction where the fillings

adapted reasonably well at the apical and coronal

parts and showed longitudinal voids in the mid

root section, thus confirming earlier findings by

Goldman and associates and Schilder16 noted that

with lateral compaction at no time a homogenous

mass is developed. The final filling consists of a

large number of separate gutta-percha cones tightly

compressed together and joined by frictional grip

and cementing substance only.

The results showed that among the subgroup-

III, Group-I showed inferior results than Group-IIand Group-III but was statistically insignificant.

This could be due to the reason that vertical

condensation using a cold plugger in the coronal

third was not done to the specimens in Group-I as

per manufacturer’s instructions,and the possible

reason for Group-II and Group-III to give better

results might be due to the vertical compaction of

the gutta-percha using a cold plugger following

lateral compaction.

The present study was done in vitro on teeth

with straight canals, further in vivo studies are

required to find its applicability in curved and

narrow canals before accepting this material for

routine obturation procedure.

CONCLUSIONFrom the results of the study it can be

concluded that

A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDY


48

1. Obturation done using GuttaFlow® with

backfilling technique is better than lateral

compaction technique.

2. Obturation done using GuttaFlow® with

backfilling technique is superior in the apical and

middle third of the root canal system but is inferior

in the coronal third.

3. Lateral compaction is better in the coronal

third of the root canal, and is inferior in the middle

third compared to GuttaFlow® with backfilling

technique

4. GuttaFlow® when used as sealer is

comparable to zinc-oxide eugenol sealer.

GRAPH - I

GRAPH - II

GRAPH - III

GRAPH - IV

FIGURE 1 - Spiral computed tomography machine used foranalysis of the specimens

Comparison of mean density (HU) Vertical section

Comparison of mean density (HU) Horizontal section

Comparison of mean density (HU) Vertical section– Sub group wise

Comparison of mean density (HU) Horizontal section– Sub group wise

P. SENTHIL KUMAR, A. R. VIVEKANANDA PAI, KUNDABALA M.ENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY


49

FIGURE 2 - Image showing horizontal sections of the speci-mens

FIGURE 3 - Image showing vertical sections of the specimens.

FIGURE .4 - Section showing maximum value in Group-I.

FIGURE 5 - Section showing minimum value in Group-I.

REFERENCES:1. Cohen S, Burns CR. Pathways Of The Pulp, 6th Edition,Mosby, St Louis , Missouri, Page 219.

2. Dow PR, Ingle JI. Isotopes Determination of Root CanalFailure. Oral Surgery 1955:8:1100-4.

3. Ingle JI. Endodontics, 4th Edition, Philadelphia, PA, U.S.A.,Lea & Febiger, Page 25.

4. Brayton SM, Davis SR, Goldman M. Gutta-Percha RootCanal Fillings. Oral Surgery 1973; 35:226-31.

5. Rizzo F, Nocca G. In Vitro Evaluation of a NewExperimental Endodontic Sealer. The 33rd Annual Meeting ofthe AADR, 2004; March 10-13, Honolulu, USA.

6. Eldeniz AU, Orstavik D. Physical Properties of NewlyDeveloped Root Canal Sealers. International EndodonticJournal 2005; 38: 928.

7. Uyanik OM. Comparative Evaluation Of Three Nickel-Titanium Instrumentation Systems In Human Teeth UsingComputed Tomography. Journal Of Endodontics 2006;32:668-70.

8. Nandini S, Kandhaswamy D. Removal Efficiency OfCalcium Hydroxide Intra Canal Medicament With TwoCalcium Chelators: Volumetric Analysis Using Spiral CT - AnIn Vitro Study. Journal of Endodontics 2006; 32: 1097-1100.

9. Gopikrishna V, Bhargavi N. Endodontic Management ofMaxillary First Molar with a Single Root and Single CanalDiagnosed With the Aid of Spiral CT: A Case Report. Journalof Endodontics 2006; 32:687-90.

10. Ingle JI. Endodontics, 4th Edition, Philadelphia, PA, USA.Lea& Febiger, 1994; Page 228.

A THREE-DIMENSIONAL EVALUATION OF DENSITY AND HOMOGENEITY OF ROOT CANAL OBTURATION WITH GUTTAFLOW® USING BACKFILLING TECHNIQUE INCOMPARISON WITH CONVENTIONAL LATERAL COMPACTION TECHNIQUE USING SPIRAL COMPUTED TOMOGRAPHY - AN IN VITRO STUDYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGYENDODONTOLOGY


50

11. Elayoti A, Achleitthner C. Homogeneity and Adaptationof a New Gutta-Percha Paste to Root Canal Walls. Journal ofEndodontics 2005; 31:687-89.

12. Pashley D. Smear Layer; Physiological Considerations.Operative Dentistry Supplement 3, 1984; 13-29.

13. Martha Brackett G. Comparision of Seal After ObturationTechniques Using a Polydimethylsiloxane Based Root CanalSealer. Journal of Endodontics 2006; 32:1188-1190.

14. Taranu R, Wegerer U. Leakage Analysis of Three ModernRoot Filling Materials after 90 Days of Storage. InternationalEndodontic Journal 2005;38:928.

15. Torabinajed M, Skobe Z. Scanning Electron MicroscopicStudy of Root Canal Obturation Using ThermoplasticizedGutta-Percha. Journal of Endodontics 1978;245-50.

16. Schilder H. Filling Root Canals in Three Dimensions.Dental Clinics of North America 1967; 11:723-44



51

Comparative Evaluation of Radiopacity of Three RootCanal Sealers Using Conventional and Digital RadiographicTechnique: An Invitro Study

* PG Student, * * Prof. and Head, Dept. Of Conservative Dentistry and Endodontics, D. A.P. M.R.V. Dental College and Hospital, Bangalore

SWETHA H.B. *SHASHIKALA K. **

INTRODUCTION:Root canal obturation is a critical determinant

of the success or failure of the endodontic

treatment, as it directly affects the outcome of the

endodontic therapy. Majority of endodontic failures

have been caused by incomplete sealing of the root

canal. Obtaining a hermetic seal in root canal is

extremely difficult. However, with the use of root

canal sealers along with well adapted gutta-percha

gives a clinician a better chance to reach this goal.1

Many different root canal sealers are currently

being used in combination with gutta-percha to

fill the root canal after biomechanical preparation.

From many years, gutta-percha has been used as a

core material with zinc oxide eugenol based

sealer.2 However zinc oxide based sealers shrink

upon setting and disintegrate over a period of time

and there by compromises the quality and the life

ABSTRACT:To compare and evaluate the radiopacity of three different root canal sealers using conventional and digitalradiographic technique.

The sealers tested were AH Plus, Endoflas and Pulpdent, by conventional and digital radiographic methods. Thesealers were mixed and placed in a stainless steel ring moulds. Aluminium step wedge was placed along side ofspecimen for the measurement of radiopacity of sealers. Radiographic films were used for conventional methodand the images were obtained after the films were developed from x-ray developing solutions. For digitalradiographic technique the images were obtained from radiovisiograph. The images obtained from both thetechniques were directly transferred to the analytical imaging software to determine the radiopacity of sealersusing grey-pixel values.

All tested materials showed radiopacity above 3mm of aluminium recommended by ANSI / ADA Specification57. Higher mean radiopacity was observed in AH Plus followed by Endoflas and Pulpdent respectively.Conventional method showed a lower value of radiopacity compare to digital radiographic technique. The meanvalues of tested sealers were varying in both the methods.

All tested materials showed radiopacity above 3mm of aluminium recommended by ANSI / ADA Specification57. Digital radiography was better than the conventional radiographic method in evaluating the radiopacity ofroot canal sealers.

KEY WORDS - Radiopacity, Digital radiography, Root canal sealers.


52

expectancy of the apical seal. Recently, a few new

endodontic sealers have been developed with

improvement in the sealing and bonding ability to

the root dentin. These improvements depend on

the incorporation of resin monomer into the sealer.3

The ideal root canal sealer of any types should

meet certain general requirements according to

International Organization of Standardization. In

ascending order of importance, they should be non-

toxic, compatible with living tissues, and exhibit

chemical, physical and radiographic properties

suitable for clinical use.4 Dental diagnosis relies

mainly on radiology. In order to identify and

distinguish a root canal filling materials from the

surrounding anatomical structures, they should be

radiopaque.The root canal filling materials should

have sufficient radiopacity to see clearly the root

canal filling to detect its presence, extent and

apparent condensation.5

Earlier, conventional periapical radiography

was the most common method used for the

evaluation of the technical quality of the obturated

canal. In the conventional radiographic method, the

radiographic images were obtained by the chemical

processing and the radiopacity was evaluated by

an optical densitometer.6 However, the digital

imaging technique is an emerging area of radiology

that offers many potential benefits over

conventional method for the evaluation of

radiopacity of root canal sealers.7 In the past, many

of the literature mainly emphasized on the

solubility, adhesion and antibacterial activity of

different root canal sealers. But there are a few

studies on radiographic properties of root canal

sealers. Hence, an attempt is made to study the

radiopacity of root canal sealers using both

conventional and digital radiographic technique.1

The aim of the present study was to compare

and evaluate the radiopacity of three different root

canal sealers (Pulpdent sealer, Endoflas sealer and

AH Plus sealer) using conventional and digital

radiographic techniques.

MATERIALS AND METHODSThree root canal sealers were evaluated in this

study: AH Plus, Pulpdent and Endoflas (Table 1).

The sample size for each method is eighteen {n=

18}. Six tests are conducted for each sealer in a

method. The sealers were mixed according to the

manufacturer’s recommendations and then

introduced immediately in to two stainless steel

ring moulds (Diameter 10mm, Height 1mm). The

application of the sealers was accomplished with

the use of a syringe to avoid the air bubbles. An

aluminum step wedge made of 1100 alloy, with a

thickness varying 1 to 12mm, in uniform steps of

1mm each was positioned along side the specimen

on a glass slide.

For the conventional method, the specimens

were placed on the radiographic film (Kodak speed

Poly soft). Dental X-ray machine operating at 70

KVp and 10mA with a focus to target distance of

30 cm (ANSI/ADA 2000) was used to take the

radiographic images (fig 1). The exposure was

standardized to 0.6 s. and the films were developed

with standard x-ray developing solutions which

were maintained at constant temperature. Where

as for digital imaging technique, the images were

taken using an RVG sensor (fig 2). The images

obtained from both the methods are transferred to

a computer for the radiopacity evaluation of

radiopacity.

SWETHA H.B., SHASHIKALA K.


53

RADIOPACITY ASSESSMENTThe digital images were analyzed with the Pro

plus 4.1 analytical software system. The ‘bone

density’ tool was applied to the region of the

radiographs containing the sample. Care was taken

to analyze only those regions, which were free of

air bubbles and other anomalies. The bone density

tool produced a graph of the grey- scale value of

each pixel 0(black) to 255(white) in the analyzed

segment, were recorded. Six radiographic images

are taken for each sealer for both conventional and

digital radiographic method. The mean value was

determined and tabulated for both methods (Table

2 & 3). Data were submitted to statistical analysis

using two-way analysis of variance and post hoc

test of Bonferroni (p<0.001).

RESULTSIn both the methods, analysis of variance

showed a statistically significant difference between

the radiopacity means of the tested sealers

(p<0.001). All tested materials showed radiopacity

above 3mm of aluminium as recommended by

ANSI/ ADA Specification 57. However higher

mean radiopacity was observed in AH Plus (D-

9.15mm, C-8.92mm) followed by Endoflas(D-

6.67mm,C-5.02mm) and Pulpdent(D-5.78mm,C-

4mm) respectively (Table 4). The mean values of

tested sealers were varying in both the methods

used. Conventional method showed a lower value

of radiopacity compare to digital radiographic

technique. The difference between them was found

to be statistically significant (p<0.001).

DISCUSSIONRadiopacity is widely acknowledged as a

desirable property of all intraoral materials,

including the endodontic sealers.8 Dental diagnosis

relies mainly on radiology. In order to identify and

distinguish a root canal filling materials from the

surrounding anatomical structures, the root canal

sealers should be radiopaque. The sealer should

contribute to the radiopacity of the root filling for

visualization on radiographs and evaluation of

obturation of lateral canals and apical ramification.

According to International Organization for

Standardization, the radiopacity of root canal

sealers should be more than or equivalent to 3mm

of aluminium.9 In the past, conventional periapical

radiography was the most common method used

for the evaluation of radiopacity of root canal

sealers. In the conventional radiographic method,

the radiographic images were obtained by the

chemical processing of radiographic film, using

developing and fixation solution which is time

consuming.6 However, digital imaging technique

is an emerging area of radiology that offers many

potential benefits such as better contrast,

visualization, sharp images and it is a quick

procedure.11 Digital imaging technique offer

computer based image processing and analysis for

the radiographic evaluation. The images can be

easily stored and retrievable compare to

conventional method.10

In this present study, the root canal sealers

were compared and evaluated for radiopacity using

both conventional and digital radiographic

technique. When digital radiographic method was

compared with conventional radiographic method,

it does not need any conventional periodical

radiographic film or the radiographic chemical

processing, thus saving time and decreasing the

stages that could interfere with the radiographic

quality. In addition, digital radiographic method

gives three dimensional images compare to

COMPARATIVE EVALUATION OF RADIOPACITY OF THREE ROOT CANAL SEALERS USING CONVENTIONALAND DIGITAL RADIOGRAPHIC TECHNIQUE: AN INVITRO STUDY


54

conventional method, which gives only two

dimensional images. It also reduces the operator’s

exposure to radiation and provides detailed analysis

of digital images.5

In this study, aluminium step wedge is used

to compare the radiopacity of root canal sealers. It

is well established that the radiopacity of pure

(99.5%) aluminium is very close to that of human

dentine. Aluminium step wedge is fabricated by

creating several steps of 1mm thickness in

increasing order from a single aluminium block.

In this present study, the steps were created up to

12mm thickness from a single aluminium block.

These steps have the added benefit of speeding

the measurement process.8 According to Steven et

al the aluminium is used for the step wedge because

it has a linear absorption coefficient similar to that

of the enamel, relating the similarity in the variation

of aluminium to hydroxyapetite.5

Results of the present study showed that all

tested materials showed radiopacity above 3mm

of aluminium which is recommended by ANSI/

ADA Specification 57. Conventional method

showed a lower value of radiopacity compare to

digital radiographic technique for the tested sealers.

This variation may be due to the radiographic

chemical processing which can interfere with the

final radiographic quality.5 Tagger and Katz found

that, the digital radiographic method can provides

more consistent results in evaluating the radiopacity

of root canal sealers.9

In the present study, the highest mean

radiopacity was observed in AH plus followed by

Endoflas and Pulpdent respectively. The root canal

sealers vary in their radiopacity, depending

primarily on their thickness, molecular structure,

density, atomic number and the most important

their composition.5 The radiopacifier agents

compatible with high atomic weight, determines

the radiopacity of the sealers. Endoflas and

Plupdent root canal sealer consists of Zinc oxide

and barium sulphate as radiopacifying agents.

Where as AH Plus root canal sealer has newer fillers

like zirconium oxide and iron oxide. This could

contributes to greater radiopacity of AH Plus sealer

when compared to the other sealers tested.6

CONCLUSIONSAll tested materials showed radiopacity above

3mm of aluminium recommended by ANSI/ ADA

Specification No. 57. AH Plus root canal sealer

exhibited highest radiopacity followed by

Endoflas.F.S. and Pulpdent root canal sealer in both

the techniques. However, digital radiographic

method showed more consistent results than the

TABLE 1.Materials used

Product Composition Manufacturer

AH Plus Diepoxide,Calcium tungstate, Zirconium oxide, Aerosil, Pigment,1-adamantane amine, N, N’-dibenzyl-5-oxa-nonandiamine-1,9,Diamine ,Calcium tungstate ,Zirconium oxide, Aerosil ,Silicone oil Dentsply

Endoflas Barium sulphate, zinc oxide, iodoform, eugenol, calcium hydroxide,zinc acetate Sanlor

Pulpdent Zinc oxide, calcium phosphate, barium sulphate, zinc stearate,Eugenol, Canada balsam Pulpdent Corporation



TABLE 4Results of Bonferroni Test

Technique Sealer Mean Std Dev Min Median Max F P-value

Digital AH Plus 9.15 4.01 1.00 11.00 11.00 3.352 0.063

Endoflas 6.67 0.52 6.00 7.00 7.00

Pulpdent 5.78 0.04 6.00 6.00 6.00

Conventional AH Plus 8.92 0.20 8.50 9.00 9.00 2798.115 <0.001*

Endoflas 5.02 0.04 5.00 5.00 5.10

Pulpdent 4.00 0.00 4.00 4.00 4.00

TABLE 2Conventional Radiographic Technique

AH PLUS ENDOFLAS PULPDENT

9 mm 5 mm 4 mm

8.5 mm 5 mm 4 mm

9 mm 5 mm 4 mm

9 mm 5 mm 4 mm

9 mm 5 mm 4 mm

9 mm 5.1 mm 4 mm

TABLE 3Digital Imaging Technique

AH PLUS ENDOFLAS PULPDENT

10.9 mm 7 mm 5.8 mm

11 mm 6.9 mm 5.7 mm

11 mm 6.9 mm 5.8 mm

11 mm 7 mm 5.8 mm

10.8 mm 7 mm 5.8 mm

1 mm 7 mm 5.8 mm

conventional radiographic method in evaluating

the radiopacity of root canal sealers. Hence, the

growing acceptance of digital technology as an

alternative to conventional radiography in day to

day clinical practice reveals demands for the

development of international standards for

electronic imaging.

FIGURE 1:

Stainless steel ring mould

Aluminium step wedge

Root canal sealer

A B C

Conventional radiographic images of A. AH plus sealer B. Endoflas sealer C. Pulpdent sealer

COMPARATIVE EVALUATION OF RADIOPACITY OF THREE ROOT CANAL SEALERS USING CONVENTIONALAND DIGITAL RADIOGRAPHIC TECHNIQUE: AN INVITRO STUDY

55


Digital radiographic images of A. AH plus sealer B. Endoflas sealer C. Pulpdent sealer

FIGURE 2:

A B C

REFERENCES:1. Gianluca Gambarini, Luca Testarelli, Giancarlo Pongione.Radiographic and rheological properties of a new endodonticsealer. Aust Endod J: 2006; 32: 31-34.

2. M.A.Verasiani, J.R.Carvalho-Jr. A comparative study ofphysicochemical properties of AH Plus and Epiphany rootcanal sealants. Int Endod J: 2006; 39: 464-471.

3. AH Plus sealer. Scientific compendium: DENTSPLY;2005:4-19.

4. M.Tanomaru-Filho, E.G.Jorge, M.Goncalves. Evaluation ofthe radiopacity of calcium hydroxide and GIC based root canalsealers. Int Endod J:2008;41:50-53.

5. Steven Gu, Brain J, Barry Lee Musikant. Radiopacity ofdental materials using digital X-ray system. Dent Mater: 2006;22: 765-770.

6. J.R.Carvalho-Jr, L.Correr-Sobrinho, M.D.Sousa-Neto.Radiopacity of root filling materials using digital radiography.Int Endod J: 2007; 40: 514-520.

7. Mario Tanomaru-Filho, Erica Gouveia Jorge. Radiopacityevaluation of new root canal filling materials by digitalizationof images. J Endod: 2007; 33: 249-251.

8. D.C.Watts, J.F.McCabe. Aluminium radiopacity standardsfor dentistry: an international survey. 1999,Dec:30

9. Michael Tagger, Alexander Katz. Radiopacity of endodonticsealers: Development of a new method for directmeasurement. J Endod: 2003; 29: 751-755.

10. J Sabbagh, J Vreven, G Leloup. Radiopacity of resin basedmaterials measured in film radiographs and storage phosphorplate (Digora). Operative Dentistry: 2004; 29: 677-684.

11. B.Guniz Baksi, Tan Firat, Bilge Hakan Sen, Necdet Erdilek.The effect of three different sealers on the radiopacity of rootfillings in simulated canals. Oral Surg Oral Med Oral PatholOral Radiol Endod: 2007; 41: 103-138.

12. M.Tagger, A.Katz. A standard for radiopacity of root end/retrograde filling materials is urgently needed. Int Endod J:2004; 37: 260-264.


56


The Effect of File Sizes in the Presence of SodiumHypochlorite and Blood on the Accuracy of Root Zx ApexLocator in Enlarged Root Canals - an In Vitro Study

PALUVARY SHARATH KUMAR *VASUNDHARA SHIVANNA **

* P. G. Student, ** Professor & Head, Dept. of Conservative Dentistry and Endodontics, College of Dental Sciences, Davangere - 577004, Karnataka.

ABSTRACT:The purpose of this study is to assess the effects of file size in the presence of Sodium hypochlorite and blood onthe efficacy of Root ZX apex locator in enlarged root canals.

The study sample comprised of 40 extracted straight, single rooted human lower premolars were used. Thecrowns of the teeth were removed with a low speed diamond saw. The actual canal length was determined byintroducing size 10 K-file in the canal until the tip of the file became visible at the major apical foramen under adigital microscope at 10X magnification.

Teeth were divided randomly into two groups, Group A (6% NaOCl) and Group B (Human blood containingEDTA as anticoagulant) of 20 teeth each (n=20). All the teeth were instrumented in three different stages.

Stage I: A 40 K-file was used as MAF, Stage II: A 60K-file was used as MAF.

Stage III: A 80 K-file was used as MAF.

Each tooth of both Groups of all stages and Root ZX apex locator were subsequently connected together in theexperimental set-up. Before electronic canal measurements, the canals were irrigated with 6% NaOCl in groupA, while in group B the canals were filled with human blood containing EDTA as an anti-coagulant. Then thereadings were taken with 10 K-File to the respective MAF sizes of the respective stages. The obtained readingswere compared with the actual canal lengths and statistically analyzed using three way ANOVA and Bonferronitests.

Three way ANOVA and Bonferroni test showed that file size, stage of preparation and type of irrigant all had asignificant influence on the measurement error (P<0.0001), with all the interactions between these three factorsbeing significant.

The present study indicates that, even in fully controlled in vitro study conditions, there is some inconsistency inthe EAL measurements. Because of this potential inconsistency, EALs should not be used to replace the routineradiographic confirmation of the canal length in endodontic therapy.

Keywords: Agar, blood, electronic apex locator, file size, root length determination, root canal preparation,sodium hypochlorite solution.

57



INTRODUCTIONDetermination of working length is the first

important step in root canal debridement. It is

imperative that root canal debridement procedure

be confined to the canal in order to prevent

irritation of the periapical tissues and possible

overextension of the root canal filling (Ingle et al.

1994).2

Many reports show a mean apex-to-apical

foramen distance of around 0.5-1 mm8. However,

this site can be misinterpreted on a two dimensional

film. In cases where the apical foramen is eccentric

to the root apex ie., exit deviates bucco-lingually14,

or superimposition of normal anatomical features

and pathological changes on apical tooth, such as

impacted teeth, tori, the zygomatic arch, excessive

bone density, overlapping roots, or shallow palatal

vaults.

In 1942 Suzuki reported a device that

measured the electrical resistance between the

periodontal ligament and the oral mucosa and

registered a consistent value of approximately 6.5

k&!3.

First generation models which work on

electrical resistance were considered not accurate

in the presence of conductive fluids in the canal.

Consequently, one manufac-turer placed plastic

insulation over the electronic probe to prevent

electrical conductance through moist canal

contents. However, the thickness of the insulating

material prevented entry of the probe into tight and

tortuous canals, especially at midroot and the apical

level5.

The recently developed Root ZX (J. Morita Co)

electronic apex locator which works on the ratio

method can ac-curately measure the canal length

even under electro conductive conditions23. The

ratio method simultaneously measures the

impedances of the canal using two different

frequency (400 Hz and 8 Hz) currents and

calculates the quotient of the impedances11.

Usually for electronic canal measurements

with EALs requires the file size to be comparable

to the diameter of the canal. But the manufacturer

claims that the canal measurements with Root ZX

can be done with a much smaller file compared to

the diameter of the root canal2.

So in this study we check the effect of file sizes

in the presence of sodium hypochlorite and blood

on the accuracy of Root ZX apex locator in enlarged

root canals (In Vitro Study).

MATERIALS AND METHODSA total of 40 extracted, straight, single-rooted

human lower premolars with complete root

formation and stored in distilled water containing

10% formalin were used. Dental digital X-ray

images were taken in both buccolingual and

mesiodistal directions to evaluate the root canal

anatomy. The crowns of the teeth were removed

with a low speed diamond saw to standardize the

root length to 14.5mm and to allow access to the

root canal and establish a level surface to serve as

a stable and unequivocal reference for all

measurements. The actual canal length was

determined by introducing a size 10 K-file in the

canal until the tip of the file became visible at the

major apical foramen under a digital microscope

at x10 magnification. A rubber stop was then

carefully adjusted to the reference level and the

distance between the rubber stop and the file tip

was measured and recorded. Gates Glidden drills

VASUNDHARA SHIVANNA, PALUVARY SHARATH KUMAR

58


(size 1-4, Mani, Tochigi, Japan) were then used to

prepare the coronal portion of the canal, while the

middle and apical portions of the canal were

prepared using size 10 K-files with six per cent

NaOCl for irrigation.

Experimental set up:

(a) K File. (b) Self cure acrylic. (c) Lid. (d) Polystyrene specimenbottle. (e) Tooth. (f) 1% agar which simulates as artificialperiodontium.

Each tooth was fixed to the lid of a polystyrene

specimen bottle with self-curing resin. A stainless

steel rod is screwed into the body of the specimen

bottle, was used as a neutral electrode. The

specimen bottles were then filled with one per cent

concentration of heated agar. The caps were

immediately placed over specimen bottles and the

model assemblies were refrigerated for two hours

to allow the agar to set. Each tooth and Root ZX is

connected together and used to take readings.

The teeth were divided into 2 groups (Group

A and Group B) depending upon the contaminants

used in the canals ie, 6% NaOCl and human blood

containing EDTA as anticoagulant.

The canal preparation of both Group A and

Group B teeth were done in three stages.

In stage I, a size 40 K-file was used as the

master apical file (MAF) and it was confirmed that

the larger size (>40 K-file) did not reach the apex.

The apical portion of the canal was then

instrumented using the step-back sequence by

decreasing the working length of larger files by

0.5mm. The canal was irrigated with 2ml NaOCl

using an endodontic syringe with a 27 gauge needle

in an up-down motion.

In stage II, the teeth were removed from the

specimen bottles and the canals were instrumented

in same manner and enlarged using a size 60 K-

file as the MAF.

In stage III, the teeth were removed again from

the specimen bottles and the canals were

instrumented in same manner and enlarged using

a size 80 K-file as the MAF.

All the teeth in each stage are connected to

the Root ZX as shown in experimental set up and

readings were taken with 10 K-file to MAF size of

the respective stage. The electronic measurement

was taken three times for each file and the average

value was calculated.

For each average reading, the error in

measurement was calculated as the absolute

difference between the electronically measured

canal lengths and the actual canal lengths. Three-

way ANOVA was conducted to investigate the

influence of file size, stage of preparation and the

type of irrigant on the measurement error. Multiple

comparisons were performed with Bonferroni test.

To compensate for the influence of differences in

the actual canal lengths on the measurement errors,

the actual canal length was set as a covariant in

the statistical analysis.

THEEFFECT OF FILE SIZES IN THE PRESENCE OF SODIUM HYPOCHLORITE AND BLOOD ON THE ACCURACY OFROOT ZX APEX LOCATOR IN ENLARGED ROOT CANALS - AN IN VITRO STUDY

59


RESULTSTable 1 & 2 shows the mean and standard

deviation of length and initial canal length

measurements obtained before canal enlargement

for both groups A and B. Three-way ANOVA and

Bonferroni test showed that the file size, stage of

preparation and type of irrigant had a significant

influence on the measurement error (P< 0.000l)

with all the interactions between these factors being

significant (P<0.0001). At stage 3, the

measurement error showed the largest absolute

difference in group B (1.11mm) when a size 10 K-

file was used. At all stages in both groups A and B,

the measurement error was less than 0.03mm when

the MAF were used.

DISCUSSIONMethods for the canal length determination

are either the manual or the radiographic

approaches for the precise localization of apical

narrowing. The manual technique obviously

depends on the sensitivity of the operator, whereas

in the radiologic approach, the calculation of the

working length is made with respect to the position

of the radiographic apex which not only does not

coincide with apical narrowing or even with the

apical foramen, but also depends on the series of

factors: tooth inclination, film position, length of

the beam cone, vertical and horizontal cone

angulation, and so forth. Nevertheless, the main

inconvenience is that both approaches are entirely

subjective and therefore scantly reproducible16.

Using radiography followed by subsequent

tooth extraction and sectioning, Stein and Corcoran

found that the radiographically established working

length did not actually coincide with the true apical

vertex. Electronic apex locators (EAL) have been

used clinically for more than 40 years as an aid to

determine the file position in the canal. These

devices when attached to a file are able to detect

the point at which the file leaves the tooth and

enters the periodontium. EALs obviate this problem

because their readings are not related to the apical

vertex but rather to the apical foramen.1

Early EALs were based upon the work of

Suzuki and Sunada. They relied on the principle

that the electrical resistance between the oral

mucosa membrane and the periodontium remained

constant ie, 6.5 k&!, regardless of the age of the

patient and type and shape of the tooth.3 These

devices allowed measurement of the canal length

by comparing the electrical resistance that was built

into the apex locator with the resistance between

the tip of the file and that of the periodontal

membrane.11

McDonald notes that resistance type EALs

should be operated in a reasonably dry canal or

may be used with RC Prep. NaOCl or saline

irrigants, being ionic solutions, are electrical

conductors that could cause false readings. When

using ionic irrigants and the resistance type EALs,

additional time must be taken to dry the canals

before taking as electronic measurement.9

A frequency dependent apex locator has

recently been introduced. Two electric frequencies

are normally used and the impedance difference

between the two frequencies reaches its maximum

at the apical constriction of the root canal. A

modification of this device is the Root ZX apparatus.

It is based on the principle that the ratio of electrical

impedance between two frequencies is nearly

equal when the tip of the file approaches the apical

constriction and expresses this quotient in terms


60


of the position of the electrode (file) inside the

canal. This quotient is hardly affected by the type

of electrolyte in the canal.8

The Root ZX needs no calibration. The

microprocessor of the device corrects the

calculated quotient so that the position of the tip

and the meter reading are directly related. This

occurrence means that root canal enlargement can

easily be performed while the length of the root

canal is simultaneously monitored.23

However, it has been proven that the

pathological changes in the pulp lead to changes

in the concentration of ions. Consequently, its

electrophysiological characteristics are changed,

which affects the accuracy of EALs. These changes

can be recorded by physical parameters, such as

measurement of the electronic potential of pulp,

electric conduction, or analysis of cations. Thus it

is possible to say that biological changes, effect on

the EAL measurements.15

In the present study, the apical portion of the

canal was enlarged and the apical constriction was

destroyed, although the conical shape of the canal

was still maintained. Group A showed statistically

significant better scores than Group B. In the

presence of NaOCl, the Root ZX was accurate and

the length measurements obtained with small and

large size files were comparable. The results of

Group A confirmed those of Nguyen et al., who

found that the Root ZX was accurate even when

the file was much smaller than the diameter of the

canal.

Many studies have used a ±0.5mm error

range to assess the accuracy of the EALs.

Measurements obtained with this tolerance are

considered highly accurate. Other studies rely on

a more lax clinical range of ±1.0mm to the

foremen. One reason cited for accepting a

±1.0mm margin of error is the wide range seen in

the shape of the apical zone. The results obtained

in Group B with the smaller size files may not be

clinically acceptable because the measurement

error showed the largest absolute difference value

(1.11mm) when a size 10 K-file was used. And it is

recommended that the use of files with sizes

comparable with the root canal diameter, claiming

that this would result in more accurate readings.

The results showed that file size, stage of

preparation and the type of irrigant all had a

significant influence on the measurement errors

(P<0.0001) with all the interactions between these

three factors being significant (P<0.0001). In Stage

III, the measurement error showed the largest

absolute difference in both Groups A (0.19mm) and

B (1.11mm) when a size 10 K-File was used. At all

stages in both Groups A and B, the measurement

error were less than 0.03mm when the MAFs were

used.

The present study and previous studies appear

to indicate that, even in fully controlled in vitro

study conditions, there is some inconsistency in

the EAL measurements. Because of this potential

inconsistency, EALs should not be used to replace

the routine radiographic confirmation of the canal

length in endodontic therapy

CONCLUSIONAs the diameter of the root canal increased,

the measured length with the smaller size files

became shorter. This suggests that the size of the

root canal diameter should be estimated with a

snug-fitting file should be chosen for root canal


61


length measurement in the presence of blood, and

possibly serum or pus. In the presence of NaOCl,

the Root ZX was highly accurate even when the

file was much smaller than the diameter of the

canal.

Table No. 1: Comparison of Stage I, II, & IIIof Group A

Group A Stage I Stage II Stage III

10 0.10 0.16 0.19

15 0.08 0.15 0.17

20 0.07 0.14 0.15

25 0.05 0.13 0.15

30 0.04 0.12 0.12

35 0.03 0.10 0.12

40 0.02 0.08 0.11

45 0.08 0.11

50 0.06 0.10

55 0.05 0.10

60 0.02 0.08

70 0.06

80 0.02

The present study, there is some inconsistency

in the EAL measurements. Because of this potential

inconsistency, EALs should not be used to replace

the routine radiographic confirmation of the canal

length in endodontic therapy. Further clinical

studies are needed to evaluate EALs.

Group B Stage I Stage II Stage III

10 0.37 0.91 1.11

15 0.30 0.78 1.05

20 0.24 0.65 1.00

25 0.16 0.50 0.91

30 0.11 0.47 0.87

35 0.07 0.38 0.75

40 0.03 0.30 0.70

45 0.20 0.65

50 0.16 0.58

55 0.10 0.45

60 0.03 0.28

70 0.22

80 0.03

Table No. 2: Comparison of Stage I, II, & IIIof Group B


62


Fig. 1. Decoronated teeth of Group AFig. 2. Decoronated teeth of Group B

Fig. 3. Group A samples embedded in Agar material Fig. 4. Group B samples embedded in Agar material

Fig. 5. ExperimentalFig. 6. Stereomicroscope


63



REFERENCES:1. Ebrahim AK, Yoshika T, Kobayashi C, Suda H. AustralianDental Journal 2006;51(2):153-157

2. Nguyen HQ, Kaufman AY, Komorowski RC, Friedman S.International Endodontic Journal 1996;29:359-364

3. Anthony Meares W, Robert Steiman H. Journal ofEndodontics 2002:28(8);595-598

4. Joslyn A. Jenkins, William A.Walker, William G. Schindler,Christopher M. Floes. Journal of Endodontics 2001:27(3);209-211

5. Ounsi H F, Naaman A. International Endodontic Journal1999:32;120-123

6. Kaufman A V, Katz A Journal of Endodontics (AAE Abstractof Papers) 1993:19(4);201

7. Roland Weiger, Christoph John, Heiner Geigle, Zahnarzt,Claus Lost. Journal of Endodontics 1999:25(11);765-768

8. Vajrabhaya L, Tepmongkol P. Endod Dent Traumatol1997:13;180-2.

9. Russell J. Czerw, Michael S. Fulkerson, Jerome C. Donnelly,

and James O. Walmann. JOE 1995: 21(11); 572-575

10. Fabio Luiz D Assuncao, Diana Santana de Albuquerque,and Linalda Correia Ferreira. JOE 2006:32(6);560-562

11. Jose L. Ibarrola, brent L. Champman, James H. Howard,Kenneth I. Knowles, and Marvin O. Ludlow. JOE1999:25(9); 625-626

12. Chihiro Kobayashi, and Hideaki Suda. JOE1994:20(3);111-114.

13. Craig A. Dunlap, Nijole A. Remeikis, Ellen A. BeGole,and Cindy R. Rauschenberger. JOE 1998: 24(1); 48-50.

14. Shahrokh Shabahang, William W.Y. Goon, and Alan H.Gluskin. JOE 1996:22(11);616-618.

15. Maja Kovacevic, and Tomislav Tamarut. JOE 1998; 24(5):346-351.

16. Lucena –Martin C, Robles-Gijon, Ferrer-Luque C M, andNavajas-Rodriguez de Mondelo J M. JOE 2004;30 (4):231-233.

17. Marat Tselnik, Craig Baumgartner J, and Girdon MarshallJ. JOE 2005; 31 (7): 507-509.


64


Sealing Ability of Four Materials in the Orifice of RootCanal Systems Obturated With Gutta-Percha

ABHISHEK PAROLIA *KUNDABALA M. **SHASHI RASMI ACHARYA ***VIDYA SARASWATHI ****VASUDEV BALLAL *****MANDAKINI MOHAN ******

* Assistant Professor, ** Professor and HOD, *** Professor and HOD, **** Associate Professor, ***** Reader, ****** Assistant Professor, Dept. of Prosthodontics,Manipal College of Dental Sciences, Mangalore. Karnataka. India.

ABSTRACTFailure to maintain the coronal as well as apical seal may expose obturated canals to microbes that could retardhealing and create infection in the periodontal ligament or supporting osseous structures. 50 single rooted teeth(Type I canal anatomy) were randomly assigned to 4 experimental and 2 control groups. Ten specimens eachwere sealed with Mineral Trioxide Aggregate (MTA), Tetric Flow, Glass Ionomer Cement (GIC) and Light CureGlass Ionomer cement (LC GIC). After creation of uniform orifice diameter, the smear layer was removed and thecanal systems obturated using lateral compaction of gutta-percha (GP). GP was removed to the depth of 3.5 mm,experimental materials placed in orifice and the roots submerged in Rhodamine-B dye in vacuum for one week.Specimens were longitudinally sectioned and leakage measured using a 10X stereomicroscope and graded fordepth of leakage. According to the result of the present study LC GIC demonstrated significantly better seal(p<.01) than MTA however there was no statistically significant difference in leakage (p>.01) between TetricFlow, GIC and LC GIC and in between MTA, Tetric Flow and GIC.

Key Words: Orifice barrier, Tetric flow, GIC, LC GIC, MTA, Dye under vacuum

INTRODUCTIONCoronal microleakage can produce complete

bacterial penetration in nonsurgical root canal

treated teeth ( 1, 2). It has been reported that 59.4%

of endodontically treated teeth failed because of

lack of an adequate post endodontic restoration

(3). Loss of coronal seal may occur due to leakage

of temporary filling material or fracture of the

permanent restoration. Perhaps the use of a material

to seal the orifice, in addition to the restoration,

could mitigate this bacterial leakage if that

restoration was lost or became unserviceable. It

has been reported that root canal treated teeth

without coronal barrier had significantly more

failure rate than teeth with coronal barrier of

amalgam, composite resin, glass ionomer or

intermediate restorative material (4).Despite

research supporting the effectiveness of coronal

barriers, a universally accepted protocol that

incorporates a coronal barrier after root canal

therapy is nonexistent. Thus, the addition of another

barrier between the oral environment and the root

canal system appeared to have a positive effect in

reducing leakage and increasing possibilities for

success.

Hence the purpose of this investigation was

65


to evaluate and compare the sealing ability of four

experimental materials as an intra-orifice barrier

after obturation of root canal system.

MATERIALS AND METHODS50single-rooted teeth, with Type I canal

system, stored at 100% humidity were used.

Crowns were removed at the cementoenamel

junction using diamond disc. A #10 K-file (Denstply

Maillefer, Swiss made, Ballaigues) was inserted and

advanced until it was visualized at the apical

foramen. The file was retracted 1 mm and working

length was established at this level. A ProTaper SX

file (Denstply Maillefer, Swiss made, Ballaigues)

was used to flare the orifice. 5.25% NaOCl (Vishal

Dentocare Pvt Ltd, India) and RC Prep (Medical

Products Laboratories INC) were used in between

each instrument. ProTaper SI, S2, Fl, F2, and F3

files were used sequentially per manufacturer’s

instructions in a crown down technique. A uniform

orifice diameter of 1.3 mm, at its widest point, was

made using a #5 Gates Glidden bur (MANI, INC

Japan) to a depth of 3.5mm. Once instrumentation

was completed, the canal was rinsed with two ml

of 5.25% NaOCl, followed by 2 ml of 17% EDTA

solution, and with a final rinse of chlorhexidine

0.2%w/v (ICPA Health Products LTD, India). Canals

were dried with sterile paper points and obturated

with .02 taper gutta-percha points (Denstply

Maillefer Swiss made, Ballaigues) and AH plus

sealer (Denstply DeTrey gMbH Germany) in lateral

compaction technique.

40 teeth randomly divided into four

experimental groups, with the remaining ten teeth

being divided equally between positive and

negative controls.

Group Number Experimental Intraorificeof teeth sealing material

Group I 10 Mineral TrioxideAggregate (MTA)

Group II 10 Tetric Flow

Group III 10 Glass Ionomer Cements(GIC)

Group IV 10 Light cured Glass IonomerCements (LC GIC)

+ve Control 5 Instrumented and obturatedteeth with gutta-perchaat the level of the orifice.

-ve Control 5 Instrumented and obturatedteeth with three coats ofnail polish

Heat carrier was used to remove gutta-percha

to the depth of 3.5 mm and verified the depth with

a periodontal probe. ProRoot MTA (Dentsply/tulsa

Dental Products), Tetric flow (Ivoclar Vivadent),

GIC (GC Corporation Tokyo, Japan) and LCGIC

(GC Corporation Tokyo, Japan) were placed into

the orifice as per manufacturer’s directions in

samples of respective groups. Each tooth was

placed into a coded container and allowed for

sealer and all experimental materials to set. All

these samples were kept in humidor for 48 hrs.

Three layers of nail varnish were placed on

all experimental teeth coating their root surface

from root apex to the level of the cementoenamel

junction. Positive controls were obturated, but not

coated with nail varnish. Negative controls were

obturated and completely coated with nail polish,

including the orifice. Samples were submerged in

a vacuum flask containing Rhodamine-B dye,

subjected to vacuum pressure of 75 torr for 30

minutes, and allowed to remain in the dye for seven

days (5). After exposure to the dye, samples were

rinsed with running water to remove dye from the

external surface. Nail varnish was gently removed

ABHISHEK PAROLIA, KUNDABALA M., SHASHI RASMI ACHARYA, VIDYA SARASWATHI, VASUDEV BALLAL, MANDAKINI MOHAN

66


with a# 15 disposable safety scalpel .These samples

were longitudinally sectioned using diamond disc

and samples were observed and leakage was

measured to the greatest penetration using a 10X

stereomicroscope (Olympus) using micrometer

from the coronal extent of the orifice material.

Results were tabulated and data were analyzed

using ANOVA & Tukey Tests.

RESULTSPositive controls leaked at least 5 mm into the

gutta-percha, and no leakage was observed in the

negative control group. Table 1 shows mean depth

of penetration, in millimeters, for each material.

MTA has shown the maximum leakage, at 1.6

mm mean penetration while LC GIC has shown

the least, at 1.1 mm mean penetration which

showed statistically significant difference between

MTA and LC GIC. There was no statistically

significant difference in leakage (p>.01) between

Tetric Flow, GIC and LC GIC and in between MTA,

Tetric Flow and GIC.

DISCUSSIONAn efficient seal to prevent leakage in the root

canal system from both oral fluids & peri-radicular

tissues is prerequisite for the success of endodontic

treatment. Teeth obturated with gutta-percha and

sealer, in the absence of a temporary restoration,

showed leakage ranging from 70% to 85% of the

root length within 56 days, when exposed to

saliva(2).

It has also been pointed out the importance

of the temporary seal lasting even after root canal

therapy is completed, emphasizing the importance

of early final restoration of the tooth (6). Iowa group

found that endotoxin can penetrate obturating

material faster than bacteria and they also extended

the caveat: “the need for an immediate and proper

coronal restoration after root canal treatment is

therefore reinforced (7). At University of Tennessee,

the Himel group reported that “the teeth without

an intraorifice barrier leaked significantly more than

the teeth with glass Ionomer barrier (8). So the

present study is undertaken to evaluate and

compare the sealing ability of four experimental

which have been shown to have good sealing

ability with coronal as well as radicular dentin (9,

5,10).

Dye penetration method to check the

microleakage is a simple, easier and cost effective

method so we decided to use this method. This

study used Rhodamine-B dye as it has small particle

size, better penetration, water solubility,

diffusability and hard tissue non-reactivity (11).we

have used dye under vacuum penetration method,

It has been reported that vacuum helps to remove

entrapped air which can prevent complete dye

penetration (12). It has been reported that 3.5 mm

of material to be the minimum thickness required

in coronal restorations to prevent leakage so in this

study material thickness of 3.5 was taken to seal

the canal orifice (13).

The results of this study indicated that LC GIC

demonstrated a significantly better seal than MTA,

Tetric Flow and GIC. This could be due to

command setting and better adhesion with tooth

structure. Resin modified glass ionomers set by two

mechanisms: acid-base reaction common to all

glass ionomers and a photochemical

polymerization of water soluble monomers and

methacrylate groups(14).Polymerization shrinkage

still occurs in these materials due largely to resin

SEALING ABILITY OF FOUR MATERIALS IN THE ORIFICE OF ROOT CANAL SYSTEMS OBTURATED WITH GUTTA-PERCHA

67


component; however immature cement continues

to take up fluid from dentin, causing the material

to expand which compensates polymerization

shrinkage(15).The adhesion of LC GIC appears to

be by development of an ion-exchange layer

adjacent to the dentin similar to conventional glass

ionomer materials(16). Moreover the shear bond

strength of LC GIC is said to be higher than

conventional GIC (17, 18). This is due to the slow

acid-base reaction in LC GIC and availability of

polyacid for a longer time So this might have

contributed for the better sealing ability.

In the present study MTA has shown

statistically significantly more leakage than LC GIC,

this could be attributed to the absence of tissue

fluid in root canal treated teeth which could

interfere in growth of hydroxyapatite crystals,

responsible for chemical bonding (19).It has also

been found that a secondary seal was required over

MTA in furcation restorations to minimize leakage

as MTA was easily discerned from dentin and easy

to remove with ultrasonics (20).

Conventional GIC and Tetric Flow have

shown more leakage than LC GIC but it is not

statistically significant. This could be due to weaker

bonding of conventional GIC (17) than LC GIC and

more polymerization shrinkage of Tetric Flow than

LC GIC (21).

So, the present study concludes that double

seal is required which could be achieved by using

an intra-orifice barrier. In this study LC GIC has

found to be superior over other experimental

materials as an intra-orifice barrier. However,

further research such as a long-term study using

other methods of microleakage detection, may

confirm better clinical results.

Materials Number Mean Std.Deviation Minimum Dye Maximum DyePenetration (mm) Penetration (mm)

MTA 10 1.6375 0.60955 0.50 2.50

Tetric flow 10 1.4250 0.38819 1.00 2.25

GIC 10 1.265 0.51603 0.50 2.10

Light cured GIC 10 1.1125 0.45505 0.50 2.00

Table1. Comparison of marginal means of depth of penetration for experimental materials

Mean PDifference

MTA Tetric flow 0.2125 0.540GIC 0.3750 0.092LC GIC 0.5250 0.008 s

Tetric flow GIC 0.1625 0.735

LC GIC 0.3125 0.207

GIC LC GIC 0.1500 0.780

P= .01s

Table 2


68

Figure1. Mean dye penetration in respective groups(Stereomicroscope 10 X)


MTA Tetric Flow

GIC LC GIC

REFERENCES:1. Swanson K, Madison S. An evaluation of coronalmicroleakage in endodontically treated teeth. Part I: timeperiods. J Endod 1987; 13:56-9.

2. Madison S, Swanson K, Chiles SA. An evaluation of coronalmicroleakage in endodontically treated teeth. Part ll: sealertypes. J Endod 1987; 13:109-12.

3. Vire DE. Failures of endodontically treated teeth:classification and evaluation. J Endod. 1991; 17:338-42.

4. Carman JE, Wallace JA. An invitro comparison ofmicroleakage of restorative materials in the pulp chamber ofhuman molar teeth. J Endod 1994; 20:571-75.

5. Jenkins S, Kulild J, Williams K. Sealing ability of threematerials in the orifice of root canal systems obturated withgutta-percha. J Endod 2006; 32:225-27.

6. Khayat A, Lee SJ, Torabinejad M. Human saliva penetration

of coronally unsealed root canals. J Endod 1993; 19(9):458-61.

7. Alves J, Walton R, Drake D. Coronal leakage: Endotoxinpenetration from mixed bacterial communities throughobturated post-prepared root canals.J Endod 1998; 24(9):587-91.

8. Wolcott JF, Hicks ML, Himel VT. Evaluation of pigmentedintraorifice barriers in endodotically treated teeth. J Endod1999; 25(9):589-92.

9. Barrieshi-Nusair KM, Hammad HM. Intracoronal sealingcomparision of mineral trioxide aggregate and glass Ionomer.Quint Int 2005; 36:539-45.

10. Barthel CR, Strobach A. Leakage in roots coronally sealedwith different temporary filling. J Endod 1999; 25(11):731-34.

11. Wu MK, Wesselink PR. Endodontic leakage studies

SEALING ABILITY OF FOUR MATERIALS IN THE ORIFICE OF ROOT CANAL SYSTEMS OBTURATED WITH GUTTA-PERCHA

69


reconsidered. Part I. Methodology, application and relevance.Int Endod J 1993; 26: 37–43.

12. Wimonchit S et al. A comparison of techniques forassessment of coronal dye leakage. J Endod 2002;28(1):1-4.

13. Webber RT , del Rio CD, Brady JM, Segall RO. Sealingquality of a temporary filling material.Oral Surg Oral MedOral pathol. 1978; 46:123-30.

14. Seiler KB. An evaluation of glass ionomer paste restorativematerial as temporary restorations in endodontics. Gen Dent2006; Jan-Feb: 33-6.

15. Wilson AD. Resin modified glass ionomer cements. Int JProsthodont 1990; 3:425-9.

16. Lin A, McIntyre NS, Davidson RD. Studies on adhesionof glass Ionomer cements on dentin. I Dent Res 1992;71:1836-41.

17. Burgess JO, Barghi N, Chan DCN, Hummert T. A

comparative study of three glass Ionomer base materials. AmJ Dent 1993; 6:137-41.

18. Kerby RE, Knobloch L. The relative shear bond strengthof visible light curing and chemical curing glass Ionomercement to composite resin. Quint Int1992; 23:641-44.

19. Sarkar NK et al. Physicochemical basis of the biologicproperties of mineral trioxide aggregate. J Endod 2005;31(2):97 – 100.

20. Hardy I, LIewehr FR, Joycc AP, Agee K, Pashley DH.Sealing ability of one-up bond and MTA with and without asecondary seal as; furcation perforation repair materials. JEndod 2004; 30:658-61.

21. Miguez PA, Pereira PN, Foxton RM, Walter R, NunesMF, Swift EJ Jr. Effects of flowable resin on bond strength andgap formation in Class I restorations. Dent Mater. 2004 Nov;20(9):839-45.


70


Current Endodontics LiteratureSowmya Shetty, Associate Professor, Department of Conservative Dentistry and Endodontics, A. J. Institute of Dental Sciences, Mangalore

71

Clinical Studies of Fiber Posts: A Literature Review

Maria C. Cagidiaco, MD, DDS, PhDa/Cecillia Goracci, DDS, PhDb/Franklin Garcia-Godoy, DDS, MSc/Marco Ferrai,MD, DDS, PhDd (2008)

This literature review aimed to find answers to relevant questions regarding the clinical outcome of endonticallytreated teeth restored with fiber posts. All clinical studies published since 1990 in journals indexed in MEDLINEwere retrieved by searching PubMed with the query terms “fiber posts and clinical studies.” The reference list of thecollected articles was also screened for further relevant citations. The strength of the evidence provided by thereviewed papers was assessed according to the criteria of evidence-based dentistry. Five randomized controlledtrials (RCTs) on fiber posts have been published in peer-reviewed journals. A meta-analysis is not applicable to thesestudies since they do not address the same specific clinical question. Retrospective and prospective trials withoutcontrols are also available. Two RCTs indicate that fiber-reinforced composite posts outperform metal posts in therestoration of endontically treated teeth. However, this evidence cannot be considered as conclusive. Longer-termRCTs would be desirable. The placement of a fiber-reinforced composite post protects against failure, especiallyunder conditions of extensive coronal destruction. The most common type of failure with fiber-reinforced compositeposts is debonding.

‘Int J Prosthodont; 21:328-336’,2008

Association between Bifidobacteriaceae and the clinical severity of root caries lesions

M. Mantzourani, M. Fenlon, D.Beighton

The isolation of members of the family Bifidobacteriaceae (bifids) from oral samples has been sporadic and arecent cloning study has suggested that they are not detectable in root caries lesions.

To better understand the presence of bifids in root caries we obtained clinical samples (15 of each) from soundexposed root surfaces, leathery remineralizing root lesions, and soft active root lesions. We investigated each for thepresence of bifids using a mupirocin-containing selective medium and identified the isolates using 16S recombinantRNA sequencing.

The proportion of bifids, as a percentage of the total anaerobic count, was significantly related to the clinicalstatus of the sites sampled, being 7.88±1.93 in the infected dentine from soft lesions, 1.61 ± 0.91 in leatherylesions, and 0.05±0.39 in plaque from sound exposed root surfaces. Bifids were isolated from all soft lesions, 13 of15 leathery lesions, and five of the plaque samples. Bifidobacterium dentium was isolated from four of the plaquesamples, from 13 samples from leathery lesions, and from 12 of the 15 samples of infected dentine from the softactive lesions. Parascardovia denticolens and Scardovia genomospecies C1 were each isolated from samples associatedwith all three clinical conditions whereas Scardovia inopicata and Bifidobacterium subtile were both isolated from


72

the infected dentine of the leathery and soft lesions. Bifidobacterium breve was isolated from the infected dentine ofsoft root caries lesions.

Bifids may be routinely isolated from root caries lesions using appropriate cultural methods.

‘Oral Microbiology and Immunology’, 24 (1):32-37,2008. Published Online 12 December 2008 Journal compilation© 2008 Blackwell Munksgaard Ltd.

Vascularization of Engineered Teeth

A. Nait Lechguer, S. Kuchler-Bopp, B. Hu, Y. Haikel and H. Lesot

The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth,crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontiumdevelopment. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study (a)blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations,and (c) Vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme, fromthe cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dentaltissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-association, newly formed blood vessels originated from the host, allowing for theirsurvival, and affording conditions organ growth, mineralization, and enamel secretion.

Key Words: tooth tissue engineering · vasculatization · VEGFR · CD31

‘J Dent Res 87(12):1138-1143, 2008’

Effects of Er: YAG Laser Irradiation on Biofilm-forming Bacteria Associated with EndodonticPathogens In Vitro.

Noiri Y, Katsumoto T, Azakami H, Ebisu S (2008).

With the development of dental laser delivery systems that can enter into the root canals, it is possible to use Er:YAG lasers to remove the residual biofilm associated with infected root canals. We examined their effects againstbiofilms made of Actinomyces naeslundii, Enterococcus faecalis, Lactobacillus casei, Propionibacterium acnes,Fusobacterium nucleatum, Porphyromonas gingivalis, or Prevotella nigrescens in vitro. After Er:YAG laser irradiationwith energy densities ranging between 0.38-0.98 J/cm2, the biofilm samples on hydroxyapatite disks were quantitativelyand morphologically evaluated. The Er: YAG laser was effective against biofilms of 6 of the bacterial species examined,with the exception of those formed by L. casei. After irradiation, the numbers of viable cells in the biofilms weresignificantly decreased, whereas atrophic changes in bacterial cells and reductions in biofilm cell density were seenmorphologically. Er: YAG lasers might be suitable for clinical application as a suppressive and removal device ofbiofilms in endodontic treatments

Journal of Endodontics34 (7):826-829, 2008.


73

Dental Pulp Stem Cells: A Promising Tool for Bone Regeneration

d’Aquino R, Papaccio G, Laino G, Graziano A (2008).

Human tissues are different in term of regenerative properties. Stem cells are a promising tool for tissueregeneration, due to proliferation, differentiation and plasticity. Although several loci or niches within the adulthuman body are colonized by a significant number of stem cells, access to these potential collection sites is oftenlimited. Interaction with biomaterials is important for therapeutic use of stem cells. Dental pulp stem cells (DPSCs)have shown to meet these requirements. Access to the collection site of these cells is easy and produces very lowmorbidity. Extraction of stem cells from pulp tissue is highly efficient. These cells have extensive differentiationability and the demonstrated interactivity with biomaterials makes them ideal for tissue reconstruction. SBP-DPSCsare a multipotent stem cell subpopulation of DPSCs which are able to differentiate into osteoblasts, synthesizing 3Dwoven bone tissue chips in vitro and that are capable of differentiating into osteoblasts and endotheliocytes. Severalstudies have found that these are multipotent stromal cells that can be safety cryopreserved, used with severalscaffolds, and have a long lifespan and build in vivo an adult bone with Haversian channels and an appropriatevascularization. A definitive proof of their ability to produce dentin has not been yet done. Interestingly, they seemto possess immune privileges as they can be grafted into allogenic tissues and seem to exert anti-inflammatoryabilities, like many other mesenchymal stem cells. The easy management of dental pulp stem cells makes themfeasible for use in clinical trials on human patients

Stem Cell Reviews 4(1):21-26, 2008

The Sodium Hypochlorite Accident: Experience of Diplomates of the American Board ofEndodontics

Kleier DJ, Averbach RE, Mehdipour O (2008).

To better understand the etiology associated with sodium hypochlorite accidents, the authors surveyed diplomatesof the American Board of Endodontics. Of the 314 diplomates who responded, 132 reported experiencing a sodiumhypochlorite accident. Questions asked involved those about the age and sex of the patient as well as the tooth beingtreated, preoperative signs, symptoms, diagnosis, and radiographic appearance. Data was analyzed by chi-squaretests. Significantly more women experienced sodium hypochlorite accidents compared with men (p < 0.0001).More maxillary teeth than mandibular teeth (p < 0.0001) and more posterior than anterior teeth (p < 0.0001) wereinvolved. A diagnosis of pulp necrosis with radiographic findings of periradicular radiolucency were positivelyassociated with such accidents (p < 0.0001). Most respondents reported that patient signs and symptoms completelyresolved within a month. The occurrence of an accident, by itself, did not adversely affect the endodontic prognosisof the involved tooth. Anatomic variations may contribute significantly to the occurrence of a sodium hypochloriteaccident

Journal of Endodontics 34(11):1346-1350, 2008


The Effect of Mineral Trioxide Aggregate on the Mineralization Ability of Rat Dental Pulp Cells:An In Vitro Study.

Yasuda Y, Ogawa M, Arakawa T, Kadowaki T, Saito T (2008).

The aim of this study was to investigate the effect of mineral trioxide aggregate (MTA) on cell viability andmineralization ability of rat dental pulp cells. The pulp capping materials, such as MTA, Dycal (Dentsply Caulk,Milford, DE), and Superbond C&B (SB; Sun Medical, Shiga, Japan) were placed on transwell inserts and cultured withrat dental pulp cells. MTA and SB exhibited no cytotoxicity, whereas almost all cells had died after 72 hours ofculture with Dycal. MTA significantly stimulated mineralization by 60% compared with the control. MTA and Dycalsignificantly upregulated by two-fold the level of bone morphogenetic protein (BMP)-2 messenger RNA expressioncompared with the control. Furthermore, MTA increased BMP-2 protein production by about 40%, whereas Dycalsignificantly reduced it. Although MTA and Dycal increased the concentration of extracellular calcium by about 0.4mmol/L, SB had no effect. These results suggest that BMP-2 may play an important role in mineralization stimulatedby MTA

Journal of Endodontics 34(9):1057-1060, 2008.

Stem cells and tooth tissue engineering

Yen A, Sharpe P (2008).

The notion that teeth contain stem cells is based on the well-known repairing ability of dentin after injury.Dental stem cells have been isolated according to their anatomical locations, colony-forming ability, expression ofstem cell markers, and regeneration of pulp/dentin structures in vivo. These dental-derived stem cells are currentlyunder increasing investigation as sources for tooth regeneration and repair. Further attempts with bone marrowmesenchymal stem cells and embryonic stem cells have demonstrated the possibility of creating teeth from non-dental stem cells by imitating embryonic development mechanisms. Although, as in tissue engineering of otherorgans, many challenges remain, stem-cell-based tissue engineering of teeth could be a choice for the replacement ofmissing teeth in the future.

Cell and Tissue Research 331(1):359-372, 2008

74

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