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Ta b l e o f C o n t e n t sTa b l e o f C o n t e n t sVolume 46 - Nº1 - June 2009

The LDA is a regular member of the FDI

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Cited in the WHO Eastern

Mediterranean Index Medicus

ISSN 1810-9632

Editorial

The seismic change

Ziad Noujeim

Meet the New Associate Editors

Maria Saadeh, Amine El-Zoghbi and Jihad Fakhouri

Implant DentistryShort implants in deficient posterior jaws: current knowledge.

Peter Tawil, Georges Tawil

Oral Medicine ResearchHost salivary antimicrobial peptides and oral candidiasis.

Mary Ann Jabra-Rizk

Laser DentistryErbium:YAG Laser in everyday periodontal practice.

Zahi Badran, Céline Bories, Assem Soueidan

Adhesive Dentistry ResearchEffect of different surface treatments on bond strength and failure type of zirconium oxide ceramic:

an in-vitro study.

Ziad Salameh, Joseph Hobeiche, Hani Ounsi, Moustafa Aboushelib

Craniomandibular DisordersTemporomandibular disorders (TMDs): a note from the field.

Nabil Tabbara

Esthetic DentistryPorcelain veneers as an esthetic restorative strategy for the treatment of stained anterior teeth: a

clinical report.

Karim Corbani

Removable ProsthodonticsYou do not have to be an FBI agent to find and register the retruded contact position in the treatment

of the prosthodontic patient.

Tony Daher, Joseph J. Massad

Restorative DentistryThe used of low intensity laser after cavity preparation in vital tooth: a clinical report.

Carlos de Paula Eduardo, Rodney Garcia Rocha, Karen Müller Ramalho

Forthcoming Dental Meetings, Exhibitions and Conventions.

ISSN 1810-9632

Layout and Printing: Metni Printing Press 961.1.283631 Beirut, Lebanon.

Address: The Lebanese Dental Association,Victoria Tower, 2nd floor, Corniche du Fleuve, Beirut, Lebanon

Tel. / Fax: 961-1- 611222, www.LDA.org.lb .

The Journal of the Lebanese Dental Association is the official organ of the Lebanese Dental Association.Statements and opinions in the papers and communications herein are those of the author(s) and not necessarily those of the Editorial Board. TheEditor(s) disclaim any responsibilities or liability for such material and do not guarantee, warrant, or endorse any product advertised in thispublication, nor do they guarantee any claim made by the manufacturer of such product or service.

Editor-in-ChiefZiad E.F. Noujeim, Dr. Chir. Dent., CES Odont.

Chir., Dipl. Oral Med., Dipl. Cell Therapy, FICD,

FACOMS, FIAOMSChairperson, Department of Research and Senior Lecturer,Departments of Oral and Maxillofacial Surgery, Oral Pathologyand Diagnosis, and Basic Science,Director, Oral Pathology and Diagnosis Graduate Diploma,Lebanese University School of Dentistry, Beirut, [email protected]@lda.org.lb

Associate EditorsZiad Salameh, Dr. Chir. Dent., DES Prostho,

M.Sc., Ph.D., FICDAssistant Professor, Department of Research, LebaneseUniversity School of Dentistry, Beirut, Lebanon,Assistant Professor, Department of Research, King SaudUniversity College of Dentistry, Riyadh, [email protected]@[email protected]

Maria E. Saadeh, BDS, MS (Human Morphology),

Residency Ortho. (AUB)Clinical Associate, Division of Orthodontics and DentofacialOrthopedics, American University of Beirut Medical Center,Clinical Instructor, Department of Orthodontics, LebaneseUniversity School of Dentistry, Beirut, [email protected]@aub.edu.lb

Jihad M. Fakhouri, Dr. Chir. Dent., CES Odont.

Chir., CES Perio., CES Prostho., DU Implant, DU

Forensic Dent., Dr. Univ. (USJ), MSLPAssistant Professor, Department of Removable Prosthodontics,Saint-Joseph University Faculty of Dental Medicine, Beirut,Lebanon,Associate Editor, ACES (Dental Journal of Saint-JosephUniversity, Beirut),[email protected]@hotmail.com

Amin El-Zoghbi, Dr. Chir. Dent., DU

Occlusodont., DEA, MEACMD, MCNOSenior Lecturer, Department of Prosthodontics and Occlusion,and Director, Occlusion Graduate Diploma, Saint-JosephUniversity Faculty of Dental Medicine, Beirut, Lebanon,Associate Editor, International Journal of Stomatology andOcclusion Medicine,[email protected]@usj.edu.lb

Fadl Khaled, BDS , DES EndoClinical Instructor,

Department of Restorative Dentistry,

Beirut Arab University Faculty of Dentistry,

Chief of Clinical Services,

Department of Endodontics,

Lebanese University School of Dentistry,

Beirut, Lebanon

[email protected]

Editors EmeritiNadim Baba, DMD, MSD, FICD, FACP

Philippe Aramouni, DCD, DEA, CAGS,

M.Sc.D.,FICD

Hani Ounsi, DCD, DES Endo., MS (Dent. Mat.),

MS (Biol.Sc.)

Michel Salameh, DCD, CES Pediat. Dent., MIADP,

MIADH, MSFOP

Antoine Cassia, DCD, CES Odont. Chir.,

DU Max. Fac. Prostho., DSO

Levon Naltchayan, DCD, CES Prostho

Pierre Riscalla, DCD

English ReviewerTala Sabbagh Yaghi, BA (Transl./Interpret.)[email protected]

Biostatistics and Epidemiology ConsultantNada E. El-Osta, DCD, DES Prostho. ,

MS (Biol . Med. S c. ), DIU Biostat. , DU Forensic

MedicineConsultant in Biostatitics / Epidemiology,

St. Joseph University Faculties of Medicine and Dental

Medicine, Beirut, Lebanon

[email protected]

[email protected]

IT Assistant / JLDA Website Manager

Fady Kayyali

Advertising and Marketing

Carole Chaccour Kassouf

Journal of the Lebanese Dental Association 3

Editorial ConsultantsGeorge Tawil, Dr. Chir. Dent., DDS, CESOdont.Chir., CES Perio., Dr.Sc.Odont., FICD,FACDProfessor of Periodontology, Saint-Joseph University Faculty ofDental Medicine, Beirut, Lebanon,Editorial Consultant, International Journal of Oral andMaxillofacial Implants, Clinical Oral Implant Research,[email protected]

Charles Sfeir, Dr. Chir. Dent., Ph.DDirector, Center for Craniofacial Regeneration and Professor,Department of Oral Biology, University of Pittsburgh, School ofDental Medicine, Pittsburgh, USA,[email protected]

Assem Soueidan, Dr. Chir. Dent., CES Perio.,Dr.Univ. (Nantes), HDR (Nantes), PU, PHProfessor and Chairperson, Department of Periodontology,Nantes University, Faculty of Dental Surgery, Nantes, France,[email protected]

Hani Adbul Salam, B.Sc., BDS, M.Sc., Ph.D Adjunct Professor and Director of Continuing Dental Educationfor the Middle East and North Africa, McGill University Facultyof Dentistry, Montreal, Canada,[email protected]@[email protected]

Marcel Noujeim, BDS, DU Oral Biol., DU OralRadiol., MS, Diplomate, AB Oral Max. Fac.RadiologyAssistant Professor, Department of Diagnostic Science, andDirector, Graduate Program of Oral and Maxillofacial Radiologyand Imaging, University of Texas, Health Science Center at SanAntonio, Texas, USA,[email protected][email protected]

Ghassan Yared, DCD, DSO, FRCD (Can.),MRCDSOFormer Associate Professor, Department of Endodontics, andformer Director of Endodontics undergraduate program,University of Toronto, Faculty of Dentistry, Toronto, Canada,[email protected]@hotmail.com

Karine Feghali, BDS, DU Perio., Ph.DResearch Fellow, Section of Periodontology, Department of HardTissue Engineering, Graduate School, Tokyo Medical and DentalUniversity, Tokyo, Japan,[email protected]

Tony Daher, DCD, CES Prostho., M.Sc. (Educ.),Diplomate AB Prosth., FACP, FICPAssociate Professor, Department of Restorative Dentistry, LomaLinda University School of Dentistry, Loma Linda, California, USA,[email protected]

Nabil Tabbara, DMD, FAAFO, FAACPAdjunct Clinical Professor, University of Western Ontario,Schulich School of Medicine and Dentistry, London, Ontario,Canada,[email protected]

Zeina A.K. Majzoub, Dr. Chir. Dent., DMD, Dott.Odont., CAGS, M.Sc.DFormer Professor of Periodontology and Research, University ofPadova, Institute of Clinical Dentistry, Padova, Italy,Professor of Periodontology and Research and formerChairperson, Department of Research, Lebanese UniversitySchool of Dentistry, Beirut, [email protected]

Sukumaran Anil, BDS, MDS, Ph.D., FICD, FPFAProfessor and Consultant, Division of Periodontics, King SaudUniversity College of Dentistry, Riyadh, KSA,[email protected]@graduate.hku.hk

Hani Ounsi, DCD, DES Endo., MS (Dental Mat.),MS (Biol.Med.Sc.), DEA (Oral Biol.), FICD,MRACDS (Special Endo. stream)Part-time Faculty, Kuwait University Health Sciences Center /Faculty of Dentistry, Department of Restorative Sciences,Kuwait,[email protected]

Dina Debaybo, Dr. Chir. Dent., CAGS, M.Sc.D.,Diplomate, AB Pediat. DentAssociate Professor and Dental Director, Boston UniversityInstitute for Dental Research and Education, Dubai HealthcareCity, Dubai, UAE,[email protected]@yahoo.com

Nadim Baba, DMD, MSD, FICD, FACPAssociate Professor, Department of Restorative Dentistry, LomaLinda University School of Dentistry, Loma Linda, California,USA,[email protected]

Mary Ann Jabra-Rizk, BS, Ph.DAssociate Professor, Department of Oncology and DiagnosticSciences, University of Maryland Dental School, Baltimore,Maryland, USA,[email protected]

Arlette Oueiss, BDS, CES Ortho., DU Ortho., MS(Stat./Epidemiol.), Dr. Univ. (Toulouse)Assistant Professor, Department of Orthodontics and DentofacialOrthopedics, Paul Sabatier University, Faculty of Dental Surgery,Toulouse, France,[email protected]@hotmail.com

Antoine Cassia, DCD, CES Odont. Chir., DU Max.

Fac. Prostho., DSOProfessor and Chairperson, Department of Oral Pathology and

Diagnosis, Lebanese University School of Dentistry,

Beirut, Lebanon,

The seismic change …

The spectacular scientific and technological advances of the past three decades are still capturing the attention

and imagination of the international scientific community, the private sector, the lay public and “first world”

political decision makers : these advances have offered dental science and clinical dental medicine an unprecedented

opportunity to further dental clinical practice and revolutionize dental profession. The challenge of transferring new

research findings to the public is now behind us and insightful scientists have already established the feasibility of

forging an international Agenda for Dental, Oral and Craniofacial (basic and clinical) research.

In Near East and Middle East regions, Lebanon is following and implementing all breakthroughs in medical and

dental biomedical sciences: innovative and disruptive new technologies are now debated and taught in its university

– affiliated hospitals and three dental schools, and almost all lebanese dentists are able to learn the most recent

advancements and cutting-edge solutions.

Far from being a naive optimistic, I constantly fight and challenge pessimism with goodwill, candor, knowledge

and realism. I perfectly acknowledge where my country stands regarding the importance of dental research, but I

also believe in the creative and legendary lebanese spirit that already applies the so-called “biologically grounded

approach to oral health care”. Indeed, and for decades, the 3Rs of dental practice (Repair, Restoration and

Replacement) were implemented, using different types of metal (amalgam, gold), ceramics, plastics (acrylics) and

rubber (for dentures): these non-biological materials are now less used thanks to minimum intervention –MI-

techniques and patients’ empowerment through awareness, information and motivation. Nowadays, and more than

ever, Lebanese dental practitioners believe in the paramount importance of minimally invasive dentistry which

focuses on almost all dental disciplines, including caries-related dentistry. Lebanon is becoming a leader in

atraumatic restorative treatment -ART- and in comparison to patients that received traditional restorative treatment

(using high-speed drilling), our patients treated with ART proved to be less fearful and anxious and more

cooperative than others. This millenium is one of periodontal medicine, and this recent amazing “discipline” taught

us that preventing or treating a periodontal infection will reduce the risk of cardiac disease, stroke, premature birth,

though we still need further studies and data to confirm these relationships and to establish whether they are really

causal or not. Dentists are now crucial players in overall health care delivery process, true primary health care

professionals, I would say.

On the other side of dental platform, we are looking forward to witness a time when diseased temporo-

mandibular joints, teeth, maxillae, and mandibles won’t be anymore replaced by artificial means (such as titanium

implants), but can rather be regenerated, using stem cells and bioengineering.

Moreover, dental scientists are extensively working on saliva in order to use it as a diagnostic tool, and apart the

advantage of the non-invasive nature of collecting it, salivary antibodies are now measured to detect oral infections,

monitor Sjögren’s syndrome and alcohol abuse, determine clinical and biological response to therapy in breast

cancer treatment, and even assess clinical progression of Alzheimer disease.

4 Journal of the Lebanese Dental Association

Volume 46 - Nº 1 - 2009

Ziad Noujeim, Oral Surgeon and Dental Educator

A Finnish multidisciplinary team also reported a stunning discovery suggesting that tooth agenesis may be used

as an indicator of susceptibility for colorectal cancer.

Facing this rapidly changing world, the Lebanese Dental Association -LDA- is maintaining core values that

revolve around medically and biologically endorsed dental education, diversity and community care. Evidence-

Based Dentistry-EBD-is now mainstream, having been claimed and sustained by a public demand for it to be so,

and it is time for us now to share contemporary knowledge for the only purpose of giving benefit to patients we

serve.

It is now proven that strong evidence is of utmost importance for adoption of innovation. Systematic reviews,

published in high-impact factor peer-review journals and periodicals, are the only means to identify studies with

low-bias, and only explicit and systematic methods designed to limit bias and chance effects should be considered,

and ultimately, more precise effects of healthcare studies and trials are provided through statistically combined

results, using META analysis.

LDA remains committed to excellence and innovation and wholly dedicated to fostering continuing dental

education (through JLDA, seminars, workshops, and conventions), clinical research and patient care with current

and emerging technologies.

Global health care, including oral health care, is now redefined and dominated by information technology sharing

and many of daunting health care challenges affecting people in Arab countries and across the globe must be firmly

met by a community of dental and medical scientists who are willing to act collaboratively and across geographic

boundaries.

A number of indicators point out to the increasing globalization of dental schools and teaching centers in

Lebanon. In the past ten years, dozens of faculty members, clinicians and gifted scientists from the Arab world

(especially Egypt, Saudi Arabia and Jordan), Europe, Australia and North America have been invited to speak at

Saint-Joseph University, Lebanese University, American University Medical Center (in Beirut) and Beirut Arab

University, and most of these prestigious academic institutions are now being involved in active collaborative

research projects, with constantly growing partnerships, and their projects include orthodontics, dentofacial

orthopedics, dental materials, oral pathology and medicine, pain, dental osseointegrated implants,

temporomandibular disorders, esthetic dentistry, oral radiology and imaging, forensic dentistry and endodontology.

Lebanese dental investigators, in Lebanon and abroad, were invited to publish in the present JLDA issue and

forthcoming ones, in order to strengthen links and gather efforts. It is now time to set new international standards

for domestic practice, and in 2009, each dental practitioner has to follow safe, efficient, predictable and evidence-

based methods, and there is no reason for lebanese clinicians not to settle with less than the best standard of dental

and oral health care.

In a world where commercial and marketing interests were rampant, dentistry established itself as a profession

and we have lately moved in Lebanon from training to education, making it more respectable, recognized and

honorable, given our enormously increased responsibility towards humanity.

During the 1990s, the LDA became a significant national and pan-Arab player in identifying, debating and

articulating positions on issues important in dental profession and one of LDA’s most crucial purposes remains to

provide opportunity for bringing senior Lebanese dental investigators into intimate contact with our domestic

practitioners and by establishing this informal contact, LDA is making a broadened and deeper understanding

5Volume 46 - Nº 1 - 2009

6 Volume 46 - Nº 1 - 2009

happening between lebanese general dental practitioners, thirsty for further knowledge, and lebanese teachers and

scientists who stand now as “vectors of change”.

In this regard, I would like to pay tribute to Professors Nadim Baba and Philippe Aramouni, former Editors-in-

Chief of JLDA, who made drastic changes in our journal’s format and content and strived to maintain a decent, non-

biased critical review, and our long-term goal is to make JLDA one of the most highly esteemed dental journals

that publish clinically relevant and scientifically- based manuscripts.

This is my first issue as editor of JLDA and I am perfectly aware that editorial work requires effort, critical

thinking, attention, integrity, ethics, hard work, knowledge, humility, and given that all these attributes are rarely

found in one person, team effort is inevitable. Dentistry is becoming complex, this field being assembled by so many

disciplines and specialties that make dental picture complicated, and if our journal aimed earlier to enhance clinical

skills and abilities only by publishing short clinical notes and case reports, we are doing our best now to emphasize

contemporary and useful clinical procedures, educational cases and research, as we look forward to embodying what

we believe to be the seismic change that lately occurred in “dental minds”.

As of now, our journal will be designed to address practical issues that mainly concern general practitioners,

providing reliable and authoritative clinical basis for different treatment modalities. We will tackle, as well, research

issues and developing innovations authored by lebanese, arab and foreign scientists and clinicians.

It is the right and duty of dentists to get state-of-the-art information and judge, for themselves, which diagnostic

and treatment concepts lead to reliable long-term results and which do not. Commercialism in Dentistry is rising:

periodontology, as science and practice, is slowly vanishing, dentists are constantly pushing implants, whitening,

and not nicotine patches, and most of them extract asymptomatic third molars and weigh only what works in their

office, regardless of what academic researchers are saying. Before this ethical issue, the LDA is striving to raise

scientific controversies, foster intelligent discussions, support and endorse a common ethical set of values, in order

to save our patients from commercialism.

This millenium is the era of molecular approaches to oral therapeutics, newest technologies are already

integrated in routine clinical practice, but there is still a number of significant challenges to be overcome in the

development of truly innovative products in dentistry.

As a practicing dentist and dental educator, I feel particularly happy and lucky to witness changes that brought

to our hands cone beam volumetric tomography, CAD-CAM technology, bonded-zirconia restorations, saliva-based

diagnostics, novel therapies and preventive agents for dental caries, biomimetic materials for regenerating tooth and

jawbones, porcelain laminate veneers, Laser dentistry, ultrasonic tips, surgical operating microscope, orthodontic

mini-screws and many technologies to come!

In the blossoming world of cosmetic dentistry, teeth whitening and smile makeover reign supreme, but behind

this facade, there are other worrying and critical dental and oral health problems waiting to be solved by “oral

physicians”. Finally, as a dental community, we constantly need to be provided with scientific rationale and

evidence-base for new technologies in order to best implement new advances and ensure their ultimate success.

Ziad NoujeimEditor-in-Chief, JLDA,

Chairperson, Department of Research,

Senior Lecturer, Departments of Oral and Maxillofacial Surgery,

Oral Pathology and Diagnosis, and Basic Science,

Director, Oral Pathology and Diagnosis Graduate Diploma,

Lebanese University School of Dentistry, Beirut.

7

Meet the NewMeet the New

Associate EditorsAssociate Editors

Journal of the Lebanese Dental Association

Volume 46 - Nº 1 - 2009

Maria Saadeh graduated with a BDS

degree from Lebanese University School of

Dentistry in Beirut. She completed her

postgraduate residency in orthodontics at the

American University of Beirut Medical Center

(AUBMC), followed by an additional year as

chief resident. In 2008, she earned a Masters

of Science degree in Human Morphology

(AUB’s Faculty of Medicine) and she is

currently enrolled in a Masters in Public

Health program (AUB’s Faculty of Health

Sciences).

Dr. Saadeh was appointed as Clinical

Instructor in the Department of Orthodontics

at Lebanese University School of Dentistry in

November 2006 and as Clinical Associate in

the Division of Orthodontics and Dentofacial

Orthopedics at AUBMC in

July 2008. She is involved

in the treatment of patients

in private and academic

settings, as well as didactic

and clinical teaching of

orthodontic residents.

Her research projects

target the effect of cancer therapy on dental

and skeletal maturity in children. Her

scholarly contributions include scientific

publications, posters and oral presentations at

national and international conventions on

various topics including her main research

interest, as well as evidence-based practice in

dentistry and orthodontics.

Amine El- Zoghbi is Director of Occlusion

Graduate Diploma and Senior Lecturer in the

Department of Prosthodontics and Occlusion

at Saint-Joseph University Faculty of Dental

Medicine, in Beirut. He is also one of the

Associate Editors of the International Journal

of Stomatology and Occlusion Medicine, a

recent European periodical devoted to

occlusion medicine, masticatory system, oral

rehabilitation and interdisciplinary dentistry.

Dr. Zoghbi received his dental degree (Dr.

Chir. Dent.) from Saint-Joseph University in

Beirut and completed a

postgraduate training in

occlusion at University of

Aix-Marseille II Faculty of

Dental Surgery, in

Marseille, France,

graduating with a diploma

(DU) in occlusodontology. He maintains a

private practice (in Beirut) covering all

aspects of restorative dentistry, with a focus

on occlusion and temporomandibular

disorders.

8 Volume 46 - Nº 1 - 2009

Meet the New Associate Editors

Jihad Fakhouri is a graduate of Saint-

Joseph University Faculty of Dental Medicine

in Beirut, Lebanon. He completed a

postgraduate training in Paris, Marseille and

Lyon (France), attaining advanced

certificates (CES) in prosthodontics,

periodontology and oral surgery. He

graduated in implant dentistry from the

Institute of Stomatology and Maxillofacial

Surgery of University of Paris VI and earned

graduate diplomas (DU) in removable

prosthodontics, anthropology and forensic

dentistry. He also earned a Masters degree in

Medical and Biological Sciences and an

advanced studies diploma (DEA) in Health

Ecomonics. Lately, he attended a doctoral

course and undertook an original research at

Saint-Joseph University leading to a

“Doctorat d’Université” in Oral Biology and

Biomaterials.

During his specialty training, he worked as

Lecturer, Clinical Associate and Researcher

for 10 years in the

Department of

Prosthodontics at the

“Hôpital Nord” in

Marseille, France.

Currently, Dr. Fakhouri

is Assistant Professor in the Department of

Removable Prosthodontics at Saint-Joseph

University Faculty of Dental Medicine, in

Beirut. He is also Associate Editor of the

dental journal of Saint-Joseph Dental Faculty

(ACES) in Beirut and of “Industries

Dentaires” journal in Marseille. He is the

author and co-author of more than 14

scientific papers. His main interests are

impression materials and techniques, implant-

supported overdentures and partial

prosthesis. He maintains a private practice in

Beirut, Lebanon and has lectured in Lebanon,

France, Syria and Germany.

Implant Dentistry


Volume 46 - Nº 1 - 20099

The long-term survival of endosseous implants is a

phenomenon dependent on multiple biological and

functional factors1. It has been shown that implant

length, diameter, location (mandible v/s maxilla)and

surface characteristics, bone quality, parafunctions,

prosthetic parameters and biomechanical load are the

main factors that can affect the success rate. Whereas

bone quality and quantity seem to be among the most

influential parameters affecting the outcome of

therapy2, implant length variation was generally

associated with a greater failure risk. In studies

comparing survival rates of short implants, mostly

machined-surface, with longer implants, failures were

more often observed on implants of short length3,4,5,6,7,8,9

placed in maxillary sites where bone is generally of

lesser density and the functional load remarkably

increased10. Failure rates varied between 2.5% and

25%3,9,11. A second group of authors, although

concluding that failure rates are higher with short

implants, still showed adequate survival rates11,12,13. A

third group of authors reported that implant length did

not appear to significantly influence the survival

rate14,15,16,17,18,19,20,21. Finally, a fourth group which focused

specifically on short implants, showed similar clinical

outcomes to those reported in longer implants with

survival rates ranging between 88%-100%22,23,24,25

26,27,28,29,30,31,32. Why are success rates of short implants

today comparable to longer implants? What has

changed? What are the factors at stake in the

improvement of therapeutic outcomes? And are short

implants a viable solution in situations of atrophic

alveolar bone, especially in posterior mandible and

maxilla?

1. Implant length and diameter: Choices based on

biology.

There was a general belief that a long implant

would offer a greater resistance to occlusal load, a

higher survival rate and a more secure option

compared to a short implant, in case of peri-implant

bone loss. In a long-term study on the effectiveness of

oral implants in the treatment of partial edentulism33,

85% of implants had a diameter of 4.1mm and only

2.7% a diameter of 4.8mm. Implant length varied

between 8mm and 14mm. The overall success rate

reported was 96.7% after 7 years, with no difference

among implants of different length and diameter.

Other reports3,4,5 using implants of different surfaces

and a conventional surgical protocol reported lower

success with short implants. It is difficult, based on the

absence of comparative long-term prospective clinical

trials on implant length in posterior jaws, to draw

definitive conclusions on influence of implant length

Short implants in deficient posterior jaws: current knowledge.

Abstract

In clinical situations where bone is severely resorbed and implant-supported prostheses indicated, the strategy may be oriented

either towards reconstructive surgery and placement of implants in regenerated bone volume and height or use of short implants.

Improvements in surgical technique, surface texture and geometry of components as well as a better understanding of the

biomechanics of short implants increased their reliability. Despite unfavorable prosthetic parameters, long-term results in cases

of good bone density, good control of occlusion and parafunctions are equal to longer implants.

Peter Tawil1, Dr. Chir. Dent. , Georges Tawil2, Dr. Chir. Dent. , Dr. S c. Odont. , FICD, FACD

1 Postdoctoral Periodontics, University of Pennsylvania,

School of Dental Medicine, Philadelphia, USA,

2 Professor of Periodontology, Saint-Joseph University

Faculty of Dental Medicine, Beirut, Lebanon.

on clinical therapeutic outcome (Fig.1). In most

reported clinical studies, implant length reflected the

state of jaw resorption. Longer implants were used

where bone height was more available. However,

when comparing different studies where implants of

different lengths were used in partially edentulous

posterior jaws, it seems today, that implant surface,

bone quality, jaw resorption and practitioner’s learning

curve influence better the success rate than implant

length32.

Finite element analysis, although not reproducing

with great precision the conditions in-vivo, allowed us

to better understand biomechanical aspects of short

implants. Pierrinard34 demonstrated that bone stress

concentrates in the marginal area, irrespective of

implant length. Implant displacement increases as

length decreases, with a small difference at implant

neck level and a greater difference at apical level.

Bicortical anchorage reduces displacement(-5.8%) for

implants of same length but increases stress

concentration. Stress concentrations are confined at

the first thread. Difference is remarkable between 12

mm and 6 mm implants when it comes to micromotion

(-88%). Greater displacement of short implants in

bone and more bone flexing may reduce the risk of

biomechanical complications. In case of overload,

short implants may ultimately fail while longer

implants display mechanical complications.

According to Himmlova35, an increase in implant

diameter decreases the maximum von Mises

equivalent stress around implant neck more than the

implant length (31.5% decrease in stress from 3.6mm

to 4.2 mm diameter). In the same context, wider

implants rather than longer implants decrease stress

level34,36. However, no relationship could be found

between marginal bone loss and implant diameter in

most studies, while low changes in crestal bone levels

were reported.

The choice of implant length depends ultimately on

long-term results. Prospective clinical studies, where

all biological and biomechanical factors are accounted

for, will define indications and limitations of treatment

approaches.

2. Implant surface: What has changed?

Among 12 published studies indicating that short

implants failed more often than longer ones, 11 used

machined-surface implants3,4,5,7,9,11,13. Change in the

implant surface has led to consistently better results.

Khang and co-workers19 compared machined and

double acid-etched implants. Double acid-etched

implants provided better outcomes than machined-

surface implants (95% v/s 86.7% success rate).

Feldman and co-workers37 compared the survival rate

of short to long machined-surface v/s dual acid-etched

(DAE) implants. There was no statistical difference

between short and long DAE implants (0.7%), while a

difference of 7.1% in posterior maxilla was found

between machined-surface implants of different

lengths. In a systematic review, Hagi and co-workers38

compared the surface (machined v/s sintered porous

v/s textured),the macrogeometry (threaded v/s non

threaded or porous) and the length of implants (>7 mm

v/s <7 mm) concluding that surface characteristics

clearly play a major role in the success of short

implants and compensates for shorter implant length.

Deporter25 demonstrated a 100% clinical success rate

with sintered porous surface implants. The addition of

a roughened surface to the machined threads increases

bone to implant contact, interlocking and

osseointegration, and therefore improves the overall

clinical performance of short implants38,39. In a meta-

analysis on the effect of implant length on survival of

short rough-surfaced implants, it was concluded that

no significant difference in survival rate could be

found between short (<8 mm) and conventional (>10

mm) rough-surfaced implants either in partially or

totally edentulous patients40, underlying again the

10 Volume 46 - Nº 1 - 2009

Tawil P, Tawil G

Fig.1. Short implants placed in sites where longer implants

can be placed .


Tawil P, Tawil G

importance of implant surface in the outcome of

therapy.

Likewise, Bernard and co-workers41, in a study on

dogs, compared the reverse torque on implants with

machined surfaces (Bränemark) and those with

roughened surfaces (ITI). Reverse torque was 104-192

N/cm for 6-10 mm ITI implants, and 61-69 N/cm for

7-10 mm Bränemark implants.

3. Poor bone quality: What to do?

One of the main challenges in implant placement in

posterior jaws is bone quality. In these sites, bone is

less cortical and more spongious, rendering primary

stability and bone-to-implant contact a difficult task.

Bahat3 advocated a modification of the drilling

sequence in case of poor bone quality.

Underpreparation of implant site, a soft precise

surgical technique, will definitely enhance implant

primary stability31. Countersinking should be

minimized27, and an adapted surgical protocol will

definitely improve osseointegration of short implants.

The use of osteotomes rather than drilling in implant

site preparation was advocated by Summers42 and may

be a good approach for bone condensation, but on the

other hand, it has been reported43 that bone

condensation is also associated with microfractures

and alteration of microcirculation and vascular fluids

flow that may potentially delay healing and diminish

bone to implant contact during the first post-operative

weeks.

4. Splinting short implants to longer ones: A real

solution?

The majority of early studies reporting acceptable

results on short implants used longer implants

concomitantly and preferably splinted short to long

implants, rendering the interpretation of clinical results

and biomechanical analysis of short implants more

difficult. Splinting short implants to longer ones

obviously alters distribution of masticatory loads and

resistance to functional stresses, and increases

anchorage surfaces25,44. As for implant positioning in an

intermediate or distal position (Fig.2), Lekholm50 and

Bahat5 found out that placing a short implant in an

intermediate position was functionally more favorable.

Other authors14,17,20 could not correlate implant failure

with implant length. Nevertheless, it seems that there

is a lack of information and standardization regarding

this subject; clinical outcomes can be misinterpreted

and conclusions incorrect.

5. Splinting short implants together: A better

solution?

Splinting of short adjacent implants was initially

indicated to increase the resistance to functional and

parafunctional load. In a study by Tawil and Younan,28

each missing tooth was replaced with a machined-

surface implant and implants were splinted together

with a 95.5% success rate (Figs. 3a,3b,4,7,8,9): in this

study, bone quality may have been a major factor of

success but it remains difficult to determine the

importance of splinting in clinical outcome in the

absence of a free-standing control group. On the other

hand, in Gentile and co-workers45 study on short Bicon

implants, 97.7% of 6x5.7mm implants used were

restored with single crowns and yet reached a 92.2 %

success rate. In a study by Deporter and co-workers25,

151 Endopore implants were placed in the maxilla,

56% of the prostheses were splinted together while

43% were not. After a mean functional time of 6

months, the cumulative survival rate was 97.3%. No

significant difference was found between splinted and

single crowns. Rokni and co-workers46 found out that

bone loss was less extensive on short porous surfaced

implants restored with single crowns as compared to

splinted implants. A biomechanical explanation to this

phenomenon was that micromovements of short

Fig. 2. A 7x5 mm Nobel Biocare (NB)* TiU** shorty

implant placed in an intermediate postion in a deficient

subsinus ridge.

* NB = Nobel Biocare®

** TiU = TIUNITE® surface

11

12 Volume 46 - Nº 1 - 2009

Tawil P, Tawil G

in a 7mm sub-sinus ridge, splinted to a

1 in site 15

Fig. 3a. Reduced subsinus ridge height

but large enough to place a short and

wide implant.

Fig. 3b. Short implants (7x5 mm and 7x6

mm NB) in terminal position replacing

#16 and 17 in a 7 mm sub-sinus ridge,

splinted to an 11.5x3.75 mm implant

placed in site 15.

Fig. 4. 7x5 mm implant replacing # 16

splinted to a 10x3.75 mm in position 15.

Two year results.

8.5x3.75mm NB TiU implant splinted to a 10x3.75mm NB TiU)

r

Fig. 5. A 7x5 mm NB implant in

position 16 replacing a single molar.

Note the C/I ratio and the dimension

of the clinical crown. Three year result.

Fig. 6. 8.5 mm x 4 NB TiU implant

replacing # 47. Four year result.

Fig. 7. A short 8.5x3.75 mm NB TiU

implant splinted to a 10x3.75 mm NB

TiU) replacing # 46. Result at three years.

Fig. 8. Three mandibular implants of

8.5x3.75 mm, 7x4 mm et 6x5 mm NB

machined surface replacing # 45,46 and

47. Result at eleven years.

Fig. 9. Two 8x5 mm NB machined-

surface implants. Result at ten years.

Fig. 10. Edge-to-edge posterior occlusion

to better distribute forces along the long

implant axis, after elimination of working

and non-working interferences.


implants under functional load distributed forces better

if free-standing than splinted and better when short v/s

long. This is in agreement with biomechanical findings

in finite element analysis of Pierrinard and co-

workers34. On the other hand, the need for implant

splinting may depend on implant marginal

configuration (external or internal hex, cone Morse or

butt joint)47. Micromovements have been described in

case of external hex connection at the abutment-

implant interface which may cause greater strain on

prosthetic components and microbial microleakage55.

These considerations most likely favor implant

splinting rather than biomechanical factors related to

resistance to functional load by short rough-surfaced

implants.

6. Survival of short implants in mandible

Early studies indicating good long-term results on

short implants, independently of surface

characteristics and prosthetic considerations, used

preferably the mandible as a primary site versus the

maxilla. Tawil and Younan28 used the mandible in

88.8% of the cases, whereas Deporter and co-workers25

used it in 100% of the cases. The main reason for

indicating short implants in mandible is better

mandibular bone quality compared to maxilla (Fig. 6).

It is also of relevance to note that vertical bone

augmentation techniques in mandible are more

difficult to achieve and less predictable than in maxilla

(lateral approach or osteotome technique sinus lifts).

Numerous reports using short implants of different

surfaces and macrogeometry confirmed the approach

validity in posterior mandible20,29,30.

7. Survival of short implants in maxilla

Few studies29,31,48,49 used exclusively short implants

in maxilla (Fig. 5). Success rates of 94.6% to 100%

were reported. Fuggazzato and co-workers27 placed

979 implants in molar position, restored them with

single crowns and followed them up to 84 months,

with a cumulative success rate of 95.1%. These

success rates may be attributed to the use of rough

surface implants and a better assessment of bone

quality, with a change in surgical technique. A study on

ultra-short implants (5x5 mm)48 with success rates of

85.7% for maxilla and 100% for mandible after a

functional period of 1 to 8 years may push even further

the limits of conservative approaches in implant

dentistry. However, long-term controlled studies and

bigger sample size are warranted to determine the

validity of these results in maxilla.

8. Influence of prosthetic parameters on short

implant survival

Bone resorption is often accompanied by

unfavorable jaw relationship and maxillo-mandibular

space increase, with inevitable prosthetic consequence

of excessive crown height and occlusal table design and

increased bucco-lingual cantilever52. Maximum applied

and tolerated occlusal forces vary greatly according to

implant position on the arch, patient’s functional and

parafunctional habits and nature of opposing dentition.

High bending moments, unfavorable distribution and

intensity of occlusal forces may contribute to

biomechanical overload on hardware and supporting

bone53 (Figs. 10,11,12,13). Biomechanical complications

such as screw loosening and fracture, abutment fracture,

implant fracture or loss of osseointegration can occur.

But, are unfavorable prosthetic parameters really

dreadful on short implants survival?

Few studies in literature addressed this subject. If

in healthy dentition the optimal crown-to-root ratio is

1/2, this is rarely the case in implant-supported

prosthesis due to uncompensated bone loss. Rokni

and co-workers46 evaluated implant length, implant

surface area and crown-to-implant (C/I) ratio in

relation to crestal bone level changes. The mean C/I

ratio in their study was 1.5 (SD*** = 0.4; range 0.8 to

3.0), with 78.9% of implants having a C/I ratio

between 1.1 and 2.0. Neither C/I ratio nor estimated

implant surface area (< 600 mm2 / > 600 mm2)

affected steady-state crestal bone levels. In a study by

Tawil and co-workers54 on 262 implants, relatively

few (C/I) ratios were < 1 or > 2 (16.2%). Occlusal

table (OT) width ranged between 5.4 and 8.3 mm. No

significant difference in peri-implant bone loss was

correlated with C/I ratios or width of occlusal tables.

Neither mesial nor distal cantilevers length (2.75 ±

1.65 mm and 2.24 ± 1.60mm) nor bruxism, nor the

type of occlusion between the opposing jaws had a

significant effect on peri-implant bone loss. Mean

bone loss was 0.74 ± 0.65 mm. If the occlusion is

Tawil P, Tawil G

*** SD = Standard Deviation

13

carefully adjusted and occlusal contact closely placed

to the emerging axis of implants, forces will be fairly

distributed, with no major risk of more biomechanical

complications (Figs. 10,11).

Consequences of increased crown to implant ratios,

occlusal table width or cantilevers are therefore

negligible in cases of favorable occlusal loading (Figs.

12,13)

CONCLUDING REMARKS

Improvement of success rates and long-term

survival of shorts implants is possible today due to

changes in implant surface that greatly enhance

osseointegration. Also, with a better assessment of

bone quality and its technical management, a better

control of implant surgical technique32 under

preparation28 and limited countersinking27, better

results are expected. With a greater understanding of

biomechanics of short implants based on finite

elements models in vitro34,36, a proper evaluation of the

prosthetic parameters53,54 and practioner’s learning

curve, higher success rates can be reached. More

investigations and controlled studies are needed before

final conclusions can be drawn.

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19- Khang W, Feldman S, Hawley CE, Gunsolley J.A multi-

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21- Lemmerman KJ, Lemmerman NE. Osseointegrated dental

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22- Bernard JP, Belser U, Scmuckler S, Martinet JP, Attieh A,

Saad PJ. Intérêt de l’utilisation des implants ITI de faible

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à trois ans. Med Bucc Chir Bucc 1995;1:1-18.

23- Texeira ER,Wadamoto M, Akagawa Y, Kimoto T. Clinical

application of short hydroxyapatite dental implants to the

posterior mandibule:A five-year survival study.J Prosth

Dent 1997;78:166-171.

24- Ten Bruggengate CM, AsikainenP, Foltzik C, Krekeler G,

Suttler F. Short (6mm) non-submerged dental implants:

Results of a multicentral clinical trial of 1to 7 years.Int J

Oral Maxillofac Impl 1998;13:791-798.

25- Deporter DA, Todescan R, Watson PA, Pharoah M, Pilliar

RM, Tomlinson G. A prospective human clinical trial of

Endopore dental implants in restoring the partially

edentulous maxilla using fixed prostheses. Int J Oral

Maxillofac Impl 2001;16:527-536.

26- Deporter DA,Watson PA, Pillar RM et al. A prospective

clinical study in humans of an endosseous dental implant

partially covered with a powder-sintered porous coating: 3

to 4 year results. Int J Oral Maxillofac Impl 1996;11:87-

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27- Fuggazzoto PA, Beagle JR, Ganeles M et al. Success and

failure rate of 9mm or shorter implants in the replacement

of missing maxillary molars when restored with individual

crowns: a preliminary report 0-84 mo in function. A

retrospective study. J Periodontol 2004;75:317-331.

28- Tawil G , Younan R.Clinical evaluation of short machined-

surface implants followed from 12-92 months. Int J Oral


29- Griffin TJ, Chung WS. The use of short wide implants in

posterior areas with reduced bone height. A retrospective

investigation. J Prosth Dent 2004;92:139-144.

30- Nedir R, Bischof M, Briaux JM, Beyer S, Smuckler-Monkler

S, Bernard JP. A 7-year life-table analysis from a

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31- Renouard F, Nisand D. Short implants in the severely

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32- Renouard F, Nisand D. Impact of implant length and

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single-tooth restorations. Clin Oral Implants Res

2002;13:133-143.

34- Pierrinard L, Renouard F , Renault P, Barquin M. Influence of

implant length and bicortical anchorage on implant stress

distribution. Clin Impl Dent Rel Res 2003;5:254-262.

35- Himmlova, L. Influence of implant length and diameter on

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2004;91(1):20-25.

36- Iplikcioglu H, Akca K. Comparative evaluation of the effect

of diameter, length and number of implants supporting

three-unit fixed partial prostheses on stress distribution in

the bone. J Dent 2002;30:41-46.

37- Feldman S, Boitel N, Weng D, Kohles SS, Stoch RM. Five

year survival distribution of short implants ( 10mm or less)

machined surfaced and osseotite implants. Clin Impl Dent

Rel Res 2004;6:16-23.

38- Hagi D, Deporter DA, Pilliar RM, Arenovich T. A targeted

review of study outcomes with short (< or = 7 mm)

endosseous dental implants placed in partially edentulous

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39- Cochran DL. A comparison of endosseous dental implant

surfaces. J Period 1999;70:1523-39.

40- Kotsovilis S, Fourmousis I, Karoussis I, Bamia C. A

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41- Bernard JP, Smuckler-Monkler S, Pessotrto S, Vazquez L,

Belser VC. The anchorage of Bränemark and ITI implants of

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45- Gentile MA,Choang SK, Dodson TD. Survival estimates and

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47- Mers B, Hunenbart S, Belser U. Mechanics of the implant

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Ultra-short sintered porous-surfaced dental implants used to

replace posterior teeth. J Period 2008;79:1280-1286.

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management of the posterior maxilla using short

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50- Lekholm U, Gunne J, Henry P, Higushi K, Linden U,

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645.

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Correspond with:

George Tawil

[email protected]

16 Volume 46 - Nº 1 - 2009

Tawil P, Tawil G

Oral Medicine Research

19

The oral cavity is a unique environment and a

primary target for opportunistic infections, particularly

candidiasis caused by the human pathogen Candida

albicans (C. albicans)1-3. This commensal fungus

commonly colonizing human mucosal surfaces, has

long been adapted to the human host and has evolved

because of the specific demands of the host

environment. Distinctively, under conditions of

immune dysfunction such as HIV infection, colonizing

C. albicans strains can become opportunistic

pathogens causing recurrent mucosal infections. The

increasing emergence of strains resistant to the

commonly used antifungal agents has made clinical

management of candidiasis increasingly difficult and

the need for improved drug therapies crucial3, 4.

The oral mucosa constitutes a critical protective

interface between external and internal environments,

serving as a barrier to hundreds of microbial species

present in this environment2, 3. In the oral cavity, saliva,

a complex mix of fluids from salivary glands, plays an

important role in the maintenance of oral mucosal

health5, 6. Specifically, saliva contains a set of

antimicrobial peptides produced by the host and

considered to be an important part of the innate

immune system, contributing to maintaining the

balance between health and disease in this complex

environment7, 8. Surprisingly, the important role of

these natural antimicrobials in the protection of the

oral cavity from constant exposure to microbial

challenges and particularly their potential as

therapeutic agents is only just beginning to be

appreciated.

Most notable among the natural immune salivary

Mary Ann Jabra-Rizk*, Ph.D

* Associate Professor, Department of Oncology and

Diagnostic Sciences, University of Maryland Dental

School, Baltimore, and Department of Pathology, School

of Medicine, University of Maryland, Baltimore, USA.

Host salivary antimicrobial peptides and oral candidiasis.

Abstract

The oral cavity is a primary target for opportunistic infections, particularly oropharyngeal candidiasis. The etiologic agent

Candida albicans is the most pathogenic human fungal species that can either colonize asymptomatically or cause superficial or

even life-threatening infections, particularly in HIV+ and other immunocompromised individuals. However, the reasons behind

this transition from commensal to pathogen and the enhanced susceptibility of HIV+ individuals to oral candidiasis, are not clear.

In the oral cavity, salivary antimicrobial peptides are considered to be an important part of the host innate defense system in the

prevention of microbial colonization. Histatin-5 has specifically exhibited potent activity against C. albicans. Our previous

studies have shown histatin-5 levels to be significantly reduced in the saliva of HIV+ individuals, indicating an important role

for this peptide in keeping C. albicans in its commensal stage. However, the versatility in the pathogenic potential of C.

albicans is the result of its ability to adapt through the regulation of virulence determinants, most notably of which are secreted

proteolytic enzymes involved in tissue degradation and invasion. In this report, we present novel findings demonstrating that C.

albicans secreted proteolytic enzymes efficiently and rapidly degrade and deactivate a host peptide involved in the protection of

the oral mucosa against C. albicans, thereby providing new insights into the factors directing the transition of C. albicans from

commensal to pathogen. The dissemination of such crucial information has important clinical implications for alternative

therapy for the prevention of oral candidiaisis, particularly in susceptible hosts.


Volume 46 - Nº 1 - 2009

antimicrobial peptides are the histatins, a family of

low-molecular-weight, histidine-rich, cationic proteins

produced and secreted by human parotid and

submandibular-sublingual glands9-11. Histatins show

killing activities against numerous oral bacteria, as

well as potent antifungal properties against pathogenic

fungi including C. albicans10, 12, 13. Histatin-5 (Hst-5)

specifically, a 24-amino acid member of the family,

has exhibited the highest level of activity against C.

albicans, including strains resistant to antifungal

agents, implicating a mode of action for this peptide

different than the commonly used drugs14, 15.

Although not substantiated since, studies in the

early 1990s have reported changes in salivary histatin

concentrations in HIV+ individuals, as a result of

salivary gland dysfunction16, 17. Given the important

role of saliva in maintaining oral health, it is

conceivable that alterations in salivary gland secretion

and/or composition are liable to contribute to the

markedly enhanced predisposition of this population

to oral candidiasis. Yet, studies confirming these

important observations have been lacking, most likely

due to the lack of feasible methods for measuring

salivary histatin concentrations. Recently, however, we

confirmed these observations in a study comparing the

levels of salivary Hst-5 between a group of HIV+ and

HIV- individuals at the University of Maryland Dental

School in Baltimore18. Results from the investigation

demonstrated significantly lower Hst-5 levels in HIV+

group, concomitant with increased prevalence of C.

albicans in the oral cavity, highlighting the

involvement of host innate immunity in the protection

against C. albicans colonization18.

In the case of C. albicans, the transition from

harmless commensal to disease-causing pathogen is

finely balanced and attributable to an extensive array

of virulence factors. This is quite obvious through the

diverse manifestations of candidiasis, for in addition to

oral and mucosal infections in the United States of

America, C. albicans is currently ranked the third most

commonly isolated bloodstream pathogen in

hospitalized patients with a mortality rate of 40-50%4,

19, 20. The versatility in the pathogenic potential of this

fungal species is the result of its ability to adapt,

evolve and evade host immune defenses through the

regulation of virulence determinants, selectively

expressed under suitable predisposing conditions21-23.

These virulence factors may well vary, depending on

the type of infection, the stage and site of infection and

the nature of the host response.

Most notable among the pathogenic factors of C.

albicans are the aspartic proteases (Saps), a family of

secreted proteolytic enzymes considered to be vital for

its pathogenesis24-26. Candida albicans Saps have been

shown to degrade a variety of host defense proteins

such as lactoferrin and immunoglobulins27. However,

despite the extensive available information on the

association of C. albicans Saps and host protein

degradation, in-depth investigations into the ability of

the Saps to degrade small salivary antimicrobial

peptides, specifically those with potent anti-candidal

properties such as histatins, has not been fully

investigated. Such findings would carry significant

implications as they may contribute to our

understanding of the quandary of the enhanced

propensity of HIV+ population to oral candidiasis. To

that end, a study was initiated in our laboratory to

analyze the ability of C. albicans to degrade Hst-5 in-

vitro and to attribute the proteolytic activity to the

secreted aspartic proteases. The following is a

summary of the findings from the recently published

work28.

In order to determine whether C. albicans possess

the ability to degrade Hst-5, degradation assays were

designed where following exposure of the peptide to

C. albicans yeast cells for 2 hours at 37°C, the

degradation reactions were subject to sodium dodecyl

sulfate polyacrylamide gel electrophoresis (SDS-

PAGE) analysis. Images from these experiments

clearly revealed a gradual loss of peptide integrity

proportional to the C. albicans cell density (Fig.1A)

and time of exposure (Fig.1B) demonstrating that C.

albicans cells efficiently and rapidly degrade Hst-5 in

as little as 20 minutes. In contrast, using a range of

Hst-5 concentrations, the level of degradation was

shown to be inversely proportional to Hst-5

concentration (50-200 µg/ml). Combined, these

observations indicated that occurrence of intricate

20 Volume 46 - Nº 1 - 2009

Jabra-Rizk MA


interactions in the oral cavity involving host and

pathogen factors, may shift the balance in favor of the

host or the pathogen. In the case of individuals with

compromised immune system, the pathogen often

prevails.

It is important to note that adherence of C. albicans

to oral tissue is a pre-requisite for colonization and

proliferation leading to tissue invasion and infection29,

30. Candida albicans cell concentrations of 1 x 102

cells/ml and below are indicative of commensal

colonization in the oral cavity29. In our experiments,

this cell density was shown to be susceptible and

unable to degrade physiological concentrations of Hst-

5 in-vitro. However, our results demonstrated that the

level of degradation of Hst-5 was proportional to the

cell density of C. albicans, supporting the hypothesis

that the role Hst-5 plays in the oral cavity is crucial in

controlling the proliferation of commensal C. albicans

strains and consequently, their over-colonization of

oral mucosa.

More importantly, in order to identify the cleavage

sites for C. albicans on Hst-5, peptide mapping was

performed on the degradation fragments using RP-

HPLC separation followed by MALDI-TOF/TOF MS

analysis. rHPLC separated degradation products into 4

peaks (Fig.2A) and subsequent MALDI analysis

showed them to correspond to Hst-5 fragment 18-24,

1~11, 1-17, and intact Hst-5 (peaks 1 - 5 respectively)

(Fig.2B). More importantly, four of the identified

cleavage sites were located within the 12-amino acid

antimicrobial fragment of Hst-5 implying that

cleavage at these sites would compromise the anti-

candidal properties of Hst-5.

Consequently, to address the implications of Hst-5

degradation on its killing potency, killing assays were

performed as previously described31. Hst-5 was

evaluated following its degradation by C. albicans

cells, where fragments liberated from degradation

reactions were used in killing assays. Briefly, C.

albicans cells at various cell densities were mixed with

Hst-5 and incubated for 2 hours at 37ºC with shaking.

Aliquots from reactions were inoculated on YPD agar

and incubated for 24-48 hours at 35ºC. Following

incubation, the number of single colonies on each plate

was counted and the percent cell killing calculated

with respect to that obtained from exposure of the

yeast cells to the intact un-cleaved Hst-5. The results

from these experiments demonstrated that in contrast

to the intact Hst-5, the fragmented Hst-5 had no effect

on C. albicans. In addition, the percentage of killing of

C. albicans by Hst-5 was inversely proportional to the

cell density where Hst-5 was able to kill 90% of the

cells at a density unable to cause any significant level

of degradation (1x106 cells/ml) (Fig.1A). Conversely,

C. albicans cell density shown to degrade Hst-5 (50%)

resulted in 50-60% drop in killing (Fig.1A). More

Jabra-Rizk MA

Fig. 1. Degradation of Hst-5 (A) Degradation by C. albicans

demonstrating degradation level proportional to cell density

(cells/ml) (B) Degradation of Hst-5 over time (minutes)

demonstrating degradation level proportional to exposure

time. Minor degradation following 20 mins incubation at

37ºC observed by the appearance of lower weight product,

whereas significantly increasing level of degradation seen

after 1 hour and 2 hours.

Fig. 2. Peptide mapping of cleaved Hst-5 (A) Separation of

Hst-5 fragments by RP-HPLC following degradation by C.

albicans resulting in 4 peaks corresponding to fragments 18-

24, 1-12, 1-17, and 1-24 on the Hst-5 amino acid sequence

(B) Comparison of cleavage fragments (1 – 4) identified by

Mass Spectrometry following degradation of Hst-5 with C.

albicans. The boxed fragment in orange represents the part

of peptide with antimicrobial properties. The green bars

represent fragments generated from cleavage within the

antimicrobial fragment.

1A

2A

2B

1B

importantly, testing the Hst-5 cleaved fragments

liberated into the supernatants for killing ability

resulted in 0% killing of C. albicans at previously

susceptible cell density. Combined, these findings

demonstrated that the ability of Hst-5 to kill C.

albicans largely depends on its integrity and the ratio

of its concentration to the cell density of C. albicans.

The novel findings from this investigation

demonstrate the ability of C. albicans to efficiently and

rapidly degrade salivary anti-candidal peptide Hst-5

through the secretion of proteolytic enzymes. In turn,

these findings seem to attribute a new function for

these enzymes in the oral cavity, where in addition to

tissue invasion they also target a host substrate

comprising the first line of defense against invading

pathogens. Furthermore, these findings combined with

those from our initial investigations demonstrating

decreased salivary Hst-5 levels in HIV+ individuals,

the most vulnerable population to oral candidiasis,

strongly support the notion of an involvement for Hst-

5 in the enhanced propensity of HIV+ individuals to

this opportunistic infection18. In summary, this report

provides new insights characterizing a defined

mechanism involving both host and pathogen factors

behind the transition from commensalism to

parasitism, ultimately leads to the development of oral

candidiasis.

ONGOING STUDIES

In light of these recent findings, our laboratory has

initiated an in-depth investigation to validate the

following hypothesis: “Decrease in levels and anti-

candidal potency of salivary Hst-5 in HIV+

individuals leads to increase in C. albicans

colonization and proliferation and attributes an

important role for the host innate immunity in the

enhanced propensity of these individuals to recurrent

oral candidiasis”. Specifically, using a large HIV-

infected and non-infected populations with various

subsets of individuals, we aim to:

1- Determine the salivary Hst-5 levels in patients’

saliva, assess the prevalence of C. albicans in

their oral cavities and determine the level of Hst-

5 degradation of the isolates recovered from the

patients.

2- Utilize the patients’ saliva with pre-determined

Hst-5 levels to assess salivary Hst-5 protection

against candidal adherence and invasion, using

an organotypic model of human oral epithelium

tissue by quantification of tissue damage,

neutralization assays and histopathological

examination.

3- Determine the protective effect of salivary Hst-5

against C. albicans infection in-vivo, using a

mouse model for oral candidiasis.

Experimental animal models of mucosal

candidiasis have been invaluable in assessing fungal

pathogenicity and host immune defenses. These

studies have informed us that C. albicans is the most

virulent Candida species in-vivo and that the immune

response to Candida is different at various mucosal

sites, consequently highlighting the gaps in our

knowledge of Candida pathogenicity and host

immunity. Therefore, in order to accomplish Aim 3 of

our proposal in determining the role of host-produced

Volume 46 - Nº 1 - 2009

Jabra-Rizk MA

Fig. 3. A murine model of sustained oral candidiasis. Mice

are infected with 1x107 C. albicans cells and euthanized 4

days post-infection and tongue was harvested and subject to

histopathological analysis. Following PASa

and H&Eb

staining, both hyphal and blastoconidial forms are seen

invading the superficial epithelial layer of the mucosa and

the invasive hyphae invading parakeratin and spinous layers.

These histological findings are similar to those for humans

with oral candidiasis. In addition, fungal culture results

demonstrated an average colonization of 2.0x104 CFUc/ml

in infected mice whereas the control mice harbored no C.

albicans as determined by plating.

a: PAS = Periodic Acid-Schiff.

b: HE = Hematoxylin and Eosin.

c: CFU = Colony Forming Unit.

22


peptides for their role in disease development and/or

progression, we have established a murine model of

sustained oral candidiasis currently utilized for in-vivo

testing of the efficacy of Hst-5 against oral

colonization and infection by C. albicans. In these

studies, three-month-old female CD1 mice are

immunocompromized, anesthetized and orally-

infected with 1x107 C. albicans cells. Four days post-

infection, mice are euthanized and the tongue is

harvested and subject to histopathological analysis. As

seen in the images (Fig.3), both mycelial and

blastoconidial forms invaded the superficial epithelial

layer of the mucosa. The hyphae are seen invading the

parakeratin and spinous layers. The characteristic

finding of candidal dimorphism, embedded within the

parakeratin, can be seen using the PAS and H&E

stains. These histological findings are similar to those

for humans with oral candidiasis. In addition, fungal

culture results demonstrated an average colonization

of 2.0x104 CFU/ml in infected mice, whereas control

mice harbored no C. albicans as determined by plating.

Currently, these in-vivo studies are being performed

on mice orally treated with Hst-5 prior to and post-

infection, in order to determine whether Hst-5 protects

the oral mucosa from C. albicans adherence.

Alternatively, Hst-5 will also be administered to mice

in drinking water throughout the course of infection, in

order to mimic the effect of constant exposure of saliva

on the health of the oral mucosa. This proposal is

currently awaiting funding from the National Institutes

of Health (NIH).

CONCLUSION

Recognizing the various factors and conditions that

play a role in candidal colonization and the

progression of colonization to infection will greatly

contribute to our understanding of the complex

mechanisms of the adaptability of C. albicans to its

environment, its pathogenesis and contributing host

factors. Such crucial information will have important

clinical implications as it aids in the identification and

design of novel therapeutic strategies aimed at the

prevention and/or treatment of infections. Specifically,

with the limited arsenal of antifungals available,

coupled with the increasing emergence of resistant

strains, the prospect of preventing C. albicans

colonization, thus precluding candidiaisis through

enhanced natural expression of innate peptides or their

development as alternative therapeutic agents, is

becoming increasingly attractive. Specifically, the

anti-candidal property coupled with its lack of toxicity

to human cells, makes Hst-5 a promising therapeutic

agent for the treatment or prevention of oral

candidiasis in immunocompromised individuals. The

dissemination of these new findings is therefore

crucial for the design of novel peptides for therapeutic

use for candidiasis, specifically those peptides based

on structure of histatins, which has been the focus of

much research lately. However, further in-depth

investigations are warranted in order to determine the

clinical implications of Hst-5 inactivation by C.

albicans, particularly in the immunocompromised

host.

Acknowledgements

The author wishes to thank her collaborators, Dr.

Tim Meiller, Dr. Mark Shirtliff, Dr. Mark Scheper and

Dr. Bernhard Hube. She would also like to thank

Alexandra Mae Rizk and Elie Jay Rizk for their

assistance in the manuscript.

REFERENCES1- Calderone RA. ed. Candida and Candidiasis. 2002, ASM

Press: Washington.

2- Klein RS, et al. Oral candidiasis in high-risk patients as the

initial manifestation of the acquired immunodeficiency

syndrome. The New England Journal of Medicine 1987; 31:

354-358.

3- de Repentigny LD, Lewandowski P, Jolicoeur P.

Immunopathogenesis of oropharyngeal candidiasis in human

immunodeficiency virus infection. Clin Microbiol Rev

2004; 17: 729-759.

4- Fidel PL Jr. Candida-host interactions in HIV disease:

relationships in oropharyngeal candidiasis. Adv Dent Res

2006; 19: 80-84.

5- Edgar WM. Saliva: its secretion, composition and functions.

Brit Dent J 1992; 172: 305-312.

6- Humphrey SP, Williamson RT. A review of saliva: normal

composition, flow, and function. J Prosth Dent 2001; 85:

162-169.

7- Helmerhorst EJ et al. Oral fluid proteolytic effects on histatin

5 structure and function. Arch of Oral Biol 2006; 51: 1061-

1070.

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24 Volume 46 - Nº 1 - 2009

8- Gyurko C et al. Killing of Candida albicans by histatin 5:

cellular uptake and energy requirement. Antonie van

Leeuwenhoek 2001; 79: 297-309.

9- Helmerhorst EJ, Troxler RF, Oppenheim F.G. The human

salivary peptide histatin 5 exerts its antifungal activity

through the formation of reactive oxygen species. PNAS,

2001; 98: 14637-14642.

10- Edgerton M et al. Candidacidal activity of salivary

histatins. J Biol Chem 1998; 272: 20438-20447.

11- Oppenheim F. et al. Histatins, a novel family of histidine-

rich proteins in human parotid secretion. J Biol Chem

1988; 263: 7472-7477.

12- Jainkittivong A, Johnson DA, Yeh CK. The relationship

between salivary histatin levels and oral yeast carriage.

Oral Microbiol Immunol 1998; 13: 181-187.

13- Helmerhorst EJ et al. The cellular target of histatin 5 on

Candida albicans is the energized mitochondrion. J Biol

Chem 1999; 274: 7286-7291.

14- Jang WS et al. The P-113 fragment of Histatin 5 requires a

specific peptide sequence for intracellular translocation in

Candida albicans which is independent of cell wall binding

Antimicrob Agents Chemother 2008; 52: 497-504.

15- Koshlukova SE et al. Salivary histatin 5 induces non-lytic

release of ATP from Candida albicans leading to cell death. J

Biol Chem 1999; 274: 18872-18879.

16- Lal K et al. Pilot study comparing the salivary cationic

protein concentrations in healthy adults and AIDS patients:

correlation with antifungal activity. Journal of Acquired

Immune Deficiency Syndrome and Human Retrovirology

1992; 5: 904-914.

17- Mandel ID, Barr CE, Turgeon L. Longitudinal study of

parotid saliva in HIV-1 infection. J Oral Pathol Med 1992;

21: 209-213.

18- Torres SR et al. Salivary Histatin-5 and oral fungal

colonization in HIV+ individuals. Mycoses 2008;52:11-15.

19- Klein RS et al. Oral candidiasis in high-risk patients as the

initial manifestation of the acquired immunodeficiency

syndrome. N Engl J Med 1984; 311:354-358.

20- Perlroth J, Choi B, Spellberg B. Nosocomial fungal

infections: epidemiology, diagnosis, and treatment. Med

Mycol 2007; 45: 321-346.

21- Brown AJ, Odds FC, Gow NA. Infection-related gene

expression in Candida albicans. Cur Opin Microbiol 2007;

10: 307-313.

22- Hube B. Infection-associated gene of Candida albicans.

Future Microbiol 2006; 1: 209-218.

23- Kumamoto CA. Niche-specific gene expression during C.

albicans infection. Cur Opin Microbiol 2008; 11: 325-330.

24- Naglik JR et al. Candida albicans proteinases and

host/pathogen interactions. Cell Microbiol 2004; 6: 915-

926.

25- Naglik JR, SJ Challacombe, B Hube. Candida albicans

secreted aspartyl proteinases in virulence and

pathogenesis. Microbiol Molec Biol Rev, 2003; 67: 400-

428.

26. Albrecht A et al. Glycosylphosphatidylinositol-anchored

proteases of Candida albicans target proteins necessary for

both cellular processes and host-pathogen interactions. J

Biol Chem 2006; 281: 688-694.

27- Naglik JR, Challacombe SJ, Hube B. Candida albicans

secreted aspartyl proteinases in virulence and

pathogenesis. Infection and Immunity, 1999; 67: 2740-

2745.

28- Meiller T.F. et al. , A novel immune evasion strategy of

candida albicans: proteolytic cleavage of a salivary

antimicrobial peptide. PLoS ONE 2009; 4: e5039.

29- Cannon RD, WL Chaffin. Colonization is a crucial factor in

oral candidiasis. J Dent Educ 2001; 65: 785-787.

30- Chandra J et al. Biofilm formation by the fungal pathogen

Candida albicans: development, architecture, and drug

resistance. J Bacteriol 2001; 183: 5385-5394.

31- Meiller TF et al. A novel immune evasion strategy of

Candida albicans: proteolytic cleavage of a salivary

antimicrobial peptide. PLoS ONE 2009; 4: e5039.

Correspond with:

Mary Ann Jabra-Rizk

[email protected]

This research was supported by the National Institutes of

Health / NIH grants DE14424 and DEO16257.

Jabra-Rizk MA

Laser Dentistry

25

The successful application of laser in different

medical fields such as ophthalmology, dermatology

and surgery1, 2 had a stimulating effect concerning

research on lasers in dentistry. The introduction of

lasers in dentistry3 opened new perspectives in

different therapeutic dental procedures. From the

beginning of the nineties, some commercially

motivated ideas presented laser as a magical

(promising) tool that could sometimes achieve all

therapeutic goals with superior results to all

conventional therapies, leading to some failure and

deception. Then, laser dentistry evolved progressively

toward a more scientific evidence-based approach,

which helped identify the indications for every kind of

laser.

In periodontal practice, many lasers were tested for

different purposes. Until now, results in literature are

sometimes inconsistent and contradictory, but a certain

consensus was elaborated over the years, considering

Erbium lasers as the most suitable lasers4 for hard

tissues ablation. Thus, Er:YAG (Erbium: yttrium-

aluminum-garnet) lasers are indicated for periodontal

pocket debridement. This makes of Er:YAG a suited

laser for periodontal practice, especially that bone

surgery could also be performed with these lasers.

Also, many dental procedures are performed with

Er:YAG lasers: periodontal soft tissues surgery, cavity

preparation, dentine desensitization, oral lesions

treatment, laser bleaching….

This article focuses on the use of Erbium:YAG

laser in different periodontal treatments delivered at

the University hospital of Nantes (CHU de Nantes,

France). The clinical research carried out by our

department will also be exposed.

ERBIUM:YAG LASER

Laser is an acronym for Laser Amplification by

Stimulated Emission of Radiation. Light is generated

by electrical excitation of a YAG matrix doped with

erbium atoms. The emitted photons are amplified in a

parallel mirrors system, and the output beam is a

coherent, unidirectional and monochromatic light, of a

2.94 µm wavelength. The latter coincides with the

highest absorption coefficient of water. This specific

wavelength of Er:YAG lasers permits the ablation of

hard tissues without substantial damage to surrounding

sound tissues. In fact, when irradiating a hard tissue

with an Er:YAG laser, the instant absorption and

evaporation of water in the tissues will create an

internal pressure in the molecules, rapidly resulting in

Erbium: YAG Laser in everyday periodontal practice.

1 University Hospital Teaching Assistant, Department ofPeriodontology-ERT 2004, Faculty of Dental Surgery,Nantes, France,

2 Intern in Odontology, Nantes University Hospital,Nantes, France,

3 Chairperson and University (Full) Professor, Department ofPeriodontology, Faculty of Dental Surgery, Nantes, France.

Zahi Badran1, Dr. Chir. Dent. , CES Perio. , DU Perio. , MS , Céline Bories2, Dr. Chir. Dent. ,

Assem Soueidan3 , Dr. Chir. Dent. , Dr. Univ. , HDR, PU, PH


Volume 46 - Nº 1 - 2009

Abstract

Laser dentistry is becoming a fast growing dental discipline. Lasers are progressively being integrated in clinical protocols

and Laser Periodontology has evolved through the years after a disappointing start. In fact, multiple parameters determined the

possibility of using lasers in periodontal practice: nature of used lasers, form of tips, output settings, water irrigation…

Nowadays, many periodontal procedures could be performed safely with an acceptable efficacy.

In this article, we will review the main periodontal laser procedures, routinely performed at Nantes University Hospital.

a “micro explosion” and a localized ablation of

irradiated tissue, without melting or carbonization of

surrounding areas.

The device we are using is equipped with automatic

calculus detector (Kavo Key Laser 3®). The

technology is based on the differential fluorescence of

calculus and root surface when excited with a light of

a 655 nm wavelength. A feedback of the fluorescence

signal is analyzed by computer software. When

calculus is detected, therapeutic laser (2.94 µm) is

automatically activated until the fluorescence signal

disappears.

PERIODONTAL DEBRIDEMENT

The mechanical treatment of periodontal pockets

has always been the main therapeutic strategy for

controlling periodontal infection and eliminating

pockets. The main goal of this strategy is to

mechanically remove the subgingival plaque/calculus

and the contaminated superficial layer of root

cementum. Manual root planning (with curettes) or

ultrasonic scalers are used to reach this objective.

The laser Er:YAG was proposed as an alternative to

mechanical debridement. Few clinical studies have

evaluated the efficacy of laser debridement (LD) in

comparison to conventional mechanical treatments5,6.

The overall impression is that laser is equivalent or, at

best, slightly superior in terms of clinical output7. LD

was also found to be less time consuming than

ultrasonic debridement when used in combination with

a calculus detection device8. Concerning the property

of laser to be bactericidal, in vitro studies confirmed

that laser irradiation has an antibacterial effect9.

Though, in a clinical study, 1 month after treatment,

bacterial reduction after LD was not significantly

different compared to that observed after mechanical

treatment10.

Another subjective impression frequently

expressed by laser clinicians and patients, is LD being

more comfortable and less painful. In our routine

activity at Nantes University Hospital (CHU)*, we

share this impression, noting that most LD sessions are

performed without local injection of anesthetics or

with an anesthetic periodontal gel (Oraqix®).

Actually, we are conducting a clinical pilot study,

comparing the clinical output of Er:YAG laser

debridement (Fig. 1) to conventional manual root

planning. In this study, a split moth design was

adopted. Laser is used with the calculus detection

feature. Clinical parameters (attachment loss, probing

depth and bleeding on probing) as well as

microbiological changing will be monitored 2 months

after initial non surgical treatment.

DENTINE DESENSITIZATION

Dentinal hypersensitivity (DH) is a frequent

manifestation affecting 4-57% of the general

population. Pain caused by DH could influence the

quality of life and the well-being of affected patients.

The etiology of DH is an exposed area of dentinal

tubules; this is a result of enamel and/or cementum

loss. Pain triggering stimulus can be thermal, chemical

or mechanical. It is admitted that different stimuli

initiate a movement of the dentinal fluid, stimuli hence

generating pain.

DH treatment aims to obliterate the exposed

dentinal tubules. Different desensitizing products are

used for this purpose, enriched with fluorides or

potassium nitrates and prescribed in different forms:

toothpastes, mouthrinces, topical gels, etc...

Recently, laser desensitization (LDS) was proposed

as a therapeutic alternative to conventional treatment

modalities, with an equivalent efficacy11,12. The main

advantage of laser is that instant pain relief could be

achieved in 50-60 seconds in a one-session treatment

(Fig. 3). Our preliminary in-vitro research showed that

Er:YAG laser, when used at a low frequency and

intensity (60 mj, 2Hz) initiates a mild superficial

melting of dentin (Fig. 2). This melting will obliterate,

partially or totally, the exposed dentinal tubules. In

clinical practice, severe DH cases were successfully

treated by LDS, where irradiation of exposed dentin

could be painless for few seconds, then pain

diminishes rapidly, and the result is instantly felt by

patient after 40-50 seconds of irradiation. One of the

limits of LDS is that exposed area should not be in

proximal areas where access of laser beam is

impossible. Long-term follow-up is necessary to

confirm the stability of LDS initial results.

26 Volume 46 - Nº 1 - 2009

Badran Z, Bories C, Soueidan A

* CHU = Centre Hospitalier Universitaire


SOFT TISSUES SURGERY AND ORAL

LESIONS

Er:YAG lasers can be successfully used to perform

different types of minor soft tissues surgery:

gingivectomy, frenectomy, fibroma elimination…The

main advantage of laser is its capacity to initiate blood

coagulation and to allow instant control of postsurgical

bleeding. As previously explained, Er:YAG laser is

rapidly absorbed by water and heat propagation in

tissues is relatively low: this characteristic permits a

safe soft tissue ablation, with minimal thermal damage

to surrounding tissues, but it also makes the

procedures time consuming in comparison to other

lasers (Nd:YAG, Diode lasers…). We have found

Er:YAG lasers particularly useful in performing

frenectomy in young patients. In fact, no sutures are

needed, postsurgical bleeding and pain are minimal

and sometimes nonexistent. We should also note that

in some cases, we carried out laser gingival surgery,

using only topical gel anesthetic. But we emphasize

that this is patient dependent and not all laser surgeries

could be performed without a conventional intra-

mucosal analgesia injection.

Another indication for Er:YAG laser is the

symptomatic treatment of oral lesions such as gingival

aphtous ulcers (Fig. 4). In our practice, ER:YAG laser

was effective in substantially reducing pain caused by

aphtous lesions. Nevertheless, the healing period was

not always reduced by Er:YAG laser irradiation.

TREATMENT OF PERI-IMPLANT

INFECTIONS

Conventional treatments of peri-implant mucositis

or peri-implantitis consist of a mechanical

debridement using non-metallic curettes or ultrasonic

tips (plastic, Teflon, etc...). Lasers were suggested as

alternatives to these modalities13. The rationale behind

this is that laser beam does not cause any damage to

the metallic implant surface. Laser light could also

decontaminate the entire implant surface, even the

rough surface type, in comparison to mechanical

treatment where the tip of the curette or the scaler

cannot effectively reach the microstructure.

We have combined mechanical and photonic (laser)

treatments in the management of peri-implant

infections (Figs. 5 A,B,C). We have been using Teflon


Fig. 1. A: Chisel shaped tip for root debridement.

B: Laser debridement of a periodontal pocket.

Fig. 2. A: Control samples of dentine with exposed tubules,

observed using a scanning electron microscope.

B: Microscopical obliteration of dentinal tubules after 60 sec

of irradiation (E: 60mJ, Fr: 2Hz) (Original magnification:

x3000).

Fig. 3. A: Detection of painful area using the tip of a probe.

B: Protection of soft tissues with a wet gauze and Er:YAG

laser irradiation of hypersensitive area

Fig. 4. A: Painful aphtous ulceration localized in the buccal

maxillary mucosa. B: Laser irradiation of the lesion with an

Er:YAG device (E: 100mJ, Fr: 6Hz). C: Healing, one week

post-treatment, pain decreased substantially 24 hours after

the laser session and, after 2 days, it was almost inexistent.

A B

28 Volume 46 - Nº 1 - 2009

ultrasonic tips for the initial debridement, followed by

an Er:YAG laser decontamination carried out

thoroughly. A specific beveled, round shaped laser tip

is used. The latter provides an angulated secondary

beam directed towards the implant surface (Fig. 5.C).

Preliminary results show that this protocol could

induce a significant reduction of probing depth and

peri-implant inflammation. A research protocol to

determine the efficacy of implant LD is under

preparation.

CONCLUSION

Er:YAG laser is a polyvalent tool laser that can be

used in a variety of dental procedures. In periodontal

practice, Laser debridement seems to be a promising

alternative to mechanical debridement. Our present

knowledge suggests that it can be effectively used to

treat periodontitis, with a clinical output comparable or

slightly superior to conventional treatments. However,

clinical studies are still insufficient to emit an

evidence-based conclusion about clinical relevance of

laser debridement in comparison to mechanical

debridement.

For desensitization, Er:YAG laser appears to be a

promising novel therapy, with an instant clinical

efficiency. The acceptance of patients has been an

interesting advantage found in clinical trials. A one-

session laser could be a valuable starting point for DH

treatment and desensitizing chemicals (mouthwashes,

toothpastes, fluoride gels…) could be later prescribed

as an adjuvant since they access proximal

hypersensitive spots. A new protocol is being

investigated (Data not shown) with encouraging

preliminary results. It consists of applying a

desensitizing topical fluoride paste (Durafat®) and

irradiating the hypersensitive area with an Er:YAG

laser.

In dental literature, a large amount of case reports

suggested the efficacy of different lasers in the

management of benign oral lesions. Lasers could be

useful to treat pain and/or to accelerate healing

process. Our experience confirms this clinical

impression. However, the biological effect of lasers on

these oral lesions is not well elucidated. Controlled

clinical trials are also needed to determine the real

efficacy of lasers compared to conventional

symptomatic treatments.

For peri-implant infection, Er:YAG laser seems

indicated to implant surface debridement. In-vitro data

confirmed its antibacterial effect on titanium

surfaces14.

In conclusion, lasers, generally, and Er:YAG

particularly, are starting to gain their place in the

general dental or specialist periodontal office. The

indications of Er:YAG laser treatment are in constant

development with the introduction of new protocols.

More time is however needed to establish an evidence-

based knowledge concerning lasers procedures.

Furthermore, controlled clinical trials are required to

determine the relevancy of different laser protocols in

clinical practice.

Acknowledgements

We would like to thank Kavo France for supporting

our clinical research and for its contribution to the

doctorate (Doctorat d’Université) project of Dr. Zahi

Badran.

REFERENCES1- Steinert RF. Femtosecond laser enabled keratoplasty (FLEK).

Ann Ophthalmol (Skokie) 2009; 41:6-9.

2- Winstanley DA, Uebelhoer NS. Future considerations in

cutaneous photomedicine. Semin Cutan Med Surg 2008; 27:

301-308.


Fig. 5. A: Periimplant attachment loss. B: Teflon ultrasonic

inserts are used for implant debridement as a first step. C,D:

Er:YAG laser debridement is then performed using a conic

shaped tip.

3- Stern RH, and Sognnaes RF. Laser inhibition of dental caries

suggested by first tests in vivo. J Am Dent Assoc 1972; 85:

1087-1090.

4- Cobb CM. Lasers in periodontics: a review of the literature. J

Periodontol 2006; 77: 545-564.

5- Schwarz F et al. Clinical evaluation of an Er:YAG laser

combined with scaling and root planing for non-surgical

periodontal treatment. A controlled, prospective clinical

study. J Clin Periodontol 2003; 30: 26-34.

6- Schwarz F et al. Periodontal treatment with an Er: YAG laser

compared to scaling and root planing. A controlled clinical

study. J Periodontol 2001; 72: 361-367.

7- Schwarz F et al. Laser application in non-surgical

periodontal therapy: a systematic review. J Clin Periodontol

2008; 35(8 Suppl): 29-44.

8- Schwarz F, et al. Influence of fluorescence-controlled Er:YAG

laser radiation, the Vector system and hand instruments on

periodontally diseased root surfaces in-vivo. J Clin

Periodontol 2006; 33: 200-208.

9- Folwaczny M et al. Antimicrobial effects of 2.94 microm

Er:YAG laser radiation on root surfaces: an in-vitro study. J

Clin Periodontol 2002; 29: 73-78.

10- Tomasi C et al. Short-term clinical and microbiologic

effects of pocket debridement with an Er:YAG laser during

periodontal maintenance. J Periodontol 2006; 77:111-118.

11- Birang R, et al. Comparative evaluation of the effects of

Nd:YAG and Er:YAG laser in dentin hypersensitivity

treatment. Lasers Med Sci 2007; 22: 21-24.

12- Dilsiz A et al. Clinical Evaluation of Nd:YAG and 685-nm

Diode Laser Therapy for Desensitization of Teeth with

Gingival Recession. Photomed Laser Surg 2009; 27:1-6.

13- Kreisler M et al. Bactericidal effect of the Er:YAG laser on

dental implant surfaces: an in-vitro study. J Periodontol

2002; 73: 1292-1298.

14- Matsuyama T et al. Effects of the Er:YAG laser irradiation on

titanium implant materials and contaminated implant

abutment surfaces. J Clin Laser Med Surg 2003; 21: 7-17.

Correspond with:

Assem Soueidan

[email protected]



Adhesive Dentistry Research

33

INTRODUCTION

The introduction of zirconia to the dental field

opened up the design and application limits of all-

ceramic restorations. The superior mechanical

properties of zirconia combined with the state-of-the-

art CAD/CAM fabrication procedure allowed the

production of large and complex restorations with high

accuracy and success rate1. In contrast to conventional

felspathic ceramic, the matrix pressure on the

tetragonal particles of zirconium oxide is reduced by

tensile stresses that induce a transformation of the

tetragonal to a monoclinic phase, known as the

transformation toughening property; this is associated

with a localized volumetric increase of 3% to 5%,

resulting in compressive stresses that counteract the

external tensile stresses and, in this way, may prevent

cracks from propagating2, 3. Based on these material

properties, it is expected that restorations with a

zirconium oxide core are able to withstand the high

occlusal stresses occurring during function4 and that

extensive all-ceramic restoration exceeding the limit

of four units are within reach.

Due to their chemical inertness, zirconia

frameworks are resistant to aggressive chemical

Effect of different surface treatments on bond strength and failure

type of zirconium oxide ceramic: an in-vitro study.

Abstract

S tatement of problem: Establishing a reliable bond to zirconia-based materials has proven to be difficult, making it the

major limitation against fabrication of adhesive zirconia restorations.

Purpose: The aim of this in-vitro study was to determine the ability of a new experimental primer to improve the bond

strength between resin cement and zirconium oxide based crowns.

Materials and Methods: 15 resin-composite discs (Filtek Supreme, 3M-ESPE) were cemented on top of zirconia discs

(Lava, 3M-ESPE) using resin cement (Panavia F2.0, GC), four test groups (n=15) according to zirconia surface treatment were

identified: group 1(control) with no treatment of the zirconia surface, group 2 the zirconia disc was sandblasted prior to bonding

procedures, in group 3 zirconia disc was coated with Panavia primer agent, and in group 4 the sandblasted zirconia disc was coated

with an experimental primer. Micro-shear bond strength was performed and failure type was evaluated under Scanning Electron

Microscopy-SEM.

Resul ts: One-way analysis of variance followed by multiple comparison were conducted. There was no significant difference

between group 1, group 2 and group 3, while significant difference was noted between the previous groups and group 4 (P<0.05).

SEM observations of the specimens showed predominant interfacial failure type, especially in groups 1, 2 and 3; while in group

4 there was a predominant cohesive failure type between adhesive cement and resin composite.

Ziad Salameh1, Dr. Chir. Dent, DES (Prostho. ), M.Sc. , FICD, Ph.D, Joseph Hobeiche2, Dr. Chir. Dent, DU

(Occlusodont. ), DEA, MBA, Dr. Univ. (USJ), Hani Ounsi3, Dr. Chir. Dent, DES (Endo. ), M.Sc. (Dental

Mat. ), FICD, MRACDS (Endo. ), Mousatafa Aboushelib4, BDS, MSc. , Ph.D

1 Assistant Professor and Researcher, King Saud University

College of Dentistry, Riyadh, Saudi Arabia and Assistant

Professor, Department of Research, Lebanese University

School of Dentistry, Beirut, Lebanon,

2 Assistant Professor, Department of Fixed Prosthodontics

and Occlusion, Saint-Joseph University Faculty of Dental

Medicine, Beirut, Lebanon, and Private Practice, Doha,

Qatar,

3 Ph.D student, Siena University School of Dentistry,

Department of Endodontics, Siena, Italy, and Part-time

Faculty, Kuwait University Health Sciences Center,

Faculty of Dentistry, Department of Restorative Sciences,

4 Assitant Professor, Department of Dental Biomaterials,

Faculty of Dentistry, Alexandria University Faculty of

Dentistry, Egypt and Researcher, Dental Materials

Science, Academic Centre of Dentistry Amsterdam

(ACTA), University of Amsterdam and Free University,

The Netherlands.


Volume 46 - Nº 1 - 2009

agents, such strong acids as hydrofluoric acid5, alkalis

or organic and inorganic dissolving agents. On the

other hand, establishing a chemical bond with these

materials was proven to be difficult, as they do not

respond to common bonding methods used with other

glass containing ceramics, as acid etching and

silanation.6

Different investigations have examined and

measured the shear bond strength of different cements

on zirconium oxide ceramic surface after different pre-

treatment; these studies providing varying and

controversial results.5, 7, 8, 9

Pre-treatment of zirconium oxide surface by micro

roughness may influence micromechanical interlocking

of bonding and composite resin luting agents.6

Recently Aboushelib and co-workers10 introduced a

novel etching technique of zirconia surface that

significantly increased the bond strength to resin based

materials.

Another recent study by Ernest and co-workers11

investigating the bonding potential of different resin

cement used in combination with zirconia-based

restorations showed superior values obtained with a

composite resin cement containing an adhesive

phosphate monomer. 7, 8

According to recent studies, the combination of

airborne-particle abrasion and 10

methacryloyloxydecyldihydrogenphosphate (MDP)

monomer is the recommended method for bonding

resin-composites to zirconia12.

A recent study showed a significant increase in

resin composite bond strength values when combining

a selective infiltration etching procedure with an

experimental primer.13

The micro-shear bond test method for measuring

bond strength was introduced in 200214, and compared

with the conventional shear bond test, the stress

distribution proved to be more concentrated at the

interface in the micro-shear bond test15 which reduces

chances of cohesive failure in the material that does

not represent the “true” interfacial bond strength.

The aim of this study was to evaluate the resin-

composite micro-shear bond strength (MSBS) to

zirconia, using different techniques of surface

treatment. The null hypothesis tested was that there

was no difference between different surface treatments

on bond strength of resin composite to zirconia.

MATERIALS AND METHODS

Preparation of specimens and bonding procedure

Fully sintered zirconia (Lava, 3M-ESPE, Seefeld,

Germany) discs (ø 19.5 mm x 3 mm high) were used

in combination with resin-composite (Filtek Z250,

shade A2; 3M ESPE, St. Paul, MN, USA) micro-discs

(1 mm in diameter × 3 mm height) that were prepared

by injecting resin composite into a plastic mold which

was held between two glass plates and light

polymerized for 20 seconds from the top and for 20

seconds from the bottom (Elipar FreeLight 2; 3M

ESPE, Seefeld, Germany). The specimens were then

ground, using 600 grit silicon carbide wet abrasive

paper to remove any excess and ensure parallelism of

the surfaces after which the specimens were stored in

distilled water at 37˚C for 24 hours prior to removal

from the plastic mold.

Specimens were divided in four groups, as follows:

Group 1 (control): 10 resin-composite discs (n=15)

were bonded on top of the surface of the zirconia disc,

using resin composite cement (Panavia F 2.0; Kuraray

Co. Ltd., Tokyo, Japan) under a fixed load of 20 N.

Excess cement was wiped off and an air barrier gel was

applied before light curing, using a light cure machine

(Elipar FreeLight 2; 3M-ESPE, Seefeld, Germany).

Group 2: n=15: same procedure as group 1 but

zirconia disc was sandblasted (with a 50µm abrasive

particles.) prior to bonding procedures.

Group 3: n=15: same procedure as group 2 but the

sandblasted zirconia disc was coated with Panavia

primer agent (ED Primer II, Panavia) prior to bonding

procedures.

Group 4: n=15: same procedure as group 2 but the

sandblasted zirconia disc was coated with an

experimental primer as described by Aboushelib and

co-workers13 (The silane monomers used in the

primers were: 3-acryloyloxypropyltrim ethoxysilane,

3-isocyanatopropyltriet-hoxysilane,

styrylethyltrimethoxysilane,

3- methacryloyloxypropyltrimethoxysil-ane and 3-(N-

allylamino) propyltrimet- hoxysilane) prior to bonding

procedures.

Testing procedure

MSBS was measured by applying an axial load on

the bonded interface, using a universal testing machine

34 Volume 46 - Nº 1 - 2009

Salameh Z, Hobeiche J, Ounsi H, Aboushelib M

(Instron, Accuforce elite test stand) (Fig. 1).

Failure load (N) was extracted from computer

generated data files.

The broken resin discs and zirconia discs were

ultrasonically cleaned, dried, gold sputter coated and

examined under a scanning electron microscope-SEM

(JEOL, JSM-6360LV, Japan) and failure type was

classified into interfacial failure across the

zirconia–resin interface, resulting in exposure of the

zirconia surface or cohesive failure in the composite

material or the adhesive resin.

One-way analysis of variance (ANOVA) was used

to analyze data with level of significance α=0.05. The

Kolmogorov-Smirnov post-hoc test was used for

multiple comparison.

RESULTS

Data analysis revealed no significant difference

between group 1, group 2 and group 3 (Table 1), while

significant difference was noted between the previous

groups and group 4 (P<0.001).

SEM observations of the specimens showed

predominant interfacial failure type, especially in

groups 1, 2 and 3; while in group 4 there was a

significant predominant cohesive failure type between

the adhesive cement and the resin composite (Fig. 2).

DISCUSSION

The results of this study led to reject the null

hypothesis tested implying that there was no

significant difference in bond strength between the

tested groups.

One of the most common methods for evaluating

adhesive properties of restorative materials is bond

strength measurement since the development of the

micro-tensile bond strength test by Sano and co-

workers16,17, many micro-bond tests were performed

showing the effective of this method in testing small

areas of tooth structure18, micro-shear bond strength

allows straightforward sample preparation giving

precise results, preserving the uniformity of the testing

area16, 18,19.

The low bond strength obtained in group 1 with no

treatment of the zirconia surface were in agreement

with results reported by other studies 20. Such findings

indicate that establishing a strong chemical bond with

zirconia is a difficult procedure for the MDP-

containing resins when not combined with airborne

particle abrasion as a recommended surface pre-

treatment.

The use of air-abrasion particles as surface

treatment increased bond strength, indicating that

mechanical retention is necessary to gain benefit for

MDP resin composite as reported in previous study21,

Fig. 1: MSBS testing.

Fig. 2: SEM showing the predominant cohesive failure type

between adhesive cement and resin composite.

Table 1: MSBS of different groups (MPa), groups with

same letter were not significantly different.



MPa = Mega Pascal.

SD = Standard Deviation.

n = sample size.

Group

1a

2a

3a

4b

Mean (in MPa)

10.43

12.17

13.03

32.56

S D

3.8

4.2

4.8

10.21

n

15

15

15

15

while the combination of sandblasting with primer

agent coating of the zirconia disc showed no difference

with only sandblasted specimens.

Results of this in-vitro study showed that

significant difference was only observed with group 4

where the experimental primer was used, explained by

the presence of an organ functional silanes in the

primer composition and their chemical reactivity with

the sandblasted zirconia surface, enhancing the

adhesion between MDP-cement and the treated

surface.

SEM observation revealed that in the group using

the experimental primer,the predominant failure type

was cohesive in the composite material or the adhesive

resin, explained by better adhesion obtained with the

novel primer, while the failure type observed in the

other groups was more interfacial type due to the weak

bond achieved.

CONCLUSION

Within the limitations of this in-vitro study, the use

of an experimental primer achieved a better bond

strength in combination with air-abrasion particles.

Further studies are warranted to evaluate the optimal

zirconia surface treatment in order to enhance the

clinical use of bonded-zirconia restorations .

REFERENCES1- Aboushelib MN, de Jager N, Kleverlaan CJ, Feilzer AJ. Effect

of loading method on the fracture mechanics of two layered all-

ceramic restorative systems. Dent Mater 2007;23:952–959.

2- Christel P, Meuniere A, Heller M, TorrJp, Peille CN.

Mechanical properties and short –term in-vivo evaluation of

yttrium-oxide –partially stabilized zirconia .J Biomed Mater

Res 1989;23:45-61.

3- Luthardt RG, Holzhuter M, Sankuhl O, Herold V, Schnapp

JD.Kuhlisch E, et al. Reliability and properties of ground Y-

TZP-Zirconia ceramics.J Dent Res 2002;81:487-491.

4- Guazzato M, Proos K, Quach L, Swain M. Strength,

reliability and mode of fracture of bilayered

porcelain/zirconia (Y-TZP) dental ceramics. Biomaterials

2004;25:5045–5052.

5- Derand P,Derand T.bond strength of luting cements to zirconium

oxide ceramics .Int J Prosthodont 2000;13:131-135.

6- Blatz MB, Sadan A, Kern M.Resin-ceramic bonding: A review

of the literature. J Prosthet Dent 2003;89:268-274.

7- Blatz MB,Sadan A, MMartin J,Lang B.In vitro evaluation of

shear bond strengths of resin to densely-sintered high-purity

zirconium oxide after long-term storage and thermal cycling.

J Prosthet Dent 2004;91 :356-362.

8- Kern M,Wegner SM. Bonding to zirconia ceramic :adhesion

methods and their durability .Dent Mater 1998;14:64-71 .

9- Piwowarczyk A Lauer HC, Sorensen JA. The shear bond

strength between luting cement and zirconia ceramics after

two pre- treatment .Oper Dent 2005;30:382-388.

10- Aboushelib MN, Kleverlaan CJ, Feilzer AJ. Selective

infiltration-etching technique for a strong and durable bond

of resin cements to zirconia-based materials. J Prosthet

Dent 2007;5:379-388.

11- Ernest CP, Cohnen U, Stender E, Willershausen B. In-vitro

retentive strength of zirconium oxide ceramic crown using

different luting agents. J Prosthet Dent 2005;93:551-558.

12- Matinlinna JP, Heikkinen T, Ozcan M, Lassila LV, Vallittu

PK. Evaluation of resin adhesion to zirconia ceramic using

some organosilanes. Dent Mater 2006;22:824–831.

13- Aboushelib MN, Matinlina JP, Salameh Z, Ounsi HF.

Innovations in bonding to zirconia-based materials:Part I.

Dent Mater 2008 (Electronic publication).

14- Mcdonogh WG, Antonucci JM, He J, Shimada Y, Chiang

MYM, Shumacher GE, Schultheisz CR. A microshear test to

measure bond strengths of dentin-polymer interfaces.

Biomaterials 2002;23:3603-3608.

15- Banomyong D, Palamara J, Burroe MF, Messer HH. Effect of

dentin conditioning on dentin permeability and micro-

shear bond strength. Eur J Oral Sci 2007;115:502-509.

16- Sano H, Shono T, Sonoda H, Takatsu T, Ciucchi B, Carvalho

R, Pashley DH. Relationship between surface area for

adhesion and tensile bond strength. Evaluation of a micro-

tensile bond test. Dent Mater 1994;10:236-240.

17- Shimada Y, Yamaguchi S, Tagami J. Micro-shear bond

strength of dual-cured resin cement to glass ceramics. Dent

Mater 2002;18:380-388.

18- Kanemura N, Sano H, Tagami J. Tensile bond strength to and

SEM evaluation of ground and intact enamel surfaces. J Dent

1999;27:523-530.

19- Senawongse P, Sattabanasuk V, Shimada Y, Otsuki M,

Tagami J. Bond strength of current adhesive systems on

intact and ground enamel. J Esthet Restor Dent

2004;16:107-115.

20- Bottino MA, Valandro LF, Scotti R, Buso L. Effect of surface

treatments on the resin bond to zirconium-based ceramic.

Int J Prosthodont 2005;18:60–65.

21- Amaral R, Ozcan M, Bottino MA, Valandro LF. Microtensile

bond strength of a resin cement to glass infiltrated zirconia-

reinforced ceramic: the effect of surface conditioning. Dent

Mater 2006;22:283–290.

Correspond with:

Ziad Salameh

[email protected]

[email protected]

36 Volume 46 - Nº 1 - 2009


Craniomandibular disorders

37

Temporomandibular disorders (TMDs): a note from the field.

Nabil Tabbara*, DMD, FAAFO, FAACP


Volume 46 - Nº 1 - 2009

TMD is defined8 by the American Academy of

Craniofacial Pain as a number of clinical problems that

involve masticatory muscles, temporomandibular joint

(TMJ) or even both (de Leeuw, 2008).

Temporomndibular joint (TMJ) is a paired synovial

joint capable of both gliding and hinge movements,

articulating mandibular condyle, articular disc and

squamous portions of temporal bone (de Leeuw,

2008).

Epidemiological studies conducted on a cross-

section of selected non-patient adult populations have

shown that 40-75% of studied individuals presented a

minimum of one sign of joint dysfunction2. Examples

of such joint dysfunctions include, but are not limited

to: movement abnormalities, joint noise and

tenderness upon palpation. Furthermore, a striking

proportion (approximately 33%) of selected non-

patient populations has a minimum of one symptom of

dysfunction, such as face or joint pain (de Leeuw

2008, Rugh et al., 1985, Schiffman et al., 1988, De

Kanter et al., 1993, Dworkin et al., 1990). These

striking statistics highlight the prevalence of TMD and

emphasize the importance for dental professionals to

address these pathologies within their practices.

According to The American Dental Association

(ADA), it is the general dental practitioner’s (GDPs)

role to identify, diagnose, and manage or refer for

treatment of TMDs. This role has been taken more

seriously and frequently by an increasing number of

dentists in the past ten years. This increase in interest

can be related to advancements in research, as well as

higher attendance at related meetings, conferences,

workshops and courses.

In addition to GDPs and dental specialists,

including orthodontists, maxillofacial surgeons and

oral medicine specialists, the domain of TMD is also

being explored by medical doctors, radiologists,

orthopaedic surgeons, physiotherapists, chiropractors,

osteopaths, massage therapists, craniosacral therapists,

psychologists11,22,24 and Chinese medicine practitioners.

With such a diversity of dental, medical and

paramedical professions, we are presented with a

tremendous opportunity to unite in an effort to provide

our patients with the highest degree of care possible

within an environment of teamwork and useful co-

operation. We, as dental practitioners, could greatly

benefit from forming an inter-professional team with a

common understanding to cross-refer patients as

needed. This sort of approach is especially relevant in

managing patient care involving pathologies with

multifactorial aetiologies, such as TMDs.

* Adjunct Clinical Professor, Schulich School of Medicine

and Dentistry, University of Western Ontario, London,

Canada.

Abstract

Temporomandibular disorders (TMDs) have become of increasing interest to dental professionals worldwide. While there may

be controversy regarding this topic, it is widely agreed that these pathologies remain largely under-diagnosed. In an effort to shed

some light on these disorders, a brief discussion of aetiology, diagnosis and possible treatments as well as a description of the

leading opinions within our profession will be highlighted.

TMDs ETIOLOGY

The underlying causative factors of TMD, and by

extension the diagnosis, prognosis and treatment, are

perceived differently, depending on which dental

school of thought one subscribes to. The American

Academy of Orofacial Pain (AAOP) and the American

Academy of Craniofacial Pain (AACP) are two of the

main organizations specializing in this field. Both

groups seem to agree with the classification of

aetiological factors into: predisposing, initiating and

perpetuating factors (de Leeuw 2008, McNeill et al.,

1983, McNeill et al., 1980, Fricton et al., 1988).

These factors can be summarized as follows:

* Trauma; classified as acute or chronic, macro or

micro.

* Anatomical factors; skeletal and/or occlusal

* Systemic factors; require the involvement of

medical specialists and may be degenerative,

endocrine, genetic, neurologic, neoplastic,

infectious, rheumatologic, or vascular (Byrd et

al., 1990- Hagberg et al., 1990)

* Muscular hyperactivity, hyperexcitability and

hyperalgesia (Reid et al. ,1994-Browne et al.,

1993- Clark et al., 1993- Hu et al.,1993)

* Intra-articular pathology, such as: disc

displacement6, stickiness, deformation, ligaments

fibrosis, elongation or inefficient functioning of

synovial fluid,

* Psychosocial factors11,22,24 (Rugh et al. ,1979-

Eversole et al., 1985- Southwell et al.,1990- Flor

et al., 1991).

However, the importance of these factors are

assessed differently between these groups. The AACP

advocates to emphasize on the importance of the

biomechanical model (occlusion, condylar position

,etc...), while the AAOP highlights the significance of

the biomedical and psycho-social model where

individual differences, such as genetic predisposition

and psychological factors, are thought to be of utmost

importance (de Leeuw 2008- McNeill et al., 1983-

McNeill et al., 1980- Fricton et al., 1988).

The main points of inquiry seem to be as follows:

* Whether or not the occlusion represents a

significant aetiological factor in TMD,

* Whether or not the majority of TMDs are self-

limiting or progressive. If some are progressive,

do they warrant treatment? How successful is that

treatment?

* Whether or not there is a significant relationship

between neck and body posture and their effect(s)

on TMJ stability.

The AACP states that occlusion and condylar

position are often two important factors in TMJ

pathology, for two reasons:

1. Mandibular condyle has to be positioned in a

physiologically acceptable position to allow the

articular disk to contribute to TMJ health,

2. When dental arches do not satisfy certain

conditions of interrelationships, muscles of

mastication may sometimes lose their synchronicity

and mutual protection, thus negatively influencing

head and neck muscles, and possibly leading to spasm,

inflammation and pain3,15.

But some authors (Henrikson and Nilner, 2003-

McNamara, Seligman and Okesson, 1995) claim that

this argument is invalid and does not hold the road, as

patients who undergo orthodontic treatments do not

suffer from spasms, inflammation or pain because of

badly related jaws nor they consult for such reason(s).

The same also applies for those patients who sustain

orthodontic treatment coupled with an orthognatic

surgery procedure.

Therefore, biomechanical strains often lead to loss

of structural integrity and function. This can in turn

decrease the adaptability, thus increasing the chance of

dysfunction and pathology (Dijkgraaf et al., 1995).

The AAOP position follows the biomedical model

of injury and healing. It expects the body to heal/be

asymptomatic, whether the disc is properly positioned

or not, and the pain/inflammation to be a temporary

occurrence in the majority of cases (de Leeuw 2008-

Seligman et al., 2000- Pullinger et al., 2000- De

Boever et al., 2000). Since teeth do not occlude more

than 15-17 minutes daily, occlusion is not expected to

cause significant harm. Consequently, it is

unjustifiable to treat the majority of patients with

TMDs, except to manage their signs and symptoms for

a period of time until body adjusts and possibly heals.

This reasoning is based on the belief that body insult

or injury is met with adaptive physiological responses,

such as muscle tone regulation and tissue remodeling.

In other words, the first view is more curative, often

38 Volume 46 - Nº 1 - 2009

Tabbara N

mechanical, while the second is palliative. The first

relies on diagnosing the specific pathology of TMD

(whether it is muscular or intracapsular) through the

use of various diagnostic procedures and treating each

pathology distinctly, whereas the second treats

symptoms while allowing the body undergo the

healing.

DIAGNOSIS OF TMDs8,13

Reaching a precise diagnosis is of utmost

importance in managing a pathology, and TMDs are,

of course, no exception. In order to identify the nature

of illness ,the AACP suggests the following tools to

establish a diagnosis:

* Clinical examination:

- Medical and dental history, previous treatments,

evolution of symptoms, history of trauma (macro

or micro), range of motion, muscle palpation and

identification of trigger points (in myofascial

pain) or tender points (as in fibromyalgia). This

examination commonly requires two hours.

* Radiographs:

- Cephalometric view(frontal and lateral cervical) to

analyze relationships of jaw bones to the rest of

the skull, the hyoid and cervical vertebrae),

panoramic radiograph to identify any major bone

discrepancies, fractures or anomalies, tomographic

cuts to study position(s) of mandibular condyle,

shape and texture of articular surfaces,

Computerized Axial Tomography (CAT) scan and

even Magnetic Resonance Imaging (MRI) to

visualize more structures including TMJ’s disc

and other soft tissues.

* Dental models to analyze occlusion:

- Premature contacts- especially balancing

contacts, cross-bites, wear facets pattern,

deviation of skeletal midlines, to confirm slants in

the occlusion seen on radiographs. Mounting on

an Acculiner is suggested (www.acculiner.com).

* Biometrics:

- Computerized analyses for advanced diagnostics:

Joint Vibration Analysis, Jaw Tracking and

Electromyography. Two companies providing

these instrumentations for TMD, head, neck and

facial pain as well as for neuromuscular dentistry

are: Bioresearch Inc. (www.biojva.com) and

Myotronics (www.myotronics.com). These

means are accepted only as complementary

diagnostic measures not necessary for the proper

diagnosis of TMDs.

The International Headaches Society has outlined

specific diagnostic classifications of TMDs based on

whether the patient is thought to have a TMJ articular

(intracapsular) disorder or a disorder of the

masticatory muscles (extracapsular). These are

especially helpful to consider when establishing a

diagnosis. The subclassifications for a TMJ articular

disorder are as follows: congenital or developmental,

(i.e. aplasia, hyperplasia, hypoplasia, dysplasia and

neoplasia), disc displacement with and without

reduction, TMJ dislocation, inflammatory disorders

(i.e. synovitis, capsulitis), degenerative disorders (i.e.

osteoarthritis9), ankylosis and lastly, fractures. The

subclassifications for masticatory muscle disorder are

as follows: Myalgia, myofascial pain, myospasm,

myofibrotic contracture, myositis and neoplasia.

TREATMENT OF TMDs2,6,7,8,13,14,16,17,18,19

Dental treatments of TMD are specific to each type

of disorder, the main sub-classifications, as mentioned

earlier, are either muscular/extracapsular or

articular/intracapsular/internal derangements. Also of

importance is whether the pathology is acute or

chronic.

Muscular pathology is treated in a conservative

fashion by the majority of dentists involved in this

field. Apart medications (muscle relaxants, non

steroidal anti-inflammatory drugs-NSAIDs-),

physiotherapy, ultrasound, acupuncture, electrotherapy,

night guards for bruxers and eradication of oxidative

stress1 (Kawai, Lee, Kubota, 2008) have been

advocated. The use of occlusal adjustment7 is no longer

accepted as a modality to treat TMDs and anterior

repositioning splints no longer used for the treatment of

articular problems, being replaced by stabilization

splints.

Internal derangements are classified as acute and

chronic and a decision is made if the disk can be

reduced (brought back to its functional position) or

not. Mouth appliances are often used to change

mandibular position. Splints6 (orthotics) of many

various types are worn 24 hours/day (one for day use

Tabbara N


and another for night use) for a period of 4-6 months.

Once the disc is reduced and stabilized, a permanent

change in the occlusion is often indicated, thus

allowing the disc to be maintained in that position.

This is achieved with orthodontics16,17, complete oral

restorations, or overdentures. Surgery is only indicated

in rare situations when anatomical modifications have

been severe and when symptoms persist. It is

important to keep in mind that in instances where the

disc has been displaced for over a year, the success in

repositioning is limited. In such cases, unloading the

joints may allow for the formation of a pseudo-disc,

which can improve function and decrease symptoms.

The alternate school of thought relies almost

exclusively on the history and clinical examination to

conclude whether there is a TMD and to recommend

treatment. It gives little value for study models,

radiographs and mandibular condyle position and does

not rely on jaw tracking, joint vibration analysis, or

electromyography. Once systemic causes1,9 (arthritis,

oxidative stress,...) are ruled out, physiotherapy,

medication, patient education and exercises are the

most commonly accepted treatment modalities. In

some cases, night guards are indicated to decrease

excessive loading when patients cannot control it.

Changing the mandibular position is not

recommended. Surgery is the treatment of last resort.

Multiple courses are available for the dentist to be

proficient in managing these patients, whether for the

TMJ pathology per se or to relieve patients from head,

neck and facial pain. When treatment includes

permanent changes of the occlusion, dentist may

follow up with orthodontic treatment or oral

rehabilitation.

CONCLUSION2,8,13,19

As the scientific literature on this topic continues to

expand, so does the potential for dental practitioners to

greatly benefit their patients in truly remarkable ways.

Although patients do not commonly discuss their

headaches and related symptoms with dental

practitioners, we should thoroughly question them in

order to identify ways in which we can help.

Treating TMDs has helped and continues to help

millions of people manage or eliminate migraines,

tension-type headaches, stiff necks, all while offering

them improved jaw function. We have reached a very

exciting point in the development of this field and with

the the advent of new insights from both practitioners

and basic researchers, we will certainly continue to

advance our diagnostic and therapeutic capabilities .

REFERENCES.1- Kawai Y, Lee M-C, Kubota E. Oxidative stress and

temporomandibular join disorders.Jap Dent Sc Rev

2008;44:145-150.

2- Turp JC, Greene CS, Strub JR. Dental occlusion:a critical

reflection on past ,present and future concepts. J Oral Rehab

2008;35:446-453.

3- Browne PA, Clark GT, Yang Q, Nakano M.

Sternocleidomastoid muscle inhibition induction by

trigeminal stimulation. J Dent Educ 1993;72:1503-1508.

4- Byrd KE, Stein ST. Effects of lesions to the trigeminal motor

nucleus on temporomandibular disc morphology. J Oral

Rehabil 1990;17:529-540.

5- Clark GT, Browne PA, Nakano M, Yang Q. Co-activation of

sternocleidomastoid muscles during maximum clenching. J

Dent Res 1993;72:1499-1502.

6- Stiesch-Scholz M,Kempert J,Wolter S,Tschernitschek

H,Rossbach A.Comparative prospective study on splint

therapy of anterior disc displacement without reduction.J

Oral Rehabil 2005;32:474-479.

7- De Boever JA, Carlsson GE, Klineberg IJ. Need for occlusal

therapy and prosthodontic treatment in the management of

temporomandibular disorders. Part I. Occlusal interferences

and occlusal adjustment. J Oral Rehabil 2000;27:367-369.

8- De Leeuw R. Orofacial Pain. Guidelines for Assessment,

Diagnosis, and Management, ed 4. Chicago: Quintessence,

2008.

9- Dijkgraaf LC, De Bont LGM, Boering G, Liem RS. The

structure, biochemistry, and metabolism of osteoarthritic

cartilage: A review of the literature. J Oral Maxillofac Surg

1995;53:1182-1192.

10- Dijkgraaf LC, De Bont LGM, Boering G, Liem RS. Normal

cartilage structure, biochemistry, and metabolism: A review

of the literature. J Oral Maxillofac Surg 1995;53:924-929.

11- Eversole LR, Stone CE, Matheson D, Kaplan H.

Psychometric profiles and facial pain. Oral Surg Oral Med

Oral Pathol 1985;60:269-274.

12- Flor H, Birbaumer N, Schulte W, Roos R. Stress related

electromyographic responses in patients with chronic

temporomandibular pain. Pain 1991;46:145-182.

13- Friction JR, Kroening RJ, Hathaway KM (eds). TM

Disorders and Craniofacial Pain: Diagnosis and

Management. St Louis: Ishiaku Euro America, 1988.

14- Hagberg C, Hellsing G, Hagberg M. Perception of

40 Volume 46 - Nº 1 - 2009

Tabbara N

cutaneous electrical stimulation in patients with

craniomandibular disorders. J Craniomandib Disord Facial

Oral Pain 1990;4:120-125.

15- Hu JW, Yu XM, Vernon H, Sessle BJ. Excitatory effects on

the neck and jaw muscle activity of inflammatory irritant

applied to cervical paraspinal tissues. Pain 1993;55:243-

250.

16- Henrikson T, Nilner M. Temporomandibular disorders,

occlusion, and orthodontic treatment. J Orthod

2003;30:129-137.

17- McNamara J,Seligman D,Okesson J. Occlusion,orthodontic

treatment,and TMD: a review. J Orofacial Pain 1995;9:73-

89.

18- McNeill C. Craniomandibular (TMJ) disorders-The state of

the art. Part II. Accepted diagnosis and treatment

modalities. J Prosthet Dent 1983;49:393-397.

19- McNeill C, Danzig WM, Farrar WB et al. Craniomandibular

(TMJ) disorders-The state of the art. Position Paper of the

American Academy of Craniomandibular Disorders. J

Prosthet Dent 1980;44:434-437.

20- Pullinger A, Seligman DA. Quantification and validation of

predictive values of occlusal variables in

temporomandibular disorders using a multifactorial

analysis. J Prosthet Dent 2000;83:66-75.

21- Reid KI, Gracely RH, Dubner RA. The influence of time,

facial side, and location on pain-pressure thresholds in

chronic myogenous temporomandibular disorder. J Orofac

Pain 1994;8:258-265.

22- Rugh JD, Solberg W. Psychological implications in

temporomandibular pain and dysfunction. In: Zarb Function

and Dysfunction. Copenhagen: Munksgaard, 1979:239-

258.

23- Seligman DA, Pullinger A. Analysis of occlusal variables,

dental attrition, and age for distinguishing healthy controls

from female patients with intra-capsular

temporomandibular disorders. J Prosthet Dent 2000;83:76-

82.

24- Southwell J, Deary IJ, Geissler P. Personality and anxiety in

temporomandibular joint syndrome patients. J Oral Rehabil

1990;17:239-243.

Correspond with:

Nabil Tabbara

[email protected]

Author’s website:

www.drtabbara.com


Tabbara N

INTRODUCTION

A challenge facing dental clinicians is the

achievement of an optimal long-term esthetic result,

mainly in the restoration of healthy anterior teeth with

dental discoloration1.

Tooth discoloration may be classified as intrinsic,

extrinsic and a combination of both.2 Intrinsic

discoloration occurs following a change to structural

composition or thickness of dental hard tissues.

Ageing, enamel microcracks, tetracycline

administration, dental restorative materials, caries and

fluorosis cause intrinsic tooth discoloration.3,4

Excessive fluoride ingestion(more than 1 to 2 ppm)

can cause metabolic alteration in ameloblasts,

resulting in a defective matrix and improper teeth

calcification5. An affected tooth shows

hypomineralized , porous subsurface enamel and acid-

resistant well-mineralized surface layer.

There is evidence to suggest that prevalence of

dental fluorosis has increased over the past decades.

This indicates that in populations consuming

fluoridated and nonfluoridared water, water supply

may be affected by other sources of fluorides, such as

exposure to higher intake of fluorides from foods and

soft drinks6 or the use of fluoridated toothpastes and

supplements7.

Bleaching or microabrasion is often ineffective or

gives transient results,8,9 while composite resin

laminate veneers not only discolor and wear with time,

but quite often become chipped or debonded.10

It is recommended that a conservative treatment be

used wherever possible as an alternative to other

options that may sacrifice tooth structures. Porcelain

laminate veneers (PLV) has been proposed as the

treatment of choice, especially when tooth alteration

or modification of alignment is required.11 Although

porcelain veneer has displayed good longevity in

clinical studies,12-15 achieving a successful outcome

can be challenging in patients with insufficient enamel

for bonding to occur, caries, parafunctional habits and

periodontitis.

Clinicians must consider multidisciplinary approach

for complex cases, provide treatment in the correct

sequence, ensuring that the outcome will meet

patient’s functional and esthetic expectations.16

The understanding of behavior and properties of

the materials used as for the PLV and luting agent, in

combination with the clinical steps, is crucial for the

final outcome.

CASE REPORT

A 34-year-old man presented to our clinic

complaining of unpleasant smile due to generalized

teeth discoloration and the presence of gaps between

his maxillary anterior teeth (Fig.1). His medical

condition was non-contributory.

Diagnosis and treatment planning

The patient had a generalized enamel fluorosis

affecting all his permanent teeth (Fig.1), confluent

Esthetic Dentistry

Porcelain veneers as an esthetic restorative strategy for the

treatment of stained anterior teeth: a clinical report.

Abstract

Porcelain laminate veneers have become a treatment of choice in solving many esthetical and functional dental problems.

Fluorosis, in some forms,causes teeth discoloration that can affect patients’ esthetic and create psychological distress. This

clinical report describes treatment sequences in a patient diagnosed with fluorosis on maxillary and mandibular teeth. The

patient’s functional and esthetic expectations were successfully met with a proper strategy and knowledge of the used material.

Karim Corbani*, Dr. Chir. Dent. , DES (Endo. ), FAACD

* Senior Lecturer,Department of Restorative and Esthetic

Dentistry,Saint-Joseph University Faculty of Dental

Medicine,Beirut,Lebanon.

43Journal of the Lebanese Dental Association

Volume 46 - Nº 1 - 2009

pitting was present on most maxillary teeth surfaces,

with wide spread of yellow-brown stains. Mandibular

anterior teeth were relatively less affected than others.

Incisal and occlusal surfaces of maxillary incisors and

premolars were worn out due to loss of enamel

structure as a result of post-eruptive trauma (Fig.2)

affecting patient’s smile line. He also sustained a mid-

line diastema of 2mm. Occlusion was in Class-I

relationship. Oral hygiene was good except in anterior

mandible, with a slight marginal gingivitis. Peri-apical

and bite-wing radiographs showed no caries or

alveolar bone loss.

After possible treatment modalities were discussed

with the patient, decision was made to construct 14

PLV on maxillary teeth # 17 to # 27 and on mandibular

teeth #37 to # 47. Regarding mandibular anterior teeth,

patient was advised to undergo generalized scaling.

Treatment sequences

The procedure was carried out in four phases1,17.

Phase I: Smile analysis, preliminary shade selection

(Vitapan, 3D Master, Vita, Zahnfabrik), photographs

and study models to evaluate the occlusion and make a

diagnostic wax up.

Phase II: Preparation for PLV (must be uniform and

whenever possible, totally restricted to enamel).

However, reduction of tooth buccal surface will

depend on severity of discoloration, position of tooth

and the amount of enamel loss. This goal was attained

in the present patient by means of calibrated spherical

diamond burs (#1012, KG Sorensen) at the cervical

region and burs with a depth-limiting device (LVS1-

Laminate Veneer System, Komet-Brasseler) at tooth

44 Volume 46 - Nº 1 - 2009

Fig. 2: Compromised patient’s smile line

Fig.3a: Different aspects of mandibular teeth preparations

for PLV

Fig. 1: Generalized enamel

fluorosis affecting all permanent

teeth

Corbani K

buccal surface. The remaining facial enamel was

reduced to the level of these grooves with a tapered-

cylinder, round-end diamond bur (#2135, KG

Sorensen); the uniform reduction was about 0.4mm.

Incisal edge was reduced by 2mm and finished as a

butt joint. To completely mask teeth, additional

attention was given to proximal areas, where limit was

placed beyond interdental contact (Figs.3a and 3b).

The final impression was taken by placing a

retraction cord (Ultrapak # 0, Ultradent, USA) in the

gingival sulcus, and a complete impression was made

using a polyvinyl siloxane material (Virtual, Ivoclar-

Vivadent, Schaan, Liechtenstein). A final shade

selection was made (Vitapan, 3D Master, Vita,

Zahnfabrik, Germany) and photographs taken. Finally,

provisional restorations (Integrity, Dentsply,

Germany) were placed and cemented (Systemp.cem,

Ivoaclar-Vivadent). Maxillary and mandibular

impressions were sent to the dental technician for

pouring, making of dies and fabrication of PLV using

a heat-pressed ceramic system (IPS Empress Esthetic,

Ivoclar-Vivadent).

Phase III: Veneers were sent by the technician and

carefully positioned on the master cast and intraorally

to verify the fit, marginal adaptation, shape and color.

Luting procedures were started after isolating gingiva

with a rubber dam (OptraGate, Ivoclar-Vivadent). A

try-in paste was used to determine the appropriate

cement shade (HV+3,Variolink Veneer, Ivoclar-

Vivadent); then the fitting surface of the restorations

were etched with 9.5% hydrofluoric acid (Porcelain

Etchant, Bisco, USA) for 1 minute, washed under

running water and air-dried, and a silane agent

(Monobond-S, Ivoclar-Vivadent) was then applied and

dried after 60 seconds. The prepared tooth surfaces

were then cleaned with sodium bicarbonate jets and

rinsed with air-water spray and air-dried. Cementation

was performed using light-cured resin cement

(Variolink Veneer, Ivoclar-Vivadent), following

manufacturer’s instructions. Excess cement was

removed with a brush and the veneer restoration light-

cured for 10 seconds using a halogen light (Astralis 10,

Ivoclar-Vivadent). Resin cement residues were

removed and the veneer was once more light-cured for

40 seconds at buccal and palatal sides.

Phase IV: Final finishing and polishing after 24

hours and end-treatment photographs.

Fig.3b: Different aspects of maxillary teeth preparations

for PLV

Fig.4: The new smile line

Fig. 5: Final result


Corbani K

Treatment outcome

Patient was satisfied with treatment outcome (Figs.

4,5) and scheduled annual follow-up visits and oral

hygiene care.

DISCUSSION

Nowadays, porcelain veneers are routinely used to

treat unesthetic anterior teeth. Despite great advances

in current ceramic systems, some difficulties persist,

such as in masking of teeth extremely discolored by

endodontic treatment or tetracycline1. The final color

exhibited by a porcelain veneer will be the resulting

interaction of three colors: the porcelain laminate, the

substrate and the luting cement. Studies showed 18,19

that the effect of porcelain translucency and thickness

influenced final esthetic result since the use of opaque

ceramic material might be more of a problem than a

solution as they cut down light transmission.20

Ideally, a porcelain veneer can completely mask

the underlying discolored tooth substance with

minimal reduction of sound tooth substance (0.3-0.7

mm for buccal surface and 0.5-1.0 mm for incisal

edge). Clinicians need to assess patients’

understanding of their dental problems and whether

they have unrealistic expectations. Patients need to

realize that severity of tooth discoloration, optical

properties of a porcelain veneer system and luting

agent can influence final results16, so it is helpful to

test the restoration with a try-in paste before final

cementation.

Acknowledgements

The author would like to gratefully acknowledge

the help of Assistant Professor Ziad Salameh for

providing expertise and support to this manuscript.

REFERENCES1- Filho MA, Vieira CCL, Baratieri LN, Lopes GC. Porcelain

veneers as an alternative for the esthetic treatment of

stained anterior teeth: clinical report. Quintessence Int

2005;36:191-196.

2- Hattab FN, Qudeimat MA, al-Rimawi HS. Dental

discoloration: an overview. J Esthet Dent.

1999;11:291–310.

3- Watts A, Addy M. Tooth discolouration and staining: a

review of the literature. Br Dent J. 2001;190:309–315.

4- Awliya WY, Akpata ES. Effect of fluorosis on shear bond

strength of glass ionomer-based restorative materials to

dentin. J Prosthet Dent. 1999;81:290–294.

5- Haywood VB, Berry TG. Natural tooth bleaching. In:

Summitt JB, Rabbins JW, Schwartz RS, editors.

Fundamentals of operative dentistry: a contemporary

approach. Chicago: Quintessence Publishing Co Inc; 2001.

p. 402.

6- Pang DTV, Philips CL, Bawden JW. Fluoride intake from

beverage consumption in a sample of North Carolina

children. J Dent Res 1992;71:1382.

7- Osuji OO, Leak JL, Chipman ML, Nikifourk G, Locker D,

Levine N. Risk factors for dental fluorosis in fluoridated

community. J Dent Res 1988;67:1488.

8- Goldstein CE, Goldstein RE, Freiman RA, Garber DA.

Bleaching vital teeth: state of the art. Quintessence Int

1989;20:729-737.

9- Train TE, Whorter AG. Examination of esthetic

improvement and surface alteration following

microabrasion in fluorotic human incisors in vivo.

Pediatric Dent 1996;18:353-62.

10- Walls AW, Murray JJ, McCabe JF. Composite laminate

veneers: A clinical study. J Oral Rehabil 1988;15:439-454.

11- Jun SK, Wilson S. Restoration of severely discolored

maxillary anterior teeth with porcelain laminate veneers.

Pract Proced Aesthet Dent 2008;20:285-287.

12- Dunne SM, Millar BJ. A longitudinal study of the clinical

performance of porcelain veneers. Br Dent J 1993;175:317-

321.

13- Miyajima K, Shirakawa K, Senda A. Application of

porcelain veneers following orthodontic treatment. J Can

Dent Assoc 1993;59:167-170.

14- Touati B. Bonded ceramic restorations: achieving

predictability. Pract Periodontics Aesthet Dent 1995;7:33-

37.

15- Smales RJ, Etemadi S. Long-term survival of porcelain

laminate veneers using two preparation designs: a

retrospective study. Int J Prosthodont 2004;17:323-326.

16- Chu FCS. Clinical considerations in managing severe tooth

discoloration with porcelain veneers. JADA 2009;140:442-

446.

17- Al Jazairy YH. Management of fluorosed teeth using

porcelain laminate veneers. A six-year recall case report.

Saudi Dent J 2001;13:106-111.

18- Yaman P, Qazi RS, Dennison JB, Razoog ME. Effect of

adding opaque porcelain on the final color of porcelain

laminates. J Prosthet Dent 1997;77:136-140.

19- Johansen R, Schlobohm C, Mullick S. Colorometric

analysis of porcelain veneer shade variance by composite

cements (abstract#956). J Dent Res 1991;70 (special

issue):385.

20- Masterdomini D, Friedman MJ. The contact lens effect:

Enhancing porcelain veneers esthetics. J Esthet Dent

1995;7:99-103.

Correspond with:

Karim Corbani

[email protected]

46 Volume 46 - Nº 1 - 2009

Corbani K

47

Complete mouth rehabilitation of any clinical

situation starts with a complete analysis of the total

oral environment1 by seeking to establish an optimum

plane of occlusion, occlusal vertical dimension,

occlusal scheme and esthetics for a proper prosthetic

restoration1,2.

To do so, one must depend on an adequate

collection of prosthodontic data that includes personal,

medical, dental and prosthetic histories, necessary

radiographs, articulated dental casts and visual and

digital extraoral and intraoral clinical examinations.1

Most practicing dentists very often underestimate the

practical usefulness of articulated dental casts. This

results in unforeseen future treatment problems and

poor outcomes. These preliminary study casts are

articulated at the correct therapeutic occlusal vertical

dimension in a retruded contact position, on a semi-

adjustable articulator using an adjusted ear-facebow

and often a protrusive record.1

Occlusal surfaces harmony between any type of

prostheses and remaining natural teeth is an important

factor in the preservation of surrounding oral tissues.

One of the final goals in complete edentulous

mouth treatment is to establish a satisfactory

articulation. This is done by evaluating the existing

occlusal scheme, correcting the existing occlusal

disharmony, recording a retruded physiologic jaw

position, recording eccentric jaw relations and

correcting occlusal discrepancies created by the fit of

final prosthesis.

Many occlusal schemes are described in dental

literature and practiced every day. There is no

scientific evidence that supports one occlusal scheme

rather than another.3 Where anterior guidance must be

reestablished or where it changes, there currently

appears to be more authorities that favor canine

guidance over group function.3 For complete dentures,

most prosthodontists are using a balanced type of

occlusal scheme where the location of centric relation

or retruded contact jaw position is an important step

for the application of any occlusal scheme.

Removable Prosthodontics

You do not have to be an FBI agent to find and register the

retruded contact position in the treatment of the prosthodontic

patient.

Abstract

Many definitions and techniques are available, describing and registering centric relation or occlusion. This paper is a brief

review of dental literature regarding centric relation (CR), depicting four categories of CR recording: direct interocclusal records,

intraoral and extraoral graphic recordings, functional recordings and cephalometrics.

Our study proposes the use of the terms Retruded Contact Position (RCP) instead of Centric Relation or Centric Occlusion.

RCP is defined as retruded, unstrained, repeatable position where mandibular movements start. With this definition, it is easy

to select a technique that meets all requirements of such position.

A new and improved Jaw Recorder, designed by J. Massad, is presented here. This jaw recorder is an intraoral graphic recording

device that results in a tracing of mandibular movements in one plane, with the apex of tracing indicating the most retruded

relationship. The intersection of arches produced by right and left working movements forms the apex of what is known as

Gothic arch tracing.

Clinical situations using jaw recorder are described, and clinicians can now, quickly, easily and accurately record RCP, balance

complete, partial or implant dentures and orthopedically reposition mandible. This has many advantages and results sound more

reliable and reproducible than many traditional manipulation techniques.

Tony Daher1, Dr. Chir. Dent. , CES Prostho. , M.S .Ed. , FACP, FICP, Dipl. ABP, Joseph J. Massad2, DDS,

FACD, FICD

1 Associate Professor, Department of Restorative Dentistry,Loma Linda University School of Dentistry, California,USA,

2 Adjunct Professor, Tufts University, Boston, USA, andDirector of Removable Prosthodontics, Scottsdale Centerfor Dentistry, Arizona, USA,

1,2 The Massad Group, Tulsa, Oklahoma, USA.


Volume 46 - Nº 1 - 2009

48 Volume 46 - Nº 1 - 2009

The purpose of this paper is to present a predictable

and easy way to locate and register a centric or

retruded and eccentric physiologic jaw positions.

LITERATURE REvIEW

Literature on centric relation is vast, and definition

and methods of attaining and recording centric relation

have always been controversial. Glossary of

Prosthodontic terms, published every 6 years by the

Academy of Prosthodontics, has changed the definition

of centric relation often. The 2005 edition of this

publication4 has 7 definitions for centric relation.

Centric relation is defined as “the maxillomandibular

relationship in which the condyles articulate with the

thinnest avascular portion of their respective disks with

the complex in the anterior-superior position against

the shapes of the articular eminencies. This position is

independent of tooth contact and clinically discernible

when the mandible is directed superiorly and anteriorly.

It is restricted to a purely rotary movement around the

transverse horizontal axis”.4

In addition, Jasinevicius and co-workers5 found out

in their study on the definitions of centric relation,

taught in seven US dental schools, that there was no

consensual definition.

Centric relation (CR) concept has undergone

constant debate and revision and “Most authors agree

that CR record is the most important and most difficult

maxillomandibular relation record to make.”6 For this

reason, many methods for recording centric relation

records have been suggested in the literature.

Categories of CR recording are as follows:

1. Direct interocclusal records,

2. Intraoral and extraoral graphic recordings,

3. Functional recordings,

4. Cephalometrics.7

1- The direct interocclusal recording was described

in the 1700’s by P. Pfaff, known as the “mush-squash”

or “bisquit” bite. Hanau and Wright improved the

technique in the 19th Century.

2- Graphic recording methods result in a tracing of

mandibular movements in one plane, with the apex of

the tracing indicating the most retruded relationship.

They can be made intraorally or extraorally, depending

on where the records are placed. The intersection of

the arches produced by right and left working

movement formed the apex of what is known as the

Gothic arch tracing (Fig.1).

Fig. 1. Gothic arch tracing on a disposable flat plastic

striker on a maxillary arch and the opposing pin and pin

receiver plate on the mandibular arch.

The earliest graphic tracings were made by

Balkwill in 1866, then improved by Hess, Gysi and

Sears around 1925. Stansberry introduced it in 1929

and Hall later modified it, using a central bearing

screw to help equalize the pressure on the supporting

structure. Phillips developed a tripoded ball bearing,

mounted on a jackscrew for the mandibular occlusion

rim. It was called “central bearing point”.

3- Functional recordings or “chew-in” records were

first described in 1910. Needles used studs mounted on

record bases to engrave arrow tracings into compound

rims in the mandibular arch.

Boos developed the gnatho-dynamometer to

determine where maximum biting force could be. He

claimed that optimum occlusal position and position of

maximum biting force are coincident.

4- Cephalometric recordings of CR were performed

by Pyott and Schaeffer in 1952 to determine CR and

the appropriate vertical dimension of occlusion using

radiographs. Due to excessive patient’s exposure to

radiation, this practice was not popular.

Techniques for CR recording have evolved,

resulting from improvements and modifications of old

CR records techniques.

Schweitzer stated that most experienced dentists

may not be able to give a precise definition of this

controversial position, but for the average patient

whom they treat, they were able to record it.8

This is due to various factors which influence

recording of CR including: pain in TMJ or masticatory

system, protective reflexes caused by faulty occlusal

contacts, emotional stress, recording media, guidance

m

Daher T, Massaad JJ


or manipulation by the clinician and neuromuscular

conditioning.7

In teaching prosthodontics and when we describe

any CR recording technique, it is very hard to

convince any clinician or dental student that the

technique will put mandibular condyles to articulate

with the thinnest avascular portion of their respective

disks with the complex in the anterior-superior

position against the shapes of articular eminencies.

This might be feasible if we have radiographic vision.

In addition, it has been argued that anterior disc

position is a variant of normal disc position and it has

been challenged: “…not all discs displaced are

associated with derangement or other joints pathosis”.9

“…50% of the condyles do not seat”10.

We propose the use of the terms Retruded Contact

Position (RCP) instead of Centric Relation or Centric

Occlusion. RCP is defined as retruded, unstrained,

repeatable position and where mandibular movements

start. With this definition, it is easy to select a technique

that meets all requirements of such position. As we

know, repeatability remains number one of most

suitable and accepted methods for evaluating a

mandibular record to be used for the articulation of a

dental cast, denture fabrication and occlusal

equilibration. If a mandibular record is not reproducible,

dentists cannot evaluate treatment outcomes. Celenza11

once stated: “The precision of the position may be more

important than the position itself”.

For all above reasons,we have selected the use of

Gothic arch tracings made by a central bearing device

for the determination of such mandibular jaw position.

The central bearing device has a long history in

dentistry. Due to the many devices available over the

years, some confusion and misuse have resulted.

However, with recent developments and refinements, it

is suggested that dentistry revisits in light of this

concept, that more than one use is applicable. Use of a

central bearing device during maxillary-mandibular

record making for edentulous patients has been debated

in great detail over the years. However, immediate

denture record using the jaw recorder (Fig. 2) facilitates

the obtention of a physiological retruded contact

position. When used during complete denture therapy,

it is generally believed that central bearing device

provides equalization of occlusal pressure and

increases record base stability when denture-bearing

mucosal resiliency is modest. Additionally, when the

bearing plate is inked prior to placement, unguided

mandibular movements through all eccentric positions

will result in a Gothic arch tracing by the central

bearing point on the bearing or striking plate. The apex

of this tracing may then be used to identify centric

relation position, right and left excursions and

protrusion along the borders of the tracing. A thin

plastic pin receiver plate single perforation or a divot

prepared with a round bur into the bearing plate can be

used to let the patient hold this position at the apex

while registration material is being placed. This Gothic

arch tracing method and maxillary-mandibular

registration technique is considered highly reliable,

even for inexperienced clinicians, if used at a given

vertical dimension12. In dentate or partially edentulous

patients or patients with implants supporting a

removable prosthesis, this method increases reliability

of record by not allowing any tooth contact which may

deflect mandibular movements.

Advantages of such record are many:

1) its repeatability,

2) with the use of a flat platform, reflex pattern of

closure or engram will be forgotten,

3) apex of the tracings is easy to identify and

represents the retruded contact jaw position,

4) its use in different clinical situations and stages

in prosthesis fabrication: for example during RCP

recording and placement of prosthesis to correct some

occlusal discrepancies or to do a clinical remount.

DESCRIPTION OF THE TECHNIqUES

ACCORDING TO SOME CLINICAL

SITUATIONS.

Record a patient’s Retruded Contact Position

(RCP):

An accurate repeatable RCP record can be made

quickly and easily with the Jaw Recorder (Fig. 2)

(LeeMark Dental). Successful identification of centric

position results in fewer appointments to removable

and fixed cases and less occlusal adjustments required

at delivery of case.

Record PRP: In order to find patient’s correct

RCP, we must first accurately record Physiologic Rest

Position (PRP), commonly known as “resting

position”. This is the position we most often find

Daher T, Massaad JJ

50 Volume 46 - Nº 1 - 2009

ourselves with teeth slightly apart during rest.

Recording this measurement usually involves five

simple steps: (1) place a dot for reference on patient’s

nose and chin, (2) coach the patient to his/her unique

relaxed position, (3) adjust each leg of a caliper to the

edge of each dot, (4) lock the caliper opening and

transfer measurement to paper, (5) adjust the pin on the

Jaw Recorder to touch the maxillary striking plate at

this measurement.

Adjust to OvD: By definition, Occlusal Vertical

Dimension (OVD) is 1-4 mm less than measured PRP.

After recording PRP and adjusting the pin to the

striking plate at PRP, the pin on the Jaw Recorder is

then adjusted to decrease the relationship to the

maxillary striking plate 1-4 mm, stabilizing the

patient’s jaws at this critical vertical position. The

patient is then directed through anterior-posterior and

retruded lateral movements. The resulting path of

contact between pin and striking plate traces the

classic “arrow” portion of a Gothic arch tracing. The

point of contact between pin and plate at the point or

tip of the arrow represents patient’s unique RCP and

can be locked and stabilized with a bite registration

material for accurate transfer to an articulator.

Balance Complete Dentures, Partial Dentures, and

Implant Dentures (Figs. 2 to 20)

One of the most difficult procedures in removable

prosthodontics is finely equilibrating the occlusion of

the finished prosthesis. Intra-orally, prosthesis moves

with every occlusal prematurity, producing erroneous

marks with the articulating paper. Extra-oral remounts

often incorporate inaccuracies, due to the remount

procedure itself! The Jaw Recorder eliminates these

problems.

When mounted on the finished prostheses, pin and

striking plate of the Jaw Recorder perform two

functions. First, they act as a central bearing point,

stabilizing the prostheses through constant, centralized

pressure. Second, the pin can be adjusted until teeth

are slightly apart, and then slowly closed. Through this

gradual closure, the smallest occlusal prematurity can

be noticed and appropriately adjusted. This process is

continued until occlusion is adequate and equal on

both sides of the arch.

Orthopedically reposition the mandible

Many times, a denture patient will present a

severely over-closed jaw position. It is important to

return facial musculature to proper vertical position

prior to final RCP Recording. Muscles programmed to

an improper occlusion will make difficult, both centric

recording and patient’s ability to adapt to the new

prosthesis. Fabrication of an accurate occlusal splint

will accomplish these goals. Splint therapy can be

simple with the Jaw Recorder.

Jaw Recorder is mounted on patient’s current

prostheses (or duplicates of them). The pin/striking

plate relationship is adjusted, until patient’s jaws are

held at desired OVD. An acrylic resin is then placed

over mandibular posterior quadrants and maxillary

posterior teeth are lubricated. While acrylic is in a

“doughy” consistency, patient is instructed to

continuously “rub” the pin against the plate in all

directions until acrylic sets. After curing and

Figs. 2a, 2b, 2c.: a) “Massad Jaw recorder” is secured in place onto maxillary and mandibular complete dentures at the new

proposed OVD. b) Auto polymerizing acrylic resin is added to mandibular occlusal surfaces. While in putty stage, patient is

asked to make eccentric movements till its final set. c) Dentures are removed from mouth and the added resin is shaped to normal

contour. Then, remove Jaw Recorder device and polish prostheses.

Daher T, Massaad JJ

2a 2b 2c


trimming, a patient-generated splint has been

fabricated at the correct OVD. Patient can wear this

splint during denture fabrication, allowing muscles to

de-program.13

1- Technique for Immediate Complete Denture

Situation:

Fig. 4. Dots are placed on nose and chin in preparation of

making a physiological resting position on a 79-year-old

patient.

Figs. 5a, 5b: a) Maxillary dentition showing deteriorating

restorations and decay.

b) Definitive maxillary cast utilizing thermoplastic heat

shapeable tray and the use of PVS gives detailed buccal areas

and tooth structures.

Figs. 6a, 6b. a) Mandibular restorations reveal decay and

fractured teeth #20 and #24 are non restorable. b) Mandibular

definitive cast giving detail necessary for final prosthesis.

Figs. 7a, 7b. a) Maxillary acrylic appliance with a striking

plate mounted with an ink solution to identify centric

relation. b) Mandibular base plate holding the pin into a

rotatable nut allowing dentist to parallel with the maxillary

striking plate.

Fig. 8. Plastic receiving disc sticky waxed over the apex of

jaw recording.

Fig. 9. Casts articulation utilizing the Jaw Recording device

at selected occlusal vertical dimension.

mouth and the added resin is shaped

t

Fig. 3. The “Massad Disposable Tracers” (Jaw Relation

Recording Device designed by Joseph J. Massad).

Daher T, Massaad JJ

5a 5b

6a 6b

7a 7b

Figs. 10a, 10b. a) Articulated casts at final OVD reflecting

an increase in existing vertical at patient’s RCP. b) Final

articulated casts demonstrating dimension used in final

prosthesis.

Fig. 11. Final prosthesis at new vertical and in RCP,

showing bilateral reverse occlusion on molars.

2- Technique for complete denture

Fig. 12. Jaw Recording device for the edentulous patient.

Articulated casts on articulator ready for set-up.

Fig. 13. Lateral view patient right and left.

3- Technique for implant patient.

Fig. 14. Maxillary and mandibular casts with and without

striking plate for implant supported and retained prostheses.

Noticed that 2 implant-impression copings are used to secure

the Jaw Recorder in place.

4- Technique for removable partial denture patient.

Fig. 15: The mandibular ball bearing plate is secured with

clear Triad® acrylic material on the clear Triad® acrylic

baseplate. (Dentsply International, York, PA,USA)

Fig. 16: The maxillary striking plate showing the Gothic

arc tracings secured on the clear Triad® acrylic wax-trial

denture. This disposable plate could be mounted also on the

wax-rim baseplate.

52 Volume 46 - Nº 1 - 2009

18a 18b 18c

Fig. 17: Records in RCP at a

slightly increased vertical

dimension of occlusion to

clear the path of mandibular

teeth during excursion

movements to trace the

Gothic arc tracings.

Daher T, Massaad JJ

10a 10b


REFERENCES1. Daher T, Hall D, Goodacre CJ. Designing Successful

Removable Partial Dentures. Compendium of Continuing

Education in Dentistry 2006;27,3:104.

2. McGivney GP, Carr AB. McCracken’s Removable Partial

Prosthodontics. 7th Edition. Chap 17:355.

3. Thornton LJ. Anterior guidance: Group function/canine

guidance. A literature review. J Prosth Dent 1990;64:479-482.

4. Glossary of Prosthodontic Terms. J Prosthet Dent

2005;94:13-83.

5. Jasinevicius TR, Yellowitz JA, Vaughan GG, et al. Centric

relation definitions taught in 7 dental schools: Results of

faculty and student surveys. J Prosthodont 2000;9:87-94.

6. Holden JE. Centric Relation treatment position concepts and

related research. American College of Prosthodontists

publication.

7. Myers ML. Central relation records. Historical review. J


8. Schweitzer JM. Dental occlusion: a pragmatic approach.

Dent Clin North Am 1969;13:687-724.

9. Stegenga B, de Bont LGM, Boering G. et al. Tissue responses

to degenerative changes in the temporomandibular joint: a

review. J Oral Maxillofac Surg 1991;49:1079-1088.

10. Scapino RP, Mills DK. Disc displacement internal

derangements. In: McNeill C. Science and Practice of

Occlusion. Quintessence Books. 1997. Chap 18.

11. Celenza FV. The centric position: replacement and

character. J Prosthet Dent 1973:30;591-598.

12. Mohamed A, El-Aramany MA, George WA, Scott RH.

Evaluation of the needle point tracing as a method for

determining centric relation. J Prosthet Dent

1965:15,1043.

13. Massad JJ, Connelly ME, Rudd KD, Cagna DR. Occlusal

device for diagnostic evaluation of maxillomandibular

relationships in edentulous patients: A clinical technique. J


Correspond with:

Tony Daher

[email protected]

18a 18b 18c

Figs.18a, 18b, 18c. a) Both baseplates are secured with a polyvinyl siloxane (PVS) material bite registration such as Futar D® in RCP.

b) another PVS bite registration in protrusion is made to program the articulator condylar inclination. This protrusive record is needed

to balance occlusion during denture fabrication. PVS centric record is needed to articulate casts on an articulator. c) PVS materials in a

gun delivery system.

19a 19b

19b

19b

20a 20b

Figs. 19a, 19b. a) RCP record is trimmed before its use in

articulating casts. b) casts articulated using Gothic arch

tracing records and PVS RCP record.

Figs. 20a, 20b. a) patient’s smile. b) final prostheses in

patient’s mouth.

Daher T, Massaad JJ

Restorative Dentistry

57

Restorative procedures are a source of pulp tissue

injury and post-operative pain, and can occur because

of several factors such as heat generated during cavity

preparation, method of restorative material placement,

chemical irritants, and others1-2. Patients regularly

report post-operative pain after cavity preparation, for

both direct and indirect restorations. Cavity

preparation induced heat can be controlled with

adequate cooling and the use of a new bur. The older

the bur, the lower its cutting capacity; consequently,

more time is required to cut hard tissues and further

forces are needed during the restorative procedure, and

hence further heat is generated. In order to prevent

post-operative sensitivity, small pellets of composites

can be inserted in the cavity to avoid polymerization

shrinkage, and irrigants and restorative materials

should be biocompatible with prepared dental hard

tissues.

Nowadays, several new technologies are able to

improve dental treatment outcome in all dental

disciplines and specialties. Low Level Laser (LLL)

technology was established as a non-invasive method

to enhance wound healing, modulate inflammatory

process and promote pain relief3-8.

The aim of the following case reports is to describe

the usefulness of LLL in preventing post-operative

pain after cavity preparation in direct and indirect

restorative procedures.

FIRST CASE REPORT

A 32-year-old woman, presented with an occluso-

distal amalgam restoration on 4.5: she asked to replace

it for esthetic reasons.

After local analgesia of right inferior alveolar

nerve, rubber dam was placed and amalgam

restoration removed with dental diamond bur (No.

1046 – KG Sorensen®- Brazil) using a high speed drill

mode under copious water irrigation (Fig.1A).

After restoration removal and cavity preparation

(Fig.1B), dentin was treated with LLL- Gallium-

Aluminum-Arsenium, GAAlAs (Compact Laser, J

Morita®, Co. Japan) with the following parameters: 30m

W power, 18 seconds/point, 790 nm wavelength (Fig.1C).

Energy density applied to the tissue was 4.15 J/cm2,

calculated according to the formula: Energy Density

The use of low level laser after cavity preparation in vital tooth: a

clinical report.

1 Full Professor, Special Laboratory of Lasers in Dentistry

(LELO), Department of Restorative Dentistry, University

of São Paulo, School of Dentistry, São Paulo, Brazil,

2 Full Professor, Department of Stomatology, University of

São Paulo, School of Dentistry, São Paulo, Brazil,

3 Ph.D student, Department of Stomatology, University of

São Paulo, School of Dentistry, São Paulo, Brazil.

Carlos de Paula Eduardo1, DDS , M. S c. , Ph. D, Rodney Garcia Rocha2, DDS , M. S c. , Ph. D, Karen Müller

Ramalho3, DDS, M. S c


Volume 46 - Nº 1 - 2009

Abstract

Patients frequently complain of post-operative pain after cavity direct and indirect preparations. Restorative procedures are

obviously a source of injury to pulp tissue as a result of several factors, such as heat generated by cavity preparation, method

of restorative material placement, chemical irritants and others. Low level lasers (LLL) are reported to be analgesic,

biomodulatory and anti-inflammatory: published studies have shown their numerous effects after cavity preparation, among those

biomodulation of pulp cells, decreased inflammatory reaction in the pulp and acceleration of dentin recovery (in the pre-dentin

region). These two case reports describe and illustrate the use of LLL as a complementary tool preventing post-operative

sensitivity after cavity preparation in direct and indirect restorative procedures.

(J/cm2)= time (s*) x laser spot size area (cm2) / power (w).

One laser beam was conveyed to the pulpal wall. Total

energy applied to the tissue was 0.54 J, according to the

formula: Energy (E) = Power (P) x time (s).

After LLL application, pulp cavity wall was protected

with a thin layer of calcium hydroxide (Dentsply®) and

dentin and enamel were then etched with 37%

phosphoric acid, followed by the adhesive step

(AdapterTM Single Bond 3M, ESPE Dental Products,

USA) in accordance with manufacturer’s instructions.

Restoration was performed with resin composite (Tetric

Ceram, Ivoclar-Vivadent, Schan, Lichtenstein).

Composite was inserted in small pellets (0.5 mm2) to

avoid polymerization shrinkage and minimize post-

operative pain (Figs. 1D,E,F). Subsequently, post-

operative course proved to be uneventful.

SECOND CASE REPORT

A 50-year-old male patient presented with severely

decayed 2.6 and indirect restoration was planned. After

local analgesia, indirect preparation was performed

with a dental diamond bur (KG Sorensen®, Brazil)

using a high speed drill mode and under copious water

irrigation. Once the preparation was completed, LLL

therapy was performed- Gallium-Aluminum-

Arsenium, GAAlAs (Compact Laser, J Morita®,

Japan) with the following parameters: 30 mW power,

18 seconds/point, and wavelength of 790 nm (Figs.

2A,B,C). The energy density applied to dental tissues

was 4.15 J/cm2, calculated according to the formula:

Energy Density (J/cm2)= time (s) x laser spot size area

(cm2) / power (w). Three points were targeted in

occlusal dentin (Figs.2A,B,C) and total energy applied

to the tissue per session was 1.62 J, according to the

following formula: Energy (E) = Power (P) x time (s).

After laser treatment, a provisional crown was

cemented temporally. During dental preparation,

impression and final luting, LLL therapy was applied

according to the method described above. The patient

did not complain of any sensitivity and pain after

treatment.

DISCUSSION

Dentin sensitivity or hypersensitivity is common in

dental practice. Human dental pulp is highly

innervated and human teeth are classified among the

most sensitive structures12. Fearnhead13 has shown that

small nerve fibrils with an approximate diameter of 0.2

µm were in close relationship with the odontoblast

process extending as far as 1.5 mm into dentin.

Moreover, Frank14, Dahl and Mjör15 studies supported

the presence of stable connections between the

odontoblast process and nerve endings in dentin.

Therefore, every stimulus applied during the

restorative procedure is captured by the pulp through

this system.

The odontoblast process continues in the form of a

large number of lateral branches16 previously seen in

predentin and dentinal tubules16. The number of tubules

was found to be 45.000/mm2, with a diameter of 2.5 µm

58 Volume 46 - Nº 1 - 2009

Fig. 1. First case report. A- Initial amalgam restoration. B-

After amalgam removal. C- Low Intensity Laser beam in

cavity. D- Pulpal wall protection with calcium hydroxide. E-

Restoration with composite resin. F- Final restoration.

Fig. 2. Second case report. A, B, C – 3 points of low level

intensity laser beam in dentin. D- Metallic onlay. E-

Metallic onlay luting. F- Final indirect restoration.

Eduardo CDP, Garcia Rocha R, Ramalho KM

* s = seconds


near the pulp; whereas in middle dentin, there were

29.500/mm2 tubules with a diameter of 1.2 µm16.

Brännström and co-workers17 proved that the main

cause of dentinal pain is a rapid outward flow of fluid

in dentinal tubules, initiated by capillary forces.

Temperature was found to have a great effect on

hydraulic conductance of dentin. Increasing the

temperature by 40ºC resulted in a 1.8 fold increase in

fluid flow in unetched dentin and in a 4 fold increase

in acid-etched dentin. This increment in hydraulic

conductance was attributed to thermal expansion-

induced increases in tubular diameter18. Therefore, a

high temperature increase occurring during dental

treatment will generate stimuli transmitted to pulp,

leading to post-operative sensitivity. Consequently,

dentists should take special care to prevent inducing

high temperatures in etched dentin.

LLL is absorbed by specific chromophore

photoreceptors, and once absorbed, light can modulate

cell biochemical reactions and stimulate mitochondrial

respiration9. This primary response will lead to

secondary responses such as increase in ATP synthesis,

collagen production, cell proliferation and migration

and biomodulation of inflammatory molecules10-11.

Advantages of LLL use in restorative dentistry

were reported in several in-vivo studies. Godoy and

co-workers2 used a laser with 670 nm wavelenghth, 30

mW and 2 J/cm2 parameters, applied directly and

perpendicularly in Class I cavities in premolars during

one single session, then the teeth were restored with

composite resin. After 28 days, teeth were extracted

and transmission electron microscopy-TEM- analysis

showed that lased groups displayed an odontoblast

process in greater contact with extracellular matrix. In

addition, collagen fibrils appeared more aggregated

and organized than those of the control group. It was

concluded that laser treatment accelerated recovery of

dental structures involved in cavity preparation in

predentin region.

Ferreira and co-workers19 used a 670 nm

wavelength/ 50 mW - 4 J/cm2 laser in Class V cavities

in premolars before restoring them with glass ionomer.

Teeth were extracted after 14 and 42 days. Histological

changes were observed using light microscopy: less

intense inflammatory reaction was found in the lased

group when compared with control group. Only in the

group of teeth extracted 42 days after laser application,

an area associated with reactionary dentinogenesis was

shown. Immunohistochemical analysis revealed that

expression of collagen type III, tenascin, and

fibronectin were greater in the treated group.

Inflammatory modulation capacity of LLL has been

documented in several studies4-5-20 that described

molecular basis of LLL in the inflammatory

biomodulation process, such as Prostaglandin E2

(PGE2) inhibition through reduction of

cyclooxygenase messenger RNA (COX-2 mRNA)

levels, as well as Interleukin-1 (IL-1) inhibition in a

dose dependent manner. Other studies on dental pulp,

using histopathological analysis, evaluated

biomodulatory effect of LLL on pulp inflammatory

process21,22 and reparative process23.

LLL can also be beneficial in pain control:l6,24-26

Mechanism by which laser controls pain has not been

completely elucidated. It has been previously

suggested that laser has an effect on peripheral

endogenous opioid24, serotonin production25, ACTH

and ß-endorphin release. Therefore, pain caused by

rapid outward flow of fluid in dentinal tubules can

probably be controlled by LLL therapy.

All beneficial effects of LLL, such as pain control,

inflammatory and reparative tissue modulation can be

indicated in restorative procedures, enhancing pulp

tissue recovery as well as providing patients with post-

operative relief.

Based on these two case reports and previously

published data, it is suggested that LLL can be

beneficial as a coadjuvant in conventional restorative

treatment. Nonetheless, dentists should always keep in

mind factors that may induce tissue damage, such as

use of old dental burs (that cause abrasion and

excessive heat during cavity preparation), restorative

material placement method and chemical irritants.

Acknowledgements

LELO – Center of Study, Clinic and Teaching of Lasers

in Dentistry, Dental School, University of São Paulo,

Brazil; CNPq (303798/2005-0).


REFERENCES 1- Murray PE, About I, Lumley PJ, Franquin JC, Remusat M,

Smith AJ. Human odontoblasts cell number after dental

injury. J Dent 2000;28:277-285.

2- Godoy BM, Arana-Chavez VE, Nuñez SC, Ribeiro MS. Effects

of low Power red laser on dentine pulp interface after cavity

preparation. An ultra structural study. Archiv Oral Biol

2007;52:899-903.

3- Moore P, Ridgway TD, Higbee RG, Howard EW, Lucroy MD.

Effect of wavelength on low-intensity laser irradiation-

stimulated cell proliferation in-vitro. Lasers Surg Med

2005;36:8-12.

4- Sakurai Y, Yamaguchi M, Abiko Y. Inhibitory effect of low

level laser irradiation on LPS-stimulated prostaglandin E2

production and cyclooxygenase-2 in human gingival

fibroblasts. Eur J Oral Sci 2000;108:29-34.

5- Shimizu N, Yamaguchi M, Goseki T, Shibata Y, Takiguchi H,

Iwasawa T, Abiko Y. Inhibition of prostaglandin E2 and

interleukin 1-beta production by low-power laser irradiation

in stretched human periodontal ligament cells. J Dent Res

1995;74:1382-1388.

6- Tam G. Low power laser therapy and analgesic action. J Clin

Laser Med Surg 1999;17:29-33.

7- Tuner J, Hode L. It's all in the parameters: a critical analysis

of some well-known negative studies on low-level laser

therapy. J Clin Laser Med Surg 1998;16:245-248.

8- Wedlock P, Shephard RA, Little C, McBurney F. Analgesic

effects of cranial laser treatment in two rat nociception

models. Physiol Behav 1996;59:445-448.

9- Karu T. Primary and secondary mechanisms of action of

visible to near-IR radiation on cells. J Photochem Photobiol

B 1999;49:1-17.

10- Conlan MJ, Rapley JW, Cobb CM. Biostimulation of

wound healing by low-energy laser irradiation. A review. J

Clin Periodontol 1996;23:492-496.

11- de Araujo CE, Ribeiro MS, Favaro R, Zezell DM, Zorn TM.

Ultrastructural and autoradiographical analysis show a

faster skin repair in He-Ne laser-treated wounds. J

Photochem Photobiol B 2007;86:87-96.

12- Loewenstein WP, Rathkamp R. A study on the

pressoreceptive sensibility of the tooth. J Dent Res

1955;34:287-294.

13- Fearnhead RW. Histological evidence for the innervation of

human dentin. J Anat 1957;91:267-276.

14- Frank RM. Attachment sites between the odontoblasts

process and the intradentinal nerve fiber. Arch Oral Biol

1968;13:833-834.

15- Dahl E, Mjör IA. The structure and distribution of nerves in

the pulp-dentin-organ. Acta Odont Scand 1973;31:349-356.

16- Kaye H, Herold RC. Structure of human dentin-I. Phase

contrast, polarization, interference and bright field

microscopic observations on the lateral branch system.

Arch Oral Biol 1966;11:355-362.

17- Brännström M. Sensitivity of dentin. Oral Surg Oral Med

Oral Pathol 1966;21:517-526.

18- Pashley DH, Thomson SM, Stewart FP. Dentin

Permeability: Effects of temperature on hydraulic

conductance. J Dent Res 1983;62:956-959.

19- Ferreira AN, Silveira L, Genovese WJ, de Araújo VC, Frigo

L, de Mesquita RA, Guedes E. Effect of GAAIAs laser on

reactional dentinogenesis induction in human teeth.

Photomed Laser Surg 2006;24:358-365.

20- Nomura K, Yamaguchi M, Abiko Y. Inhibition of

Interleukin-1B production and Gene Expression in Human

Gingival Fibroblasts by Low-energy Laser Irradiation.

Lasers Med Sci 2001;16:218-223.

21- Myers TD. Lasers in dentistry. J Am Dent Assoc

1991;122:46-60.

22- Frentzen T, Koort HJ. Laser in Dentistry: a new

possibilities with advancing laser technology. In Dent J

1990;40: 323- 332.

23- Paschoud Y, Holz J. Effect du soft laser sur la néoformation

d’un pont dentinaire après coiffage direct de dents humaines

à l´hydroxyde de calcium. I-étude histologique et au

microscope életronique à balayage. Rev Mens Suisse

Odonto-Stomatol 1988;98:345-356.

24- Hagiwara S, Iwasaka H, Okuda K, Noguchi T. GAAlAs (830

nm) low-level laser enhances peripheral endogenous opioid

analgesia in rats. Lasers Surg Med 2007 ;39:797-802.

25- Walker J. Relief from chronic pain by low power laser

irradiation. Neurosci Lett 1983; 43:339-344.

26- Laakso EL, Cabot PJ. Nociceptive scores and endorphin-

containing cells reduced by low-level laser therapy (LLLT)

in inflamed paws of Wistar rat. Photomed Laser Surg.

2005;23:32-35.

Correspond with:

Carlos de Paula Eduardo

[email protected]

60 Volume 46 - Nº 1 - 2009


61

Forthcoming Dental Meetings,

Exhibitions and Conventions.

Forthcoming Dental Meetings,

Exhibitions and Conventions.


Volume 46 - Nº 1 - 2009

Reported by Maria Saadeh and Jihad Fakhouri

MEETING LOCATION DATES WEBSITE

2009

American Dental Association (ADA)

Annual Session

Honolulu,

USA

Sep 30- Oct 3 www.ada.org

European Association for

Osseointegration: 18th

Annual Scientific

Meeting

Monaco,

Monaco

Oct 1-3 www.eao.org

1st JOR Colloquium on Oral Rehabilitation Sienna,

Italy

Oct 7-11 www.jor-net.com

17th

Scientific International Conference of

Syrian Dental Association

Damascus,

Syria

Oct 14-16 www.scs-net.org

37th

International Expodental Rome,

Italy

Oct 15-17 www.expodental.it

5th

Bahrain Dental Society Conference Manama,

Bahrain

Oct 27-29 www.bahrain-dental.com

TMJ Bioengineering Conference Boulder, Colo.,

USA

Nov 4-7 www.TMJconference.org

First Dental-Facial Cosmetic International

Conference

Dubai,

UAE

Nov 6-7 www.cappmea.com/aesthetic

Dubai International Implant Summit

(Biology meets technology)

Dubai,

UAE

Nov 10-12 www.diis.ae

6th

Conference of the Gulf Dental

Association

Al Khubar,

KSA

Nov 10-12

www.sds.org.sa

14th

International Dental Congress of the

Egyptian Dental Association (Problems

solving in Dentistry)

Cairo,

Egypt

Nov 11-13 www.eda-egypt.org

6th

International Conference on Problem-

Based Learning (PBL) in Dentistry

Hong Kong,

China

Nov 13-15

www.facdent.hku.hk/pbl

Congress of the French Dental Association

(Association Dentaire Francaise- ADF)

Paris,

France

Nov 24-28 www.adfcongres.com

Greater New York Dental Meeting New York, NY,

USA

Nov 27- Dec 2 www.gnydm.com

2010

São Paulo International Dental Meeting

(CIOSP)

São Paulo,

Brazil

Jan 3 - Feb 3 www.apcd.org.br/ciosp

144th

Chicago Dental Society Midwinter

Meeting

Chicago, USA Feb 26-Mar 1 www.cds.com

39th

Annual Meeting and Exhibition of the

American Association for Dental Research

(AADR)

Washington DC,

USA

Mar 3-6 www.dentalresearch.org

EvENT LOCATION DATES WEBSITE

Solving

62 Volume 46 - Nº 1 - 2009

UAE Dental Exhibition Dubai,

UAE

Mar 9-10 www.aeedc.com

Congrès International de Chirurgie

Dentaire

Marseille,

France

Mar 11-13

www.adpmarseille.org

8th

International Implantology Congress of

the Alexandria Oral Implantology

Association

Alexandria,

Egypt

Mar 24-26 www.aoiaegypt.com

Pacific Dental Conference Vancouver,

Canada

April 15-17 www.pacificdentalonline.com

26th

Annual Scientific Session of the

American Academy of Cosmetic Dentistry

Grapevine,

USA

Apr 27-May 1

www.aacdconference.com

110th

Annual Session of the American

Association of Orthodontists (AAO)

Washington DC,

USA

Apr 30-May 2 www.aaortho.org

WID - Vienna International Dental

Exhibition

Vienna,

Austria

May 7-8 www.wid-dental.at

Saudi Dentistry - International Dental

Health Exhibition

Riyadh,

Saudi Arabia

May 9-12 www.recexpo.com

Stomatology St. Petersburg- 13th

International Dental Exhibition and

Conference

St. Petersburg,

Russia

May 11-13 www.primexpo.ru/dental

32nd

Asia Pacific Dental Congress Colombo,

Sri Lanka

May 12-15 www.apdc2010.com

British Dental Conference and Exhibition Liverpool,

UK

May 20-22 www.bda.org

Spring Meeting 2010 of the European

Academy of Esthetic Dentistry

London,

UK

May 27-29 www.eaed.org

Annual Meeting of the American Academy

of Pediatric Dentistry (AAPD)

Chicago,

USA

May 27-31 www.aapd.org

88th

General Session & Exhibition of the

International Association for Dental

Research (IADR)

Barcelona,

Spain

July 14-17 www.dentalresearch.org/i4a

FDI Annual World Dental Congress Salvador,

Brazil

Sep 2-5 www.fdiworldental.org

19th

Annual Scientific Meeting of the

European Association for Osseointegration

Glasgow,

Scotland, UK

Oct 7-9 www.eao.org

19th

Annual Scientific Meeting of the

European Association for Osseointegration

Orlando,

USA

Oct 9-12 www.ada.org

96th

Annual Meeting of the American

Academy of Periodontology (AAP)

Honolulu,

Hawaii

Oct 30-Nov 2 www.perio.org

Trans-Tasman Endodontic Conference:

Endodontics—Continue the Learning

Christchurch,

New Zealand

Nov 4-6 www.tteconference.com

Annual Congress of the French Dental

Association (Association Dentaire

Francaise- ADF)

Paris,

France

Nov 24-27 www.adfcongres.com

American Dental Association

Hazmieh - Sayyad

Phone: 05/452555

Email: [email protected]

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