Loyola University ChicagoLoyola eCommons

Master's Theses Theses and Dissertations

1976

A Quantitative Analysis of Microleakage inEndodontic Reverse FillsJerome PisanoLoyola University Chicago

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This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.Copyright © 1976 Jerome Pisano

Recommended CitationPisano, Jerome, "A Quantitative Analysis of Microleakage in Endodontic Reverse Fills" (1976). Master's Theses. Paper 2799.http://ecommons.luc.edu/luc_theses/2799

A QUANTITATIVE ANALYSIS OF MICROLEAKAGE

IN ENDODONTIC nEVERSE FILLS

by

Jerome V. Pisano, B.s., D.D.S.

A Thesis Submitted. to the Faculty of' the Graduate School of'

Loyola University of' Chicago in Partial Fulf'illment

of' the Requirements for the Degree or

Master of' Science

April

1976

OOYOW\ UNiVEF:.SJTY MEDICAL CE.NTEB

DEDICATION

To my parents, Salvatore and Alice Pisano, whose many sacri£ices

made possible my many dreams, and to my wi£e, Noreen, who always

understood and helped me in so many ways.

i

ACKNOWLEDGMENTS

Special thanks to the people at Argonne National Laboratory,

especially Dr. Walter Kisieleski, for their interest, guidance

and physical help; without their assistance this project would

not have been possible.

To Dr. Marshall Smulson, who gave me the opportunity to train

under a most understanding and helpful faculty, and who

guided me throughout the program.

To Dr. Joseph Gowgiel for constant encouragement and ideas.

To Dr. Norman Wood who stimulated ideas that I never knew

existed, and whose friendship and assistance made this study

a reality.

To Dr. James Sandrik whose knowledge of dental materials and

scien-tif'ic method as well as his unselfish cooperation added

greatly to this paper.

To Dr. Franklin Weine who has the ability to combine warm

personal friendship and individual interest with teaching

ability unsurpassed by anyone.

ii

VITA

Jerome Victor Pisano was born in Chicago, Illinois, on

October 14, 1946, to Salvatore Victor and Alice Rose Pisano.

He received his elementary education at St. Priscilla's

school on Chicago's northwest side and at st. John ~rebeuf'

school in suburban Niles, Illinois. He is a graduate of' Niles

West High School in Skokie, Illinois. In 1964, he entered

Loyola University and r;jceived a Bachelor of' Science degree

in June, 1968. His achievements there included induction into

the Blue Key National Honor Society.

In September of' 1968 he entered the Loyola University

School of' Dentistry (Chicago College of' Dental Surgery}. His

actions as a student leader included his serving· as class

president f'or three years and f'inally student body president

as a senior. Graduation in 1972 included such honors as

induction into Omicron Kappa Upsilon, Alpha Sigma Nu Jesuit

honor f'raternity and the Presidents Medallion of' Loyola

University.

Af'ter receiving his D.D.s., he served as a Captain in the

United States Air Force at Mc Guire Air Force Base, New Jersey.

In 1974, he again returned to the Loyola University School

of' Dentistry to pursue a Masters Degree in Oral Biology and a

specialty certif'icate in the Department of' ~"'ndodontics.

iii

TABLE OF CONTENTS

DEDICATION • • • • • • • • • • • • • • • • • • • • • • • •

ACKNOWLEDGMENTS • • • • • • • • • • • • • • • • • • • • •

VITA • • • • • • • • • • • • • • • • • • • • • • • • • • •

TABLE OF CONTENTS • • • • • • • • • • • • • • • • • • • •

LIST OF TABLES • • • • • • • • • • • • • • • • • • • • • •

CONTENTS OF APPENDIX • • • • • • • • • • • • • • • • • • •

CHAPTER

I INTRODUCTION • • • • • • • • • • • • • • • • • • •

Review 0£ the Literature • • • • • • • • • • • • •

Endodontic case £ailures

Surgical endodontics • • • • • • • • • • •

• • • • • • • • • • • • • Tissue response to endodontic surgery and its materials • • • • • • • • • • • • • • • • • • •

Microleakage and thermal cycling

Bacteria in microleakage studies • • • • • • •

• • • • • • •

Page

i

ii

iii

iv

vi

vii

1

J

J 6

8

9 1)

Microleakage studied by air pressure 15 techniques • • • • • • • • • • • • • • • • • •

Radioisotopic research • • • • • • • • • • • • 16

II MATERIALS AND ME';I.'HODS • • • • • • • • • • • • • • 25

Sample Collection and Materials • • • • • • • • • 25

Pilot Studies • • • • • • • • • • • • • • • • • • 28

The Experiment • • • • • • • • • • • • • • • • • .31

iv

TABLE OF CONTENTS CONTINUED

CHAPTER Page

III RESULTS • • • • • • • • • • • • • • • • • • • • • 35

Scinti11ation Counting and Percentages • • • • • 35

Samp1e Combustion • • • • • • • • • • • • • • • • 37

IV DISCUSSION • • • • • • • • • • • • • • • • • • • 41

SUMMARY AND CONCLUSIONS • • • • • • • • • • • • • • • • • 47

REFERENCES • • • • • • • • • • • • • • • • • • • • • • • 49

APPENDIX • • • • • • • • • • • • • • • • • • • • • • • • 58

v

TABLE

1

2

3

4

5

LIST OF TABLES

Comparison of Weights, Charge, and Relative Radioactivity of Alpha, Beta and Gamma Rays • • • • • • • • • • • • • • • • • •

DPM/Wash Samples • • • • • • • • • • • • • • • • •

Percentage of Injected Dose Recovered • • • • • •

Summary of F Values and Significant Differences Between-Within ••••• • • • • • • •

c14 D-Glucose-Oxidized Roots • • • • • • • • • • •

vi

Page

17

36

39

40

CONTENTS OF APPENDIX

FIGURES Page

A Plugger fitted into prepared canal •••••••• 59

B Apical filling placed and plugger removed • • • • 59

c The closed system • • • • • • • • • • • .• • • • • 60

D One lambda syringe • • • • • • • • • • • • • • • • 61

E A One lambda sample • • • • • • • • • • • • • • • 61

F Platinum wire combustion basket • • • • • • • • • 62

G Example between-within statistics total study •• 63

vii

CHAPTER I

INTRODUCTION

Endodontic £ailures are kept at a minimum by exacting tech­

nique, microbiological control, a thorough understanding 0£

pulpal and periapical disease processes, and the potential £or

repair in these two environments. Yet, a certain number 0£

cases still £ail, and a common recourse employed by the prac­

titioner is surgical curettage 0£ the periapical area, apico­

ectomy and reverse £illing the involved roots. The sealing

potential 0£ the materials and methods used in this alternative

treatment is 0£ paramount importance to its success. I£ the

original root canal £illing is suspected 0£ microleakage, the

aim 0£ treatment must be ~o improve on the seal that should

exist between the tooth root canal space and the periapical area.

Clinically, the materials used as reverse £illing agents are

materials £amiliar to operative dentistry. Even gutta percha, a

most popular root canal £illing material has its roots in_

operative dentistry as temporary stopping. Cavit* is recognized

as a popular temporary £illing used between endodontic visits.

*Premier Dental Products Company, Philadelphia

1

2

Amalgam is probably the most widely used restorative dental

material. But these materials have been adopted by those doing

surgical endodontic therapy for use in an environment and in a

situation for which these materials were not designed originally.

It is for this reason that the sealing potential of these mater­

ials has been studied for the most part as they function in the

oral environment, not the periapical region. The works to date

have studied the subject of microleakage mostly on a qualitative

basis leaving much to be desired in clear cut differences between

materials and their sealing abilities. If the sealing properties

of these materials and methods are of prime importance, they

should be critically, scientifically and quantitatively deter­

mined as reverse filling agents. The purpose of this study is

to. quantitatively compare and contrast three di~ferent rever~e

filling materials and methods on extracted human tooth roots

through the use of a radioisotopic technique new to the study of

microleakage.

.3

REVIEW OF THE LITERATURE

EJ1dodontic Case Failure

As far back as 1931, Rickert and Dixon were stressing the

importance of root canal obturation and tissue tolerance of the

canal sealants. They, even at this early date, realized that

there are many factors that may be responsible for root canal

treatment failures. Specifically, bacteria could not be the only

contributing factor to case failures, and that even though their

importance must not be minimized, culture techniques were frought

with error. But it was in this early paper, concerned with the

gross response of living tissue to impJ.anted materials that the

hollow tube theory began. It was implied that a simple hollow

tube of platinum or steel implanted in living animal tissue could

result in severe inflammation. Hence, the root canal, a hollow

tube after instrumentation should be filled completely with a

material well tolerated by the periapical tissue.

More recently, Dow and Ingle (1955) contended too that the

greatest cause of failure was poorly filled root canals •. To

prove their point, a lab study was designed in which extracted

teeth were instrumented; one-half of the sample was filled "well"

and the other half was poorly filled. Autoradiography showed

considerable leakage of I 131 into the canals of the poorly filled

canals. Their contention was that Rickert was correct--that in

4

fact, !!!. vivo, serum leaks into poorly filled canals, undergoes

degradation and flows back out into the periapical tissue as an

inflammatory agent. This process was purported to eventually

result in granuloma formation.

Ingle's paper stressing complete canal filling, in 1956,

pointed out that if, in fact, the serum leakage theory is true,

bacteria do not even have to play any role at all in case failure.

The periapical lesion may be sterile, yet be a mass of toxic

tissue destruction products.

Rickert's hollow tube theory has since been the subject of

considerable criticism and doubt. Goldman (1965) showed that

tissue fluids do definitely circulate in and out of open tubes

implanted in rats and guinea pigs, but no unusual inflammation

persisted at the ends of the open tubes. Torneck 1 s first poly­

ethylene tube study (1966) seemed to show that tissue response

to a hollow tube implant was not severe. His emphasis was on

correlating his study with the premise that thorough debridement

of the root canal, as opposed to complete obturation of the

space, was more important. To dramatize this theory, he implan­

ted tubes filled with muscle tissue debris or microorganisms in

rats, in 1967. The tissue response to these contaminated chan­

nels was considerably more severe. Therefore, his key to

endodontic failure reduction was thorough canal debridement.

Seltzer ~ .21.• (1967) approached endodontic failures dif­

ferently by evaluating over one-hundred clinical cases.

5

Certain trends seemed to emerge: cases that had periapical areas

prior to therapy £ailed more frequently than those without

areas; posterior teeth with some abnormal periodontal condition

£ailed more £requently than those without; culture results had

no bearing on success or failure; and most cases.that would

eventually £ail, £ailed within the first twenty-four months.

Seltzer summarized by saying that there is no general concensus

on what constitutes success or failure. Therefore, making study

'comparisons on this subject is extremely di££icult. As an

example 0£ further diversity, Mattila (1968) states that there

is a propensity £or other oral lesions in the same individual

who has a £ailing endodontically treated tooth.

The controve~sy concerning whether endodontic clinical

emphasis should be placed on debridement, disinfection or

obliteration 0£ the canal still exists. Even though, in addition

to the already mentioned studies, Browne (1955), Seltzer {1965),

and Kennedy (1969), all contributed considerable information

refuting Rickert's hypothesis, studies from Grossman, in 1939,

to more recent investigations by Strindberg (1956), Allen (1964)

and Grieve, in 1972, show that considerable attention must still

be given the attempt at a hermetic seal in root canal therapy

even though that end may very well be impossible.

6

surgical Endodontics

Luks (1956) listed several reasons £or employing a root end

filling technique in endodontic therapy. Included in this list

were calci£ied canals, cemented gold posts and broken instruments.

What is common to these situations is the £act that either these

cases are failing or have a potential £or failure. Matsura (1962)

added perforations to the list of indications, and altered the

type of apical preparation suggested £or a reverse filling tech­

nique. Yet, he, too, implies that surgical endodontics is

indicated in £ailing cases. Thorough and complete endodontic

therapy is advocated by Sommer (1946); doing reverse £ill endo­

dontic therapy on teeth with canals that have never been attempted

conventionally is contraindicated. Herbert, in 1941, advocated

the removal of the "porous" apical third 0£ the root during sur­

gical endodontic therapy to enhance sealing this vital area of

the root. He strongly believed the poorly filled canal to be

the cause of treatment failure. On the contrary, Rud (1972)

favors leaving as muc~ as possible of the apical root intact

before reverse filling. Periapical surgery was described as not

a cure £or apical inflammation, but rather an attempt to remove

all necrotic debris and more completely seal the root canal.

Although the approach to endodontic surgery has changed

considerably since the views of Farra~ (1884) and Rhein (1890),

the trend is still to create a better environment than previously

7

existed by thorough curettage and improving on the existing seal

in the apical one-third of the root canal. Kopp (1973) has gone

so far as to advocate the use of gold foil as a reverse filling

material with this goal in sight. Evaluation of the betterment

of the case has taken several forms. Most clinical, and prob­

ably least significant, have been radiographic follow-up studies

assessing success or failure of endodontic surgeries. One

thousand cases were evaluated by Rud (1972) over a four year

post-operative period. It was found that most cases classified

as having complete healing at one year remained in that category

as did those cases showing poor healing at one year. Cases

classified as incomplete healing or uncertain healing vacillated

from group to group throughout the four year period. In another

o~ Rud's 1972 papers, criteria were established for radiographic

interpretation of healing. At least a one year post-operative

evaluation is necessary. If healing is unsatisfactory at four

years, it must be considered a failure.

Nord (1970) completed a radiographic study concerning 346

patients whose teeth were reverse filled with Cavit. A sixty-one

per cent success rate was reported using this material. In

general, Persson {1974) reported a range of success by several

investigators studying reverse fills from eighteen to eighty­

nine per cent. Persson 1 s comparison of silver amalgam to Cavit

on a one year term showed amalgam to be superior, although Cavit

had the edge at the shorter six month radiographic check.

8

Andreason (1972) made an attempt to compare histologic findings

with roentgenographic interpretation of healing after endcdontic

surgery. He found that the size of the lesion detected radio­

graphically was indicative of at least the quantity of granula­

tion or scar tissue or "inflammation" present at that time in the

lesion.

Tissue Response to Endodontic Surgery and Its Materials

The modes of healing and the classic tissue response after

endodontic surgery as described by Andreason (1972) are only of

some value in this review as a base line for comparison of other

tissue response studies. It is obvious that the reverse filling

materials used in endodontic surgery produce some type of tissue

response of their own. These materials are chosen not only for

their ability to improve an apical seal in a questionable case,

but certainly for their tissue tolerances.

One 0£ the very first and classic articles concerning tissue

tolerances to foreign materials was that of Dixon in 19JJ.

This study, similar in technique to one performed three years

earlier, concerned itself particularly with root canal filling

materials. Materials implanted in the dorsal tissue and muscle

tissue of rabbits produced various gr.oss inflammatory responses.

Since the overextension of filling material into the periapical

tissue was desirable to some extent at that time, the search for

a material with low inflammatory potential was a high priority

9

consideration. More recently, and more pertinent to the present

investigation, was the report 0£ Feldman and Nyborg (1962).

Implants 0£ disinfected samples 0£ silver amalgam and gutta

percha were implanted into the mandibles of rabbits. On the

basis 0£ a greater capsule thickiless, absence of fibrin fibers,

a greater number of inflammatory cells, absence of bone apposi­

tion and abundance 0£ macrophages around the gutta percha

implants, it was concluded that there was generally a more favor­

able histologic response to amalgam in osseous sites. Flanders

(1975) studied the tissue response of rats to zinc-free amalgam

and Cavit. His criteria were similar to Feldman's, and amalgam

was again found to be considerably more biologically acceptable

than Cavit. Marqotte•s (1975) !Q ~study of twelve monkey

incisor teeth reverse filled with amalgam versus gutta percha

showe<l little difference in response in samples collected at

times from three to fifteen weeks.

Microleakage and Thermal Cycling

Microleakage has been defined by Azim (1972) as "the phenom­

enon denoting the presence 0£ microscopic spaces in between the

tooth structure--restorative material interface." He attributes

the formation of this space in general to several £actors includ­

ing the linear coefficient of thermal expansion, modulus of

elasticity, material solubility, volumetric changes of the

10

restorative material, permeability of the involved tooth struc­

tures, influence of oral or body fluids and finally manip:1lative

variables. These spaces are readily demonstrable through the

use of the scanning electron microscope. Most recently, Moodnik

(1975) measured defects between tooth structure and silver amal­

gam that varied from six to one-hundred and fifty microns. Even

a case that was filled ~ vitro showed significant defects at

the margins. Obviously, defects such as these are not recog­

nizable through the use of clinical radiography, yet are present

in most clinical cases.

The work of Nelson, Wolcott and Paffenbarger (1952) can shed

considerable light on the possible significance of these spaces

that exist between tooth structure and restorative material.

The limit of visual acuity is roughly fifty microns. Since the

scanning electron microscope can easily point out six micron de­

fects, and the average defect between a resin filling and dentin

immediately after placement is ten microns, these defects are

not discernable clinically. White blood cells have an average

diameter of twenty-five microns, red blood cells average a

diameter of seven and one-half microns and lactobacilli are only

two microns in size. Passage of these sample substances as well

as thousands of smaller than fifty micron particles or molecules

can be of great significance in the clinical success or failure

of an occlusal restoration, or for that matter, an endodontic

apical filling. Forces involved in the passage of substances

11

through these recognized defects between tooth and material must

include capillarity, dialysis, diffusion, changes in hydraulic or

gas pressures and simple thermal variation so common in the oral

cavity.

Thermal cycling and dimensional changes of restorative

materials was specifically studied by Jacobson (1975). The

interface between glass tubes, simulating cavity preparations,

and the materials tested was made part of an electrochemical cell

which measured the passage of current indicative of a dimensional

change in this space. Only anterior restorative materials were

perused. Gilles (1975) held many of the same views on dimen-

sional change and temperature saying that many materials perform

0 admirably at a constant 37 C but fail to seal at fluctuating

te.mperatures. A strip chart recorder measured the dimensional

changes of materials commonly used in root end filling techniques.

These materials inserted in teflon molds were thermally cycled

in a dry environment. Surprisingly, Cavit showed considerably

greater stability than unmodified zinc oxide and eugenol and not

so surprisingly, greater sealing potential than gutta percha.

Microleakage Dye Studies

Historically, several techniques have been used to study

microleakage and to try to determine which materials had the

best sealing qualities. One of' the oldest and most popular

12

techniques involved the use of a dye. Substances used have

included eosin, methylene blue, methyl violet, gentian violet,

hematoxylin, mercuric chloride, Prontosil, soluble red, aniline

red, basic fuchsin, chromotrope 2-R, crystal violet and fluores­

cein (Going, 1972). Massler (1954) inserted filling materials

into glass tubes, submerged the filled ends of the tubes in

methylene blue and gentian violet and recorded any uptake of the

dye by cotton wicks above the filling material barriers. Zinc

oxide and eugenol and amalgam showed no leakage at all, even

though the amalgam was purposely mishandled. Gutta percha,

silicates and acrylic leaked within hours. A similar study by

Parris, in 1960, using extracted teeth and aniline blue dye,

showed again that zinc oxide and eugenol as well as amalgam

sealed very well. Gutta percha, and this time zinc phosphate

cement, leaked easily. Thermal cycling was believed to be the

determining factor in his study. A portion of Going's paper

(1960) dealt with the leakage of crystal violet dye around class

V cavity preparations in extracted teeth. Ground sections showed

the most leakage around acrylics and zinc phosphate cements,

while copper amalgam showed the least marginal percolation.

Tani (1969) studied anterior restorative materials using basic

fuchsin dye as the tracing agent, and added the extra precaution

of coating the extracted teeth (except near the test preparatiort

site) with wax to eliminate leakage from anywhere but around the

restoration in question. Barry published three methylene blue

13

leakage studies in 1975; one specifically dealt with the sealing

capacity of amalgam, heat sealed gutta percha and a carboxylate

cement when used as reverse root filling agents. He too coated

the roots of the teeth, this time with a clear enamel to elimi­

nate leakage from lateral canals or cracks. There seemed to be

only small differences between the materials tested, but the

carboxylate cement appeared to allow the most penetration of

blue dye. One glaring fact common to all dye studies is that the

results are at best qualitative between groups of samples, never

quantitative. Often the results are so similar that investigator

interpretation may have been a factor.

Bacteria in Microleakage Studies

Bacteria have been and are of considerable concern to endo­

dontist s. Their penetration between filling material and tooth

structure could be of great significance. As early as 1929,

Fraser had developed a.technique using bacterial cultures.

Glass tubes were seal~d at one end which were immersed in cul­

tures of Bacillus, Streptococcus and Escherichia S2.!i• A volume

of broth above the filling material was_ sampled and cultured for

growth. Any positive growth indicated some movement of bacteria

past the restorative materials. Temporary stopping seemed most

permeable, while copper cements and silver amalgam formed the

best barriers against the bacteria in question. Grossman (1939)

14

performed a similar study replacing the volume 0£ broth with a

sterile cotton wick. The materials tested included gutta percha,

zinc oxyphosphate cement, zinc oxide and eugenol cement and com-

binations 0£ these materials. The only material affording any

seal at all was zinc oxide and eugenol. Seltzer (1955) utilized

a different bacteriologic technique to study microleakage.

Certain microorganisms, namely Serratia marcescens and Bacillus

globigii produce an easily identifiable color when cultured at

low temperature, red and orange respectively. Fxtracted teeth

were prepared for filling under sterile conditions. Cavity

preparations were filled with materials ranging from the acrylics

to amalgam. Teeth treated alike were submerged in viable cul-

tures and some samples were thermally cycled. After varying

time periods, dentin shavings from under each filling were cul-

tured and observed £or the appearance 0£ the appropriate color

indicative 0£ contamination. Samples not thermally cycled showed

no leakage. Of those materials subjected to temperature changes,

acrylics allowed the highest degree of contamination while on1y . one 0£ twenty amalgam samples allowed bacterial invasion of the

underlying dentin. Serratia were again used by Mortenson (1963);

after thermal cycling, five 0£ twelve amalgam samples showed some

leakage. In one of Parris' early studies (1964), motile bacteria

which y~re two-hundred and fifty times. larger than most dye par-

ticles were used to penetrate suspect margins. These bacteria

vhieh were approximately five-hundred millimicrons in size could

15

easily penetrate a marginal crevice as wide as ten thousand

millimicrons as described by Nelson (1952). Even under extreme

thermal cycling conditions, Cavit and amalgam both prevented

bacterial contamination 0£ sterile cotton sealed in the pulp

chambers 0£ these extracted teeth.

Again, although all 0£ these investigations yielded variable

information, the results have been criticized £or the lack 0£

quantitation. Leakage was determined on an all or none principle

--a positive or negative culture.

Microleakage Studied by Air Pressure Techniques

One 0£ the only quantitative methods used £or the comparison

0£ microleakage involves the measurement 0£ air under pressure.

Pi'ckard (1965) describes a technique by which air under pressure

is forced through root canals from the apical end, and the

critical pressure recorded at which air bubbles under water are

detected emerging from around coronal amalgam restorations.

Diffusion, percolation, or microleakage per se were not studied.

Rather, actual defects between the restoration and cavity walls .

were located through the use 0£ this technique. Granath, in

1970, described a complicated and ingenious apparatus to measure

virtually this same critical pressure. Admittedly, the test

samples were subjected to nonbiologic and nonphysiologic stresses

and conditions £or which these materials were not designed to

withstand.

16

Radioisotopic Research

Radioactive isotopes have established themselves as indis­

pensable tools in biologic and physical research. They can be

used as tracers !!! YiY.Q. as part of tagged molecules allowing the

investigation of development and molecular transfer (Bartelstone,

1950)~ Mc Cauley (1942) outlined one specific use in dentistry

--to study the development and remodeling of tooth structure.

The use 0£ isotopes to study microlea.kage is removed from these

objectives, but no less signi£j.cant to dental research.

Wainwright (1953) described the new avenues open to microlea.kage

research through the use of isotopes. But O'Brien, in 1968,

was more skeptical when he stated that unless quantitative tech­

niques were developed and the problem of absence of controls in

most studies solved, the present avenues of study were of little

value.

An element's atomic number identifies its chemical and

p~ysical properties. Different atomic weights, that is, a

different number of neutrons in the nucleus coupled with the

same atomic number, designate the isotopes of an element. These

isotope forms have a tremendous scientific advantage over their

more stable elements in that they react the same chemically,

but disintegrate due to their unstable nuclear structure and are

detectable quantitatively. Three types of atomic particles are

emitted: alpha, beta, and gamma rays. A table adapted from

17

Jeffay (1961} summarizes and contrasts the weights, charges and

relative radioactivity of these particles.

TABLE 1

Velocity Relative

to Light

Penetrating Ability

Relative Ionizing

Unit Mass Unit Charge power

Alpha 4 +2 5% 1 10,000

Beta 0.0054 +l or -1 95% 100 100

Gamma 0 0 100% 10,000 1

It will be helpful in future discussions ~o describe at this

time some of the terminology and characteristics unique to iso-

topes and their use. Radioactivity is classically measured in

10 units called curies. One curie is equal to 3.7 x 10 atomic

disintegrations per second, or 2.22 x 1012 disintegratio~s per

minute. The rate of decay of radioactive isotopes is measured

by their half life which is the time required for the number of

unstable nuclei to be reduced by decay to more stable structures

to one-half the original number. This value can be helpful in

selection of isotopes for long or short term studies and the

18

determination 0£ the term 0£ their potentially hazardous effects.

The specific activity 0£ a source 0£ disintegration is measured

by comparing its activity to the unit mass, that is, in curies

per gram or millicuries per gram, etc. These values must be

established as a base line £or comparison in quantitative analysis

(Kisieleski, 1972). In general, the use 0£ isotopes rather than

chemicals has the great advantage 0£ their being measurable in

considerably smaller quantities allowing sensitive comparisons

and relative quantitation if certain techniques are used {Je££ay,

1961).

Materials exposed to ionizing radiation have various inter­

actions with the particles or rays emitted by the isotope. Alpha

or beta particles have the potential to remove electrons from

other atoms by electrical forcefield interaction. Once an elec­

tron ~=-s removed from an atom, that atom is left positively charged

and is termed an ion. The negatively charged electron released

by the ionization process can be free £or some time or can be

attached to another atom giving it a negative charge. Thus, an

ion pair is formed, one positive and one negative. It is by

detection 0£ this ionization process that radioactivity is detec­

ted and measured {Kisieleski, 1972). It is the basis £or radio­

isotope leakage studies using autoradiography and scintillation

counting.

Autoradiography by £ar has been the most popular technique

in microleakage investigation. This type of research is based on

19

the use of low energy beta and sometimes alpha particle emitters

and photographic emulsions. A photographic plate coated with

emulsion can register the presence of an ionizing particle.

When the emulsion, usually silver bromide embedded in a vehicle

like gelatin, is struck by beta particles, the silver crystals

are ionized and form a latent image which can be developed and

fixed to produce black dots on the picture plate. It is impor-

tant that the radiation be of' short range because a source emit-

ting long range particles can produce images far from the source

atoms, therefore falsely identifying the physical location of

the source (Kisieleski, 1972). Nixon (1964) in dental research,

and authors of more general biologic research (Roth, 1969), have

espoused the tool of autoradiography in tissue development studies.

Its use in material leakage studies is also well documented.

Kapsimalis, Evans and Tuckerman (1965) described a most

accurate variance of the autoradiographic principle. Their re-

search indicated that low energy level, soft radiation emitting

beta sources produced the best images on dental film or glass

plates with small grain size emulsion particles giving better

resolution. The sources used in the extracted teeth included

s35 , tritiated glucose and tritiated proline. The earliest

autoradiographic studies were performed to determine the mar-

ginal penetration around coronal filling materials. Armstrong,

45 in 1951, used Ca to compare the penetration around class V

fillings, and found amalgam to be most resistant to percolation.

20

Crawford and Larson (1956) used the same radiation source and

f'ound marginal percolation around. all materials, and that wea-

thering of the test fillings in the oral cavity did not lessen

the leakage potential. Phillips, in 1961, and Swartz, in 1961,

disagreed with Crawford's contention when they showed amalgam

margins leaked less after forty-eight hours of oral exposure and

even less after long term salivary exposure. Going, Massler and

Dute, in 1960, conducted a study incorporating over one-hundred

and f'orty-five extracted teeth to demonstrate the marginal

penetration around such materials as amalgam, gold inlays, gold

foil, acrylic, silicates, zinc oxide and eugenol and gutta

percha. Several beta emitters were used as energy sources

35 32 22 86 45 including S o4, P o4, Na , Rb and Ca to determine the

eff'ects of different ion charges and possibly different chemical

affinities. s35 and ca45

produced the best autoradiographs

22 while Na showed the poorest definition.

Marshall and Massler, in 1961, made one of the first appli-

cations of autoradiography to the field of endodontics. Over

two-hundred and sixty root canals of extracted teeth were filled

with several materials using various popular methods to deter-

mine if canals can be completely obliterated, if there is a

superior filling technique and how good sealers are in preventing

leakage of small molecules and ions. ·Their contention was that·

canals can be made completely impervious to small ions and

mol.ecules through the use ·of gv.tta percha and the appropriate

21

sealer (the sealer being an important filling adjunct). They

J5 also found that S gave the sharpest, most detailed autoradio-

graphs while also demonstrating the most vigorous penetration.

131 Holland, in 1974, used I to study several sealers with gutta

percha, and showed considerable differences in the type and

consistency of mix of the sealers tested as it related to their

sealing ability. His findings did indicate, however, that

lateral condensation was superior to single cone fills in every

case. Kapsimalis and Evans (1966), continuing on the premise

that one of the major causes of endodontic failures may be poorly

filled canals, used autoradiography to compare different filling

methods, coros and sealers. Most significant were the choices

of radioisotopes. s 35 was selected because it is an inorganic

polar ion. Tritiated glucose was chosen because of its molecular

size and non-polarity. Proline was chosen for its non-polarity

and molecular size and for its unique ability to react as an

acid or base when the pH is altered. Sealers were shown to have

better or worse sealing potentials, but the different isotopes

and different particle sizes had no effect on leakage patterns

or potentials. It was shown in the case of proline that different

functional groups accompanied by changes in pH caused a change in

polarity which did affect the results significantly. Three

studies by Avny (1970), Heiman (1971) and Taylor (1973) analyzed

the diffusion and penetration of aqueous or campborated para-

chlorophenol through the use of autoradiography. The only

22

available reference where autoradiographic techniques specifically

studied the sealing potential of' endodontic reverse fillings

was that of Goldberg and Frajlich (1973). 131

I was shown to

perf'use around apical amalgam seals into unf'j_lled root canals

and to penetratA the dentine of' the canal.

A quantitative, more sophisticated use of' radioisotopes in

leakage studies centers about the principle of' liquid scintilla-

tion counting. This principle is used to measure the sof't beta

radiation of usually tritium {H3 ), carbon-14 or sulf'ur-35. A

solvent and liquid scintillator compound are necessary to dis-

solve the sample. Electrons given of'f by beta interaction pass

through matter and lose energy in the process. Some substances

called phosphors can absorb the energy and emit a portion of' it

in the f'orm of violet or ultraviolet light. The number of' pho-

tons of visible light produced is proportional to the energy

absorbed and therefore, also to the ionizing radiation present.

A photomultiplier tube can transform the photons produced into

a measurable pulse which can be a quantitative indication of the

amount of radioactivity present (Kisieleski, 1972). Soremark,

in 1961, used scintillation counting to determine the passage

22 of Na around and through acrylic facings. In 1965, Arwill

22 used Na , part of a NaCl solution, to compare the permeability

of' fresh versus coagulated dental tissues. Quantitatively, the

coagulated tissue samples were decidedly less permeable to the

tagged sodium chloride. Going (1968) modified the simple use of'

23

scintillation counting to develop yet another quantitative

method oi' studying microleakage ,!.!! vivo or in vitro of' coronal

f'illings. A crown was f'itted with the restoration of' choice and

then bathed in a solution of' Mn(No3

)2 • The Mn55 was "neutron

activated" to Mn56

and an accurate determination of' the volume

of' Mn~6 retained by the sample was measured. Zurbrigger (1975)

irrigated the canals of' extracted teeth with c14

-labelled

chelating agent. The samples were oxidized, and the liberated

carbon collected, dilut?.d with scintillation cocktail and counted.

He discovered only a J.8% retention of' labelled material by the

roots. Yee's study in 1975 included only a f'ew extracted teeth

and materials not normally used to seal root canals such as

silicone master cones, cyanoacrylate and polycarboxylate cements.

These materials when compared to f'ills of' gutta percha and zinc

oxide and eugenol, showed no permeation in either group of' ca45

between the canal walls and f'illings.

It is well established that no matter where the emphasis

lies in endodontic therapy, an attempt to seal the canal as well

as possible to avoid f'ailure at a later date is desirable.

Certainly the sealing ability of' a material used to better a

f'illing already suspected of leakage is important. Techniques

to study the leakage potential of restorative materials, many of'

which are used as reverse filling materials, have been developed,

but the quantitation of' data allowing accurate comparisons and

24

statistical significance has been lacking. It is the design of

this papnr to demonstrate a radioisotopic technique that can be

used to specifically quantitate microleakage around or through

three endodontic reverse filling materials.

CH.APTER II

MATERIALS AND METHODS

Over one-hundred and fifty human maxillary central incisors

were collected for this study. All samples were supplied by

oral surgeons without identification as to the age or history

associated with each tooth. The teeth were immediately wiped

with sterile gauze moistened with saline and then submerged and

stored in baths of physiologic saline to which was added a small

amount {less than one percent of the total volume) of colorless

merthiolate* to control bacterial growth. The samples were

collected weekly and transferred to larger storage baths of

refrigerated solution. Any adherent tissue fragments were

removed prior to final storage by sterile dry gauze wipings.

The solutions in the larger storage baths were changed every

second day to further control bacterial growth. All teeth were

used within thirty days of their collection. .

The anatomic crowns of the teeth were removed through the

use of a 700 high speed carbid.ehlr to facilitate engine reaming

as the method of canal preparation All canals were reamed

*Lilly--Indianapolis, Indiana

2.5

26

through the apex in step wise :fashion with the preparation ending

with a number :five engine reamer. A number 10 endodontic plugger*

was :fitted into each canal simulating a canal :filling against

which a reverse :filling material may be placed. Using a milli­

meter periodontal probe, the apex o:f each root was trimmed back

until one and one-half millimeters o:f unfilled canal extended

from the tip of the plugger inside the canal to the external

surface o:f the apicoectomied root (see Appendix :figure A). The

cut root tip surface was not beveled and was perpendicular to the

long axis o:f the root. A #35 inverted cone carbide bur in a high

speed handpiece using water spray was inserted once into each

apex to the depth of the head o:f the bur, approximately one milli­

meter, and withdrawn, creating uniform preparations to accept

the reverse :filling materials. The samples were allowed to

adapt to room temperature while being kept moist and were again

:fitted with the plugger and the :filling materials were placed

apically. Cavit was dispensed directly from its tube and placed

in the apical preparations with a #3 Woodson plastic instrument

under normal digital pressure packing the material against the

plugger which substituted as an existing root canal :filling.

According to Wilderman (1971), the make up o:f Cavit is as :follows:

zinc oxide, calcium sulfate, glycol acetate, polyvinyl acetate,

polyvinyl-chloride acetate, triethanolamine and red pigment.

Water or saliva reacting with the calcium sulfate and zinc oxide

*Star Dental Manufacturing Co., Conshohocken, Pennsylvania

27

induces hardening and a high coefficient of linear expansion

accounting for its purported excellent marginal sealing potential.

Similar fillings were made with heated gutta percha obtained

from large size master cones*. The gutta percha was placed by a

Woodson #3 instrument, this time warmed to manipulate the gutta

percha. A doughy rather than molten consistency of gutta percha

was used to minimize post placement shrinkage on cooling. Zinc

free spherical silver amalgam** was the last material examined.

This material supplied in compartmentalized single spill capsules,

was triturated uniformly £or each fill £or eighteen seconds in a

WIG L BUG single speed amalgamator*** and each reverse fill was

placed in three small increments measured by a K-G retrofill

amalgam carrier**** with intermittent condensation with a flat

faced amalgam plugger. The excess material in all cases was

carved flush with the flat root tip surface. The intra canal

plugger was removed immediately after filling and the teeth were

stored in saline baths for forty-eight hours before being

utilized as test samples.

Scintillation vials with screw top caps (see Appendix

picture c) were used and 1.5 ml of sterile physiologic saline was

injected into the bottom 0£ the bottle via a tuberculin syringe.

This saline volume was the wash or collection bath designed to

absorb any leakage from inside the root canal. The void left in

the canal after removal of the plugger served as a space to

*Premier Dental Products Co., Philadelphia, Pennsylvania **Kerr Dental Manufacturing, Detroit, Michigan

***Crescent Dental Manufacturing Co., Chicago, Illinois ****Union Broach Co., Long Island City, New York

28

deposit the radioactive solution. Disposable dental needles of

25 gauge and short length* had their short ends removed and were

sealed over the root stump with melted Sticky Wax** to serve as

a handle for each root and as a pressure vent so that active

solutions were not forced through the apex as the canal orifice

was sea1.ed. This system allowed the screw tops of the vials to

be sealed, closing the experimental model and isolating it from

the room environment.

PILOT STUDIES

Several pilot studies ranging from six to twelve teeth each

were conducted. ·These original studies were done to test the

overall feasibility of the new technique. The first study in-

volveJ six roots prepared in the previously described manner and

sealed with amalgam. Ten lambda (one lambda is a microliter or

one one-thousandth of ~ milliliter) of tritiated water was injec­

ted into each canal. This solution produced 4.78 x 107 disin-

tegrations per minute per milliliter (DPM). One hundred percent

5 recovery would yield 4.78 x 10 DPM for a ten lambda sample.

Immediately after injection of the solution, the root stumps

were sealed with the disposable needles and Sticky Wax. The

apex of each root was placed in only one-half milliliter of

*Sherwood Industries, Deland, Florida **Kerr, Detroit, Michigan

29

saline contained in a small glass cup placed in the bottom of

each scintillation vial and the vials were sealed. One-hulf

hour and one hour after initiation of the experiment, the teeth

were removed :from the wash baths. Fifteen milliliters of scin­

tillation liquid were added to each vial and thoroughly shaken.

The vials were placed in a Packard scintillation counter Model

3375 and ten minute counts were recorded. Significant amounts of

radiation were detected in the wash baths encouraging other pilot

studies.

In an attempt to account for one-hundred per cent isotope

recovery, roots removed :from the baths at the conclusion of the

specified time periods were oxidized in a Packard Tri Carb

oxidizer Model 306. The water was collected and diluted with

scintillation cocktail and analyzed. The residue of the tooth

after combustion was placed in another vial containing fifteen

milliliters of counting :fluid. All vials pertaining to an

individual sample were counted and their values were summed. In

no case was one-hundred percent recovery of the test solution

realized. In many cases less than sixty per cent o:f the original

activity was recovered, although in one case, a 90.7% value was

recorded.

Lack of control was solved through the use of glass tubes

sealed at one end approximating the average length and outside

diameter o:f a human central incisor root. This model tested with

tritiated water showed that this particular isotope has the

30

unique ability to penetrate glass. For this reason as well as

other biological considerations (molecular size and physiologic

value} the isotope used was changed to c14-labelled glucose* with

an activity of 5 microcuries per milliliter and a standard DPM

4 0£ 1.2 x 10 per one lambda sample. Glass was impenetrable by

this isotope, but oxidation recoveries were still not nearly one-

hundred per cent.

Other pilot studies eliminated previously unforeseen errors

such as the possibility 0£ some material either volatilizing, or

in some other way, escaping the system via the vent needle and

reaching the interior 0£ the vial in this other way contributing

additional radioactivity to the wash bath that did not represent

microleakage. Venting the needle through a rubber diaphragm

that replaced the screw cap showed no di££erences between these

samples and those counted in the closed system. Another signi£i-

cant development was the use of the same sample tooth transferred

from bath to bath at distinct time intervals. The summation of

detectable radioactivity from all the baths per sample gave a

total leakage figure as well as an idea as to when most 0£ the

leakage occurred in each sample. Elimination of the wash bath

cups and simply tripling the volume of the wash bath placed

directly into the scintillation vials was the result of another

p±lot study, as was the reduction from ten lambda to one lambda

of radioactive solution injected into each canal.

*Schwarz Inc., Orangeburg, New York

31

Finally, autoclaved teeth, kept moist after sterilization,

were used as samples. It was suspected that bacteria could be

breaking down the radioactive glucose and affecting the total

recovery data. Total recovery on these teeth was the same as in

non-autoclaved samples.

Based on the pilot studies, trial and error and laboratory

practice of the involved techniques, a final protocol was drawn

up and the experiment was conducted.

THE EXPERIMENT

Seventy-two maxillary central incisor teeth were selected

at random from storage stock in physiologic saline solution.

The crowns of all teeth were removed at roughly the cemento­

enamel junction on the mesial and distal surfaces. All canaJ.s

were engine reamed as previously described. A plugger was fitted

in each canal, an apicoectomy performed and an apical preparation

to receive the reverse filling agent was made as in the pilot

studies. The canals were irrigated with saline to insure patency

from the coronal orifice through the apical preparation.

The teeth were randomly divided into three groups of. twenty­

four teeth each. Each group was filled with one of the three

test materials, amalgam, Cavit and heat sealed gutta percha as

described earlier. One-half of the teeth in each group were

coated with clear finger nail polish* as described by Crawford

(1956) to minimize the possibility of leakage through indiscernable

*Chesebrough Ponds Inc., Greenwich, Connecticutt

32

cracks and lateral canals, although a goodly portion of the more

porous apex of each root had already been removed. Great care

was taken not to paint the flat apicoectomied and filled sur-

face; only lateral root surfaces were coated, but were coated

twice. All samples were again allowed to stand for forty-eight

hours at room temperature.

On the first day of the experiment, all canals were injected

t . . . b 14 1 at imed intervals with one lam da of C -labelled D-g ucose

4 solution with a determined standard DPM of 1.2 x 10 • The orifice

of each canal was capped with the disposable needle and wax,

being careful not to occlude the canal orifice or needle opening.

One and one-half milliliters of sterile physiologic saline was

injected in each scintillation vial. Each sample was lowered

into its wash bath, apex down, and the time recorded. All samples

were transferred one hour aft~r injection to another vial with a

fresh wash bath. This was repeated at twenty-four and forty-

eight hours yielding a total of three wash values per sample tooth.

To each vial was added fifteen milliliters of Monophase 40 scin-

tillation fluid*. Six g~ass tubes were used as controls and

manipulated exactly the same way as the test samples. During the

experiment, seven sample teeth were lost, mostly due to an acci-

dental break in the seal between the root surface and needle hub.

Consequently, two-hundred and ten scintillation vials as well as

several standards and blanks were placed in a Packard scintillation

*Packard Instruments, Downers Grove, Illinois

33

counter, and ten minute counts were recorded for each vial.

Blanks cr:-nsisted of 1.5 ml of saline solution and 15 ml of scin-

tillatj_on fluid. Standards were the same make up as blanks plus

one lambda of the radioactive glucose solution. Counting effi-

14 ciency was determined by using C toluene as a calibration

stand~rd. Efficiency was determined to be approximately 75% with

a background counting rate of 50 CPM.

Results were placed in table form and converted into total

percentage leakage. An analysis of variance was performed using

the between within method considering the following comparisons:

Was there a significant difference between any of' the six groups

tested? I£ so, which groups were significantly different from

each other, and was there specifically a difference between roots

coated with varnish and those lef't uncoated for each material?

Sample teeth randomly selected, were oxidized in a Packard

Tri Carb Oxidizer to again attempt to recover one-hundred per

cent of the injected solution's radioactive content. The samples

were individually placed in a platinum wire oxidation basket

(see Appendix figure F) with the addition of equal amounts of

cellulose powder and filter paper to support better combustion.

The system was closed and the test samples were electronically

ignited and burned for one to two minutes. The gaseous products

of combustion were collected, namely co2 and water, liquified

and deposited within the closed system into two vials, one

designed to collect carbon labelled products. Fifteen milliliters

of scintillation fluor were automatically added and the vials

were sealed and placed in the counter as were the wash samples.

CHAPTER III

RESULTS

SCINTILLATION COUNTING AND PERCENTAGES

The results of the scintillation measurements from the wash

baths at one, twenty-four and forty-eight hours for all samples

are listed in Table 2. Table 3 lists this data in the form of

4 percentages of the total standard DPM count of 1.2 x 10 per

lambda of injected solution.

The material groups were broken down into two groups each,

those whose roots were coated with nail varnish and those left

uncoated. It can be readily seen from the tables that the most

significant leakage occurred between one hour and twenty-four

hours. In almost all cases, the measurable radioactivity mea-

sured had begun to taper off at the forty-eight hour sample time.

Glass controls showed insignificant wash bath counts indicating

no broken seals and no penetration through the glass of carbon-

labelled molecules.

There appeared to be significant differences between the

materials tested but not between those samples with coated and

unaltered root surfaces. Between within statistics affirmed

these observations. An example of the calculator form of

35

TABLE 2

DPM / Wash Samples

Gutta Percha Amalgam

Coated Plain Coated Plain 1 hr 24 hr 48hr 1 hr 24hr 48hr lhr 24hr 48hr lhr 24hr 48hr

l..3 189 69 6 758 73 21 215 2.3 1 89 35 l.887 234 141 59 475 167 57 769 99 19 55 84

1 154 420 47 354 507 23 126 78 105 43 56 488 97 18 132 519 704 163 22 21 51 l.4 17

.3 156 98 265 172 94 ll. 370 118 30 37 27 631 49 257 490 187 234 84 134 33 7 28 19 853 114 380 931 311 452 136 114 30 14 159 88 640 201 188 174 203 244 112 245 30 134 35 17 .340 94 1J4 309 159 48 66 405 42 42 410 59

5 71 166 289 128 343 130 361 197 10 450 72 486 292 574

7 52 108

Cavit Glass

Coated Plain lhr 24hr 48hr lhr 24hr 48hr lhr 24hr 48hr

0 481 98 6 198 71 0 8 17 19 458 374 23 364 109 0 10 13

3 307 64 2 482 l.32 3 15 21. 2 515 40 38 620 114 o· 4 7 8 151 42 15 139 119 5 10 15

21 622 81 103 719 125 0 6 9 0 .387 76 6 1472 133 8 262 69 19 437 124

33 408 64 7 281 54 4 629 82 2 598 79

10 .'.314 47 16 1447 274

J7

statistics used is shown in the Appendix figure G. The mean for

the entire study was 5% excluding the controls. A comparison of

all six groups gave an F value of 11.7, well above the value of

J.J6 at the 0.01 level of significance. When each material was

studied individually to determine if a significant difference,

even at the 0.05 level existed between coated and uncoated roots,

none could be demonstrated. Therefore, the remainder of the

statistical analysis combined the sample results for coated and

uncoated samples creating a larger sample size for each material

tested. From this analysis it was shown that there was no

significant difference between the leakage values of Cavit and

amalgam, but amalgam showed significantly better sealing capabil­

ities than gutta percha at the 0.01 level of significance. Cavit

showed better sealing capacity not at the 0.01 level, but at the

0.05 level of significance. A summary of the F values and sig­

nificant differences between test groups can be seen in Table 4.

SAMPLE COMBUSTION

Oxidation values for the randomly burned samples are shown

in Table 5 along with the percentage wash values from Table 3.

The total recovery approaches over sixty percent in less than

one-half the samples, and over eighty percent only four times.

A total of twenty-eight roots were oxidized.

TABLE .3

Percentage of Injected Dose Recovered

Gutta Percha Amalgam Coated Plain Coated . Plain

1 hr 24hr 48hr sum lhr 24hr 48hr sum lhr 24hr 48hr sum lhr 24hr 48hr sum

0.11 1.6 0.56 2.3 o.o4 6.2 0.60 6.8 0.17 1.8 0.19 2.2 0.01 0.73 0.29 1.0 15.5 1.9 1.2 18.6 o.48 3.9 l..4 5.8 o.46 6.3 0.81 7.6 0.16 o.45 0.69 1.3

0.01 1.3 3.4 l~. 7 0.39 2.9 4.2 7.5 0.19 1.0 o.64 1.8 o.86 0.35 o.46 1.7 4.o 0.80 0.15 5.0 1.1 4.3 5.8 11.2 1~3 0.18 0.17 1.6 o.42 0.12 0.14 0.7 0.02 1.3 0.80 2.1 2.2 1.4 0.77 4.4 0.09 3.0 0.97 4.1 0.25 0.30 0.22 o.8 5.2 o.4o 2.1 1.1 4.o 1.5 1.9 7.4 0.69 1.1 0.27 2.1 0.06 0.23 0.16 o.4 7.0 0.94 3.1 11.0 7.6 2.6 3.7 13.9 1.1 0.94 0.25 2.3 0.12 1.3 0.72 2.1 5.3 1 •. 60 1.5 8.4 1.4 1.7 2.0 5.1 0.92 2.0 0.25 3.2 1.1 0.29 0.14 1.5 2.8 0.77 1.1 4.7 2.5 1.3 0.39 4.2 0.54 3.3 0.34 4.2 0.34 J.4 o.48 4.2 o.o4 0.58 1.4 2.0 2.4 1.0 2.8 6.2 1.1 J.O 1.6 5.7 0.08 3.7 0.59 4.4 4.o 2.4 4.7 11.1

co 0.06 o.43 o.89

""' Cavit Glass

Coated Plain lhr 2lihr 48hr sum lhr 24hr 48hr sum lhr 24hr 48hr sum

0 4.o 0.80 4.8 0.05 1.6 0.58 2.2 0 0.07 0.15 0.22 0.16 3.8 3.1 7.1 0.19 3.0 0.90 4.1 0 0.09 0.11 0.20 0.02 2.5 0.53 3.0 0.02 4.o 1.1 5.1 0.03 0.13 0.18 0.34 0.02 4.2 0.33 4.6 0.31 5.1 0.94 6.4 0 o.o4 0.06 0.10 0.07 1.2 0.34 1.6 0.12 1.1 0.98 2.2 o.o4 0.09 0.13 0.26 0 3.2 0.62 3.8 0.05 12.1 1.1 13.2 0 0.05 0.08 0.13 0.07 2.2 0.57 2.8 0.16 3.9 1.0 4,8 0.17 5.1 o.66 5.9 0.85 5.9 1.0 7.8 0.27 3.4 0.53 4.2 0.96 2.3 o.44 2.8 0.03 5.2 0.67 5.9 0.02 4.9 0.65 5.6 0.08 2.6 0.39 3.1 0.13 11.9 2.2 14.2

39

TABLE 4

Summary 0£ F Values and Signi£icant

Di££erences Between-Within

Test Group(s)

total

Gutta percha-amalgam-Cavit

Gutta percha vs. Amalgam

Amalgam vs. Cavit

Gutta percha vs. Cavit

Coated vs. Plain

F value F value 0.01

11.7 J.36

22.1 4.99

17.2 7.31

o.64 7.31

6.36 7.29

2.7 8.10

F value 0.05 Signi£icant

2.38 yes/yes

J.16 yes/yes

4.08 yes/yes

4.08 no/no

4.07 no/yes

4.J5 no/no

40

TABLE 5

14 c D-Glucose-Oxidized Roots

mg. % RECOVERY

Treatment wt. DPM/Sample Wash Burn Total

GP Coated 458 7474 18.6 61.3 79.9 348 10010 2.0 82.2 84.2 403 7444 4.7 58.8 63.5 445 6277 2.1 49.6 51.7 437 6291 8.4 49.7 58.l. 321 6333 4.7 50.1 54.8

GP Plain 455 5589 11.2 45.9 57.1 383 6224 7.4 49.2 56.6 412 6706 5.1 53.0 58.1 488 5183 6.2 41.0 47.2

Amalg Coated 409 7717 5.7 63.4 69.1 451 8496 2.2 67.2 69.4 426 5614 1.8 44.4 46.2 462 11211 2.1 88.6 90.7 400 6812 4.2 53.8 58.0

Amalg Plain 432 10266 o.4 84.2 84.6 380 7144 l.O 56.5 57.5 408 10335 1.3 81.7 8J.O 494 9070 o.8 71.7 72.5 463 9401 4.4 74.3 78.7

Cavit Coated 374 5536 2.8 45.5 48.J 400 5461 4.8 43.2 48.o J84 844J J.8 66.7 70.5

Cavit Plain 414 6697 14.2 55.0 69.2 J66 6307 4.1 49.8 53.9 J29 5302 5.1 41.9 47.0 454 4359 13.2 J4.5 47.7 416 7507 5.6 59.3 64.9

CHAPTER IV

DISCUSSION

It is obvious that even Coolidge, in 1930, recognized the

potential 0£ surgical procedures in the correction 0£ endodontic

£ailures. No matter what the status 0£ the hollow tube theory,

almost all investigators agree that sealing of the root canal

has great value when attempting the highest rate 0£ endodontic

treatment success.

The literature is replete with studies showing that all

£illing materials exhibit marginal percolation, microleakage,

micromarginal leakage, £luid exchange, liquid di££usion, or

capillary penetration (Going, 1972). The major problems with

the studies to date is that all materials that have demonstrated

marginal leakage have not been ideally compared. Quantitative

autoradiography is di££icult to attempt, and di££icult to analyze

in order to draw valid comparisons £rom (Baserga, 1969). Auto­

radiography is a qualitative tool that has been £orced into action

as a method 0£ answering what appears to be a quantitative ques­

tion. Scintillation counting provides a much more reliable

method 0£ leakage detection with highly reproducible data

41

42

collection as shown in this study. The selection of the isotope

appears to be critical. Tritiated water proposed problems here

and has a history of difficulties associated with its use.

Burke (1975) successfully used tritium to study the diffusion

fluxes across human enamel. A diaphragm of enamel was placed

between two diffusion cells, and different rates of diffusion

were measured for canine versus incisor teeth. This penetrability

and diffusion potential of tritium across enamel membranes could

well be established some day across cementum or dentin in like

manner. Leakage data using tritiated water therefore could be

masked by diffusion through the tooth structure as well as around

and through the restorative material. The penetration of glass

by tritiated water in this study should be considered a clear

contraindication for its use in leakage potential studies. As

early as 1937, Bodecker demonstrated this porosity of tooth

structure using dyes. Wainwright (1953) believes cementum and

enamel are permeable to some substances selectively, but not all

14 substances. Calcium chloride, C -labelled urea and radioiodine

were all shown to penetrate intact tooth structure and reach the

pulp. He also stated that the dentinal tubules and cellular

cementum near the root apex are probably more permeable than the

acellular cementum more occlusally on the root surface.

The results of this study using c14-labelled glucose showed

no through penetration of the root itself as indicated by the

coated and plain samples. At least on the forty-eight hour

short term basis, all the radioactivity detected in the wash

baths came from around or through the restoration placed at the

apex of the root. This fact can be attributed to the molecular

size and other physical and chemical properties of the glucose

molecule. Also, that most porous apical portion 0£ the roots

had already been removed in the apicoectomy procedure prior to

the preparation and filling.

Results showing that amalgam and Cavit sealed considerably

better than gutta percha alone seem to agree with most previous

qualitative studies. It should be noted that amalgam sealed

better than gutta percha at a level of significance higher than

that of Cavit. Parris (1964) stated that Cavit and amalgam were

equally superior to gutta percha in sealing ability. This was

found not to be true. Comparison with Yee's study (1975) is

difficult in that his model differed considerably; the tooth's

crown acted as the reservoir of radioactive material and the

canals were filled their entire length.

Finally, of concern were the attempts at quantitative

recovery 0£ the isotope used. One-hundred percent recovery was

never realized, and rarely were recovery values consistent.

The possibility of bacteria present in the canals breaking down

the glucose to some other form and ingesting or processing any

of the test solution was ruled out by the pilot study on auto­

claved teeth handled aseptically. Recovery for this group was

the same--irregular and never near one-hundred per cent.

44

Two explanations seem plausible but have not been proven.

The oxidation temperature 0£ ·.the samples in the Tri Carb 0

Oxidizer is said to be between 600-1000 C. Is this temperature

su££icient to break down the carbon in the compact, highly

intricate tubular and calci£ied structure 0£ the dental root £or

quantitative conversion to co2 ? I£ it is, is a temperature .0£

0 1000 C actually realized in the combustion chamber, and are the

combustion times long enough? Nixon (1964) said,

n ••• radioisotopes have been used to show that transport

of ions takes place through dental tissues. This trans­

port is two way and occurs £rom the pulp through dentin

and enamel and also £rom saliva through enamel and dentin.

Substances like glucose can be labelled and made radio­

active and its passage through the enamel studied."

Going (1960) stated that isotopes, because 0£ their differ-

ent ion charges, have distinctive chemical a£finities and there-

£ore particular adsorption potentials and diffusion patterns

through and around tooth substances and restorative materials.

14 Wainwright (1953) showed the passage 0£ C -labelled urea through

tooth roots in twenty-four hours. With these documented conclu-

14 sions, is it not practical to assume that C -labelled glucose

could be held in a bound or converted state somewhere in the

root structure that does not allow it to be volatilized and

measured? Could diffusion through and adsorption to the walls of

the dentinal tubules account £or such results? It was shown in

14 · pilot studies prior to this £inal experiment that C -labelled

45

glucose injected into teeth and oxidized immediately showed the

highest recovery values of all. Possibly tubular penetration,

binding or adsorption was not allowed to occur in such a short

time. At any rate, the work of Zurbriggen (1975) would be highly

suspect to error in light of the results of this experiment.

14 . He instrumented canals with a C -labelled chelating agent and

measured, by combustion analysis and subsequent l_iquid scintilla-

tion counting, the amount of labelled material retained in the

canals after irrigation with sodium hypochlorite. Only 3.8% of

the initial activity was recovered as retained in the roots. It

can now be shown that a considerably higher percentage may have

been retained but never counted.

All studies to date could be termed only exercises unless

some significance is attached to microleakage potential.

Molecules of various substanc~s surely diffuse around or through

restorative materials. Whether this phenomenon can potentiate

endodontic failures or failures of endodontic reverse fills is

still only speculation. An in vivo study demonstrating this --potential might add more credence to this argument, but so many

factors would be involved that attributing a certain percentage

of failure to one shortcoming would be impossible. It can be

said that if all considerations are weighed, the best apical seal

possible with a material well tolerated by living tissue should

be the filling material of choice in endodontic reverse filling

46

techniques. Silver amalgam seems to meet these requirements

better than any other material tested including Cavit.

SUMMARY AND CONCLUSIONS

Seventy-two extracted human central incisors were reverse

filled with silver amalgam, Cavit and warm gutta percha in an

attempt to quantitatively investigate the differences between

the marginal sealing capabilities of these materials and the

possible relationship between this factor and the treatment of

endodontic failures. 14

A C -labelled solution of glucose was

measured and injected into each sample and scintillation counting

and sample oxidation were performed to measure the amount of

radioactive material lost around or through the test materials.

The experiment clearly showed the following:

a) That microleakage of molecular size particles does occur

a~ound what appears to be clinically adequate fills.

b) That a quantitative measurement of this microleakage is

possible and can be used to compare materials used as endo-

don tic reverse frll:1-ng agents.

c) That amalgam appears to be superior to Cavit and gutta

percha as an endodontic reverse filling material.

d) Tritiated water is not suitable for the. measurement of

microleakage in this technique.

47

48

Further experimentation is necessary to consider the problem of

quantitative recovery of test solutions as it pertains to this

study and as it pertains to the structure and function of the

tooth.

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52

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53

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54

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55

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56

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96.

57

Yee, F., Lugauy, A. and Peterson, Canals with Adhesive Materials," 1: 145-152, April, 1975.

J.: "Fi1ling of Root Journal of Endodontics,

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I

ii 'I

APPENDIX

FIGURE A

Plugger f'itted into prepared canal

59

FIGURE B

Apical. filling placed and pl.ugger removed

60

FIGURE C

The Closed System

FIGURE D

One Lambda Syringe

FIGURE E

A One Lambda Sample

62

FIGURE F

Platinum Wire Combustion Basket

63

2 Total sums of' squares = x

{Ix)2 N

Between sums of'

Within sums of'

(319.6)2

= 2048.6 - 64

= 2048.62 - 1596

squares (Ix1

) 2

~~x2) 2

= + Nl N2

= 228

squares Total - Between =

= 224.6

Sums of'

(~x)2 + etc. --N

Variance Degrees of' Freedom Sguares Mean Sguare

Between

Within

5 228.0 45.6

58 224.6 3.9

F value is 3.36 at the 0.01 level;

therefore, there are significant di:ff'erences

because 11.7 is greater than 3.36.

FIGURE G. Example Between Within Statistics Total Study

F

11.7

. APPROVAL SHEET

The thesis submitted by Jerome V. Pisano, D.D.S., has been read and approved by the following committee:

Dr. Joesph M. Gowgiel Associate Professor and Chairman Department of Anatomy, Loyola

Dr. Walter E. Kisieleski Clinical Associate Professor, Oral Pathology, Loyola

Dr. Marshall H. Smulson Professor and Chairman Department of Endodontics, Loyola

Dr. Norman K. Wood Associate Professor and Chairman Oral Diagnosis, Loyola

Dr. James L. Sandrik Assistant Professor, Dental Materials, Loyola

The final copies h.a:ve been examined by the director of the thesis and the signature which appears below verifies the fact that any necessary changes have been incorporated and that the thesis is now given final approval by the Committee with reference to content and form.

The thesis is therefore accepted in partial fulfillment of the require­ments for the degree of Master of Science.

Date