associate editors for research - lda€¦ · professor of restorative dentistry and endodontics,...

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Ziad Salameh, Dr. Chir. Dent., DES Prostho., M.Sc.,Ph.D., HDR, FICD,Chairperson, Department of Research,Professor, Departments of Prosthodontics andResearch, Lebanese University, Faculty of Dental Medicine, Beirut,Adjunct Associate Professor, Center for Craniofacial Regeneration,University of Pittsburgh, Pittsburgh, [email protected]@drziadsalameh.com

Marcel Noujeim, BDS, DESS Oral Biol., DESS OralRadiol., MS Oral/Max.Fac. Radiol.,Diplomate, American Board of Oral/MaxillofacialRadiology,Professor, Department of Comprehensive Dentistry,Director of Oral and Maxillofacial Radiology Postgraduate Program,University of Texas Health Science Center at San Antonio -UTHSCSA, San Antonio, Texas, [email protected]

Charles Sfeir, Dr. Chir. Dent., Cert. Perio., MS, Ph.D.,Associate Dean for Research and Associate Professor, Departments of Oral Biology and Periodontics, and Founding Director, Center for Craniofacial Regeneration, University of Pittsburgh, School of Dental Medicine, Pittsburgh, Pennsylvania, USA [email protected]

Associate Editors for Research

Editors-in-Subchief

Editor-in-ChiefZiad E.F. Noujeim,

Dr. Chir. Dent., CES Oral Biol., CES Surg. Dent., Dipl. Oral Pathol., DU Cell Therapy, DIU Anti-Aging Medicine, DU Oral Dermatology, Diplomate of the European Board of Oral Surgery,Fellow, American College of Oral and Maxillofacial Surgery, International College of Dentists,Senior Lecturer and Postgraduate Tutor, Departments of Oral and Maxillofacial Surgery / Oral Medicine and Dentomaxillofacial Radiology, Former Director, Oral Pathology and Oral Surgery Postgraduate Programs, Former Chairperson of Research Department, Lebanese University, Faculty of Dental Medicine, Beirut, Lebanon,Atending Oral Surgeon, Baabda University Hospital, Baabda, Lebanese Army Central Hospital, Beirut,Scientific Chairperson, Lebanese Society of Oral Surgery, Former Scientific Chairperson, Lebanese Dental Association,Section Editor, Annals of Maxillofacial Surgery - AMS,Reviewer, Journal of the American Dental Association - JADA www.drziadnoujeim.com | [email protected]

Hani F. Ounsi, Dr. Chir. Dent., DES Endo.,M.Sc. Dental Mat., DEA Oral Biol., Ph.D., FICDAssistant Professor, Department of Endodontics and Restorative Dentistry, Lebanese University, Faculty of Dental Medicine, Visiting Professor, Department of Endodontics and Restorative Dentistry, Tuscan School of Dental Medicine, University of Siena, [email protected]

Mary Ann Jabra-Rizk, BS, Ph.DProfessor, Department of Oncology and Diagnostic Sciences, University of Maryland School of Dentistry, Baltimore,Professor, Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, [email protected]

Jaime S. Brahim, DDS, MS, FACOMS, FAAOMS,Diplomate, American Board of Oral and MaxillofacialSurgery, American Board of Oral Medicine,Clinical Professor, Department of Oral and Maxillofacial Surgery,Director, Clinical Research Unit and Undergraduate Program, University of Maryland School of Dentistry, Baltimore, Maryland,Former Senior Oral and Maxillofacial Surgeon, National Institutesof Health-NIH, Bethesda, Maryland, [email protected]

Michel Goldberg, Chir. Dent., Dr. Sc. Odont., D. Sc., PU,Emeritus Professor and Research Scientist, Saints-Pères Biomedical College, INSERM/Unité 747-Equipe 5, Paris Descartes University, Paris, [email protected]

Josette Camilleri, B.Ch.D., M.Phil., Ph.D., FADM, FIMMM, FHEA, FAAEProfessor of Restorative Dentistry and Endodontics, School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, England, [email protected]

Elie M. Ferneini, B.Sc., MS Health Sciences, DMD,MD, MHS, MBA/HCM, FACS, FACDAssociate Professor, Oral and Maxillofacial Surgery Division, Department of Craniofacial Sciences, University of ConnecticutSchool of Dental Medicine, Farmington, Connecticut, USAEditor-in-Chief, American Journal of Cosmetic [email protected]

Ziad S. Haidar, DDS, Cert. Implant, M.Sc. (OMFS), FRCS(C), MBA, Ph.D.,Profesor Investigador y Director BioMAT'X,Facultad de Odontologia, Universidad de Los Andes, Santiago, [email protected]

Journal of the Lebanese Dental AssociationVolume 52 - Nº 2 - July-December 2017

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Senior Associate Editors

Zeina A.K. Majzoub, Dr. Chir. Dent., DMD, Dott. Odont.,CAGS, M.Sc.D,Professor of Periodontology and Research and FormerChairperson, Department of Research, Lebanese University,Faculty of Dental Medicine, Beirut,Former Professor of Periodontology and Research, University ofPadova, Institute of Clinical Dentistry, Padova, [email protected]

Assem Soueidan, Dr. Chir. Dent., CES Perio.,DU Perio., DU Oral Rehab./Implant., DU OralDermatology, DEA, Dr. Univ., HDR, PU, PH,First Vice-Dean and Director of Clinical Investigation Unit, Professor and Chairperson, Department of Periodontology,Nantes University, Faculty of Dental Surgery, Nantes, [email protected]

Sami Mouwakdié, Dr. Chir. Dent., DU Perio.,DU Implant., DEA Génie Biologique, MBA,Assistant Professor, Department of Periodontology,Former Director, Periodontology Postgraduate Program, Former Director, Clinical Dental Management Postgraduate Program, Member of Quality Assurance CommitteeLebanese University, Faculty of Dental Medicine, Beirut,[email protected]

Roula Abiad, BDS, MS Endo., Dr. Dent. Sc.,Assistant Dean, Associate Professor of Endodontics,Director, Division of Endodontics, Department of Restorative Sciences,Beirut Arab University, Faculty of Dentistry, Beirut, [email protected]

Pascale Habre Hallage, Dr. Chir. Dent., CES Oral Biol.,CES Fixed Prostho., DUICP, MSBM, DEA Neurosc.,Dr. Biomed. Sc.,Assistant Professor and Director of Postgraduate Program,Department of Fixed Prosthodontics and Occlusion,Saint-Joseph University, Faculty of Dental Medicine,Beirut, [email protected]

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

Radhouane Dallel, Dr. Chir. Dent., Dr. Univ., HDR, PU, PH,Senior Scientist and Director, Neurobiology of Trigeminal Pain/Migraine Laboratory, NEURO-DOL, INSERM/UdA, U1107,Professor, Clermont 1 University, Faculty of Dental Surgery,Clermont-Ferrand, [email protected]@u-clermont1.fr

Tony Daher, Dr. Chir. Dent., CES Fixed Prostho.,CES Remov. Prostho., PG Cert. Prostho., MS (Education), FACP, FICP, FICD, MAO, MPFA,Diplomate, American Board of Prosthodontics,Co-Director, Global Dental Implant Academy - GDIA, La Palma, California, USA, and Visiting Clinical Professor of Prosthodontics, Saint-Joseph University Faculty of Dental Medicine, Beirut, [email protected]

Joseph J. Massaad, DDS, MAGD, FACD, FICD, MIA Dent. Fac. Esth., MPFA,Clinical Associate Professor of Prosthodontics, University of Tennessee Health Science Center -UTHSC- College of Dentistry, Memphis, Tennessee, and, Adjunct Associate Professor, Department of Restorative Dentistry, Loma Linda University School of Dentistry, Loma Linda, California, [email protected]

Fadl Khaled, BDS, CES Endo., DES Endo., FICD,Adjunct Clinical Assistant Professor of Endodontics, Department of Restorative Sciences, Beirut Arab University, Faculty of Dentistry, Beirut,Chief of Clinical Services, Department of Endodontics,Lebanese University, Faculty of Dental Medicine, BeirutChairperson, Continuing Education Committee, [email protected]

Carla Zogheib Moubarak, Dr. Chir. Dent., DES Endo.,MS Oral Biomat. Res., Dr. Univ.,Assistant Professor, Department of Endodontics,Saint-Joseph University, Faculty of Dental Medicine, Beirut, [email protected]@gmail.com


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Associate EditorsTara Renton, BDS, M. Dent. Sc., FRACDS,FDSRCS (Engl.), Ph.D., ILTM, FHEA,Consultant Oral Surgeon, Professor and Head, Department of OralSurgery, King’s College London -KCL- Dental Institute, London, UK,[email protected]

Dimitar Filtchev, DDS, MS, Ph.D,Chief Assistant Professor, Department of Prosthetic Dentistry, Faculty of Dental Medicine, Medical University of Sofia, Sofia, Bulgaria [email protected]

Chimène Chalala, BDS, DESS Orthod., ResidencyOrthod. AUB,Clinical Associate, Division of Orthodontics and DentofacialOrthopedics, American University of Beirut Medical Center,Associate Chief of Clinical Services, Department of Orthodontics,Lebanese University, Faculty of Dental Medicine, Beirut,[email protected]

Sonia Ghoul-Mazgar, Dr. Chir. Dent, Dr. Univ.,Professor of Oral Biology and Research Scientist, Laboratory of Histology and Embryology, University of Monastir Faculty of Dental Medicine, Monastir, Tunisia,Founder/President, Tunisian Association of Dental Research - TADR,[email protected]

Rima Abdallah, BDS, CAGS, D.Sc. (Oral Biol.),Diplomate, American Board of Periodontology,Assistant Professor, Department of Periodontology, Lebanese University, Faculty of Dental Medicine, Beirut,Adjunct Clinical Assistant Professor, Periodontology andImplantology Divisions, Oral Surgical Sciences Department,Beirut Arab University, Faculty of Dentistry, Beirut, Editor-in-Chief, International Journal of Oral and Dental Sciences,[email protected]

Setareh Lavasani, DDS, MS, Diplomate, American Board of Oral and Maxillofacial Radiology, MABOMR, MADEA, MAAMC, MAAOMR,Assistant Professor, Department of Oral and Maxillofacial Radiology, Western University of Health Sciences, College of Dental Medicine, Pomona, California, [email protected][email protected]

Dina Debaybo, Dr. Chir. Dent., CAGS, MSD,Diplomate, American Board of Pediatric Dentistry,Former Clinical Associate Professor of Pediatric Dentistry,European University College, Dubai, UAE,President, Emirates Club of Pediatric Dentistry, [email protected]

Carmen Doumit, BDS, CAGS, MS,Clinical Assistant Professor, Temple University - Kornberg School of Dentistry, Department of Orthodontics, Philadelphia, Pennsylvania, [email protected]

Anil Sukumaran, BDS, MDS, Ph.D., FDS RCPS (Glas), FICD, FPFA,Professor and Consultant, Division of Periodontics, Department of PDS, King Saud University, College of Dentistry, Riyadh, KSA,[email protected] / [email protected]

Karine El Feghali, BDS, DESS Perio., Ph.D., FRCD (C),Diplomate, American Board of Periodontology,Former Associate Professor, Department of Periodontics,Former Research Scientist, Oral Ecology Research Group (GREB),Laval University, Faculty of Dental Medicine, Quebec City, [email protected]

Editors EmeritiClinical Professor Philippe E. Aramouni, DCD, DEA, CAGS Prostho., M.Sc.D., FICDProfessor Nadim Z. Baba, DMD, MSD, FICD, FACP, Dipl. ABPMichel Salameh, DCD, CES Pediat. Dent., MIADP, MIADH, MSFOPAssociate Professor Georges Aoun, BDS, DES Oral Biol., DES Prostho., DSOAssociate Professor Antoine Cassia, DCD, CES Oral Biol. Bucc., CES Surg. Dent., DU Maxillofacial Prostho., DSOProfessor Levon Naltchayan, DCD, CES Prostho.Pierre Souaid, DCD

Manuscript Editors

Abbass El-Outa, BDS, DES Clin. Dent. Management, MEAOM, Dental Surgeon, Beirut, Lebanon [email protected]

Lara Nasr, BDS, Dental Surgeon, Kfarchima, Lebanon [email protected]


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Editorial Advisors

Biostatistics and Epidemiology Consultants

Essam Osman, BDS, MSD, Ph.D.Vice-President for Medical Sciences, Beirut Arab University,Dean, Faculty of Dentistry,Chairperson, Departments of Restorative Sciences and OralSurgical Sciences, and Director, Division of Dental Biomaterials,Professor of Dental Materials, Faculty of Dentistry, [email protected]@bau.edu.lb

Nadim Z. Baba, DMD, MSD, FICD, FACP, Diplomate, American Board of Prosthodontics,President-Elect, American College of Prosthodontists,Professor, Advanced Education Program in Prosthodontics, Loma Linda University, School of Dentistry, Loma Linda, USAAssociate Editor, Dental Traumatology, Former Editor-in-Chief, Journal of the Lebanese Dental [email protected]

Antoine F. Saadé, DCD, CES Orthod., Du Orthod., CECSMOFormer Chairperson, Senior Lecturer, and Postgraduate Tutor, Department of Orthodontics and Dentofacial Orthopedics, Lebanese University, Faculty of Dental Medicine, Beirut,[email protected]

André Assaf, BDS, CES Dent. Mat., CES FixedProstho., CES Remov. Prostho., DU Occlusodont.,DU Implant., DU Med. CommunicationAdjunct Clinical Associate Professor, Department of RestorativeSciences, Beirut Arab University, Faculty of Dentistry, BeirutSenior Lecturer, Department of Prosthodontics,Lebanese University, Faculty of Dental Medicine, Beirut, President, Lebanese Society of Prosthodontics,[email protected]

Leila Chahine, DMD, FAADSM,Diplomate, American Board of Dental Sleep Medicine,Dental Staff, Danbury Hospital, Western Connecticut HealthNetwork, Connecticut, [email protected]

Nada E. El-Osta, DCD, DES Prostho., MS (Biol. Med.Sc.), DIU Biostat., DU Forensic ScienceConsultant in Biostatitics / Epidemiology,Saint-Joseph University, Faculties of Medicine and DentalMedicine, Beirut, [email protected] / [email protected]

Antoine Berbéri, BDS, MS, DU Perio,CES Odont. Chir., Dr. Univ., HDR, FICD,Diplomate of the European Board of Oral Surgery,Professor and Chairperson,Department of Oral and Maxillofacial Surgery,Lebanese University, Faculty of Dental Medicine, Beirut,Research Scientist, Doctoral School of Sciences and Technology,Lebanese University, Beirut,[email protected]

Georges Tawil, Dr. Chir. Dent., DDS, CES Odont.Chir., CES Perio., Dr.Sc.Odont., FICD, FACDFormer Professor and Chairperson, Department of Periodontology, Saint-Joseph University, Faculty of Dental Medicine, Beirut, Lebanon,Editorial Consultant, International Journal of Oral andMaxillofacial Implants, Clinical Oral Implant [email protected]

Joseph Bouserhal, Dr. Chir. Dent., Specialist Ortho., DURCO, Ling. Ortho. Dip., Dr. Sc. Dent., MWFO, MAAO,Professor and Former Chairperson, Department of Orthodontics, Saint-Joseph University Faculty of Dental Medicine, Beirut, Adjunct Clinical Professor of Orthodontics, Boston University Henry M. Goldman School of Dental Medicine, Boston, USAPast President, Lebanese Orthodontic Society, Beirut, Lebanon,Instructor, Tweed Foundation for Orthodontic Research, USA,Visiting Professor in Orthodontics, Beirut Arab University, Universities of Paris V and VII (France), Aristotle University of Thessaloniki (Greece), and Paul Sabatier University of Toulouse (France)[email protected]

Zoubeida Yahfoufi Al Hage, DDS, Dr. Dentistry, FITI,Assistant Professor, Department of Periodontology, Lebanese University, Faculty of Dental Medicine, Beirut, [email protected]

Maria E. Saadeh, BDS, MS (Human Morphology),Residency Orthod. AUB, Ph.DClinical Associate, Division of Orthodontics and DentofacialOrthopedics, American University of Beirut Medical Center,Lecturer, Department of Orthodontics,Lebanese University, Faculty of Dental Medicine, Beirut,[email protected]

M Fouad Ziadé, Ph.D Biostat., C. Stat., FRSS, MASA,MIEAAssociate Professor, Lebanese University, Faculty of PublicHealth, Beirut/Tripoli, [email protected] / [email protected]


5Journal of the Lebanese Dental AssociationVolume 52 - Nº 2 - July-December 2017

EditorialThe fluoride debate.

Ziad Noujeim

Human dental pulp stem cells conditioned medium for bone regeneration: A preliminary in vitro study.Batoul Chouaib, Frédéric Cuisinier, Elodie Middendorp, Pierre-Yves Collart-Dutilleul,

Preparation of curved and narrow canals with only one Reciproc Blue instrument. Ghassan Yared

Percutaneous radiofrequency thermocoagulation for trigeminal neuralgia: A retrospective case series study of 232 patients.

Joseph Maarrawi, Patrick Paul Tabet, Joe Faddoul, Sandra Kobaiter-Maarrawi, Sharon Weinberg, Elie Samaha

Management of atrophic mandible fractures: A mini-review and case series. Waleed Zaid

Antibiotic prescribing in dental practice: Problems and recommandations. Hala Jawad, Kayode Adelaja

Esthetic management of a dental trauma: A case report. Ramón Serrat Barón, Joan de Ribot Porta, Luís Jané Noblom, Akram Hussein Ali

Outcomes of increased occlusal vertical dimension on the stomatognathic system: A systematic review. Amine El Zoghbi, Ranim Abou Chakra, Lory Abrahamian, Ghina Daoud

Endodontic management of mandibular molars with three mesial root canals: Two case reports. Ziad Moujaes, Roula Abiad

A clinical report on two adjacent mandibular radicular cysts: Radiographic computed analysis, differential diagnosis, and surgical treatment.

Georges Aad, Elie Abdo, Alexandre Khairallah, Nabih Nader

Saliva as a potential tool for cancer diagnosis and prognosis: A clinical reminder and mini-review. Nisrine El Arrouf Bisbis, Souad Nechad

Semi-direct restoration as a potential alternative for endodontically-treated posterior teeth: A case report and mini-review.

Abbass El-Outa, Lara Nasr

Conventional semi-rigid frame and stress breaker designs on the same partial denture for a mandibular Kennedy Class I: A case report.

Naji Hayek, Ghassan Masri

JLDA Guide for contributors and authors

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The Fluoride Debate

IntroductionIn 1892, the importance of fluoride was emphasized by Sir James Crichton- Browne, a leading British psychiatrist,

neurologist, and medical psychologist, known for his studies on the development of public health policies in relation to mental health: Crichton-Browne intelligently suggested that fluoride missing from the husk parts of wheat should be reintroduced into the diet of child-bearing women and children in order to decrease the incidence of dental caries.

In 1901, Dr. Frederick McKay addressed the impact of water fluoridation by studying the so-called “Colorado stain” in children living in the Colorado Springs all their lives: the permanent stain on children’s teeth was called “mottled enamel”. In 1916, McKay and Dr. Greene Vardiman Black (one of the founders of modern dentistry and the father of operative dentistry) mapped the geographical area of the stain and discovered that 9 out of 10 children displayed permanent stain on their teeth.

In July 1933, FS McKay published a paper in the Journal of the American Dental Association-JADA- entitled “Mottled enamel: The Prevention of its Further Production Through a Change of the Water Supply at Oakley, Idaho, USA”; at that time, the McKay epidemiological studies clearly proved the relationship of the fluorine content of domestic water supply to the so-called “mottled enamel”, a disfiguring dental condition expressing chronic intoxication with fluorine.

In 1936, Henry Trendley Dean, a dentist working with the American Public Health Service, published a paper in the Journal of the American Medical Association -JAMA- on “Chronic Endemic Dental Fluorosis” ( known as “mottled enamel”); in this paper, the author addressed “the endemic hypoplasia of permanent teeth”, “a water borne disease associated with the ingestion of toxic amounts of fluorides in the water used for cooking and drinking during the period of calcification of the affected teeth”. According to Dean, “teeth affected with mottled enamel erupt showing a dull, chalky white appearance which in many instances later take on a characteristic brown stain, the frequency of brown stain increasing with age. In areas of marked severity, the surface of the teeth may in addition be marked by discrete or even confluent pitting”. “Mottled enamel” features hypomineralization of enamel caused by excessive fluoride ingestion during enamel formation, but apart from fluorosis, “mottled enamel” can be associated to tetracycline therapy, regional odontodysplasia, and amelogenesis imperfecta.

In June 1939, HT Dean and FS McKay addressed the “ Production of Mottled Enamel Halted by a Change in Common Water Supply” in the American Journal of Public Health: this unique epidemiological experiment tackled arresting the production of the endemic mottled enamel at Oakley-Idaho, Bauxite –Arkansas, and Andover-South Dakota, in the USA, by changing the common water supply from one containing toxic amounts of fluorides to one in which fluoride content does not exceed the permissible maximum, which is 1 part per million - ppm (the equivalent of 1 milligram per liter).

Ziad E.F.Noujeim,Editor-in-Chief, JLDA

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Harmful effects of excess fluoride were acknowledged by some medical organizations; on September 18,1943, one of the editorials of the JAMA addressed a special topic entitled “Chronic Fluorine Intoxication” in which it was stated that “apparently teeth require traces of fluorine for optimum dental health”: the paper stated also that “fluorides are general protoplasmic poisons, probably because of their capacity to modify the metabolism of cells by changing the permeability of the cell membrane and by inhibiting certain enzyme systems. The exact mechanism of such actions is obscure. The sources of fluorine intoxication are drinking water containing 1 ppm or more of fluorine,...”

Even though fluoride was added to U.S. public drinking in 1945, controversy on possible health hazards of drinking fluoridated water still remains 72 years later.

Fluoridation became an official policy of the American Public Health Service - PHS - in 1951, and in 1962, the PHS officially recommended to include fluoride (F) in public water supplies in order to prevent tooth decay: three types of fluoride were added to water systems, and they included sodium fluoride, sodium fluorosilicate, and fluorosilicic acid. Since that time, levels of fluoride became regulated by government agencies in America. The 1962 PHS recommendation stated that water supplies should contain between 0.7 mg and 1.2 mg of fluoride per liter (mg/L); this recommended value was updated in 2015 to a level of 0.7 mg/L, knowing that the maximum amount of F allowable in drinking water (as determined by the US environmental protection agency – EPA) was 4.0 mg/L.

To reach an optimal dental health, the World Health Organization -WHO- Expert Committee on Oral Health Status and Fluoride use recommended, in 1994, a fluoride level from 0.5 to 1.0 mg/L, depending on climate: the Committee stated that, “ Community water fluoridation is safe and cost-effective and should be introduced and maintained wherever it is socially acceptable and feasible. The optimum water fluoride concentration will normally be within the range of 0.5 ppm - 1.00 ppm”. Adverse effects may arise at fluoride levels above these recommended dosages.

Regarding water fluoridation, the USA Health and Human Services Department recommended, in 2011, a maximum of 0.7 mgs of fluoride per liter of water, 0.7 mgs being the lower limit of recommended range (at that time) of 0.7-1.2mgs.

Like many soluble materials, fluoride compounds are easily absorbed by stomach and intestines, and excreted in urine. According to RJ Baez and co-workers (2000) who studied urinary fluoride excretion by 4 to 6 -year-old school children in the American South Texas rural community that had concentrations of fluoride in drinking water supplies generally around the optimal level. Authors took supervised collections of urine samples in the morning and afternoon at school, and parents of participating students collected nocturnal samples. According to Baez and his team, “the data from this study will help in developing upper limits for urinary fluoride excretion that are appropriate for avoiding unsightly fluorosis while providing optimal protection against dental decay” (RJ Baez et al., 2000).

Does ingested fluoride significantly reduce dental decay? Is fluoride primary effect exclusively topical? Is fluoride level incorporated into dental mineral by systemic ingestion, sufficient to play a significant role in caries prevention?

Fluoride factsFluorides combine the element fluorine with a metal; such compounds may be sodium fluoride, stannous fluoride,

and monofluorophosphate. Fluoride is found in food and drinks (tea, coffee, shellfish, grapes such as raisins, wine, grape juice, artificial sweeteners, sodas, potatoes, flavored popsicles, baby foods, broths, stews, and hot cereals made with tap water) and if ingested, it will travel through bloodstream, ultimately tending to collect in high calcium areas such as teeth and bones.

During the late 1970s and early 1980s, we were taught at dental school that ingested fluoride incorporates into developing teeth enamel of children, rendering them more resistant to dental caries. At that time, the dental community worldwide was also convinced that topically applied fluorides would lead to an enamel surface rich in fluoroapatites that would obviously be more resistant to bacteria-produced acids that usually cause dental decay.

Dr. Paul Connett (a retired chemistry professor and executive director of the Fluoride Action Network - FAN) made a famous quote in which he stated that “ingesting fluoride for cavity prevention makes about as much sense as swallowing sun block to protect the skin from sunburn”. Indeed, it is well-known that, at low concentrations, F is safe

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for dental and general health, but sustained consumption of excessive amounts of soluble F salts can be hazardous, and even life-threatening.

In 1987, Brunelle and Carlos published the largest survey ever conducted in the USA. The study, commissioned by the National Institute of Dental Research – NIDR, looked at 39,000 children in 84 different communities; as a result, it was concluded that average difference in tooth decay in children aged 5-17 years who had lived all their lives in fluoridated versus non-fluoridated communities was not statistically significant. This large scale study used a specific index named DMFS (counting Decayed, Missing, and Filled Surface of teeth) and the difference was less than one half of one percent.

“Based on the overwhelming weight of peer-reviewed, credible scientific evidence, the American Dental Association (ADA) has long supported community water fluoridation as a safe, effective means of preventing tooth decay” (Brunelle and Carlos, NIDR fluoridation survey, 1987). Indeed, water fluoridation was addressed as a public health policy priority and many studies determined a so-called “optimal” level of fluoride in drinking water, which was 1 ppm, a level that resulted in decreased cavities incidence in children.

In 1996, another study, published in the Journal of Dental Research, addressed the estimation of caries prevalence in small areas; the study was conducted in Washington State (west coast of the USA), and it examined caries prevalence in only 3,000 third-grade children in 39 different state counties: statistical results were amazingly almost similar to those of Brunelle and Carlos study (1987), and authors reported that “this study did not find a statistically significant effect of water fluoridation”.

Between 2000 and 2001, the WHO collected data on tooth caries trends over the last several decades in 20 different countries: the organization found a significant decline in tooth caries in 12-year-old children since early 1970s; and what was stunning is that this decline was virtually similar in countries that were fluoridated, partially fluoridated, or totally non-fluoridated.

In 2017, the situation has changed drastically if we look at the science aspect rather than looking at “proclamations” and endorsements.

As a matter of fact, adverse health effects are more addressed nowadays than safety. Effectiveness of water fluoridation became debatable and controversial after the publication of peer-reviewed, broad-based, large-scale, epidemiological studies that showed “no substantial statistical difference between fluoridated and non-fluoridated communities” (PG Rubin, 2008).

At low concentrations, soluble fluoride salts are useful and safe but sustained consumption of excessive, large, amounts of soluble fluoride salts is dangerous for general health ; sodium fluoride (NaF), a common fluoride salt, could be lethal to adult humans if delivered at 32 to 64 mg/kg of body weight, the lethal dose for most adult humans was estimated at 5-10 grams ( RE Gosselin et al., 1984; RC Baselt, 2008; International Program on Chemical Safety-IPCS of the World Health Organization -IPCS/WHO, 2002). Gastro-intestinal discomfort and upset can result from fluoride ingestion at doses of 0.2 – 0.3 mg/kg or 10-15 mg for a 50-kg-person (D Bradford et al., 1994). Also, fluoride poisoning can arise after consumption of abnormally fluoride-rich ground water (F Pearce, 2006).

Acute toxicity of fluoride Acute fluoride toxicity often results from accidental ingestion of sodium fluoride- based rodenticides or insecticides

(G Nochimson, 2008); this toxicity can occur after accidental ingestion of dental fluoride products as well. Indeed, in 1991,WL Augenstein and co-workers published in the journal “Pediatrics” a review of 87 cases of fluoride ingestion in children: all reviewed cases of fluoride ingestion occurred in children younger than 12 years; these cases were reported to the Rocky Mountain Poison Center, in Denver, Colorado, USA, between January 1 and December 31, 1986. Eighty-four cases involved accidental ingestion of dental fluoride products in children aged 8 months to 6 years at their homes (tablets, drops, or rinses).Two older children (8 and 9 years old) became symptomatic after dentist’s fluoride treatment, and a 13-month-old child died after ingesting an unknown amount of sodium fluoride insecticide, the only insecticide exposure in these series. Among these children, 26 (30%) became symptomatic,


with 25 with gastro-intestinal symptoms (abdominal pain, nausea, vomiting, diarrhea) and drowsiness in one child. Only 3 children had symptoms later than one hour after ingestion. “Analysis of data from 70 cases with sufficient information revealed that as the amount of fluoride ingested increased, the percentage of patients with symptoms increased”. Excluding the fatal case, children who ingested up to 8.4mg/kg of elemental fluoride in dental products had mild and self-limited symptoms, mostly gastro-intestinal. All the 17 symptomatic cases had complete resolution of symptoms (12 of them within 3 hours of onset, 2 of them within 3 to 6 hours, and 3 within 6 to 24 hours) and most of children were treated at home.

In 1997, JD Shulman and LM Wells discussed, in the “Journal of Public Health Dentistry”, the problem of acute fluoride toxicity resulting from ingestion of home-use dental products in children, from birth to 6 years of age; in their study, authors reported that between 1990 and 1994, over 628 people-mostly children-experienced gastro-intestinal distress after ingestion of excessive amounts of flavored toothpaste. Indeed, these gastro-intestinal effects resulted from ingestion of too much fluoride-containing toothpaste. “The outcomes were generally not serious” but gastro-intestinal symptoms were the most common reported problem in Shulman and Wells study.

Chronic toxicity on bones Fluoridated water is linked to decreased levels of fractures in human populations (MS McDonagh et al., 2000), but

toxic levels of fluoride in drinking water are associated with bone weakening and increase in wrist and hip fractures (American National Research Council-NRC, Washington,DC-2006); the NRC concluded, at that time, that bone fractures may occur at 1-4mg/L fluoride levels.

According to Fred Pearce (2006), an English science writer and journalist reporting on the environment and development issues from 64 countries, chronic exposure to large amounts of fluoride certainly interferes with bone formation and fluoride poisoning results from consumption of “abnormally fluoride -rich ground water”. Indeed, skeletal fluorosis can occur after a long-term exposure to fluoride levels higher than 4.0 mg/L. Over 60 million people were poisoned in India after ingesting water “contaminated” by excessive fluoride, the fluoride being dissolved from the granite rocks; these harmful effects were obvious in children bone deformations. In this regard, similar effects were anticipated in other countries such as Ethiopia, Uzbekistan, and China.

Consumption of fluoride at levels beyond those normally used in fluoridated water for long periods of time can cause skeletal fluorosis that proves to be endemic in the Asian subcontinent; in 2007, R Gupta and associates published a paper in the Scandinavian Journal of Rheumatology in which they reported that early stages of skeletal fluorosis are not clinically obvious and may mimic seronegative rheumatoid arthritis or ankylosing spondylitis.

Chronic toxicity on kidneysToxic levels of serum fluoride results in fluoride –induced nephrotoxicity, a kidney injury commonly caused by

a release of fluoride from fluorine-containing drugs, such as methoxyflurane (known in the market as Penthrane and Penthrox ), a volatile inhalational anesthetic agent (MJ Cousins et al.,1983; JM Baden et al.,1982; RI Mazze,1976). Chronic ingestion of more than 12mg/day may cause serious adverse effects (USA National Research Council, 2006; J Baez et al., 2000); the resulting kidney injury features failure to concentrate urine, resulting in polyuria, and subsequent dehydration with hyperosmolarity and hypernatremia.

Fluoride –induced nephrotoxicity is dose-dependent and occurs when serum fluoride levels exceed 50 micromoles/L (about 1 ppm), provoking clinically significant renal dysfunction (MJ Cousins et al., 1976).

Effects of excess fluoride consumption on the brain: is fluoride a neurotoxin?In 2012, Choi, Sun, Zhang, and Grandjean published, in “Environmental Health Perspectives” journal (a reputable

journal supported by the U.S. National Institute of Environmental Health Sciences), a systematic review and meta-analysis on “Developmental Fluoride Neurotoxicity”. Authors investigated “the effects of increased fluoride exposure and delayed neurobehavioral development”. This position paper was led by author Philippe Adam Grandjean, a


Danish physician and renowned expert in developmental toxicity in children, head of environmental medicine unit at the University of Southern Denmark and Adjunct Professor of environmental health at the Harvard School of Public Health, in Boston, USA: authors identified 27 eligible epidemiological studies for their meta-analyses and concluded that “children who lived in areas with high-fluoride exposure had lower IQ scores than those who lived in low- exposure or control areas”. These findings were consistent with an earlier review (Tang et al., 2008). The results of Choi and associates study support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.In this leading paper, authors reported that high fluoride exposure may adversely affect children neurodevelopment but the evidence (at that time) was of insufficient quality to draw any firm conclusion: authors concluded that “future research should formally evaluate dose-response relations based on individual-level measures of exposure over time, including more precise prenatal exposure assessment and more extensive standardized measures of neurobehavioral performance, in addition to improving assessment and control of potential confounders” (Choi et al,2012).

In March 2014, one of the world’s prestigious medical journals, the “Lancet Neurology”, addressed fluoride as a “newly recognized developmental neurotoxicant”: this paper was written by authors Philippe Grandjean and Philip John Landrigan (an American epidemiologist and pediatrician, director of the Children’s Environmental Health Center-CEHC, in Denver, Colorado, USA, and Ethel Wise Professor and Chair of the Department of Preventive Medicine at Mount Sinai Medical Center in New York City, USA, and one of the world’s leading advocates on children’s health). Based only on Choi and associates paper (2012), Grandjean and Landrigan categorized fluoride as neurotoxicant: furthermore, they proposed a global prevention strategy for prevention from industrial chemicals identified as developmental neurotoxicants and control of the pandemic of developmental neurotoxicity.

The possible link between fluoride and cancerIn 1990, the U.S. National Toxicology Program (NTP) reported a study on male rats in which researchers found

“equivocal” evidence of osteosarcoma caused by fluoridated drinking: in this study, there was no such evidence of fluoride cancer-causing potential in female rats and male and female mice.

Much concern remains nowadays about fear from fluoride-caused osteosarcomas; more than 50 population-based studies inspected the potential link between cancer and water fluoride levels and most of them did not find a strong link.

Osteosarcoma is a very rare type of cancer; according to the American Cancer Society, around 400 cases only are diagnosed in children and teens each year in the USA, and this limited number of cases doesn’t allow scientists to conduct large studies. Unfortunately, small studies can usually detect big differences in cancer rates between 2 different groups but they are often unable to detect small differences. Consequently, if fluoride slightly increases the risk of cancer, these studies might not be able to detect this risk.

In 2006, the Harvard School of Public Health, in Boston, USA, published a partial report of a study in which researchers concluded that exposure to higher levels of fluoride in drinking water was linked to a higher risk of osteosarcoma in boys but not in girls; the second part of the study –published in 2011- did not appear to match the report’s results: indeed, this part compared fluoride levels in bones near tumors in people with osteosarcoma to those in patients with other types of bone tumors; researchers were not able to find a difference between fluoride levels in both groups.

Latest studies in England, Ireland, and USA compared osteosarcoma rates between areas with higher levels of fluoridation and those with lower levels: the studies were not able to find an obvious increased risk to develop osteosarcoma in areas with fluoridated water.

In 2010, the Scientific Committee on Health and Environmental Risks (SCHER) thoroughly studied and reviewed the evidence on risks of water fluoridation and concluded that evidence linking fluoridated water to cancer is “equivocal”: this European committee concluded therefore that “fluoride cannot be classified as to its carcinogenicity”.

In 2011, the state of California’s carcinogen Identification Committee (CIC) studied and reviewed the evidence; the committee concluded that “fluoride and its salts have not been clearly shown to cause cancer”.

11

It is clear and obvious that further studies and research are warranted in order to clarify the possible link between fluoride and cancer.

ConclusionIn 2017, safety and effectiveness of water fluoridation remain controversial in dentistry. Since the release of the

National Research Council - NRC report (NRC, 2006) in the USA, adverse effects of high fluoride concentrations in drinking water became a very serious concern worldwide. It is proven that fluoride may induce neurotoxicity in laboratory animals: effects on learning and memory were well documented (Chioca et al., 2008; Mullenix et al., 1995). The human developing brain is more susceptible to injury and damage induced by toxicants than is the mature brain, and fluoride exposure to the developing brain may possibly induce its permanent damage (Grandjean and Landrigan, 2006).

During the last 10 years, there have been many movements and efforts aiming to remove industrial sodium fluoride from the world’s water supply, with evidence provided against the additive from several sources worldwide.

Natural levels of fluoride in some places can be higher than 4mg/L, even without fluoridation and community water systems in such areas of the world should mandatorily lower the level of fluoride below the international acceptable standard.

In 2011 and in response to NRC recommendations (2006), the US Department of Health and Human Services-DHHS and the US Environmental Protection Agency - EPA - suggested to change the fluoride recommended level in drinking water to 0.7mg/L from the currently recommended range (at that time) of 0.7-1.2 mg/L. Also, the EPA reviewed (at that time) the maximum amount of fluoride allowed in drinking water which was set at 4.0 mg/L (U.S. EPA 2011).

The U.S. Centers for Disease Control and Prevention (CDC), a federal agency under the DHHS, in Atlanta, Georgia, already recommended that parents provide children under age of 6 years a pea-sized amount of toothpaste for brushing: parents should also make sure their children are not swallowing the paste, as this can be a significant source of fluoride. No-fluoride and low- fluoride toothpastes are also available on the markets.

Last but not least, and in order to reduce fluoride exposure, people have to know, in advance, the level of fluoride in their drinking water; also, people who live in areas where water contains naturally high levels of fluoride should seriously consider using alternate sources of drinking water, such as bottled water.

Ziad E.F. Noujeim, Editor-in Chief, JLDAwww.drziadnoujeim.com


12 Journal of the Lebanese Dental AssociationVolume 52 - Nº 2 - July-December 2017

The JLDA JULY-DECEMBER 2017 ISSUE

is

DEDICATED

to the MEMORY

of

SAMI CHARTOUNI(1940-2015)

Pioneer in Dentistry and Dental Education

- Assistant Professor, Department of Oral Pathology and Diagnosis,Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon, 2000-2013

- Lecturer and Clinical Tutor, Department of Oral Pathology and Diagnosis, Dental Section II, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon, 1985-2000

- President of the Lebanese Dental Association - LDA, 1994-1997

- President of Professional Syndicates Union in Lebanon, 1997

- "Oral Surgery Specialist", Lebanese Ministry of Public Health, 1996

- Oral Surgery training at Saint-Joseph University Dental School, Beirut, September 1969 to July 1971

- "Docteur en Chirurgie Dentaire", Ecole Dentaire de la Faculté Française de Médecine et de Pharmacie, Saint-Joseph University, Beirut, Lebanon, 1967

13

1. INTRODUCTIONBone tissue engineering after maxillofacial trauma

aims to provide new therapeutic solutions in the field of regenerative medicine to significantly improve facial reconstruction. Tissue engineering consists of associating a matrix with mesenchymal stem cells and bioactive molecules. Nevertheless, different difficulties

for this combined medical device (advanced therapy medicinal product) make it difficult to predict its possible marketing1. Studies have shown that the beneficial effects of different stem cell-based cellular therapy is actually due to the ability of these cells to secrete trophic factors that exert a positive impact on damaged tissues, rather than to their differentiation ability to transform into necessary cells2-3. Various studies on cell-derived secreted factors have shown that these secreted factors alone are sufficient to cause tissue repair, even without the use of stem cells4. These factors are found in the medium where stem cells are cultured. After centrifugation, the obtained medium, containing the secreted factors only, is called the conditioned medium (CM)5. The use of CM has

Human dental pulp stem cells conditioned medium for bone regeneration: A preliminary in vitro study.

Batoul Chouaib1, Dental Surgeon, MScFrédéric Cuisinier2, Dr. Chir. Dent., CES Perio, MS, DEA, Dr. Univ., HDR, PU, PHElodie Middendorp³, MScPierre-Yves Collart-Dutilleul⁴, Dr. Chir. Dent., DU Clin. Res., DU Cell Therapy, MS, Dr. Univ., PH

AbstractRegenerative medicine and tissue engineering use a combination of scaffold, stem cells, and bioactive molecules

to repair and restore the function of damaged tissues or organs. Secreted factors, alone without the stem cells themselves, may be sufficient to achieve regeneration. Such secreted factors can be collected in the medium where stem cells are cultured; this recovered supernatant is called conditioned medium. Stem cell-derived conditioned medium has a promising prospect to be produced as pharmaceuticals for regenerative medicine, as it avoids the legislative barriers linked to clinical stem cell use.

This preliminary study was conducted to test the in vitro influence of human dental pulp stem cells conditioned medium (hDPSC-CM) on osteoblast proliferation, maturation, and mineralization. MG-63 osteoblast cells were studied in presence and absence of 50% hDPSC-CM over a period of 3 weeks. Cell proliferation was assessed by cell counts during the first three days of culture. Specific bone cell markers: alkaline phosphatase (ALP), type I collagen (Col), and osteocalcin (OC), were studied by immunostaining and mineralization was evaluated by histological staining (alizarin red).

During the initial culture steps, hDPSC-CM significantly increased osteoblast proliferation. hDPSC-CM also enhanced osteoblast maturation and further mineralization. Immunostaining of bone mineralization markers (ALP, OC, and Col) tended to show an increased maturation of osteoblast in presence of hDPSC-CM. Calcium deposits stained by alizarin red after 3 weeks were also more abundant when osteoblasts were cultured in hDPSC-CM.

This study provides encouraging preliminary data about positive influence of hDPSC-CM on osteoblast proliferation, maturation, and mineralization, confirming its potential role for bone regeneration.

1. Doctoral student in tissue engineering. 2. Director of LBN Laboratory, Professor, and Vice-Dean of research, UFR d'Odontologie, University of Montpellier, Montpellier, France.3. Laboratory technician. 4. Head of Bioengineering team of LBN and Associate Professor, UFR d'Odontologie, University of Montpellier, Montpellier, France.1,2,3,4 Laboratory of Bioengineering and Nanoscience - LBN, University of Montpellier, Montpellier, France.

Dental Research



* αMEM = Minimum Essential Medium Eagle-alpha modification (Alpha MEM) with nucleosides.

several advantages over the use of stem cells; it can be manufactured, lyophilized, packaged and transported easily. Furthermore, since it is cell-free, there is no need to match the donor and the recipient to avoid rejection problems6. In addition, its use could be a viable alternative to stem cell transplantation, which is often hampered by low efficacy and its carcinogenic potential after grafting. For all these reasons, many teams are currently focusing on the use of CM.

In this study, our aim was to evaluate the influence of conditioned medium derived from human dental pulp stem cells (hDPSC-CM) on proliferation, maturation, and further mineralization of human MG-63 osteoblast-like osteosarcoma cells.

Osteosarcomas are malignant bone tumors and osteosarcoma-derived cells are commonly used for osteoblastic models. "MG-63 osteoblast-like osteosarcoma cells" is one of the osteossarcoma cell lines used in research.

2. MATERIALS AND METHODS2.1 Isolation and culture of dental pulp cells -DPSCs

Human impacted third molars extracted for orthodontic reasons were recovered from healthy patients (15−18 years of age). Written informed consents were obtained from patients' parents. The present protocol was approved by the local ethical committee (Comité de Protection des Personnes, Montpellier Hospital, France). Dental pulp stem cells were recovered as previously described7. Briefly, teeth were disinfected with chlorhexidine and dissected with a piezotome at the cementoenamel junction. Under sterile conditions, pulp tissues were gently separated from crown and root. Pulps were submitted to enzymatic digestion in a collagenase-dispase solution (3 mg/ml collagenase and 4 mg/ml dispase) that hydrolyzed the tissue structure proteins and allowed the collection of pulp cells only. After one hour of incubation, the solution was immersed in αMEM* supplemented with 10% fetal bovine serum (FBS), 100 U/ml penicillin, 100 μg/ml streptomycin and filtered through 70 μm Falcon cell strainers. Culture medium was changed after 24 hours to remove non-adherent cells and later twice a week. Cells were passed when they reached 90% confluence.

2.2 DPSC CharacterizationSubconfluent cells were collected and analyzed for

minimal criteria to define human mesenchymal stem cells, such as adherence to plastic, expression of cell surface antigens, and the ability to differentiate into osteoblasts, adipocytes, and chondroblasts in vitro8. Antigen profiles of cultured DPSCs were analyzed by detecting the expression of the cell surface markers CD90, CD146, CD117, and CD45 (Fig. 1C) using flow cytometry (all antibodies were provided by Miltenyi Biotec, Paris, France).

2.3 Preparation of hDPSC-CM At the fourth passage, cells were divided in 75

cm² flasks with conventional culture medium. At 70% confluence (Fig. 1A), the medium was removed from each flask and cells washed with phosphate-buffered saline (PBS) twice, then 10 ml of fresh (serum-free) medium were added. After 48 hours, the medium was collected having DPSC-secreted factors (the conditioned medium); it was later submitted to centrifugation at 1500 rpm for 5 minutes, then at 3000 rpm for 3 minutes. Supernatant was collected after each centrifugation. The conditioned media were used directly.

2.4 Culture of osteoblastsMG-63 osteoblast-like osteosarcoma cells were

obtained from the European collection of cell cultures. Frozen ampoules were transferred to the 37 °C water bath for 1 to 2 minutes. The contents were transported by pipette into a 75 cm² flask containing 12 ml of the culture medium. The conventional culture medium of MG-63 is composed of Eagle’s minimal essential medium (Sigma-Aldrich), 1% glutamine, 1% non-essential amino acids (Sigma-Aldrich), 1% penicillin-streptomycin (PS) and 10 % fetal bovine serum (FBS). After 2 days, MG-63 were confluent, they were then passed and used (Fig. 1B).

2.5 Proliferation of MG-63 cells In order to test the proliferation of MG-63 cells,

they were transferred into plates at a density of 50,000 cells/well, in the presence of: (1) 50% of conventional MG-63 culture medium + 50% hDPSC-CM, (2) 50% conventional MG-63 culture medium with 10% FBS


Fig. 1. Images of (A) Human dental pulp stem cells, reaching 70% of confluence and (B) MG-63 in culture, observed under phase contrast microscopy with 32× and 20× magnification respectively. Scale bar: 100 μm. (C) Flow cytometry analysis of subconfluent dental pulp cells. Single-parameter histograms showing the expression of markers CD 45, CD 146, CD 90, and CD 117.

Fig. 2. Cell counts after 24 hours, 48 hours, and 72 hours of incubation with or without 50% hDPSC-CM. Cells counted on areas measuring 2362×1325 μm. Experiment made in triplicate, with 13 measurements per sample. ***p <0.001.

Fig. 3. The effect of DPSC-CM on the formation of ALP positive cells after 10 days, the mineralization of col and the formation of OC after 21 days in MG-63 cultures. Image analysis was performed by measuring the area covered by ALP, Col and OC positive cells from 2 replicate cover slips for each one. When compared to the control, the p values were 0.333, 0.333 and 1 with 50% DPSC-CM for ALP, Col, and OC respectively.


+ 50% alpha-MEM without serum (to have the same percentage of FBS in both samples). Cells were counted after 24 hours, 48 hours, and 72 hours of incubation: cells were fixed with 4% paraformaldehyde and stained with DAPI** (to stain nuclei). Experiments were made in triplicate, with 13 measurements per sample in attempt to cover the surface. Images were taken by an epi-fluorescence microscope, at 10x magnification and analyzed with ImageJ software (National Institutes of Health -NIH, Bethesda, Maryland, USA). Results were presented as mean ± standard deviation, with the error bar representing standard deviation.

2.6 Alkaline phosphatase (ALP), type I collagen (Col), and osteocalcin (OC) staining

For ALP evaluation, 200,000 cells/well were cultured in a 6-well plate under the same conditions (1) and (2) monitored for multiplication. At day 9, immunohistochemical analysis was performed. For OC and collagen, osteoblasts were transferred into glass petri dish at a density of 200,000 cells / petri dish in the presence of: (3) 50% classical MG-63 culture medium +50% hDPSC-CM +5Mm β-glycerophosphate calcium, (4) 50% conventional MG-63 culture medium with only 5% FBS + 50% DPSC conventional culture medium with only 5% FBS + 5Mm β-glycerophosphate calcium. A 50% proportion of hDPSC-CM was chosen similarly, as for the proliferation tests. β-glycerophosphate calcium was added to help MG-63 mineralization induction. Immunocytochemistry was tested after 21 days. Experiments were conducted in duplicate.

Osteoblasts MG-63 were fixed with paraformaldehyde 4%, rinsed with PBS, and covered with blocking buffer solution (BSA 1% + 0.3% Triton X-100) at room temperature overnight. Later on, they were incubated for one hour at room temperature with conjugated antibodies (for ALP, collagen, OC) diluted 1:100 in a blocking buffer solution. Images were taken by an epi-fluorescence microscope, at 10x magnification and analyzed with ImageJ by measuring the area covered by ALP, Col, and OC positive cells. Results were presented as mean ± standard deviation, with error bar representing standard deviation.

2.7 Alizarin red stainingA total of 100,000 cells/well were seeded in 24

well plates under the same conditions as for OC and collagen. After 21 days, cells were rinsed with PBS and fixed with 95% ethanol for 30 minutes at room temperature. Then, they were washed with water twice and incubated with a 2% alizarin red solution at a pH between 4.1 and 4.3 for 5 minutes. They were then rinsed 5 times with distilled water and observed rapidly. Experiments were conducted in triplicate.

2.8 Statistical analysisStatistical analyses were performed using SigmaStat

software (SigmaStat 4.0, Systat Software Inc., Chicago, Illinois, USA). Normality was tested by Shapiro-Wilk test. Then, depending on it, we performed either Student t-test or non-parametric Mann-Whitney test.

The data of cell proliferation at 24 and 48 hours were compared with Student t-test. Those at 72 hours were compared with Mann-Whitney test, as the normality test was failed. The Mann-Whitney test was used also to compare the data of ALP activity, collagen, and OC expression.

Quantitative data were expressed as mean ± SD. A p-value less than 0.05 was considered to be statistically significant.

3. RESULTS3.1 hDPSC-CM stimulates osteoblast MG-63 proliferation

Any significant difference was observed, at 24 hours, among samples with or without hDPSC-CM. After that, the hDPSC-CM increased significantly (***p<0.001) the number of MG-63 cells compared to the control (63.7 ± 25.4 vs. 40.3 ± 22.8 cells) at 48 hours and (122.1 ± 38.2 vs. 71.6 ± 46) at 72 hours (Fig. 2).

3.2 hDPSC-CM enhances insignificantly MG-63 ALP, Col, and OC expressions

The ALP and OC amount increased with hDPSC-CM (0.02 ± 0.01 vs. 0.01 ± 0.001 control and 0.0019 ± 0.02 with hDPSC-CM vs. 0.006 ± 0.006 control respectively), and the non-mineralized collagen decreased (0.002 ± 0.0003 with hDPSC-CM vs. 0.005 ± 6.95E-05 control), but both evolutions were not significant compared to the control (Fig. 3).

** DAPI (4', 6-diamidino-2-phenylindole) is a fluorescent stain that strongly binds to A-T rich regions in DNA. This stain is extensively used in fluorescence microscopy.


3.3 hDPSC-CM increases stained calcium nodulesCalcium nodules stained with red alizarin were

more numerous with hDPSC-CM (Figs. 4A, B). The same aspect of DAPI images shows a similar level of cell number in both samples (Figs. 4C, D).

4. DISCUSSIONMany research teams have already studied the

influence of conditioned medium on osteoblast differentiation; the majority of them used the CM from bone marrow mesenchymal stem cells (MSCs): only few researchers used the DPSC-CM. Differentiation of MSCs into osteoblasts is studied the most, and differentiation and mineralization need further investigations on true osteoblasts.

Conclusions of previous studies were contradictory: Santos and co-workers10 (2015) have shown that MSC-CM decreased the proliferation and the differentiation of MSCs10. Osugi and associates11 (2012) and Katagiri and co-workers13 (2016) have demonstrated that MSC-CM enhances MSC migration, proliferation, and differentiation into osteoblasts; in another study14,

Katagiri and associates (2015) proved that conditioned medium from MSCs enhances early bone regeneration after maxillary sinus floor elevation in rabbits. Sun and associates15 (2012) showed that MSC-CM transiently retards proliferation and differentiation of primary osteoblasts by downregulating RUNX2 (Runt-related transcription factor 2), a key transcription factor associated with osteoblast differentiation. On the other hand, Fujio and co-workers16 (2015) have demonstrated that hypoxic DPSC-CM promotes bone healing during distraction osteogenesis, but their findings were just dependent on angiogenesis because they found that hDPSC-CM did not enhance mineralization in vitro.

In the present study, the effect of the conditioned medium derived from human DPSCs was tested on the proliferation and the mineralization of human MG-63 osteoblast-like osteosarcoma cells.

The development of the bone cell phenotype progresses from a proliferating cell to a mature osteocyte in a mineralized type I collagen extracellular matrix. The temporal sequence of osteoblasts gene expression has defined three distinct phases: growth

Fig.5. Reciprocal and functionally coupled relationship between cell growth (prolifera-tion, matrix production, and mineralization) and differentiation-related gene expression (ALP, Col, and OC).

Fig.4. Calcium nodules (in brown) formed after 21 days in the presence (A) or no (B) of 50% hDPSC-CM, stained with red alizarin and observed under light microscope with 10× magnification. Corresponding DAPI staining images of cells growing with (C) or without (D) hDPSC-CM show the same compact MG-63 layer. Scale bar=200 μm.


proliferation, extracellular matrix maturation, and extracellular matrix mineralization9 (Fig. 5).

Matrix maturation phase is characterized by maximal expression of alkaline phosphatase. ALP is an osteoblast-secreted enzyme present in high levels at sites of bone mineralization; it is involved in the mineralization process by hydrolyzing organic phosphates to release free inorganic phosphate17 which, after accumulating later with Ca2+, induces the formation of hydroxyapatite (HA)18.

Furthermore, genes for proteins, such as osteocalcin (OC), bone sialoprotein (BSP), and osteopontin (OPN), are expressed at the beginning of matrix mineralization, and once mineralization is completed, calcium deposition can be visualized using adequate staining methods. Analysis of bone cell-specific markers like ALP, OC, and collagen type I or detection of functional mineralization, is frequently used to characterize osteoblasts in vitro19.

In the present study, the effect of DPSC-CM was tested on these 3 phases of differentiation of MG-63. Matrix maturation and mineralization were studied by evaluating ALP, non-mineralized collagen type I, and OC amount, and by assessing the calcification with red alizarin staining. The secretion of ALP increases with the effectiveness of hDPSC-CM and matrix is mainly composed of mineralized collagen with smaller but significant amounts of OC. A 50% proportion of hDPSC-CM was chosen as the mean value for testing its effect.

Our results showed that the hDPSC-CM promotes the MG-63 proliferation significantly more than the conventional medium αMEM; its influence on matrix maturation and mineralization is not yet clear. ALP and OC amounts increased with hDPSC-CM and non-mineralized collagen decreased, but non-significantly compared to the control. However, when calcification of matrix was assayed by the measurement of deposited calcium, calcium nodules stained with red alizarin were more numerous with hDPSC-CM. Microscopic images were very clear showing higher frequency of calcium nodules in presence of hDPSC-CM and nearly the same cell number in both samples.

5. CONCLUSION The role played by paracrine factors produced by

stem cells in tissue regeneration and healing has been

investigated and many reports have demonstrated that osteogenesis is promoted by conditioned medium (CM) collected from bone marrow mesenchymal stem cells. In this study, we suggest, for the first time, the possible role of hDPSC-CM in the osteogenesis process. Our results indicate that hDPSC-CM promotes osteoblast proliferation. Further studies are warranted in order to confirm its positive effect on bone regeneration.

Conflict of Interest Disclosure StatementThe authors affirm that they have no financial

affiliation (employment, honoraria, direct payment, stock ownership, consultantships, patent licensing arrangements) or involvement with any commercial organization or corporation, with any direct financial or economic interest in the subject or materials discussed in this manuscript. Any other potential conflict of interest is disclosed.

Acknowledgements:Lebanese University Faculty of Dental Medicine

(Beirut, Lebanon) is acknowledged for awarding a scholarship to Batoul Chouaib.

REFERENCES1. Collart-Dutilleul P-Y, Chaubron F, De Vos J, Cuisinier FJ. Allogenic banking of dental pulp stem cells for innovative therapeutics. World J Stem Cells 2015; 7(7): 1010-1021.2. Yang D, Wang W, Li L, Peng Y, Chen P, Huang H, et al. The relative contribution of paracine effect versus direct differentiation on adipose-derived stem cell transplantation mediated cardiac repair. PloS One 2013; 8(3): e59020.3. Ghannam S, Bouffi C, Djouad F, Jorgensen C, Noel D. Immunosuppression by mesenchymal stem cells: mechanisms and clinical applications. Stem Cell Res Ther 2010; 1(1): 22-29.4. Alves da Silva ML, Costa-Pinto AR, Martins A, Correlo VM, Sol P, Bhattacharya M, et al. Conditioned medium as a strategy for human stem cells chondrogenic differentiation. J Tissue Eng Regen Med 2015; 9(6):714-723.5. Kim HO, Choi SM, Kim SH. Mesenchymal stem cell-derived secretome and microvesicles as a cell-free therapeutics for neurodegenerative disorders. J Tissue Eng Regen Med 2013; 10(3): 93-101.6. Pawitan JA. Prospect of stem cell conditioned medium in regenerative medicine. BioMed Res Int 2014; 2014: 1-14.7. Collart-Dutilleul P-Y, Secret E, Panayotov I, Deville de Périère D, Martin-Palma RJ, Torres-Costa V, et al. Adhesion and proliferation of human mesenchymal stem cells from dental pulp on porous silicon scaffolds. ACS Appl Mater Interfaces 2014; 6(3):1719-1728.


8. Collart-Dutilleul P-Y, Panayotov I, Secret E, Cunin F, Gergely C, Cuisinier F, et al. Initial stem cell adhesion on porous silicon surface: molecular architecture of actin cytoskeleton and filopodial growth. Nanoscale Res Lett Springer 2014; 9(1): 564-574.9. Stein GS, Lian JB. Molecular Mechanisms Mediating Proliferation/Differentiation Interrelationships During Progressive Development of the Osteoblast Phenotype. Endocr Rev 2008; 14(4): 424-442.10. Santos TS, Abuna RPF, Castro Raucci LMS, Teixeira LN, de Oliveira PT, Beloti MM, et al. Mesenchymal stem cells repress osteoblast differentiation under osteogenic‐inducing conditions. J Cell Biochem 2015; 116(12): 2896-2902.11. Osugi M, Katagiri W, Yoshimi R, Inukai T, Hibi H, Ueda M. Conditioned media from mesenchymal stem cells enhanced bone regeneration in rat calvarial bone defects. Tissue Eng Part A 2012; 18(13-14): 1479-1489.12. Katagiri W, Osugi M, Kawai T, Ueda M. Novel cell-free regeneration of bone using stem cell-derived growth factors. Int J Oral Maxillofac Implant 2013; 28(4): 1009-1016.13. Katagiri W, Osugi M, Kawai T, Hibi H. First-in-human study and clinical case reports of the alveolar bone regeneration with the secretome from human mesenchymal stem cells. Head Face Med 2016; 12(5): 1-10.14. Katagiri W, Osugi M, Kinoshita K, Hibi H. Conditioned medium from mesenchymal stem cells enhances early bone regeneration after maxillary sinus floor elevation in rabbits. Implant Dent 2015; 24(6): 657-663.15. Sun J, Zhou H, Deng Y, Zhang Y, Gu P, Ge S, et al. Conditioned medium from bone marrow mesenchymal stem cells transiently retards osteoblast differentiation by downregulating runx2. Cells Tissues Organs 2012; 196(6): 510-522.16. Fujio M, Xing Z, Sharabi N, Xue Y, Yamamoto A, Hibi H, et al. Conditioned media from hypoxic‐cultured human dental pulp cells promotes bone healing during distraction osteogenesis. J Tissue Eng Regen Med 2015.17. Bellows CG, Aubin JE, Heersche JNM. Initiation and progression of mineralization of bone nodules formed in vitro: the role of alkaline phosphatase and organic phosphate. Bone Mineral Res 1991; 14(1): 27-40.18. Balcerzak M, Hamade E, Zhang L, Pikula S, Azzar G, Radisson J, et al. The roles of annexins and alkaline phosphatase in mineralization process. Acta Biochim Pol 2003; 50(4): 1019-1038.19. Kasperk C, Wergedal J, Strong D, Farley J, Wangerin K, Gropp H, et al. Human bone cell phenotypes differ depending on their skeletal site of origin. J Clin Endocrinol Metab 1995; 80(8): 2511-2517.

Corresponding author:Batoul [email protected]

21

INTRODUCTIONThe Reciproc® instruments (VDW, Munich,

Germany) were developed according to the concept of canal preparation using only one Ni-Ti rotary instrument1. The manufacturer claimed that Reciproc instruments do not require the creation of a glide path for the majority of canals including second mesio-buccal canals in maxillary molars. These claims were later confirmed in different studies. 2-4

The Reciproc® Blue (VDW, Munich, Germany) endodontic instruments are a new generation of reciprocating instruments. They are made from a thermally treated nickel-titanium wire which gives the file a blue color and offers greater flexibility and resistance to fatigue, in comparison with the traditional nickel-titanium M-wire.5-8

The purpose of this article is to describe the use of the Reciproc® Blue size 25 (R25B®) instrument (Fig. 1) in an asymmetric reciprocation movement for the preparation of narrow and / or curved canals, including second mesio-buccal canals in maxillary molars, without any prior instrumentation and without a glide path. The limitations of this technique and the need to

create a glide path will also be addressed.The R25B instrument has an S-shaped cross section,

2 cutting edges, and a non-cutting tip similar to the traditional Reciproc instrument. It has a diameter of 0.25 mm at the tip and an 8% taper (0.8 mm/mm) taper over the first 3 mm from the tip. The diameter at D16 is 1.05 mm.

The R25B can be used in conjunction with different reciprocating devices (Fig. 2). The reciprocating air-driven contra-angle (Direct, VDW, Munich, Germany) offers two benefits: increased fatigue resistance of the Reciproc Blue instruments used with it9 and lower cost compared to a reciprocating motor used with a 6:1 reduction ratio. The reciprocating air-driven contra-angle is programmed with the angles of reciprocation and speed for this instrument. The values of the forward and reverse reciprocating angles are unequal, the forward angle being greater than the reverse angle. When the instrument rotates in the forward cutting direction, it will advance in the canal and engage dentine to cut it. When it rotates in the opposite reverse direction, the instrument will be immediately disengaged. The forward angle of rotation being larger than the reverse angle of rotation, the end result is an advancement of the instrument in the canal. Consequently, only light

Preparation of curved and narrow canals with only one Reciproc® Blue instrument.Ghassan Yared*, Dr. Chir. Dent., Dr. Sc. Odont., FRCD (Canada), MCAE, MAAE

AbstractIn 2008, the concept of canal preparation with a single mechanical file used in reciprocation with unequal forward

and reverse angles and without a glide path was introduced in the International Endodontic Journal. The present article describes the use of only one mechanical instrument in asymmetric reciprocation for the preparation of narrow and curved canals without any prior instrumentation and without the creation of a glide path. The need to create a glide path in specific clinical situations will also be discussed.

* Endodontist, Toronto, CanadaFormer Assistant Professor of Endodontics, Lebanese University Faculty of Dental Medicine, Beirut, Lebanon,Former Tenured Professor of Endodontics, University of Toronto Faculty of Dentistry, Toronto, Canada Fig 1. The R25 blue instrument.

Endodontics



pressure should be applied on the instrument. Forward and reverse angles determine the

amplitude of reciprocation. These set angles are lower than the elastic limit angles of the instruments10 and, consequently, lower than the angles at which the R25B instrument would fracture if bound. Even if the reciprocating instrument binds in the canal, it will not rotate past its specific fracture angle. For this reason, a glide path is not required prior to using the R25B instrument. On the other hand, during the use of a rotary instrument, the tip of the instrument may bind in the canal; the motor will then keep rotating the instrument while its tip is bound.11,12 The instrument will rotate past its plastic limit and will eventually fracture. For this reason, it is necessary to create a glide path before using continuous rotary nickel-titanium (NiTi) instruments. The glide path will minimize the incidence of instrument binding and, therefore, minimize the risk of fracture.13-15

TECHNIQUEIn the majority of narrow and / or curved canals

(Fig. 3) including MB2 canals (Fig. 4), only one R25B instrument is used in an asymmetric reciprocation movement to complete the canal preparation without any prior hand filing and without a glide path.

The access cavity guidelines, the straight-line access to canals, and the irrigation protocol are the same as for standard preparation techniques.

Before initiating preparation, the root canal's length is estimated with the help of an adequately exposed and angulated pre-operative radiograph. The silicone

Fig. 3. First maxillary molar with calcified canals prepared with only one R25 Blue instrument without any prior instrumentation and without the creation of a glide path.

Fig 2. Top: VDW Direct air-driven reciprocating angle. Middle: VDW Gold reciprocating motor. Bottom: VDW Connect Drive reciprocating motor.


stopper is set on the R25B instrument at two thirds of that length. The R25B instrument is introduced in the canal with a slow in- and out- pecking motion without pulling the instrument completely out of the canal. The amplitude of the in- and out-movements should not exceed 3-4 mm. Only light pressure should be applied. The instrument will advance easily in the canal. After 3 in- and out-movements, the instrument is pulled out of the canal to clean its flutes. A size 08 or 10 stainless steel hand file is used to check patency to two thirds of the estimated working length. The canal is copiously irrigated. The R25B is used in this manner followed by a patency check and irrigation until it reaches two thirds of the estimated length as indicated by the stopper on the instrument. The instrument is then removed from the canal, the canal is irrigated, and a #10 file is used

to determine the working length with the aid of a radiograph and / or an apex locator. The R25B is then re-used as described above until it reaches the working length.

The increased flexibility and fatigue resistance of the R25B allow its safe use in clinical situations with difficult access to the tooth such as a limited mouth opening (Fig. 5).

Glide pathThe R-Pilot (VDW, Munich, Germany) is a

reciprocating glide path instrument made from nickel-titanium (Fig. 6). It has an S-shaped cross section similar to the R25B. It has a diameter of 12.5 mm at its tip and a constant taper of 0.04 mm/mm. The R-Pilot is used in the same air-driven reciprocating contra-angle

Fig. 4. First and second maxillary molar prepared with only one R25 blue instrument. The canals were very calcified and invisible on the pre-operative radiograph. The first maxillary molar had a curved MB2 canal.


at the same settings of the R25B instrument. The R-Pilot reciprocating glide path instrument

has higher fatigue resistance than rotating glide path instruments.16-19 A glide path may have to be created with the R-Pilot in some canals when the R25B stops from advancing in the canal or if the advancement becomes difficult. In this situation, pressure should not be exerted on the R25B instrument. The instrument

is removed from the canal and the canal is copiously irrigated. A size 08 or 10 stainless steel hand file is placed in the canal to the working length and used with a filing motion or a watch-winding motion at that length until it becomes loose in the canal (i.e. when it is possible to move it freely 4-5 mm up and down). The R-Pilot instrument is then used to create a glide path. When the R-Pilot reaches the working length, the

Fig. 5. Difficult access to a first mandibular molar due to a limited mouth opening (Courtesy of Dr. Thodoris Mandas, Greece). The increased flexibility and fatigue resistance of the R25 Blue instrument in conjunction with an asymmetric reciprocating movement allow a safe canal preparation with only one instrument without any prior instrumentation and without the creation of a glide path. Top left: pre-operative radiograph. Top right: limited mouth opening. Bottom left: bent R25 blue instrument. Bottom right: post-operative radiograph.

Fig. 6. R-Pilot VDW reciprocating glide path instrument.


R25B is re-used in the canal until the preparation is complete.

It is also possible to create a glide path at the start of the root canal preparation procedure, prior to using the R25B.

CONCLUSIONSThis article discusses the use of only one R25B

instrument in an asymmetric reciprocation movement without a glide path to completely prepare narrow and / or curved canals including second mesio-buccal canals in maxillary molars. This clinical procedure is implemented with an inexpensive and safe air-driven reciprocating contra-angle. Indirect evidence supports the impression that the R25B is as safe and as efficient as the R25 M-wire instrument in the preparation of those canals without any prior instrumentation.20-25

The R-Pilot reciprocating glide path instrument can be safely used to create a glide path when required. Its physical properties are better than those of the rotary glide path instruments.

REFERENCES1. Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. Int Endod J 2008;41:85-90.2. Zuolo ML, Carvalho MC, De-Deus G. Negotiability of Second Mesiobuccal Canals in Maxillary Molars Using a Reciprocating System. J Endod 2015;41:1913-1917.3. Rodrigues E, De-Deus G, Souza E, Silva EJ. Safe Mechanical Preparation with Reciprocation Movement without Glide Path Creation: Result from a Pool of 673 Root Canals. Braz Dent J 2016;27:22-27.4. Bartols A, Robra B-P, Walther W. The ability of Reciproc instruments to reach full working length without glide path preparation: a clinical retrospective study. Peer J 2017 July 19; 5:e3583. 5. Topçuoğlu HS, Topçuoğlu G. Cyclic Fatigue Resistance of Reciproc Blue and Reciproc Files in an S-shaped Canal. J Endod 2017 Oct;43(10):1679-1682.6. Keskin C, Inan U, Demiral M, Keleş A. Cyclic Fatigue Resistance of Reciproc Blue, Reciproc, and WaveOne Gold Reciprocating Instruments. J Endod 2017 Aug;43(8):1360-1363.7. De-Deus G, Silva EJ, Vieira VT, et al. Blue thermomechanical treatment optimizes fatigue resistance and flexibility of the Reciproc files. J Endod 2017 Mar;43(3):462-466.8. De-Deus G, Belladonna FG, Zuolo AS, et al. Effectiveness of Reciproc Blue in removing canal filling material and regaining apical patency. Int Endod J 2018 [Epub ahead of print].

9. Silva EJNL, Vieira VTL, Gabina TTG, et al. The impact of using a pneumatic contra-angle device on the lifespan of M-Wire- and Blue-treated instruments. Clin Oral Investig 2018 [Epub ahead of print].10. Ha JH, De-Deus G, Versluis A, Kwak SW, Kim HC. Safe pseudo-elastic limit range under torsional loading with Reciproc Blue. Int Endod J 2018 [Epub ahead of print].11. Yared G, Kulkarni GK. Accuracy of the Nouvag torque control motor for nickel-titanium rotary instruments. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004 Apr;97(4):499-501.12. Yared G, Kulkarni GK. Accuracy of the DTC torque control motor for nickel-titanium rotary instruments. Int Endod J 2004 Jun;37(6):399-402.13. Peters O, Peters I, Schonenberger K, Barbakow F. ProTaper rotary root canal preparation: assessment of torque and force in relation to canal anatomy. Int Endod J 2003;36:93-99. 14. Yared G. In vitro study of the torsional properties of new and used ProFile nickel titanium rotary files. J Endod 2004 Jun;30(6):410-412.15. Patiño PV, Biedma BM, Liébana CR, Cantatore G, Bahillo JG. The influence of a manual glide path on the separation rate of NiTi rotary instruments. J Endod 2005 Feb;31(2):114-116.16. Keskin C, İnan U, Demiral M, Keleş A. Cyclic fatigue resistance of R-Pilot, WaveOne Gold Glider, and ProGlider glide path instruments. Clin Oral Investig 2018 [Epub ahead of print].17. Uslu G, Özyürek T, Yılmaz K, Gündoğar M. Cyclic fatigue resistance of R-Pilot, HyFlex EDM and PathFile nickel-titanium glide path files in artificial canals with double (S-shaped) curvature. Int Endod J 2018 [Epub ahead of print]. 18. Serefoglu B, Kaval ME, Micoogullari Kurt S, Çalişkan MK. Cyclic Fatigue Resistance of Novel Glide Path Instruments with Different Alloy Properties and Kinematics. J Endod 2018 [Epub ahead of print].19. Yılmaz K, Uslu G, Gündoğar M, Özyürek T, Grande NM, Plotino G. Cyclic fatigue resistances of several nickel-titanium glide path rotary and reciprocating instruments at body temperature. Int Endod J 2018 [Epub ahead of print].20. Topçuoğlu HS, Demirbuga S, Düzgün S, Topçuoğlu G. Cyclic fatigue resistance of new reciprocating files (Reciproc Blue, WaveOne Gold, and SmartTrack) in two different curved canals. J Investig Clin Dent 2018 [Epub ahead of print].21. Özyürek T, Uslu G, Yılmaz K, Gündoğar M. Effect of Glide Path Creating on Cyclic Fatigue Resistance of Reciproc and Reciproc Blue Nickel-titanium Files: A Laboratory Study. J Endod 2018 [Epub ahead of print].22. Belladonna FG, Carvalho MS, Cavalcante DM, Fernandes JT, de Carvalho Maciel AC, Oliveira HE, Lopes RT, Silva EJNL, De-Deus G. Micro-computed Tomography Shaping Ability Assessment of the New Blue Thermal Treated Reciproc Instrument. J Endod 2018 [Epub ahead of print].23. Bürklein S, Flüch S, Schäfer E. Shaping ability of reciprocating single-file systems in severely curved canals: WaveOne and Reciproc versus WaveOne Gold and Reciproc blue. Odontology 2018 [Epub ahead of print].


24. Silva EJNL, Hecksher F, Antunes HDS, De-Deus G, Elias CN, Vieira VTL. Torsional Fatigue Resistance of Blue-treated Reciprocating Instruments. J Endod 2018 [Epub ahead of print].25. Silva EJNL, Vieira VTL, Hecksher F, Dos Santos Oliveira MRS, Dos Santos Antunes H, Moreira EJL. Cyclic fatigue using severely curved canals and torsional resistance of thermally treated reciprocating instruments. Clin Oral Investig 2018 [Epub ahead of print].

Correspond with:Ghassan Yaredghassanyared@gmail.comwww.endodonticcourses.comwww.drghassanyared.com

Professor Yared is the inventor of single file reciprocation, Reciproc Blue, and R-Pilot endodontic instruments. He is a reviewer for the Journal of Endodontics and the International Endodontic Journal.

27

INTRODUCTIONTrigeminal neuralgia -TN- or “tic douloureux”22 is a

paroxysmal pain, usually intermittent and unilateral, in one (or more) of the territories innervated by trigeminal nerve branches. Pain is characterized by sensations of piercing, tormenting electric shock, cursorily felt in the skin or oral mucosae: it is often momentary, followed by refractory interludes lasting a few minutes. Paroxysms of pain occur in regular intervals and may succeed each other almost endlessly (Potter, 1984 - Lazzara et al., 2013). Pain typically responds to medical treatment, especially carbamazepine (anticonvulsant). When it becomes resistant to medical treatment, surgical or

percutaneous techniques are then proposed.1,23,24

Percutaneous radiofrequency thermocoagulation -RFT- for trigeminal neuralgia has been described by Sweet and Wepsic2 and this technique was introduced to Hôtel-Dieu de France Hospital, Beirut, Lebanon in the early 1990s with the acquisition of the equipment necessary for the technique.

MATERIALS AND METHODSPercutaneous RFT of the Gasserian ganglion through

the foramen ovale (FO) has proven to be an effective treatment for TN: it is a minimally invasive procedure and it specifically involves cannulating through the FO in combination with electrophysiological testing to identify the target (Gusmão et al., 2003 - Steward, 2006). Two hundred and thirty two patients affected by TN were treated by thermocoagulation at the Hôtel-Dieu de France Hospital, Beirut, Lebanon, between June 1992 and December 2014. The diagnosis was established clinically, and all patients underwent a brain imaging (computed tomography -CT- scan or magnetic resonance imaging -MRI-) to rule out secondary trigeminal neuralgia.

Percutaneous radiofrequency thermocoagulation for trigeminal neuralgia: A retrospective case series study of 232 patients.Joseph Maarrawi1, MD, MSc, Dr. Univ.,Patrick Paul Tabet2, MBBS, BSc, MS (Surg. Sc.), Cert. (Learning / Teaching),Joe Faddoul3, MDSandra Kobaiter-Maarrawi4, BSc, MSc, Dr. Univ.,Sharon Weinberg5, MBBS,Elie Samaha6, MD

AbstractPrimary Trigeminal Neuralgia -pTN- is one of the most common causes of persistent severe facial pain, especially

in elderly patients. Many clinical studies advocated that microvascular compression and demyelination of the trigeminal nerve at the root entry zone are the causes of trigeminal neuralgia. Microsurgical vascular decompression -MVD- is a relatively common procedure to manage this chronic condition. Beside MVD, percutaneous radiofrequency thermocoagulation -RFT- of the Gasserian ganglion through the foramen ovale is an efficient treatment for trigeminal neuralgia. This minimally invasive procedure is usually performed using Hartel anterior approach.

In this retrospective study, we are reporting a series of 232 patients treated by RFT at Hôtel-Dieu de France Hospital (Saint-Joseph University), Beirut, Lebanon, between June 1992 and December 2014.

1. Associate Professor, Laboratory of Research in Neurosciences, Faculty of Medicine, Saint-Joseph University, Beirut, and Department of Neurosurgery, Hôtel-Dieu de France Hospital, Beirut, Lebanon

2. University of Edinburgh, Edinburgh, Scotland, UK3. Clinical Fellow in Neurosurgery, Pitié-Salpétrière Hospital,

Paris, France4. Assistant Professor, Laboratory of Research in Neurosciences,

Faculty of Medicine, Saint-Joseph University, Beirut, Lebanon5. Morriston Hospital, Swansea, Wales, UK 6. Professor, Department of Neurosurgery, Hôtel-Dieu de France

Hospital, Faculty of Medicine, Saint-Joseph University, Beirut, Lebanon

Craniofacial Research



150 women (64.65%) and 82 men (35.35%) with a mean age of 66 years (30-82 years) were included in this retrospective study. Duration of symptoms ranged from 2 months to 15.5 years with an average of two and a half years. All patients included in the study did not receive any other medical or surgical procedure before their inclusion. The territory of the neuralgia was maxillary (V2) in 97 patients (41.81%), mandibular (V3) in 68 patients (29.31%), ophtalmic (V1) in 14 patients (6.03%) and mixed with more than a single territory involved in 53 patients (22.85%) (19 patients with territories V1 - V2 and 34 with territories V2 -V3 being affected) (Table 1).

Pain was triggered by chewing in 145 patients (62.5%), skin contact in 74 patients (31.89%), and mixed stimuli in 13 patients (5.6%). Physical examination was normal in all patients. MRI was performed on 159 patients and CT on the 73 remaining patients.

Previous medical treatment undertaken was essentially carbamazepine (Tegretol®) with doses ranging from 600 to 1200 mg/day; phenytoin (anti-seizure medication) and baclofen (skeletal muscle relaxant) were added in 23 cases. Only 8 patients were on oxcarbazepine (anticonvulsant). Indication for thermocoagulation was based on a previous failure of medical management with a maximum tolerable dose. Symptomatic forms such as multiple sclerosis (18 cases) weren’t considered as contraindications to the use of this method.

Material used in our study was manufactured in Germany (FL Fischer, N50 Lesion Generator). Patients were short-term hospitalised on a "day care procedure" basis. Insertion of the electrode through the FO was performed using the Hartel technique3 (Fig. 1). C-arm was used to ensure accurate placement of the electrode (Fig. 2). Stimulation test to locate the position of the electrode tip in the Gasserian ganglion was positive in all patients by electrostimulation between 0.15 and 0.2 V. Thermocoagulation procedure was at an average temperature of 70°C for 45 seconds and 72°C for 20 seconds, under assisted anesthesia with propofol, a barbiturate-like sedative and ultra-short acting agent usually used for general anesthesia, procedural sedation, or reduction of intracranial pressure after traumatic brain injury. The needle used was stripped over a length of 5 mm.

RESULTSResults were evaluated on the same day and during

a period of 6 months to 11 years, with an average follow-up of 4 years and 7 months. Results were considered “Excellent” when there was a full effect on pain with or without a well-tolerated dysesthesia, and “Satisfactory” when medication was still necessary for full control of pain.

Fig. 1. Insertion of the needle, 6 cm lateral to midline.

Fig. 2. Lateral skull radiograph displaying the accurate placement of the needle (electrode).

Table 1. Patients' distribution of pain territory.

Distribution of the territory of trigeminal neuralgiaTerritory Number of patients %

V1 14 6.03V2 97 41.81V3 68 29.31

Mixed 53 22.85Total 232 100


At discharge, 225 patients (96.98%) had an "Excellent" result. The medium-term outcome (one year) was positive in 205 patients (88.36%), of which 185 had "Excellent" result and 20 were "Satisfactory" with the need for supplemental medication with carbamazepine or other drugs.

No major complications were reported. Anesthesia dolorosa* was expressed only by 3 patients (1.29%). Recurrence was observed in 38 patients (16.37%) with a mean recurrence interval of 16 months and 18 patients responded adequately to repeated thermocoagulation.

DISCUSSIONTrigeminal neuralgia is a multifactorial medical

condition that can be explained by two theories: the first favors a central seizure producing discharge4, the second promotes a peripheral cause secondarily generating a central mechanism4,5, the primum movens would be a demyelination of fibers due to compression (compression is vascular in 95% of cases). This focal demyelination leads to abnormal multineuronal reflexes exciting the core of the trigeminal nerve6-7. This conflict clarifies the role of decompressive surgery8-13,27, especially MVD of the trigeminal nerve, which is the indication of choice for a young person in a good condition presenting with TN with imaging revealing a vascular loop14. The cure rate of this decompressive procedure in the literature is estimated at 83% with 10% of partial results, 4% of failure, and 3% of recurrence4. This surgery was always first proposed to our patients if their age was less than 65 years25. Young patients unwilling to undergo this technique were treated by thermocoagulation.

Compression of the trigeminal (Gasserian)ganglion by a Fogarty balloon in the Meckel’s cave** is to be discussed when the neuralgia takes the ophthalmic branch (V1) in order to avoid corneal anesthesia induced by thermocoagulation. We began to use this technique, when indicated, in 2005.

Glycerol rhizotomy, a technique still advocated by some neurosurgeons, includes potential hazards and a high recurrence rate of 30%16. We never use this technique which has been largely replaced by thermocoagulation.

In our series, the technical conditions applied were those recommended by authors of large series4,17,18,19,26. Anesthesia during heating was performed using propofol which has many advantages: spontaneous breathing, rapid elimination, good awakening, and profound pain control during the procedure. Other drugs such as midazolam and fentanyl have been proposed as well20. In our experience, propofol proved to be very satisfactory and this encourages us to continue using it4,17,18.

Results of thermocoagulation are considered in the literature as excellent or satisfactory in 94% and poor in 6% of cases, with a recurrence rate of around 7%4,16. Our results are close to those numbers, except for a relatively high recurrence rate, due to long-term follow-up and to less aggressive thermocaogulation than in other series.

Among complications described after thermolesion such as corneal anesthesia, keratitis, anesthesia dolorosa4,16,19, we noted four cases of corneal anesthesia, which was predictable in one case (neuralgia of V1) and a thermolesion extension from V2 fibers to V1 territory in the second case; the latter complication occured without any ophthalmic consequences. Occurrence rate of anesthesia dolorosa in our series was close to the literature.

CONCLUSIONRFT is currently the treatment of choice in elderly

patients and those with poor general condition, presenting with TN that is refractory to properly conducted medical treatment4,16, especially for V2 and V3 territories. It could also be considered in young patients, in absence of conclusive evidence of vascular or other compressions21. It should be applied as well in case of recurrence following application of other techniques4.

Many neurosurgeons favor RFT due to the ability to perform it in a minimally invasive manner, with little mortality and morbidity, with effectiveness and satisfactory functional outcome. And despite possible complications that may result from RFT (facial palsy, keratitis, corneal anesthesia, anesthesia dolorosa, blindness, deafness, and even death may occur,

* Anesthesia dolorosa (or deafferentiation pain)= constant, burning, aching, severe pain in the face. Pain is accompanied by numbness, as well.

** Meckel's cave (or trigeminal cave or cavum trigeminale) = a dura mater pouch containing cerebrospinal fluid. This cave houses the trigeminal ganglion.


especially with high temperatures), RFT is nowadays considered as a first-line technique in the management of TN refractory to medical treatment21, especially for patients older than 65 years.

Our results indicate that RFT is a safe, effective, and reliable mean of treating trigeminal neuralgia.

REFERENCES1. Adams R, Victor M. Headache and other craniofacial pains. In: Adams R, Victor M, editors. Principles of neurology, 5th edition. New York: Mc Graw Hill 1993. p. 165.2. Sweet WH, Wepsic JG. Controlled thermocoagulation of trigeminal ganglion and rootlets for differential destruction of pain fibers. J Neurosurg 1974;40:143-156.3. Nugent R. Trigeminal neuralgia: Treatment by percutaneous electrocoagulation. In: Wilkins R, Rengachary S, editors. Neurosurgery. New York: Mc Graw Hill 1985. p. 2347-2348.4. Sindou M, Keravel Y, Abdennebi B, Szappiro J. Traitement neurochirurgical de la névralgie trigéminale. Abord direct ou méthode percutanée? Neurochirurgie 1987;33:89-111.5. Kirkpatrick D. Familial trigeminal neuralgia: Case report. Neurosurg 1989;24 (5):758-761.6. Kruger L. Structural aspects of trigeminal neuralgia: A summary of current findings and concepts. J Neurosurg 1967;26:107-109.7. List CF, Williams JR. Pathogenesis of trigeminal neuralgia, a review. Arch Neurol Psychiatry 1957;77:36-43.8. Babu R, Murali R. Arachnoid cyst of the cerebello-pontine angle manifesting as controlateral trigeminal neuralgia: case report. Neurosurg 1991;28 (6):886-887.9. Delfini R, Innocenzi G, Ciapetta P, Domenicucci M, Cantore G. Meningiomas of Meckel’s cave. Neurosurg 1992;31(6):1000-1005.10. Haddad F, Taha J. An unusual cause of trigeminal neuralgia: controlateral meningioma of the posterior fossa. Neurosurg 1990;26(6):1033-1038.11. Jannetta PJ. Cranial rhizopathies. In: Youmans JR, editor. Neurological surgery. Philadelphia: WB Saunders 1990;6:4169-4182.12. Sindou M, Mertens P. Microsurgical vascular decompression in trigeminal and glosso-vago-pharyngeal neuralgias. A twenty-year experience. Acta Neurochir Suppl Wien 1993;58:168-170.13. Szapiro J, Sindou M. Traitement microchirurgical de la névralgie du trijumeau. Résultats et facteurs pronostiques de la décompression vasculaire microchirurgicale. Neurochirurgie 1986; 32:103-121.14. Sindou M, Amrani F, Mertens P. Décompression vasculaire microchirurgicale pour névralgie du trijumeau. Comparaison de deux modalités techniques et déductions physiopathologiques. Etude sur 120 cas. Neurochirurgie 1990;36:16-26.15. Brown J, Mc Daniel M, Weaver M. Percutaneous trigeminal nerve compression for treatment of trigeminal neuralgia: Results in 50 patients. Neurosurg 1993;32(4):570-573.16. Fraioli B, Esposito V, Guidetti B, Cruccu G, Manfredi M. Treatment of trigeminal neuralgia by thermocoagulation, glycerolyzation, and percutaneous compression of the Gasserian ganglion and/or retrogasserian rootlets; long-term results and therapeutic protocol.

Neurosurg 1989;24(2):239-245.17. Frank F, Gaist T, Fabrizi A et al. Résultats de la thermocoagulation percutanée sélective du ganglion de Gasser dans la névralgie faciale essentielle. Synthèse des résultats obtenus chez 939 patients traités. Neurochirurgie 1985;31:179-182.18. Onofrio BM. Radiofrequency percutaneous Gasserian lesions. Results in 140 patients with trigeminal pain. J Neurosurg 1975;42:132-139.19. Siegfried J. Percutaneous controlled thermocoagulation of Gasserian ganglion in trigeminal neuralgia. Experiences with 1000 cases. In: Samii M, Janetta PJ, editors. The cranial nerves. Berlin: Springer Verlag 1981:322-330.20. Brisman R. Analgesia and sedation during percutaneous radiofrequency electrocoagulation for trigeminal neuralgia. Neurosurg 1993;32(3):400-406.21. Dahan JM, Tew JM. Comparison of surgical treatment of trigeminal neuralgia: Percutaneous techniques and posterior fossa exploration. Neurochirurgie 1994;40:203-204.22. Nurmikko TJ, Eldridge PR. Trigeminal neuralgia–pathophysiology, diagnosis and current treatment. Br J Anaesth 2001;87:117–132.23. Kanpolat Y, Savas A, Bekar A, Berk C. Percutaneous controlled radiofrequency trigeminal rhizotomy for the treatment of idiopathic trigeminal neuralgia: 25-year experience with 1,600 patients. Neurosurg 2001:48(3):524-532; discussion 532-534.24. Campbell GH, Lutsep HL. Trigeminal neuralgia. [Internet] eMedicine 2006; Available from: http://www.emedicine.com/neuro/TOPIC593.HTM. 25. Cheshire WP. Trigeminal neuralgia: for one nerve a multitude of treatments. Expert Rev Neurother 2007;7:1565-1579.26. Hunt K, Patwardhan R. Trigeminal neuralgia: a modern-day review Int Rev Neurobiol 2007;79:621-631.27. Tatli M, Satici O, Kanpolat Y, Sindou M. Various surgical modalities for trigeminal neuralgia: literature study of respective long-term outcomes. Acta Neurochir 2008;150:243-255.

Corresponding author:Joseph [email protected]@usj.edu.lb

32

INTRODUCTIONMandibular fractures constitute the bulk of facial

fractures that require treatment, given that mandible is the second most commonly fractured bone in facial skeleton after nasal bones.1 Etiologies of mandibular fractures seem to vary from country to another. Martinez and associates2 noticed the significant change in facial trauma etiology during the past 2 decades. Of relevance to this article, there was a clear documented increase in fractures caused by falls in 2010 when compared to 19902. With increased life expectancy of the elderly, surgeons are more likely to face more difficult injuries in this group of patients; the extended life expectancy of this population has been attributed to various advances in medicine along with accessibility to healthcare. A typical example of these injuries is atrophic edentulous mandible fractures.3

Atrophy of the mandible is strongly linked to edentulism which is estimated to be around 20% worldwide4. The link between edentulism and mandibular atrophy has been attributed to loss of both soft tissue and bone. Atwood4 introduced the famous classification of atrophic anterior mandible after tooth loss and published the changes occurring in mandible

after tooth/teeth extractions or loss4.

HISTORICAL BACKGROUNDIt is universally agreed upon that an atrophic

mandible is defined as any mandible with a vertical height less than 20mm (2cm). Historically, mandibular fractures and edentulous mandible fractures were treated in a closed fashion; the closed approach to edentulous mandible fractures included using the patient's own mandibular dentures, if he/she had one; mandibular denture was secured with circummandibular wiring: this technique was referred to as the mono-mandibular fixation, and if this maneuver was inadequate to reduce and stabilize the fracture, maxillary denture is fixated with circumzygomatic wires, and the two dentures would then be secured together using wires. This modality of treatment was not the most convenient for this subset of population and had unpredictable outcomes.5,6

If the patient had no available maxillary and mandibular dentures or if these were broken during trauma, Thomas Brain Gunning (1813-1889) designed the "Gunning splint" (1863) which basically mimicked both maxillary and mandibular dentures without teeth and incorporated an anterior window which facilitated breathing and nutritional supplementation.

Hugo L. Obwegeser (1920-2017), the father of modern orthognathic surgery, described his concept and approach to atrophic mandible fractures: in his 1973's

Management of atrophic mandible fractures: A mini-review and case series.

Waleed Zaid*, DDS, MSc, FRCD(C), DABOMS

AbstractIn this article, we address atrophic mandible fractures, a very special phenotypical variation of mandibular

fractures. We also discuss the historical management of these fractures, the classifications of atrophic mandible and their implications on the treatment. Finally, we elaborate on the surgical management of these fractures along with the risks and complications commonly encountered with them and we share a case series of atrophic mandible fractures managed at Louisiana State University, in New Orleans, USA.

* Oral and Maxillofacial Surgeon, Head and Neck & Microvascular surgeon,Associate Professor, Department of Oral and Maxillofacial Surgery, and Co-Director, Head and Neck Oncology and Microsurgery Fellowship, Louisiana State University, School of Dentistry, New Orleans, Louisiana, USA

Oral and Maxillofacial Surgery



landmark publication, he described many facts which hold true up-to-date, such as the increased likelihood of these fractures being bilateral ones, and that mental foramen area is the most likely affected anatomical site. Also, he described many concepts that remain valid, such as the need to augment the fracture site with a bone graft in order to increase the surface area of bony contact and achieve better stability. His bone grafting donor site included non-vascularized bone harvested from iliac crest or chest wall rib; an intra-oral approach was used according to his original description which allowed him to fixate the graft material to mandible using circummandibular wires.5-7

Historically, external pins were used as well (Converse and Waknitz 1942, Moule 1968, Schiile 1957); this technique didn't allow direct visualization of fracture segments and proper reduction, and there was an increased risk of inferior alveolar and facial nerves injuries, as well as cutaneous tract infection around external pins; all these made surgeons abandon this technique.

Nowadays, it is universally accepted that open reduction and internal fixation is the approach of choice for atrophic mandible fractures. The only contraindication to open reduction and internal fixation of these fractures is a significant medical comorbidity or the inability to tolerate general anesthesia5. Some authors refer to the closed reduction approach as the “Skillful Neglect”6.

CLASSIFICATIONS OF ATROPHIC MANDIBLE

Many factors play a role in the rate of bone resorption after dental extraction. Examples of these factors include parafunctional habits, systemic medical conditions that might accelerate the bone resorption process, pharmacological agents, and finally, mechanical forces applied on mandible4: all these factors and many others contribute to atrophy of mandible.

Hans-Georg Luhr and his oral and maxillofacial surgery group (University Hospital of Göttingen, Germany) created the Luhr classification10,11 of atrophic mandible according to height of mandible: class I (16-20 mm of height at fracture site), class II (11-15 mm), and class III (≤10 mm).

Cawood and Howell8 (1988) established a

classification of six atrophy stages in the mandible: class I (dentate before extraction), class II (immediately post-extraction), class III (high well-rounded ridge), class IV (knife-edge shaped ridge), class V (low well-rounded ridge), and class VI (depressed bone level).8 The latter classification is more popular and useful in dental implant placement in atrophic mandibles and gives the operator an idea whether adjunct bone grafting is necessary or not.

ANATOMICAL AND PHYSIOLOGICAL CHANGES IN ATROPHIC MANDIBLE

Tooth loss and resorption of mandibular alveolar process causes significant decrease in blood supply; this physiological change may contribute negatively to atrophic mandiblular healing, increasing the risk of malunion or nonunion of fractures.

The continued process of mandibular atrophy leads to significant anatomical changes: examples of these changes include the prominent mylohyoid ridge covered by thin mucosal lining, which makes it prone to dehiscence from ill-fitting dentures or traumatic insult; a second example is genial tubercles which become prominent and superiorly located in relation to the anterior mandibular ridge (Fig. 1); both locations are areas of muscle attachment which increases blood supply to these areas, hence making them resistant to post-extraction resorption.

Overlying mucosa seems to decrease in thickness with age, which increases the risk of traumatic laceration and soft tissue dehiscence4. The significant decrease of stem cells in elderly population contributes to prolonged healing period in these phenotypical fractures of mandible. Overall, the vascularity of atrophic mandibles is decreased due to narrowing of the inferior alveolar artery, causing vascular dependence on the periosteal blood supply; these physiological changes play an important role in the treatment selection of atrophic mandible fractures3,9.

It should be mentioned that patients with atrophic mandible fractures usually sustain multiple concomitant systemic diseases that might complicate healing of these fractures or require pre-, intra-, or post-operative modifications. Medical optimization should be attempted, as this step might minimize the negative impact on fracture healing; examples include nutritional


optimization (based on pre-operative albumin and pre-albumin), controlling blood sugar levels in diabetic patients, and coordinating pharmacological agents with primary care physicians as often these patients are on many drugs and the treating surgeon should always be aware of cross-interactions between these multiple medicines, which may lead to increasing or decreasing of some drugs pharmocolgical effects. Looking at the various anatomical locations of mandibular fractures, the body (of mandible) seems to be mostly involved (Fig. 2), followed by the condylar/sub-condylar region, and the (mandibular) angle's region10.

SURGICAL MANAGEMENT OF ATROPHIC MANDIBULAR FRACTURES

As any other facial trauma, careful detailed examination of patients should be performed to rule out any other concomitant facial or non-facial fractures; as mentioned earlier, the likelihood of patients suffering from a systemic disease is high; also of great importance is the airway because of increased risk of compromised airway secondary to anatomical location of the fractures: a good example is the bilateral parasymphyseal fractures case where there is a risk of having a free floating anterior mandibular segment (“bucket handle fracture”), risking a posterior displacement of tongue and blocking of the airway; expanding hematomas in the floor of mouth may compromise the airway as well13.

The surgeon should always be alert regarding early diagnosis of these complications, he/she should be ready to secure the airway via direct laryngoscopy with oral-tracheal intubation or surgically via cricothyrotmy or tracheostomy.

Maxillofacial computerized tomography (CT) is the gold standard for diagnosing facial fractures including mandibular ones; if the patient presents in the out-patient setting, cone beam CT (CBCT) can be obtained. If the surgeon doesn’t have access to facility with CT-scanner, two films are the minimum accepted: panoramic and postero-anterior radiographs (usually available in most of oral and maxillofacial surgery centers).

Currently, open reduction is highly accepted by majority of oral and maxillofacial surgeons, especially with increasing safety of general anesthesia; literature

Fig. 1. Three-dimensional CT reconstruction showing left parasymphyseal and right mandibular body fractures.

Fig. 2. Post-operative CT reconstruction showing well reduced bilateral atrophic mandible fractures.

Fig. 3. Miniplates were used to reduce the fractures while reconstruction plate was bent and adapted to mandibular form.


reports the use of rigid reconstruction plates and smaller semi-rigid miniplates: however, atrophic mandible fracture three-dimensional finite element analysis has shown that 2.0-mm-locking plates is the minimum acceptable thickness for the plate profile that can resist functional load and forces applied on atrophic mandible.6 Wittwer and associates12 retrospectively evaluated 30 patients with 40 fractures and looked into the degree of mandibular atrophy and the method of fixation used: they concluded that surgeons should consider the degree of mandibular atrophy as a guide to determine which fixation method should be used. It was suggested that rigid fixation (load bearing plates) may be necessary when mandibular height is less than 15mm12.

Intra and extra-oral approaches have been reported in the literature, but intra-oral approach has been associated with increased risk of complications secondary to excessive periosteal stripping, and increased risk of surgical site contamination by oral flora.

The author (WZ) prefers to utilize an extra-oral approach which minimizes periosteal stripping1,12; our modification to skin incision is to make it larger than the classical 2cm incision below the inferior border of mandible. We prefer to reduce the fracture using a mini-plate with monocortical screws in order to maintain the reduced segments together: this helps bending the reconstruction plate on mandible without

the interference of bone reducing clamps. After the reconstruction plate is bent, it is fixated with bi-cortical screws (posterior segment posterior to mental foramen, and anterior segment are the locations of choice for screw placement5) (Fig. 3). Concomitant bone grafting has been advocated by some surgeons to enhance osteogenic potential and accelerate bone healing; although still controversial, we use this technique only for severe atrophic mandibles or if there is a defect resulting from surgical extraction of impacted wisdom teeth, or if there is a severe comminution of fractured segments resulting in a segmental defect. Conventionally, the anterior iliac crest is the most commonly used donor site for bone grafting. Some authors advocate the supra-periosteal dissection; however, this concept conflicts with the very basic principles of open reduction and fixation, which requires fracture exposure, direct reduction, and fixation. The concept of load bearing is important when selecting osteosynthesis plate for atrophic mandibular fractures. Reconstruction plate with bicortical screws is defined as a load-bearing plate; hence, it is widely used in atrophic mandibular fractures (Fig. 4).

SURGICAL STEPSPatient is positioned in supine position, and

attention should be paid not to hyperextend the neck, especially in elderly population. Clear communication is established with the anesthesia team regarding the

Fig. 4. Reconstruction plate secured in anterior mandible and mandibular angle area.


type of intubation; muscle relaxation is very important as well. Ideally, nasal intubation is the common method of intubation for oral and maxillofacial surgery procedures; however, with atrophic mandible fractures, there is no added advantage of nasal intubation and oral endotracheal tube is usually satisfactory. The surgeon should be able to stimulate and test the marginal mandibular nerve* (during the transcervical approach) with a nerve stimulator; muscle relaxation is preferred after this step. A neck skin crease is used to make the incision: this helps hiding the scar resulting from incision. After the crease is selected, skin is incised and bleeding is controlled with electrocautery; dissection is continued until the platysma muscle is exposed. The platysma is cut and platymsal flaps are elevated using electrocautery. The superior elevation should be extended till the inferior border of the mandible; dissection is then proceeded in a blunt fashion in the superficial layer of the deep cervical fascia on top of submandibular gland, guided by a nerve stimulator. Identification of the facial vein and artery is done and a Hayes-Martin maneuver (ligation of posterior facial vein and superior reflection of the investing fascia below the mandible in order to preserve the marginal mandibular nerve) is performed. The pterygomasseteric sling is then sharply cut as well as the periosteum. Using a periosteal elevator, the periosteum is reflected; surgeon should minimize unnecessary reflection of the periosteum and try to maintain lingual and alveolar periosteum. The fracture is then exposed and reduced using bone reducing forceps or mini-plates on inferior border of mandible, then the reconstruction plate is bent on mandible: the plate should be as passive as possible, and small gaps not exceeding 5mm are tolerated. After satisfactory bending of the plate, bicortical screws are then drilled under copious irrigation with sterile and cool normal saline solution. Direction of the screws should avoid inferior alveolar and mental nerves. The wound is washed and hemostasis is confirmed; suction drain is then placed and secured. The platysma is then closed in simple interrupted fashion and the skin is closed using staples.

COMPLICATIONSAs any surgical procedure, open reduction and

internal fixation in atrophic mandibles are associated with risks and complications. Complications include infection and bleeding which can be subcategorized into intra-operative bleeding or post-operative bleeding. Hypertrophic scars and keloids formation are complications resulting from using a transcervical approach; this can be minimized with proper planning of the incision in a skin crease and proper surgical closure and wound care. Screw failure, infection, and neurological injuries can occur as well; marginal mandibular nerve (branch of the facial nerve), inferior alveolar nerve (branch of the trigeminal nerve), and mental nerve (part of trigeminal as well) are mainly at risk. Risk of lingual nerve (part of trigeminal) injury is low, but can occur with the use of long bicortical screws. Delayed union (prolonged period of healing more than 6 weeks), malunion, and nonunion are also possible complications.

CASE SERIES

CASE 1 A 67-year-old female sustained mandibular left

angle and right parasymphyseal fractures after a mechanical fall. Patient complained of bilateral numbness over the distribution of V3 (mandibular nerve). Patient was breathing well with no airway compromise; her medical history was significant for chronic obstructive pulmonary disease (COPD) and was taking ipratropium (a muscarinic antagonist). Informed consent was obtained to undergo open reduction and internal fixation of both fractures under general anesthesia via transcervical approach. Intra-operatively, a decision was made to use two separate 2.7 reconstruction plates with bi-cortical screws (Fig. 5). In this case, no bone grafting was done.

CASE 2A 55-year-old male with edentulous mandible

underwent a placement of 2 endosseous implants

* Marginal Mandibular nerve -MMN- is the marginal mandibular branch of facial nerve: it passes forward beneath the platysma muscle and depressor anguli oris muscle and supplies the muscles of lower lip and chin and communicates with the mental nerve. MMN innervates three muscles, depressor labii inferioris, depressor anguli oris (triangularis), and mentalis. An injury to this nerve can distort smile expression as well as other facial expressions.


for an implant-supported overdenture via a transoral approach (in anterior mandibular region) by another surgeon, and no bone grafting was done. Two days after the procedure, patient heard a cracking sound and felt pain in left parasymphyseal region. He returned to his surgeon who removed the endosseous implant on left side and an iatrogenic fracture was confirmed on a panoramic radiograph (Fig. 6). Past medical history of the patient was significant for coronary artery disease and compensated heart failure. After medical clearance, informed consent was obtained to undergo open reduction and internal fixation via a transcervical approach with concomitant bone grafting from the anterior iliac crest. Two surgical teams were involved in order to minimize operative time. Bone graft increased the osteogenic potential and accelerated bone healing: it also provided enough bone width and height for future implant placement after achieving osseous healing. Bone grafting was performed on posterior mandible where bicortical screws were placed. A lag screw was secured as well (Fig. 7) to reduce the fracture prior to reconstruction plate application (Fig. 8). Bone Morphogenic Proteins** (BMP’s) were used to avoid donor site morbidity and extended operating time on fracture sites and around the screws (Fig. 9).

CASE 3A 76-year-old female developed a pathological

fracture of the mandible as a complication of a stage IV medication-related osteonecrosis of the jaw (MRONJ)

due to the use of a bisphosphonate: because of the nature of this disease, a free vascularized fibula flap was planned, with the use of virtual surgical planning. Fibula free flap (based on perineal artery and the two venae comitantes, which are the vascular pedicle for this flap) was harvested using compression tourniquet. Mandible fracture was exposed via a transcervical approach, cutting guides were used to shape the fibula free flap in order to mimic the native mandible, allowing simultaneous implant placement into the fibula; this is possible because of immediate vascularization of the fibula after microvascular anastomosis, which allows osseointegration of dental implants. And due to the bicortical nature of the fibula, dental implants have excellent primary stability, allowing osseointegration and reducing the need for multiple surgical procedures (Fig. 10).

CASE 4A 45-year-old male patient sustained comminuted

left subcondylar and right body fractures after physical

Fig. 6. Panoramic radiograph showing left parasymphyseal fracture resulting from endosseous implant placement.

Fig. 5. Miniplates were placed at the inferior border of mandible to allow reduction of the fracture until reconstruction plate is adapted and fixated. Two reconstruction plates can also be used rather than one long-span plate.

* * BMPs are multifunctional growth factors that belong to the transforming growth factor beta (TGF beta) superfamily.


Fig. 7. Lagging of the fracture segments was achieved using a lag screw and, in this case, concomitant bone grafting was performed.

Fig. 8. Post-operative 3D reconstruction of the CT showing adequate reduction and bone particles at the fracture site.

Fig. 9. BMPs used as an alternative for autogenous bone graft (BMPs are mixed with freeze dried bone allograft -FDBA).


Fig. 10. The fibula free flap position was shaped to restore the form and shape of the native mandible. Also, dental implants were planned for a future implant-supported overdenture.

Fig. 11. Post-operative CT scan showing well-reduced left subcondylar and right body fractures (A and B). Retractors showing miniplates used to fixate the comminuted subcondylar fracture (C). Closure of retromandibular approach is done in a layered fashion in order to prevent a parotid sialocele (D, E, F).

A

D

B

E

C

F


assault. Patient didn't have any denture, therefore we proposed an open reduction and internal fixation of both fractures via a retromandibular/transparotid approach to access, reduce, and fixate the left subcondylar fracture, and a submandibular approach to access the right body fracture. The comminuted subcondylar fracture mini-plates were adequate for fixation. However, in the body of mandible, a reconstruction plate was necessary for fixation. When closing retromandibular incision, we managed to have a layered closure in order to prevent a parotid sialocele, a possible complication, as the parotid gland capsule was opened during this approach (Fig. 11).

CONCLUSIONIn a study on 2,094 patients13 with facial bone

fractures, the most common isolated fractured site was the nasal bone (37.7%), followed by the mandible (30%), orbital bones (7.6%), zygoma (5.7%), maxilla (1.3%), and the frontal bone (0.3%)13.

Compromised vascularity in atrophic mandible patients as well as the confounding medical comorbidities that these patients usually have increase complication rates with this type of fractures; however, open reduction and internal fixation should always be preferred unless there is a severe medical comorbidity preventing the surgical option or general anesthesia. Concomitant bone grafting should be reserved for atrophic mandibles with < 10 mm of height or severely comminuted fractures. Rigid load bearing fixation is critical for these fractures.

It was once said, “The thinner the mandible gets the thicker the plate should be”: this holds true because atrophic mandibles have reduced resistance to functional load, especially after a fracture. In addition, osseous microvascular reconstruction can be used in extreme cases of severely comminuted atrophic mandible fractures or pathological fractures which occur because of an existing pathology like osteoradionecrosis or medication-related osteonecrosis of the jaw.

REFERENCES 1. Ellis E 3rd. An algorithm for the treatment of noncondylar mandibular fractures. J Oral Maxillofac Surg 2014 May;72(5):939-949. 2. Martinez AY, Como JJ, Vacca M, Nowak MJ, Thomas CL, Claridge JA. Trends in maxillofacial trauma: a comparison of two cohorts of patients at a single institution 20 years apart. J Oral Maxillofac Surg 2014 Apr;72(4):750-754. 3. Madsen MJ, Haug RH, Christensen BS, Aldridge E. Management of atrophic mandible fractures. Oral Maxillofac Surg Clin North Am 2009 May;21(2):175-183. 4. Atwood DA. Postextraction changes in the adult mandible as illustrated by microradiographs of midsagittal sections and serial cephalometric roentgenograms. J Prosth Dent 1963 Sep-Oct;13(5):810-824. 5. Haggerty CJ, Laughlin RM (Eds). Atlas of Operative Oral and Maxillofacial Surgery. Wiley - Blackwell;2015 March. pp. 107-140.6. Vajgel A, Camargo IB, Willmersdorf RB, de Melo TM, Laureano Filho JR, Vasconcellos RJ. Comparative finite element analysis of the biomechanical stability of 2.0 fixation plates in atrophic mandibular fractures. J Oral Maxillofac Surg. 2013 Feb;71(2):335-342. 7. Obwegeser HL, Sailer HF. Another way of treating fractures of the atrophic edentulous mandible. J Craniomaxillofac Surg 1973;1:213-221. 8. Cawood JI, Howell RA. A classification of the edentulous jaws. Int J Oral Maxillofac Surg 1988 Aug;17(4):232-236. 9. Aziz SR, Najjar T. Management of the edentulous/atrophic mandibular fracture. Atlas Oral Maxillofac Surg Clin North Am. 2009 Mar;17(1):75-79. 10. Fonseca RJ, Barber HD, Walker RV, Powers MP, Frost DE. (Eds.). Oral and Maxillofacial Trauma. Fourth Edition. Elsevier/Saunders, 2013, St. Louis, Missouri, USA. 11. Luhr H-G, Reidick T, Merten H-A. Results of treatment of fractures of the atrophic edentulous mandible by compression plating: a retrospective evaluation of 84 consecutive cases. J Oral Maxillofac Surg 1996 Mar;54(3):250-254.12. Wittwer G, Adeyemo WL, Turhani D, Ploder O. Treatment of Atrophic Mandibular Fractures Based on the Degree of Atrophy—Experience With Different Plating Systems: A Retrospective Study. J Oral Maxillofac Surg 2006 Feb;64(2):230-234. 13. Hwang K, You SH. Analysis of facial bone fractures: an 11-year study of 2,094 patients. Indian J Plast Surg 2010 Jan;43(1):42-48.

Correspond with:Waleed [email protected]

41

INTRODUCTIONAntibiotics are prescribed by dentists for treatment

as well as prevention of infections. Dentists prescribe medications for the management of a number of oral conditions, mainly orofacial infections. Since most human orofacial infections originate from periodontal and dental structures, prescribing of antibiotics by dentists has become a vital aspect of dental practice and, as such, antibiotics account for the vast majority of medicines prescribed by dentists. Dental practitioners prescribe between 7% and 11% of all common antibiotics (betalactams, macrolides, tetracyclines, clindamycin, metronidazole, and fluoroquinolones). In the UK, for instance, dentists accounted for 7% of all community prescriptions of antimicrobials. Conversely, the National Center for Disease Control and Prevention estimates that approximately one-third of all outpatient antibiotic prescriptions are unnecessary3,8,9.

Antibiotic prescribing may be associated with side-effects such as gastrointestinal disturbances, fatal allergic reactions, and development of resistance4,5,7. The increasing resistance problems of recent years are probably related to overusee or misuse of

broad-spectrum agents such as cephalosporins and fluoroquinolones. These complications associated with antibiotics use have encouraged studies investigating antibiotic prescribing practices of dentists.

THERAPEUTIC ANTIBIOTIC PRESCRIBING BY DENTISTS

Most oral diseases are primarily inflammatory conditions that are associated with pain2,6. A considerable percentage of dental pain originates from acute and chronic infections of pulpal origin, which necessitates operative intervention, rather than the use of antibiotics. Non-indicated clinical cases for antibiotic use include acute periapical infection, dry socket, and pulpitis. Chronic inflammatory periodontal conditions are also not indicated for antibiotics; systemic antimicrobials should only be used in acute periodontal conditions where drainage or debridement is impossible, where there is local spread of the infection, or where systemic upset has occurred1,6.

Data reported from different countries show differences in dentists’ knowledge of clinical situations indicated for antibiotic prescribing1,8,9,11-18. Almost half or more of the dentists investigated in England, Kuwait, and Turkey would prescribe for dry socket. Another non-indicated condition is localized swelling, which

Antibiotic prescribing in dental practice: Problems and recommandations.Hala Jawad1, MPharm, MIFWIPKayode Adelaja2, MPharm

AbstractAntibiotics are prescribed by dentists for treatment as well as prevention of infection. Indications for the use of

systemic antibiotics in dentistry are limited since most dental conditions and diseases are best managed by operative intervention and oral hygiene measures. This paper addresses the problem of inadequate prescribing practices by dentists, due to a number of factors ranging from inadequate knowledge to social factors. Therefore, studies that investigated the pattern of antibiotic use by dentists worldwide were reviewed. The main defects in the knowledge of antibiotic prescribing were outlined. The conclusion was that, unfortunately, the prescribing practices of many dentists appear to be inadequate and this is manifested by over-prescribing. Recommendations to improve antibiotic prescribing practices are suggested in an attempt to help fighting the increasing incidence of antibiotic resistance, antibiotic allergies, and other side-effects of antibiotic abuse.

1. Practice Pharmacist / Community Pharmacist, GPHC Registered Pharmacist, Surrey, England, UK2. GPHC Registered Pharmacist, London, England, UK

Clinical Pharmacology



was also among the conditions for which antibiotics were prescribed in Norway, South Australia, Kuwait, and England.

More common dental infections present in the form of pulpitis and periapical periodontitis, which require only operative measures like fillings, root canal therapy, or extraction if the tooth is not restorable. Unfortunately, some dentists still prescribe antibiotics for these conditions. An uncomfortable finding was that a number of dentists prescribe antibiotics for viral infections like herpes simplex virus-1 infections. Clinical situations that require antibiotic therapy on empirical basis are limited, and they include oral infection accompanied by elevated body temperature and evidence of systemic spread like lymphadenopathy and limitation of mouth opening.

There are also a limited number of localized oral lesions that are indicated for antibiotic use and these include periodontal abscess, acute necrotizing ulcerative gingivitis, and pericoronitis. Other aspect of antibiotic over-prescribing is prescribing based on non-clinical factors. Patient’s expectation of an antibiotic prescription, convenience, and demand necessitated by the social background of the patients are considered unscientific reasons for antibiotic prescription. Whereas English and Scottish dentists would not prescribe for non-clinical factors8,9,31, dentists in the Eastern Mediterranean region have shown a tendency to prescribe on a patient-demand basis.

The most commonly used antibiotics in dental practice are penicillins, with the most commonly prescribed one being amoxicillin, followed by penicillin V, metronidazole, and the association amoxicillin-clavulanic acid. Penicillin is still the gold standard in treating dental infections. Among the group of penicillins, penicillin V, amoxicillin, and amoxicillin-clavulanic acid (co-amoxiclav®) have been advocated for the treatment of odontogenic infections.

The frequency of prescribing is usually mentioned in the known resources for antibiotic prescribing20. Duration of treatment recommended in therapeutic guidelines is commonly based on expert opinion. A survey in Canada found that the average duration of antibiotic use prescribed by dentists is 6.92 days20. Another survey in the USA found that endodontists prescribe antibiotics for an average of

7.58 days13,22. Recent studies on attitudes of dentists in the Eastern Mediterranean region showed that dentists preferred to prescribe a lower dosage of an antibiotic over a longer period1,15-18.

In recent years, more attention has been given to short courses3. It is frequently suggested that short-course antibiotic therapy requires that antibiotics have certain characteristics, such as rapid onset of action, bactericidal activity, lack of propensity to induce resistant mutants, easy penetrability into tissues, activity against non-dividing bacteria, not being affected by adverse infection conditions (low pH, anaerobiasis, presence of pus, etc.), administration at an optimal dose, and optimal dosing regimen. A two-dose, 3-gm regimen of amoxicillin has been shown to be effective in certain situations. On the other hand, oral antibiotic use for 2 or 3 days has been advocated for the treatment of acute dentoalveolar infections, and in doses recommended by the British National Formulary (BNF). Indeed, in some cases, patients improved after 2 or 3 days of antibiotic therapy.

In general, reducing the frequency of antibiotic intake (without compromising the dose) has yielded improved results: a twice-daily dosage of amoxicillin/clavulanic acid had several advantages over the three times-daily dosage, including increased convenience, improved compliance, and improved tolerability.

Additionally, antibiotic short courses are preferred to long courses particularly when treating children since children’s compliance with conventional courses is poor. A false conception about the use of antibiotics is that antibiotics should be used for a certain number of days to ‘kill the resistant strains’ as the vast majority of strains acquire resistance via transposable elements that are preferentially transferred when antibiotics are used in sub-therapeutic doses or for long durations. Therefore, antibiotics should be prescribed at the correct frequency, dose, and duration so that the minimal inhibitory concentration (MIC) is exceeded and side-effects and the selection of resistant bacteria are prevented. Prolonged courses of antibiotics destroy oral, pharyngeal, and gastro-intestinal commensal florae. Furthermore, longer durations of up to 21 days may result in the selection and development of resistant strains of bacteria and a reduction in the ability of the oral flora to resist the colonization by harmful micro-


organisms that are not normal residents, resulting to superimposed infections by multi-resistant bacteria and yeasts.

Prophylactic antibiotic prescribingProphylactic antibiotics, taken prior to a number of

dental procedures, have been advocated to reduce the likelihood of postoperative local complications, such as infection, dry socket (post-extractional alveolar osteitis) or serious systemic complications (e.g infective endocarditis). The evidence for antibiotics acting to prevent infection from surgical wounds in the mouth is poor to non-existent, indicating that preoperative parenteral antibiotic prophylaxis for routine third molar surgery in medically fit patients is unwarranted. It was also found that a single dose of metronidazole was ineffective in preventing the development of dry socket. For most dentoalveolar surgical procedures in fit, non-medically compromised patients, antibiotic prophylaxis is not required or recommended.

In the case of bacterial endocarditis, the absolute risk rate after dental treatment, even in at-risk patients, is considered very low. This is consistent with recent guidelines from the British Society for Antimicrobial Chemotherapy33 and the American Heart Association34 which recommend that only patients in the high risk category require antibiotic coverage: the basis for this recommendation is:

• There is no consistent association between having an intervention, dental or non-dental, and the development of bacterial endocarditis.

• Regular tooth brushing almost certainly presents a greater risk of bacterial endocarditis than a single dental procedure because of repetitive exposure to bacteremia with oral flora.

• The clinical effectiveness of antibiotic prophylaxis is not proven.

• Antibiotic prophylaxis against bacterial endocarditis for dental procedures may lead to anaphylaxis.

It is important to note that most studies on prophylactic antibiotic use were carried out in developed countries3,4,8-14,19,31 and the results generally indicated that dentists have a good knowledge of prescribing. Although, the few studies conducted in developing countries1,15-18 reported that abuse of

prophylactic antibiotics was to prevent postoperative infection following surgical dental manipulations or to cover either a defect in aseptic clinical technique or improperly sterilized equipment and instruments.

Antibiotic resistance in dental practiceBacteria have the ability to change and develop

resistance to antibiotics which is either plasmid- mediated or maintained on the bacterial chromosome; this can happen in several ways including production of bacterial enzymes which inactivate antibiotics, modifications in the bacterial cell walls rendering them impermeable to antibiotics, activation of drug efflux pumps reducing the concentration of antibiotics in bacterial cells, and alterations in target sites for antibiotics.

The main reasons of growing antibiotic resistance21,23,31,32 include: overprescription of antibiotics in humans as well as livestock and fish farming, patients not completing their course of treatment, self-prescription including use of left-over antibiotics, poor hygiene and sanitation, and inadequate infection control in healthcare facilities including hospitals and clinics.

Unfortunately, there is lack of new antibiotics to target the growing populations of resistant bacteria. Current research is focused on developing alternate and new treatments to tackle antibiotic resistance including the use of probiotics, vaccines, bacteriophage therapy, inhibitors of drug efflux pumps, photodynamic therapy, and new classes of antimicrobial agents. However, most of these treatments are still under development and antibiotic resistance remains a massive challenge.

Most dental problems do not warrant antibiotic prescriptions and are best managed with appropriate operative treatment. Antibiotics should only be used as an adjunct to operative intervention when strictly indicated. Moreover, antibiotics do not compensate for poor operative treatment. When prescribing, dental practitioners need to consider dosage, duration, and recognition of adverse effects / contra-indications of antibiotics. Any temptation to prescribe antibiotics due to patients insisting on antibiotics must be avoided.

Dental pain resulting from pulpitis and localised endodontic infection does not warrant use of antibiotics and should be managed by operative treatment (root


canal treatment / tooth extraction if indicated) with appropriate analgesic coverage. Similarly, localised dental abscesses due to a pulpal or periodontal cause are treated by establishing drainage using appropriate methods (pulp access opening; surgical incision, or extraction of the offending tooth). Lastly, mild pericoronitis and dry socket (alveolar osteitis) do not require antibiotics and can be managed conservatively with curettage, irrigation, and analgesics.

Antibiotics may be required19 for patients presenting with acute necrotizing ulcerative gingivitis, aggressive generalized periodontitis, severe pericoronitis, rapidly progressing diffuse infection involving fascial spaces, severe limitation of mouth opening, and jaw osteomyelitis.

Patients with signs of a spreading orofacial infection should be referred to secondary care urgently and should not be managed in primary care. Indications for referral include: difficulty in breathing/swallowing due to diffuse swelling, severe malaise or toxic appearance with elevated temperature (>390C), severe limitation of mouth opening, compromised host defences, and need for a general anaesthetic.

Allergies to antibiotics in dental practiceAdverse reactions to antibiotics prescribed or

administered in dental practice can be worrying. Most of these reactions are somewhat predictable based on the pharmacodynamic properties of the drug. Others, such as allergic and pseudoallergic reactions, are generally unpredictable and unrelated to normal drug action35,36,37.

Penicillins and cephalosporins are the most commonly used antibiotics in dental practice. Both have been confirmed as producing allergic and pseudoallergic reactions, but the actual incidence is well overstated35. As many as 1 in 10 patients reports a history of allergy to penicillin, but up to 90% of these are able to tolerate penicillin and are designated ‘‘penicillin allergic’’ unnecessarily. Many patients claiming history of allergy to penicillin can tolerate cephalosporins. One might also consider the time elapsed since the allergic reaction occurred. It is not unusual for adults to offer a vague history of reaction as a child. Approximately 50% of patients with actual IgE reactions to penicillin lose their sensitivity after 5 years, and this increases to

80% after 10 years38.Issues regarding the potential for cross-allergenicity39

between penicillins and cephalosporins were formerly thought related to the beta-lactam ring, but recent evidence has established that they are related more to similarities in the R side chains. It is generally accepted that patients having a history of IgE-mediated reaction to a penicillin drug should be managed using a non-beta-lactam antibiotic. Urticaria (hives) is IgE-mediated but accounts for only 10% of all exanthematous drug reactions. The overwhelming majority of cutaneous reactions to penicillins are pruritus or rash, and these are not IgE-mediated. Any potential for cross-reaction is unlikely. Although macrolides and clindamycin are conventionally considered the alternatives of choice in patients allergic to penicillins, the macrolides have become less attractive. It is preferable to substitute an alternate penicillin or cephalosporin for a patient claiming penicillin allergy, provided the nature of the reaction was merely pruritic (itch) or a maculopapular rash. A history of urticaria (hives) or anaphylactoid symptoms are more convincing evidence that the patient’s reaction to penicillin was truly IgE mediated, and in this case, there is little recourse but to refrain from prescribing any beta-lactam derivative.

Allergic or pseudoallergic reactions to other classes of antibiotics used in dentistry are more uncommon and less understood. Nonetheless, clinical reports of such reactions do appear in literature. Simply stated, a patient’s claim of a cutaneous reaction or airway compromise leaves little recourse but to avoid prescribing the offending drug.

RECOMMENDATIONSDrainage is the recommended treatment for

localized dentoalveolar abscess. Empirical antibiotic therapy and drainage are recommended for more severe infections such as facial cellulitis, pericoronitis, lateral periodontal abscess, and necrotizing ulcerative gingivitis. The type of antibiotic chosen and its dosing regimen are dependent upon the severity of infection and the predominant type of causative bacteria.

According to the BNF, amoxicillin is recommended for dental infections in doses ranging from 250 mg to 500 mg, every 8 hours. The use of 3 g amoxicillin repeated after 8 hours is also mentioned as a short course of oral


therapy. Another drug that is also recommended by the BNF is the association of amoxicillin with clavulanic acid, which can be used in doses ranging from 375 mg to 625 mg every 8 hours. However, in patients allergic to penicillin, clindamycin can be used in doses ranging from 150 mg to 450 mg every 6 hours. Another option for penicillin-allergic patients as recommended by the BNF is metronidazole, which can be used in a dose of 200 mg to 400 mg every 8 hours, for 3–7 days.

For severe odontogenic infections, higher doses of a broad-spectrum antibiotic may be required. Lewis3 has shown that only 5% of the main isolates from dental abscesses are resistant to amoxicillin/clavulanic acid.

Amoxicillin/clavulanic acid and clindamycin are the only orally administered antimicrobials with adequate pharmacokinetic/pharmacodynamic properties to be effective against the most commonly isolated oral pathogens for the treatment of orofacial infections2,6,40,41.

Patients who are allergic to penicillin should benefit from clindamycin40,41; it is active against some oral anaerobes and facultative bacteria and has the advantage of good bone penetration. However, increasing the dose may increase the possibility of serious side-effects such as pseudomembranous colitis, Sweet’s syndrome, and neutropenia.

Infections with predominant anaerobic bacteria such as pericoronitis, periodontal abscess, and necrotizing ulcerative gingivitis are better treated with metronidazole.Other inflammatory/painful oral conditions such as cracked tooth, dentine hypersensitivity, and bacterial sialadentitis are outside the scope of this paper.

In addition to the proper dosing regimens and professionally responsible prescribing practices, the general public needs to be educated about the importance of restricting the use of antibiotics to only cases of severe infections. Patients have become used to being given an antibiotic for a range of medical complaints. Unfortunately, patients presenting at dental surgeries also routinely expect an antibiotic for the treatment of toothache.

Dental patients not only pressure their dentist to get an antibiotic prescription, but they often self-medicate; self-medication with antibiotics was found to be alarmingly high in some developing countries.

In conclusion, prescribing practices of dentists can be improved by increasing awareness among them on the

recommended guidelines. Furthermore, the importance of initiating awareness programs among the general public should be encouraged.

REFERENCES1. Dar-Odeh N, Ryalat S, Shayyab M, Abu-Hammad O. Analysis of clinical records of dental patients attending Jordan University Hospital: documentation of drug prescriptions and local anesthetic injections. Ther Clin Risk Manag 2008;4(5):1111-1117.2. Laskin DM, Laskin JL. Odontogenic infections of the head and neck. In: Laskin DM, editor. Oral and maxillofacial surgery. St Louis: Mosby; 1985. pp. 219–252.3. Lewis MA. Why we must reduce dental prescription of antibiotics: European Union Antibiotic Awareness Day. Br Dent J. 2008;205(10):537–538. 4. Cleveland JL, Kohn WC. Antimicrobial resistance and dental care: a CDC perspective. Dental Abstracts 1998;43:108-110.5. Sweeney LC, Dave J, Chambers PA, Heritage J. Antibiotic resistance in general dental practice - a cause for concern. J Antimicrob Chemother 2004;53:567-576. 6. Swift JQ, Gulden WS. Antibiotic therapy – managing odontogenic infections. Dent Clin North Am 2002;46:623–633. 7. Wise R, Hart T, Carrs O, et al. Antimicrobial resistance is a major threat to public health. BMJ 1998;317:609-610. 8. Palmer NO, Martin MV, Pealing R, Ireland RS. An analysis of antibiotic prescriptions from general dental practitioners in England. J Antimicrob Chemother 2000;46:1033–1035. 9. Palmer NO, Martin MV, Pealing R, Ireland RS. Paediatric antibiotic prescribing by general dental practitioners in England. Inter J Paediatr Dent 2001;11:242–248. 10. Addy M, Martin MV. Systemic antimicrobials in the treatment of chronic periodontal diseases: a dilemma. Oral Dis 2003;9(Suppl 1):38–44. 11. Demirbas F, Gjermo PE, Preus HR. Antibiotic prescribing practices among Norwegian dentists. Acta Odontol Scand 2006;64(6):355-359. 12. Al-Haroni M, Skaug N. Incidence of antibiotic prescribing in dental practice in Norway and its contribution to national consumption. J Antimicrob Chemother 2007;59(6):1161-1166.13. Epstein JB, Chong S, Le ND. A survey of antibiotic use in dentistry. J Am Dent Assoc 2000;131(11):1600–1609. 14. Jaunay T, Sambrook P, Goss A. Antibiotic prescribing practices by South Australian general dental practitioners. Aust Dent J 2000;45(3):179-186.15. Salako N, Rotimi VO, Adib SM, Al-Mutawa S. Pattern of antibiotic prescription in the management of oral diseases among dentists in Kuwait. J Dent 2004;32:503–509. 16. Al-Mubarak S, Al-Nowaiser A, Rass MA, et al. Antibiotic prescription and dental practice within Saudi Arabia; the need to reinforce guidelines and implement specialty needs. J Int Acad Periodontol 2004;6(2):47–55. 17. Al-Haroni M, Skaug N. Knowledge of prescribing antimicrobials among Yemeni general dentists. Acta Odontol Scand 2006; 64(5):274–280.


18. Dar-Odeh NS, Abu-Hammad OA, Khraisat AS, El Maaytah MA, Shehabi A. An analysis of therapeutic, adult antibiotic prescriptions issued by dental practitioners in Jordan. Chemotherapy 2008; 54(1):17–22. 19. Öcek Z, Sahin H, Baksi G, Apaydin S. Development of a rational antibiotic usage course for dentists. Eur J Dent Educ 2008;12:41-47. 20. Ogunbodede EO, Fatusi OA, Folayan MO, Olayiwola G. Retrospective survey of antibiotic prescriptions in dentistry. J Contemp Dent Pract 2005;6(2):64–71. 21. Standing Medical Advisory Committee Subgroup on Antimicrobial Resistance (1998). The Path of Least Resistance. The Stationery Office, London, UK.22. Austin DJ, Kristinsson KG, Anderson RM. The relationship between the volume of antimicrobial consumption in human communities and the frequency of resistance. Proceedings of the National Academy of Sciences 1999;96:1152-1156.23. O’Connor BC, Newman HN, Wilson M. Susceptibility and resistance of plaque bacteria to minocycline. J Periodontol 1990;61:228-233. 24. Stjernquist-Desatnik A, Samuelsson P, Walder M. Penetration of penicillin V to tonsillar surface fluid in healthy individuals and in patients with acute tonsillitis. J Laryngol Otol 1993;107:309-312.25. Nelson JD, Ginsburg CM, McLeland O, et al. Concentrations of antimicrobial agents in middle ear fluid, saliva and tears. Int J Pediat Otorhinolaryngol 1981;3:327-334.26. Henry J, Turner P, Garland M, et al. Plasma and salivary concentrations of erythromycin after administration of three different formulations. Postgrad Med J 1980;56:707-710.27. Ducci M, Scalori V, del Tacca M, et al. The pharmacokinetics of two erythromycin esters in plasma and in saliva following oral administration in humans. Int J Clin Pharmacol Ther Toxicol 1981;19:494-497.28. Malizia T, Tejada MR, Ghelardi E, et al. Periodontal tissue disposition of azithromycin. J Periodontol 1997;68:1206-1209.29. Blandizzi C, Malizia T, Lupetti A, et al. Periodontal tissue disposition of azithromycin in patients affected by chronic inflammatory periodontal diseases. J Periodontol 1999;70:960-966.30. Malizia T, Batoni G, Ghelardi E, et al. Interaction between piroxicam and azithromycin during distribution to human periodontal tissues. J Periodontol 2001;72:1151-1156.31. Priest P, Yudkin P, McNulty C, et al. Antibacterial prescribing and antibacterial resistance in English general practice: cross sectional study. Brit Med J 2001;323:1037-1041.32. Carrie AG, Zhanel GG. Antibacterial use in community practice - Assessing quantity, indications and appropriateness, and relationship to the development of antibacterial resistance. Drugs 1999;57:871-881.33. Cahill TJ, Dayer M, Premdergast B, Thornhill M. Do patients at risk of infective endocarditis need antibiotics before dental procedures? Brit Med J 2017;358:j3942.doi:10-1136/bmj-j3942.34. Antibiotic prophylaxis 2017 update. AAE quick reference guide. American Association of Endodontists 2017; Pages 1-3.

35. Romano A, Warrington R. Antibiotic allergy. Immunol Allergy Clin North Am 2014;34(3):489-506.36. O'keefe A, Ben-Shoshan M. Diagnostic challenges, the evaluation of antibiotic allergy. Curr Opin Otolaryngol Head Neck Surg 2017;25(3):252-254.37. Caimmi S, Caimmi D, Lombardi E, et al. Antibiotic allergy. Int J Immunopathol Pharmacol 2011;24(3 Suppl):S47-53.38. Pongdee T, Li JT. Evaluation and management of penicillin allergy. Mayo Clini Proc 2018 [Epub ahead of print].39. Buonomo A, Nucera E, Pecora V, et al. Cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins. J Investig Allergol Clin Immunol 2014;24(5):331-337.40. Addy LD, Martin MV. Clindamycin and dentistry. Brit Dent J 2005;199(1):23-26.41. Bhargava D. Are we under-estimating first line drug regimes of beta-lactam antibiotics clindamycin and metronidazole in dental and oral and maxillofacial infections? Ann Maxillofac Surg 2013;3(1):104-105.

Corresponding author:Hala [email protected]@hotmail.co.ukwww.askhala.com

47

INTRODUCTIONMost cases of dento-alveolar trauma occur in

maxillary incisor area1. Patients' high expectations and demands make dental fractures a big challenge in our daily practice. A clinical approach is presented here in accordance with the principles of minimally invasive dentistry.

CASE REPORTA twenty-nine-year-old Caucasian woman presented

at the University Dental Clinic of the International University of Catalunya with a chief complaint: “I hate my black teeth and I do not like my smile”. Patient

referred to a trauma with a wooden chair fifteen years ago: at that time, tooth 11 was endodontically treated along with composite fillings on teeth 11 and 12.

ExaminationFollowing the university protocol (based on the

Fradeani’s esthetic analysis2), all the necessary facial and intra-oral photographs were taken. For the extra-oral analysis, a front and lateral photographs were taken to evaluate nasolabial angle, convex profile, and facial proportions. Three closer photos captured rest position, social smile, and forced smile, revealing a high lip-line with 2-3 millimeters of gum exposure (Fig. 1). No other relevant information was taken from intra-oral analysis in static and dynamic photos.

Hard and soft tissues were analyzed in a close-up photo; this view displayed unesthetic ancient class IV composite restorations on both maxillary right incisors. Zenith point and teeth axes were normal and the old fillings in maxillary right central and lateral incisors had a correct shape, but there was a high degree of

Esthetic management of a dental trauma: A case report.

Ramón Serrat Barón1, DDS, MSc.,Joan de Ribot Porta2, DDS, MSc.,Luís Jané Noblom3, DDS, MD, Ph.D, MEAED, MSEPE, MSEOC,Akram Hussein Ali4, DDS, PhD

AbstractThis paper addresses the treatment of a twenty-nine-year-old woman who presented at the dental clinic of the

International University of Catalunya, Spain, complaining of a dark tooth. She had undergone a root canal treatment fifteen years ago following a trauma to her maxillary right central incisor. Heavy discoloration of both maxillary right incisors was present at that time also, due to unesthetic ancient class IV composite restorations on both teeth. After complementary radiographic and esthetic studies, decision was made to perform internal and external tooth bleaching using 16% carbamide peroxide for ambulatory use. Subsequently, composite restorations were replaced for better esthetic and functional integrations.

Results showed that combination of internal and external tooth bleaching helps achieving a favorable esthetic appearance. The use of direct composite restorations can be an efficient tool to achieve patients' expectations, following the principles of minimally invasive dentistry. Accurate diagnosis and treatment planning allow predictable, optimal, and satisfactory results.

1,2,3,4. Department of Odontology, Faculty of Dentistry, Universitat Internacional de Catalunya -UIC-, Barcelona, Spain1. Clinical Instructor of Esthetic and Restorative Dentistry2. Associate Professor of Esthetic and Restorative Dentistry, Masters Program3. Professor and Director of the Esthetic and Restorative Dentistry, Masters Program4. Professor and Coordinator of the Esthetic and Restorative Dentistry Masters Program

Restorative and Esthetic Dentistry



discoloration and disharmony (Fig. 2).Orthopantomogram and cast models were analyzed

as well but didn’t add any relevant information for the case. Having a thorough idea of patient’s demand and possible treatment planning, a specific analysis was carried out: transillumination photo to study the possible dentine anatomy, black and white photo to determine the tooth value (Fig. 3), and a spectrophotometric study3 for color evaluation (Fig. 4).

At this stage, three points needed to be studied: 1. The root canal treatment of 11 (done fifteen years

ago).

Fig. 1. Full smile analysis of the patient.

Fig. 3. Black and white photograph.

Fig. 5. Etching the cavity. Fig. 6. Flowable composite application. Fig. 7.Etching the cavity again.

Fig. 2. Intra-oral analysis.

Fig. 4. Spectrophotometric analysis.

Fig. 8. Table comparing results.


2. The best technique to achieve a good shade on 11 discoloration.

3. The high esthetic expectations of the patient.For a complete evaluation of tooth 11, patient was

referred to the endodontic department. There was no sign of vitality and no tenderness to percussion. Tooth was asymptomatic for the last fifteen years. Since Cone Beam Computed Tomography -CBCT- showed statistically larger number of periapical radiolucencies than did periapical radiographs4,5, a CBCT scan was taken. Despite a radiographically average root canal treatment, no periapical lesion was observed. Endodontic retreatment was suggested but rejected by the patient.

Internal and external bleaching are non-invasive techniques used to change the shade for a favorable esthetic appearance. Three materials were discussed and searched in the literature: a first option was sodium perborate, which was declined because it has been banned in cosmetic products by European Union legislation after being classified as carcinogenic, mutagenic, or toxic for reproduction (CMR) in December 2010; as a second option, we considered the use of hydrogen peroxide, but due to possible recession of the intertubular dentine surface6, and to prevent possible cervical resorption, hydrogen peroxide was rejected. The material chosen was 10-16% carbamide peroxide due to its lower concentration and risk.

Treatment planningDifferent restorative options were suggested: indirect

porcelain veneers, indirect composite veneers, or direct composite restorations on 12 and 11. Advantages and disadvantages were exposed for each option and patient chose direct composite.

The sequence of final treatment planning was as following:

1. Palatal preparation for the access of internal bleaching material,

2. Internal and external bleaching processes,3. Evaluation of bleaching outcome, and4. Direct composite filling on 12 and 11.Palatal cavity was prepared under rubber dam

isolation. Root filling was reduced 1-2 mm below the cemento-enamel junction7,8, adhesion protocol was followed, and the floor was sealed with flowable

composite (Figs. 5, 6). An Endo-Z carbide bur was used to clean the cavity walls and a last application of orthophosphoric acid removed the smear layer.

16% carbamide peroxide was chosen as an at-home internal and external bleaching agent. Patient was instructed to apply the material in the palatal cavity every 2 hours until desired bleaching was achieved (it usually takes 1 to 2 days). That material was held in there with a custom-made bleaching tray that was used during the night for the external bleaching. This technique offers several advantages (faster, conservative), in comparison with conventional techniques and materials, and the only disadvantage is the patient’s non-compliance.

Three weeks later, results were evaluated and compared with the initial presentation: initial and final results are shown in a table based on the Color Guide VITA classical A1-D4® (Fig. 8), and photography (Fig. 9).

Direct composite restorations

Composite restorations were replaced: old restorations were removed with an Endo-Z bur and polishing discs were used. It was decided to save the palatal wall of the teeth (Fig. 10).

A light-curing, highly esthetic nano-hybrid composite filling material was used (IPS Empress Direct® by Ivoclar Vivadent). A color map was used on adjacent tooth in order to choose the most appropriate dentine and enamel shades (Fig. 11).

Under (dental) rubber dam isolation of teeth 13 to 23, both restorations were constructed after following the adhesion protocol, and sandblasting with 30 microns aluminum oxide was performed (Fig. 12). Palatal wall was reshaped with a silicon guide from cast model (Fig. 13). Then, two different layers of dentine were placed to recreate dentine mamelons (Fig. 14). An opaque resin was placed to cover up fracture line and tooth darkness. Opalescent resin was used in the incisal edge area to mimic the halo effect of contralateral tooth (Fig. 15).

The last layer of enamel was applied on tooth 11. It was important not to exceed maximum thickness of 0,5mm in order to avoid a greyish aspect of the restoration. We repeated the same procedure on tooth 12, taking into account the contact point


Fig. 9. Initial situation compared after internal and external bleaching treatments.

Fig. 12. Sandblasting.

Fig. 15. Opalescent resin application.

Fig. 18. Final aspect before finishing and polishing.

Fig. 21. Final polishing.

Fig. 13. Reshaping of palatal wall.

Fig. 16. Lateral contact point reconstruction.

Fig. 19. Transitional lines.

Fig. 22. Micro-texture.

Fig. 14. First layer of dentine.

Fig. 17. Final isolated aspect.

Fig. 20. Astropol® polishing system.

FIg. 10. Palatal wall preserved. FIg. 11. Color map and shade selection.


between maxillary right central and lateral incisors (Fig. 16).

The final aspect was analyzed with and without isolation, and the patient was advised to return in a week for final polishing (Figs. 17, 18).

During final polishing session, transitional lines were marked (Fig. 19). Following Ivoclar Vivadent® recommendations, Astropol® three-step polishing system was used to reshape angles and retouch length and volume (Fig. 20). Then, Micerium diamond paste shiny A and B and aluminum oxide paste shiny C were used for final polishing (Fig. 21). At last, a wear down Endo-Z bur was used to reproduce micro-texture and micro-anatomy present on buccal face of incisors (Figs. 22, 23).

CONCLUSIONAccurate diagnosis and treatment planning allow

a predictable, optimal, and satisfactory esthetic result. The use of 16% carbamide peroxide as a simultaneous external and internal bleaching agent helps achieving a favorable esthetic appearance. The use of direct composite restorations helps meeting high esthetic demands as well.

REFERENCES1. Andreasen JO, Ravn J. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1(5):235-239.2. Fradeani M. Esthetic analysis: a systematic approach to prosthetic treatment. Quintessence Publishing Company, 2004.3. Bentolila O, Roig M. Selección de color dental con la utilización del SpectroShade™ "Micro" Dental. Revista Odontológica de Especialidades 2009:04:04.

4. Abella F, Patel S, Durán-Sindreu F, Mercadé M, Bueno R, Roig M, Patel S. An evaluation of the periapical status of teeth with necrotic pulps using periapical radiography and cone-beam computed tomography. Int Endod J 2014 Apr;47(4):387-396.5. Estrela C, Bueno M, Leles CR, Azevedo B, Azevedo JR. Accuracy of cone beam computed tomography and panoramic and periapical radiography for detection of apical periodontitis. J Endod 2008 Mar;34(3):273-279.6. Chng HK, Ramli HN, Yap AU, Lim CT. Effect of hydrogen peroxide on intertubular dentine. J Dent 2005 May;33(5):363-369.7. Plotino G, Buono L, Grande NM, Pameijer CH, Somma F. Nonvital tooth bleaching: a review of the literature and clinical procedures. J Endod 2008 Apr;34(4):394-407.8. Attin T, Paqué F, Ajam F, Lennon AM. Review of the current status of tooth whitening with the walking bleach technique. Int Endod J 2003 May;36(5):313-329.

Corresponding author:Akram Hussein [email protected]

Fig. 23. Initial aspect (at left) compared with final result (at right).

53

INTRODUCTIONOcclusal vertical dimension (OVD) is defined as the

distance between two points measured in maxilla and mandible when teeth are in maximum intercuspation1. This distance is usually measured between nasal tip and gnathion2.

According to Matsumoto’s classification3, OVD can be divided into 3 classes:

Class I: The OVD is maintained by tooth contact; this situation extends from complete dental arches to the most extreme situation where only two antagonistic teeth are in contact.

Class II: Despite the presence of teeth, none of them come in contact with their antagonist; thus, the OVD cannot be maintained because there is no inter-arch

contact.Class III: Occlusal contact is totally absent as one of

the arches is completely edentulous3. OVD is increased or altered in full occlusal

rehabilitations for gaining space for the planned restorations4. This loss of prosthetic space is frequently caused by tooth wear. Gradual wear of tooth surface is a physiological process5, unlike excessive occlusal wear which is pathological6. In many cases, loss of OVD is compensated by tooth eruption and alveolar bone growth7. Nevertheless, in case of lost OVD, full rehabilitation should be carried out to restore the physiological one.

It is suggested that any alteration in OVD during restorative procedures is deemed unsafe to the stomatognathic system. In fact, some authors assert that expected consequences of increasing OVD include hyperactivity of masticatory muscles, elevation of bite force, and occurrence of temporomandibular disorders8. However, basic uncertainties and erroneous concepts regarding the outcomes of increasing OVD still prevail.

Outcomes of increased occlusal vertical dimension on the stomatognathic system: A systematic review.

Amine El Zoghbi1, Dr. Chir. Dent., DU Occlusodont., DEA, Dr. Univ., MEACMD, MCNO,Ranim Abou Chakra2, Dr. Chir. Dent., DU Occlusodont., Lory Abrahamian3, Dr. Chir. Dent., DU Occlusodont., DU Oral Pathol., Ghina Daoud4, Dr. Chir. Dent., DU Occlusodont.

AbstractObjective: To review the outcomes of increasing occlusal vertical dimension (OVD) on the stomatognathic system

including temporomandibular joint (TMJ) and masticatory muscles.Materials and Methods: A search in PubMed and MEDLINE was conducted in which the keywords ‘occlusal

vertical dimension’, ‘altered vertical dimension’, ‘increasing vertical dimension’, ‘rehabilitation’, ‘adverse effects’, ‘temporomandibular joint’, ‘masticatory muscles’ and ‘stomatognathic system’ were included. Literature search was further supplemented with a manual search of peer-reviewed journals and reference lists of selected articles.

Results: A total of 50 articles were initially retrieved, but only 13 of them met the specific inclusion criteria. The results of the studies regarding the effects of increasing OVD were screened for the following 4 subcategories: on TMJ, on masticatory muscles, on function and esthetics, and on implant-supported restorations.

Conclusion: Considering the limitations of this review, it could be concluded that since the stomatognathic system adapts well, OVD can be safely increased up to 5 mm whenever indicated.

1,2. Department of Fixed Prosthodontics and Occlusion, Saint-Joseph University Faculty of Dental Medicine, Beirut, Lebanon1. Associate Professor2. Resident, Master's Degree Program in Prosthodontics3. Resident, Master's Degree Program in Periodontology, Saint-Joseph University Faculty of Dental Medicine, Beirut, Lebanon4. Private practice, Beirut, Lebanon

Occlusal Rehabilitation



The aim of this systematic review is to assess the outcomes of an increased OVD on the stomatognathic system.

MATERIALS AND METHODSReview Protocol

Our review aimed to analyze a miscellany of studies investigating the outcomes of increased OVD on the stomatognathic system in adult patients. Prior to the review, the protocol was developed and agreed upon by the investigators. The PICO (Population, Intervention, Control, Outcome) format was used in formulating the research question. Investigated subjects, selected from the adult population, received an OVD increase treatment. No control or comparison group was selected, and the reviewed outcome mainly consisted of reviewing the adverse effects. Consequently, the formulated review question was, ‘What are the outcomes of increasing OVD in adults?’

Search StrategyAn electronic literature search in PubMed and

MEDLINE was conducted to identify articles meeting inclusion criteria. Investigators (RAC, LA, and GD) independently searched and reviewed the titles and abstracts of 50 retrieved articles. Outcomes of the following keywords were combined: ‘occlusal vertical dimension’, ‘altered vertical dimension’, ‘increasing vertical dimension’, ‘rehabilitation’, ‘adverse effects”, ‘temporomandibular joint’, ‘masticatory muscles’, and ‘stomatognathic system’. No publication year filter was applied. The electronic search was supplemented with a manual search of the following journals: Journal of Oral Rehabilitation, Journal of Prosthetic Dentistry, and Quintessence International. Furthermore, the references of each selected article were reviewed for possible inclusion.

Article SelectionFor the purpose of the present systematic review,

investigators agreed on including experimental studies that reviewed the effects of increasing OVD as well as literature reviews. Animal studies were also considered for review. All articles published before the year 2000 were excluded. Observational studies and case reports were excluded as well (Fig. 1).

RESULTS1. Effects of increasing OVD on TMJ

In 2015, Moreno-Hay and Okeson9 conducted a comprehensive review of the current scientific evidence regarding the effect of altering OVD on producing symptoms of temporomandibular disorders (TMDs); results of the review addressing the effects of increasing OVD did not suggest that increased OVD leads to the development, aggravation, or perpetuation of TMD symptoms. Authors concluded that the stomatognathic system adapts when OVD is increased (< 5 mm) and that further studies are needed in order to better understand the process of adaptation9. In some patients, mild transient symptoms of TMD may occur, but they are often self-limiting and without any major consequence.

In a systematic review of 9 studies in which OVD was increased using both fixed and removable methods, Abduo8 (2012) found that TMD signs and symptoms as well as muscle and joint fatigue had been reported in only one study; the author concluded that, within the limitations of his review, permanent increase of OVD of up to 5 mm, whenever indicated, is a safe and predictable procedure that does not cause any detrimental consequence8.

Fig. 1. Flowchart of the selection of studies for our review.


2. Effects of increasing OVD on masticatory musclesChandu and co-workers10 (2004) studied the

effect of increasing OVD on bite force and masseter electromyography in patients with temporomandibular pain dysfunction disorders (TMPD); they used an interocclusal appliance (IOA) to increase OVD in the test group (TMPD: n = 10) comparing it to a control group (n = 8): they found a decrease in masseter electromyography (EMG) activity during clenching at greater vertical dimensions in patients with TMPD while at-rest EMG activity was greater compared to that of the control group10.

In an animal study, Yabushita and associates11 (2006) investigated the changes in masseter muscle spindle function over periods of 1 day to 8 weeks following OVD increase; thirty-five female albino rats were used; rats were randomly divided into a control group (n = 10) and an increased OVD group (with a 2-mm resin buildup between mandibular and maxillary molars) (n = 25): Results did not show any significant differences among the one-day, two-week, four-week, six-week, and eight-week subgroups in dynamic index (to test the muscle-spindle speed sensitivity) in the control group, while there was a significant decrease of masseter muscle-spindle sensitivity up to 2 weeks after the establishment of an increased OVD condition. Both the dynamic index and the static index (to test the length sensitivity) of masseter muscle spindles were able to recover to their original values in 4 to 6 weeks of increased OVD11.

In 2009, Ohnuki and co-workers12 analyzed the effects of increased OVD on daily activities and fiber-type compositions in jaw muscles; they measured the total duration of daily activity (duty time) in the masseter and digastric muscles of freely moving control group (n=6) and bite-opened rats group (by 3mm) (n=6); they found that bite opening appliance changed EMG activity of masseter and digastric muscles from alternating to overlapping during mastication, without changing the chewing cycle. Authors concluded that increasing the OVD caused muscular hyperactivity in the masseter muscle12.

In a study conducted on guinea pigs (2011), Kanayama and associates13 investigated whether a short-term and reversible increase in OVD, followed by a reduction in OVD to the normal level, resulted

in a time-correlated change in EMG activities of masseter and digastric muscles during chewing; the burst durations of both muscles and chewing rhythm were not significantly affected by the change in OVD during the experimental period. And within the limited recording period of the study, the return of OVD from increased to normal levels did not reverse the increased chewing-related masticatory muscle EMG activity that was induced by the bite-raising treatment13.

Terebesi and co-workers14 (2016) tested 20 healthy subjects to determine if changes in vertical jaw relation induced differential localized recruitment of motor units (MU) in the masseter during biting; the study revealed that small vertical jaw relation changes significantly affected the nature of MU recruitment in the subvolumes of masseter. In addition, EMG activity decreased with raising vertical distance despite the development of a constant bite force14.

Nanda and associates15 (2011) conducted a clinical trial on 10 patients in which they raised OVD with removable splints and measured the EMG of anterior temporalis and masseter muscles prior to the initiation of treatment, immediately after placement of a splint and at subsequent recall visits, with and without the splint; results showed that, after immediate insertion of the splint, an immediate drop in muscle activity was recorded at both postural rest and maximal voluntary clenching. This study advocates using reversible means to increase OVD for a minimum period of 3 months prior to carrying out an irreversible intervention to achieve neuromuscular deprogramming aiming at allowing the muscle to adapt to the new postural position and attain stability in occlusion following splint therapy15.

3. Effects of increasing OVD on function and esthetics- Effects on masticatory function

In the study conducted by Chandu and associates10 (2004), the effect of clenching was investigated with or without the presence of an inter-occlusal appliance (IOA) on bite force (BF) and masseter EMG in patients with TMPD disorders. As a result, the bite force significantly increased with increasing vertical dimension in healthy subjects10.

Olthoff and co-workers16 (2007) studied the immediate impact of OVD increase on masticatory


performance of dentate individuals, using anatomical maxillary splints. Masticatory performance of the subjects was determined via the use of the chewing test aiming at quantifying the degree of fragmentation of an artificial test food; authors found that masticatory performance was not significantly influenced by anatomical maxillary splints which increased OVD16.

MacAvoy and associates17 (2016) investigated the effects of acute changes in OVD on individual swallowing patterns in 10 volunteers; their investigation demonstrated that as OVD increased, the swallowing duration and the EMG activity of upper and lower lips significantly increased17.

Makiguchi and co-workers18 (2016) conducted a study to investigate the effects of increased OVD on the jaw-opening reflex (JOR) in mature rats; the JOR was recorded from digastric muscle; results showed that an increased OVD affected the latency and amplitude of the JOR, but not its duration. The JOR adapted after 10 weeks of increasing OVD18.

- Effects of increasing OVD on estheticsChou and associates19 (2014) evaluated the effects

of increasing OVD of 30 dental students (21-39 years old) with bite splints of 2 mm, 4 mm, 6 mm, and 8 mm thicknesses on the smile's dimension; at second session, the investigators observed an increase in the interlabial gap height, the incisal edge-to-lower lip distance, and the display zone following OVD increase. However, the smile index decreased while the width of the smile and the length of upper lip remained unchanged with an increased OVD19.

Orenstein and co-workers20 (2015) evaluated the effect of increasing OVD on lower face height and on facial esthetics of 20 students with overlays of 2 mm, 3 mm, 4 mm, and 5 mm; results of objective changes in lower face height and the subjective changes in facial esthetics were not statistically significant20.

- Effects of increasing OVD on implant-supported restorations

Ormianer and Palty21 (2009), in a non-randomized retrospective study, increased OVD of 30 patients who needed either implant- or tooth-supported fixed partial dentures by a range of 3 to 5 mm. A bone loss of 2 mm on buccal aspect of implants was noticed.

There were no other commonly reported mechanical complications such as screw loosening or component fractures; authors concluded that increasing OVD was an acceptable procedure in patients with implant-supported fixed restorations, but precautions should be taken to prevent mechanical problems, peri-implant bone loss, abutment and prosthesis screw loosening, loss of osseointegration, and fractures within the implant-restorative complex21.

Abduo and Lyons22 (2012) found that, despite adaptation of all patients to the increase of OVD, few of them with implant-supported prostheses suffered from prolonged grinding that resolved within 2 to 3 months following the use of an occlusal splint22.

DISCUSSIONThere is still considerable debate in the literature on

treatment modalities used to increase OVD and their effects on stomatognathic system. Throughout decades, it was believed that any alteration of OVD subsequently interferes with the physiology of masticatory system and patient’s ability to adapt. Reported consequences of increasing OVD were hyperactivity of masticatory muscles, elevation in occlusal forces, bruxism, and temporomandibular disorders22.

In our review, we found that increasing OVD doesn’t seem to lead to the development, exacerbation, or perpetuation of TMD symptoms, and that it is relatively safe to increase OVD up to 5 mm without witnessing any detrimental repercussion on TMJ. Both reviews by Moreno-Hay and Okeson9 (2015) and Abduo and Lyons22 (2012) concluded that the TMJ adapts to increased OVD. However, these results should be interpreted with caution because of the lack of adequate sample size, control groups, randomization, and long-term follow-up9,22.

Literature is filled with controversial results on the effects of increasing OVD on masticatory muscles. In fact, Ohnuki and co-workers12 (2009), and Kanayama and associates13 (2011) found that increasing OVD induced an increase in muscle EMG activity while Terebesi and co-workers14 (2016), and Chandu and associates10 (2004) found that EMG activity decreased after an OVD increase. The study of Yabushita and co-workers11 (2006) identified the adaptation of muscle activity 4 to 6 weeks subsequent to OVD increase.


The studies’ limitations were related to their design complexity and to the existence of confounding factors.

Moreover, the masticatory performance was not influenced by increased OVD16. On the other hand, bite force and swallowing duration increased with the vertical dimension10,17. However, these studies had different amounts of OVD increase as well as different treatment modalities.

Furthermore, we found that increasing OVD altered the smile's dimensions19 but failed to generate a change in lower face height and in the facial esthetics20. Thus, clinicians should not increase a patient’s OVD in fixed prosthetic rehabilitations based solely on the objective of favorably improving lower face height and facial esthetics. However, the participants included in this study20 didn’t have a loss of OVD preoperatively, and thus didn’t have a facial collapse. The results of these studies19,20 may be questioned, given that the variables measured were cutaneous landmarks and the samples were not homogeneous.

Based on the study conducted by Ormianer and Palty21 (2009), we inferred that increasing OVD is a safe procedure in patients with implant- supported fixed restorations. While there are few published researches on the ability of patients with implant-supported restorations to adapt to new OVD relationships, it is known that an increase in bite force and periodontal ligament (PDL) absence are two consequences of implant-supported restorations: together, these factors may reduce a patient’s ability to accommodate to OVD changes and adversely affect the survival of implants and their restorations21.

CONCLUSIONThis review demonstrates that the stomatognathic

system (comprising temporomandibular joint and masticatory muscles) may adapt well to OVD increment. Within the limitations of this review, we can claim that the following guidelines are worth to be considered:

First, it is safe to increase OVD in adult patients up to 5 mm in one stage. As to masticatory muscles, they would adapt 4 to 6 weeks subsequent to OVD increase.

Second, clinicians shouldn’t increase OVD for the sole purpose of improving esthetics.

Third, patients should be informed of the possible increase in the duration of swallowing.

In conclusion, due to the limited number of available studies and the heterogeneity of the experimental design, randomized, controlled, and adequately designed clinical studies are warranted to validate the outcome of this review.

REFERENCES1. Bloom DR, Padayachy JN. Increasing occlusal vertical dimension - why, when and how. Br Dent J 2006 March;200(5):251-256. 2. The Glossary of Prosthodontic Terms. J Prosthet Dent 2005 July;94(1):10-92.3. Discacciati JAC, de Souza EL, Vasconcellos WA, Costa SC, Barros V de M. Increased Vertical Dimension of Occlusion: Signs, Symptoms, Diagnosis, Treatment and Options. J Contemp Dent Pract 2013 Jan;14(1):123-128.4. Gopi Chander N, Venkat R. An appraisal on increasing the occlusal vertical dimension in full occlusal rehabilitation and its outcome. J Indian Prosthodont Soc 2011 Jun;11(2):77-81.5. Katsoulis J, Nikitovic SG, Spreng S, Neuhaus K, Mericske-Stern R. Prosthetic rehabilitation and treatment outcome of partially edentulous patients with severe tooth wear: 3-years results. J Dent 2011 Oct;39(10):662-671.6. Muts EJ, van Pelt H, Edelhoff D, Krejci I, Cune M. Tooth wear: A systematic review of treatment options. J Prosthet Dent 2014 Oct;112(4):752-759.7. Song MY, Park JM, Park EJ. Full mouth rehabilitation of the patient with severely worn dentition: a case report. J Adv Prosthodont 2010 Sept;2(3):106-110.8. Abduo J. Safety of increasing vertical dimension of occlusion: a systematic review. Quintessence Int 2012 May;43(5):369-380.9. Moreno-Hay I, Okeson JP. Does altering the occlusal vertical dimension produce temporomandibular disorders? A literature review. J Oral Rehabil 2015 Nov;42(11):875-882. 10. Chandu A, Suvinen TI, Reade PC, Borromeo GL. The effect of an interocclusal appliance on bite force and masseter electromyography in asymptomatic subjects and patients with temporomandibular pain and dysfunction. J Oral Rehabil 2004 Jun;31(6):530-537.11. Yabushita T, Zeredo JL, Fujita K, Toda K, Soma K. Functional adaptability of jaw-muscle spindles after bite-raising. J Dent Res 2006 Sep;85(9):849-853.12. Ohnuki Y, Kawai N, Tanaka E, Langenbach GEJ, Tanne K, Saeki Y. Effects of increased occlusal vertical dimension on daily activity and myosin heavy chain composition in rat jaw muscle. Arch Oral Biol 2009 Aug;54(8):783-789.13. Kanayama H, Masuda Y, Adachi T, Arai Y, Kato T, Morimoto T. Alteration of masticatory muscle EMG activities during chewing after a reversible bite-raising in guinea pigs. Arch Oral Biol 2011 Aug;56(8):793-798.14. Terebesi S, Giannakopoulos NN, Brüstle F, Hellmann D, Türp JC, Schindler HJ. Small vertical changes in jaw relation affect motor unit recruitment in the masseter. J Oral Rehabil 2016 Apr;43(4):259-268.


15. Nanda A, Jain V, Srivastava A. An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth. Indian J Dent Res 2011 Mar-Apr;22(2):303-308.16. Olthoff LW, van der Glas HW, van der Bilt A. Influence of occlusal vertical dimension on the masticatory performance during chewing with maxillary splints. J Oral Rehabil 2007 Aug;34(8):560-565.17. MacAvoy SK, Jack HC, Kieser J, Farella M. Effect of occlusal vertical dimension on swallowing patterns and perioral electromyographic activity. J Oral Rehabil 2016 Jul;43(7):481-487.18. Makiguchi M, Funaki Y, Kato C, Okihara H, Ishida T, Yabushita T, Kokai S, Ono T. Effects of increased occlusal vertical dimension on the jaw-opening reflex in adult rats. Arch Oral Biol 2016 Dec;72:39-46.19. Chou JC, Thompson GA, Aggarwal HA, Bosio JA, Irelan JP. Effect of occlusal vertical dimension on lip positions at smile. The J Prosthet Dent 2014 Sep;112(3):533-539.20. Orenstein NP, Bidra AS, Agar JR, Taylor TD, Uribe F, Litt MD. Changes in lower facial height and facial esthetics with incremental increases in occlusal vertical dimension in dentate subjects. Int J Prosthodont 2015 Jul-Aug;28(4):363-370.21. Ormianer Z, Palty A. Altered vertical dimension of occlusion: a comparative retrospective pilot study of tooth- and implant-supported restorations. Int J Oral Maxillofac Implants 2009 May-Jun;24(3):497-501.22. Abduo J, Lyons K. Clinical considerations for increasing occlusal vertical dimension: a review. Aust Dent J 2012 Mar;57(1):2-10.

Corresponding author:Amine El [email protected]@usj.edu.lb

59

INTRODUCTIONMandibular molars are the most frequently

endodontically-treated teeth1 and have complex root canal anatomy2, rendering the outcome of their root canal treatment less predictable. Touré and associates3 showed that more mandibular molars were extracted after root canal treatment than any other tooth. Common anatomy of mandibular molars (as described in the literature) comprises two roots, but occasionally it may have three, with two or three canals in the mesial root and one, two, or three canals in the distal one4.

Nevertheless, variations may be encountered, such as 3 mesial canals, 2 mesial canals with an isthmus, additional third D-L root, C-shape canal in the mandibular second molar; even the presence of 5, 6, and 7 canals were described in the literature5. Vertucci and Williams6 reported the presence of an independent middle mesial (MM) canal with a separate orifice and a separate apical foramen.

Studying internal anatomy of 22 mandibular molars using micro-CT* reconstruction, Harris and Bowles7 noticed the presence of an isthmus in 100% of the specimen and 36% of studied molars had more than two canals, de Pablo and associates8 found 2.3% of MM canal; Goel and co-workers9 found the MM in 15% of cases, and Nosrat and Raney10 found the MM

in 20% of studied molars.Age seems to be the most significant factor in locating

the MM canal10. In a recent in vivo study using CBCT**, Akbarzadeh and associates11 found that patients less than 42 years of age were 4 times more likely to have an MM canal compared with patients older than 42. Azim and co-workers12 concluded that high magnification, troughing, and patient age appeared to be determining factors in accessing the MM canal that was present in 46.2% of mandibular molars.

Pomeranz and associates13 described the anatomy of the MM canal as fin (the file passes freely between the main mesial canals), confluent (the MM canal originates as a separate orifice but apically joins the MB or ML canal), or independent (the MM canal originates as a separate orifice and terminates as a separate foramen). Most frequently, the MM canal is located closer to the ML canal13,14,15. In this paper, we are reporting 2 clinical cases of mandibular first and second permanent molars with 3 mesial canals in 2 Lebanese patients.

CASE REPORT 1: MANDIBULAR RIGHT SECOND MOLAR WITH 3 MESIAL CANALS

A 40-year-old male was referred for root canal treatment on mandibular right second molar (47). After clinical and radiographic examinations, tooth was diagnosed with symptomatic irreversible pulpitis. (Fig. 1).

Endodontic management of mandibular molars with three mesial root canals: Two case reports. Ziad Moujaes1, BDS, DU Oral Biol., CES Endo.,Roula Abiad2, BDS, MS Endo., Dr. Dent. Sc.

AbstractThe main objective of root canal therapy is complete cleaning, shaping, and three-dimensional filling of the root

canal system, which, in some cases, may display anatomical variations; it is important to be familiar with these variations that aid locating, negotiating, and managing canals during endodontic treatment. Magnification loupes and operating microscope can be helpful in the detection and negotiation of accessory mesial canals in permanent mandibular molars. This paper reports the endodontic management of a first and a second permanent mandibular molars with three mesial root canals.

1. Clinical Instructor, Division of Endodontics, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon2 . Assistant Dean, Assistant Professor of Endodontics, and Director, Division of Endodontics, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon

* CT = Computed Tomography** CBCT = Cone Beam Computed Tomography

Endodontics



After analgesia of right inferior alveolar nerve with mepivacaine (Scandonest® 2% special, Septodont) and placement of (dental) rubber dam, caries were removed with a round diamond bur, and access cavity was performed with an Endo-Z bur (Dentsply, Maillefer, Ballaigues, Switzerland).

First step was scouting the canals with a # 10 K-File (Dentsply, Maillefer, Ballaigues, Switzerland) and determining the working length of the 5 canals using the apex locator (Root ZX, Morita, Tokyo, Japan). Coronal flaring was accomplished with the One Flare (Micro Mega, France), followed by a copious irrigation with 5% NaOCl after each file. Apical shaping was done using a reciprocating SmartTrack™ X1 (25/06) (Nikinc dental, The Netherlands) for the main mesial canals, and a SmartTrack X1 (20/06) file for the MM canal; MM canal appeared to join ML canal at apex (confluent type) (Fig. 2).

Master cones used were non-standardized FM*** gutta percha (Meta Biomed, Korea), with an apical tug back and confirmed with a periapical radiograph. Obturation technique was warm vertical condensation using the system B (Sybronendo, Kerr Dental, Orange, California, USA) as a heat carrier and the Machtou pluggers (Dentsply, Maillefer, Ballaigues, Switzerland) for compaction (Fig. 3). Pluggers reached 5 mm coronally from apex and Sealite Ultra (Pierre Rolland, Merignac Cedex, France) was used as a sealer.

CASE REPORT 2: MANDIBULAR LEFT FIRST MOLAR WITH 3 INDEPENDENT MESIAL CANALS.

A 38-year-old male was referred for endodontic treatment of mandibular left first molar (36). Patient was asymptomatic, and after clinical and radiographic examinations, tooth was diagnosed with pulpal necrosis and asymptomatic apical periodontitis, hence endodontic therapy was started (Fig. 4).

Treatment was done without giving analgesia. After placement of (dental) rubber dam, caries were removed using stainless-steel round bur (Edenta, Liechtenstein) until pulp chamber was reached. Access cavity was done using Endo-Z bur (Dentsply, Maillefer, Ballaigues, Switzerland). Mesial cavity was sealed with Liquidam (Denu-Dam, Seoul, Korea) for better

Fig. 1. Pre-operative periapical radiograph showing the distal caries on tooth 47.

Fig. 2. The 3 mesial canals after cleaning and shaping.

Fig. 3. Three separate mesial orifices after obturation.*** FM = Fine Medium


Fig. 4. Pre-operative periapical radiograph showing mesial caries on tooth 36.

Fig. 7. Post-operative radiograph showing the 3 separate obturated mesial root canals.

Fig. 9. Three mesial roots as seen on CBCT (Vatech, Korea). Fig. 10. CBCT cross-section showing 3 obturated mesial canals.

Fig. 8. Four separate canal orifices after obturation.

Fig. 5. Periapical radiograph with K-file #10 showing the 3 files in the mesial canal and one in the distal canal.

Fig. 6. Three separate canal orifices in the mesial root after shaping.


hermeticity. Canals were then scouted with a # 10 K-file (Dentsply, Maillefer, Ballaigues, Switzerland) and working length was determined with apex locator (Root ZX, Morita, Tokyo, Japan) and confirmed with a periapical radiograph (Fig. 5).

Shaping was implemented with crown-down technique to minimize extrusion of bacteria to the periapex; coronal flaring was done with One Flare (Micro Mega, France), patency of the canals was confirmed, and shaping finished with reciprocation using SmartTrack™ files X1 (25/06) for MB and ML canals, and SmartTrack™ X1 (20/06) for the MM (Fig. 6). Copious irrigation with 5% NaOCl was necessary between instruments and final irrigation of canals was done with 17% EDTA for one minute followed by 5% NaOCl. Customization of non-standardized gutta-percha cones to fit apical diameters of canals preceded obturation. After vertical compaction of gutta-percha and sealer, obturation of all three mesial canals was confirmed (Figs. 7-8-9-10).

CONCLUSION

Knowledge of normal and atypical internal anatomy of root canals is of utmost importance for the success of endodontic treatment. Erroneous knowledge or lack of knowledge of anatomic variations and their three-dimensional aspects in different teeth is certainly a main cause of endodontic failure.

When root canal treatment is indicated, clinicians should be aware of the large variations of root canal anatomy. Different tools are available to predict variations such as careful examination of periapical radiographs or use of multiple radiographs in different angulations. Even more advanced methods such as CBCT could be used when complex anatomy is anticipated. Consequently, performing root canal treatment under high magnification using loupes and preferably microscope, will enhance practitioner's performance and increase success rate of endodontic treatment.

REFERENCES1. Hull TE, Robertson PB, Steiner JC, del Aguila MA. Patterns of endodontic care for a Washington state population. J Endod 2003 Sep;29(9):553-556.2. Hess W, Zürcher E. The anatomy of the root-canals of the teeth of the permanent and deciduous dentitions. New York: William Wood and Co; 1925.3. Touré B, Faye B, Kane AW, et al. Analysis of reasons for extraction of endodontically treated teeth: a prospective study. J Endod 2011;37(11):1512-1515.4. Hargreaves K, Berman LH. Cohen’s Pathways of the pulp. 11th ed. Edinburgh: Elsevier; 2016. p. 193-195.5. Polesel A, Castellucci A. Mandibular first molars with four canals: Report of two cases. Dentistry Today 2007 Dec;26(12):54-59.6. Vertucci FJ, Williams RG. Root canal anatomy of the mandibular first molar. J New Jersey Dent Assoc 1974;45(3): 27-28.7. Harris SP, Bowles WR. An anatomic investigation of the mandibular first molar using micro-computed tomography. J Endod 2013;39(11):1374-1378.8. de Pablo OV, Estevez R, Péix Sánchez M, et al. Root anatomy and canal configuration of the permanent mandibular first molar: A systematic review. J Endod 2010 Dec;36(12):1919-1931.9. Goel NK, Gill KS, Tanjea JR. Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev Dent 1991 Mar;8(1):12-14.10. Nosrat A, Raney J. Middle mesial canals in mandibular molars: incidence and related factors. J Endod 2015;41(1):28-32.11. Akbarzadeh N, Aminoshariae A, Khalighinejad N, et al. The association between the anatomic landmarks of the pulp chamber floor and the prevalence of middle mesial canals in mandibular first molars: An In Vivo analysis. J Endod 2017 Nov;43(11):1797-1801. 12. Azim AA, Deutsch AS, Solomon CS. Prevalence of middle mesial canals in mandibular molars after guided troughing under high magnification: An In Vivo Investigation. J Endod 2015;41(2):164-168.13. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod 1981 Dec;7(12):565-568.14. de Carvallo MC, Zuolo ML. Orifice locating with a microscope. J Endod 2000 Sep;26(9):532-534.15. Karapinar-Kazandag M, Basrani BR, Friedman S. The operating microscope enhances detection and negotiation of accessory mesial canals in mandibular molars. J Endod 2010 Aug;36(8):1289-1294.

Corresponding author:Ziad [email protected]

64

INTRODUCTIONPeriapical cyst (radicular cyst) is the most common

jaw cyst. It originates from the epithelial cell rests of Malassez, in association with inflammation, usually after the necrosis of dental pulp1. It is a slow-growing cyst with a tendency towards bone resorption. Generally, its size is around 0.5 to 1 cm but few cases of large cysts has been reported1,2. Radicular cyst commonly shows no sex or region preferences. Peri-radicular cysts have been regularly associated with carious non-vital teeth or teeth with a history of trauma2. A case of two adjacent radicular cysts in anterior mandible showing some atypical features is presented in this article.

CASE REPORTA 45-year-old male patient presented to our office

with an external fistula and a painless swelling in the submental region (Fig. 1). Patient noticed the swelling about a month ago during which it slowly increased to its current size. Submental (suprahyoid) and submandibular lymph nodes were enlarged and palpable. Patient had no significant past medical history.

During intraoral examination, a firm, diffuse, swelling of the vestibule was noticed, and extended from teeth 35 to 45. Teeth 32 to 42 and 34 were already restored with full ceramo-metallic crowns: cold thermal pulp testing was negative on these teeth while positive on teeth 43, 44, and 45. Patient reported a history of blunt trauma on mental region about ten years ago, with no particular external injuries.

Panoramic radiograph (Fig. 2) showed a large ovoid, bilocular, and well-defined first radiolucency extending from apical region of teeth 34 to 42 horizontally, and a second well-defined tunnel-shaped one extending laterally from apices of 41-42, and finishing in a round shape at the level of apical regions of teeth 43-44, with a separation from the first radiolucency. No radiological signs of root canal treatment were apparent.

A cone beam computed tomography (CBCT) was done in order to evaluate bucco-lingual extensions of

A clinical report on two adjacent mandibular radicular cysts: Radiographic computed analysis, differential diagnosis, and surgical treatment.

Georges Aad1, BDS, DU Oral Biol., DU Oral MaxFa. Radiol., DESS Oral Surg., Elie Abdo2, BDS, DU Oral Biol., DU Oral Surg.,Alexandre Khairallah3, BDS, DU Oral MaxFa. Radiol., DESS Oral Surg., MBAIRD, FEADMFR,Nabih Nader4, BDS, CES Oral Biol., CES Surg. Dent., CES Fixed Prostho., DU Perio.

AbstractRadicular cyst is the most common inflammatory odontogenic cyst affecting the jaws. It is usually due to a

periapical inflammatory process following bacterial insult. It usually arises from epithalial residues (cell rests of Malassez) in the periodontal ligament, as a consequence of inflammation, usually after the necrosis of dental pulp. Due to its chronic etiology, this cyst may undergo silent phases. It has no sex predilection and may involve any tooth. This article addresses a case of two adjacent radicular cysts in anterior mandible, their radiological features, differential diagnosis, management, and follow-up for a two-year period.

1. Clinical Instructor, Department of Oral Medicine and Dentomaxillofacial Radiology, Lebanese University, Faculty of Dental Medicine, Beirut, Lebanon.2. Associate Chief of Clinical Services, Department of Dentomaxillofacial Radiology, Lebanese University, Faculty of Dental Medicine, Beirut, Lebanon.3. Chief of Clinical Services, Department of Oral and Dentomaxillofacial Radiology, Lebanese University, Faculty of Dental Medicine, Beirut, Lebanon.4. Chief of Clinical Services, Department of Oral and Maxillofacial Surgery, Lebanese University, Faculty of Dental Medicine, Beirut, Lebanon, and Former Scientific Chairperson, Lebanese Dental Association, Beirut, Lebanon.

Oral Surgery



both lesions and the relations with right and left mental foramina and nerves. Panoramic reconstruction (Fig. 3) showed that apices of teeth 34-41 were in relation with both lesions. Cross-sectional cuts (Fig. 4) revealed buccal bone fenestration of 0.6 cm horizontally and 0.7 cm vertically in anterior mandible (cuts 63-68). No communication was noticed between both lesions (cut 58) or with mental foramina.

Root canal treatments of teeth 32 to 42 and 34 were done with rubber dam isolation. After a complete biomechanical preparation, calcium hydroxide was used as an intracanal medication for one week. Three days prior to root canal treatment completion, a prophylactic antibiotic (amoxicillin) treatment was prescribed: Ospamox® 1000 mg (Sandoz; Novartis, Basel-Stadt, Switzerland), twice daily for 6 days. Non-

steroidal anti-inflammatory diclofenac potassium 50 mg (Cataflam® 50; Novartis, Basel-Stadt, Switzerland) was also prescribed for three days, divided into two daily doses of 100 mg, starting the day of surgery.

After administration of local analgesia (2% articaine with 1:100,000 adrenaline; 3M ESPE, Seefeld, Germany), intrasulcular incision was made, and it extended from teeth 46 to 36: a full-thickness flap sparing mental foramina was raised and the fenestrated bone site exposed (Fig. 5). The clinical situation confirmed the presence of two distinct bone lesions.

In order to have access to left lesion, an enlargement of the (left) present fenestration was done. The second lesion (on right side) was reached through an independent osteotomy. Granulation tissue was removed after curettage, and root ends of involved

Fig. 1. Clinical picture showing the external fistula.

Fig. 2. Panoramic radiograph showing the two radiolucencies.

Fig. 3. Panoramic reconstruction showing the relation between teeth and lesions and the absence of relation with right and left mental foramina.

Fig. 4. Cross-sectional cuts showing buccal perforation (cuts 63-68) and the relation between teeth and lesions.


teeth were resected (Fig. 6).Following homeostasis, flap closure was done using

4-0 nylon monofilament. One week after surgery, histopathological report confirmed the diagnosis of two infected radicular cysts.

Patient was instructed to follow a soft diet for 7 days after surgery, and to use 0.12% chlorhexidine gluconate mouthwash for 5 minutes after each meal, for 14 days. Sutures were removed 7 days after surgery.

Patient was recalled at intervals of 1 day, 3 days, 7 days, 1 month, 3 months, 6 months, 1 year, and two years after surgery.

Panoramic and 3D reconstructions (retrieved from a CBCT done one year later) showed significant bone formation (Figs. 7-8).

A panoramic radiograph done two years later

showed an almost total bone formation. (Fig. 9)

DISCUSSIONDue to pulp necrosis and presence of epithelial

residues (Malassez cell rests) after odontogenesis, radicular cysts develop in jaw bones1. Pulpal necrosis leading to inflammation appears to be the most frequent etiology of the radicular cyst2,3,4,8-10. A less known but possible cause of pulpal necrosis reported in the literature is the traumatic injury of teeth. In our case, the associated teeth were non-vital, while only first left mandibular premolar (34), left mandibular canine (33), and right mandibular canine (43) were vital. Patient reported a blunt trauma to the chin about ten years ago but no injury or bleeding occured at that time.

Pathogenesis of radicular cyst2-4,8,9,12 undergoes

Fig. 5. Clinical situation after flap raising: the left buccal fenestration can be seen.

Fig. 6. Clinical situation after enucleation of both lesions and apicectomies.

Fig. 7. One-year-post-operative panoramic reconstruction showing significant bone formation.

Fig. 8. One-year-post-operative 3D reconstruction.

Fig. 9. Two-year-post-operative panoramic radiograph showing an almost complete bone formation.


three phases of development: initiation, cyst formation, and enlargement. During initial phase and due to chronic inflammation, epithelial cell rests of Malassez (in the periodontal ligament) begin proliferating. As a result of pulp necrosis, debris and bacterial antigens start to accumulate. Meghji and associates13 studied radicular cyst, keratocyst, and follicular cyst’s fluids and cultured explants, and showed the existence of high levels of endotoxins in radicular cysts in comparison with other cyst types.

During second phase of radicular cyst development, a central cavity is formed within the proliferating epithelium by degeneration and death of cells. Grupe and co-workers14 reported high levels of acid phosphatase activity in central cells of apical granulomas, while Summers15 found a weak proteolytic activity present centrally within the proliferating epithelium: both studies suggest that these cells undergo autolysis.

The phase of growth and enlargement is the third phase of cyst development: absence of lymphatic drainage and contents of the cystic cavity are subjected to an osmotic imbalance with surrounding tissues, thus leading to a difference in pressure and constant growth2,3,12. Skaug16 suggested that cyst walls have many layers of diverse functions: vascular endothelium, basement membranes, ground substance, and lining epithelium.

Most cases of periapical cysts have been reported in the anterior maxilla;11,12 possible reasons for that are the spongy nature of maxillary bone and patient's reluctance to extract anterior teeth: over retention of these “diseased” teeth may lead to cyst formation. This prevalence has been confirmed by many studies1,10,11. Very few studies17,18 contradict the above findings and suggest that radicular cyst is more common in the mandible.

According to Wood, Goaz, and Jacobs3, most of radicular cyst cases show some history of trauma, poor oral hygiene, caries, retention of carious teeth, and no sex predilection. Sharifian and Khalili11 found that radicular cyst is 1.3 times more frequent in men, while Tortorici and associates10 found about 67% of these cysts in males. In our case, patient was a male with a history of blunt trauma to the chin, about ten years ago.

Generally, radicular cysts are limited radiolucent periradicular lesions associated with one or more carious teeth, attaining a size of 1-2cm. A few long-standing large radicular cysts (larger than 5 cm), have been reported2.

In our case, two different radicular cysts were present in mandible, extending (bilaterally) from 44 to 34; the right cyst had an unusual radiographic feature, resulting in an initial constriction leading to an ovoid locular image.

Periapical (radicular) cyst can rarely lead to lip paresthesia during its evolution. However, surgeries can be traumatizing to the inferior alveolar or mental nerves, leading to lower lip paresthesia. In our case, flap raising and dissection spared both mental nerves. Root canal treatment of all involved teeth was performed, along with enucleation of the lesions, and, in order to achieve a good periapical seal, apicectomies were implemented on teeth 44 to 33.

DIFFERENTIAL DIAGNOSISBased on patient's present history, careful clinical

examination, and radiographic computed analysis, the following differential diagnosis can be established.

According to Wood, Goaz, and Jacobs3, and if anatomic structures were ruled out, a well-defined radiolucency observed at the apex of an untreated, asymptomatic, tooth with a non-vital or diseased pulp, is a periapical granuloma or cyst in approximately 90% of the cases. If the radiolucency diameter is larger than 1.6 cm, it is more likely to be a cyst4,5.

Simple bone cyst -SBC- or solitary bone cyst (formerly known as "traumatic bone cyst") can mimic radicular cyst. SBC is an inter-radicular radiolucency generally seen in asymptomatic patients during the first two decades of life, with few cases reported over 40 years2. The typical lesion features a round to oval-shaped radiographic image with well-defined borders. Quite often, the superior border of this lesion extends between the roots of the teeth, giving a scalloped borders appearance. SBC does not usually exceed 3cm in diameter, although some lesions invading the entire ramus and mandibular body have been reported; it is an idiopathic cavity occurring usually in the mandible as well as in other bones (long bones), and this unilocular or multilocular lesion is always associated with vital teeth. Since epithelial lining is missing in SBC, this lesion is classified as false cyst (pseudocyst)2.

Central giant cell lesion -CGCL- may occur initially as a solitary, cyst-like radiolucency. As it grows larger, it frequently appears as a soap-bubble, multilocular radiolucency. This lesion is usually painless and expands


slowly by thinning cortical plates. It rarely reaches soft tissues but due to its expanding potential, teeth migration and root resorption have been reported. Histopathologically, cellular fibrous tissue with multinucleated giant cells are encountered throughout the lesion along with lots of granules of hemosiderin and hemorrhage foci. An osteoid may often be observed within the lesion. CGCLs localized in periapical regions or laterally to teeth roots can be confused with radicular cysts, especially if these teeth are not root filled or if their vitality is negative or doubtful. A careful study of serum chemistry tests should be done to exclude the possibility of hyperparathyroidism5,7.

Periapical cemento-osseous dysplasia -PCOD- is by far the most common fibro-cemento-osseous lesion. In its early stage of development, PCOD appears as rounded periapical radiolucency, with well-defined borders; associated teeth are vital, and the lesion is rarely observed before 40 years of age. There is a clear female predilection and it is commonly seen in anterior mandible with no detectable cortical expansion6,7.

Cemento-ossifying fibroma -COF- is a very common lesion of the mandible with no specific gender predilection; it can also be confused with radicular cyst. Patients' average age is 30 years. Due to the progressive deposition of cementum and spicules of bone, the initially radiolucent lesion becomes radio-opaque within years; the mature lesion appears as a well-defined radiopacity, usually surrounded by uniform radiolucency8.

Odontogenic keratocyst -OKC- frequently appears as a well-defined radiolucency. Occurring more commonly in the mandible, it has a net male predilection. OKC is known for its aggressive behavior, high recurrence rate (2% to 62%), and association with the nevoid basal cell carcinoma syndrome (NBCCS). It most often affects posterior mandible (molar region and ramus). Considering its "neoplastic" features, many clinicians classify this lesion as a benign "tumor".

Finally, ameloblastoma is an odontogenic tumor that may be confused with radicular cyst. It is locally invasive and aggressive, initially asymptomatic; it causes cortical expansion and often cortical perforation. Radiographically, a multilocular soap-bubble or honeycomb appearance is usually observed but the lesion may also appear as a unilocular image; many cases of mandibular ameloblastomas are associated

with an unerupted tooth with most cases diagnosed in posterior mandible (more than 80%) during the third and fourth decades.

CONCLUSIONIn this clinical report, we address a case of two

adjacent mandibular radicular cysts in a 45-year-old male patient; radiographic computed analysis, endodontic treatment, surgical enucleation, and apicectomies were necessary for a comprehensive management of the case.

Though radicular cyst is a common pathology with obvious clinical and radiological features, care should always be taken to rule-out uncommon lesions that may mimic its features, such as SBC, OKC, CGCL, PCOD, COF, and ameloblastoma.

REFERENCES 1. Ramachandra P, Maligi P, Raghuveer HP. A cumulative analysis of odontogenic cysts from major dental institutions of Bangalore city: A study of 252 cases. J Oral Maxillofac Pathol 2011 Jan-Apr;15(1):1-5. 2. Marx RE, Stern D (Editors). Oral And Maxillofacial Pathology: A rationale for diagnosis and treatment. Chicago, Illinois, USA: Quintessence Publishing Co., 2003. 3. Wood NK, Goaz PW, Jacobs MC. Periapical Radiolucencies. In: Wood NK, Goaz PW, editors. Differential diagnosis of Oral and Maxillofacial lesions, 5th ed. Mosby, St. Louis, Missouri, USA 1997; p.252-278. 4. Kizil Z, Energin K. An evaluation of radiographic and histopathological findings in periapical lesions. J Marmara Univ Dent Fac. 1990 Sep;1(1):16-23. 5. Krishnamurthy V, Haridas S, Garud M, et al. Radicular cyst masquerading as a multilocular radiolucency. Quintessence Int 2013 Jan;44(1):71-73.6. Joshi NS, Sujan SG, Rachappa MM. An unusual case report of bilateral mandibular radicular cyst. Contemp Clin Dent 2011 Jan-Mar;2(1):59-62.7. Tay JY, Bay BH, Yeo JF, et al. Identification of RANKL in osteolytic lesions of the facial skeleton. J Dent Res 2004 Apr;83(4):349-353. 8. Ochsenius G, Escobar E, Godoy L, Peñafiel C. Odontogenic cysts: analysis of 2,944 cases in Chile. Med Oral Patol Oral Cir Bucal 2007 Mar;12(2):E85-91. 9. Jacob S. Rushton bodies or hyaline bodies in radicular cysts. A morphologic curiosity. Indian J Pathol Microbiol 2010;53:846-847.10. Tortorici S, Amodio E, Massenti MF, et al. Prevalence and distribution of odontogenic cysts in Sicily: 1986-2005. J Oral Sci 2008;50(1):15-18.


11. Sharifian MJ, Khalili M. Odontogenic cysts: a retrospective study of 1227 cases in an Iranian Population from 1987 to 2007. J Oral Sci 2011 Sep;53(3):361-367. 12. Shear M, Speight P. Cysts of the oral and maxillofacial regions, 4th ed. Oxford: Blackwell, Munksgaard, 2007. 13. Meghji S, Qureshi W, Henderson B, Harris M. The role of endotoxin and cytokines in the pathogenesis of odontogenic cysts. Arch Oral Biol 1996 Jun;41(6):523-531. 14. Grupe HE Jr, Ten Cate AR, Zander HA. A histochemical and radiobiological study of in vitro and in vivo human epithelial cell rest proliferation. Arch Oral Biol 1967 Dec;12(12):1321-1329. 15. Summers L. The incidence of epithelium in periapical granulomas and the mechanism of cavitation in apical dental cysts in man. Arch Oral Biol 1974 Dec;19(12):1177-1180. 16. Skaug N. Soluble proteins in fluid from non-keratinizing jaw cysts in man. Int J Oral Surg 1977 Apr;6(2):107-121. 17. Meningaud JP, Oprean N, Pitak-Arnop P, Bertrand JC. Odontogenic cysts: A clinical study of 695 cases. J Oral Sci 2006 Jun;48(2):59-62. 18. Torres-Lagares D, Segura-Egea JJ, Rodriguez-Caballero A, et al. Treatment of a large maxillary cyst with marsupialization, decompression, surgical endodontic therapy and enucleation. J Can Dent Assoc 2011;77:b87.

Corresponding author:Alexandre [email protected]

70

INTRODUCTION Saliva is a watery substance located in the mouth of

humans; it is secreted by three main salivary glands: the submandibular, the parotid, and the sublingual, as well as hundreds of minor salivary glands (total number of 800 to 1000). It contains a large array of proteins, many of which can be informative for the detection of oral and systemic diseases1.

Saliva is an attractive diagnostic fluid; it has several key advantages for disease diagnosis and prognosis, such as low invasiveness, minimal cost, and easy sample collection and processing2.

On the other hand, since the discovery of polymerase chain reaction (PCR) and other molecular biology techniques, the use of DNA as a diagnostic tool has grown rapidly. Indeed, human DNA has been shown to be useful as a biological marker and its utilization has been studied for the detection of some types of neoplasia2,3,5,6.

A fraction of these tests already use saliva as a sample source, but thanks to research using RNA and proteins (proteomics) as diagnostic tools, saliva has become a diagnostic method of choice4,7-11.

In light of the above, saliva testing may be an

effective diagnostic modality of oral cancer and distant malignancies, as well as for monitoring post-therapy status.

HUMAN SALIVA COMPOSITIONHuman saliva is one of the most complex, versatile,

and important body fluids; it reflects a large range of physiological needs and information. Saliva is also known as the “mirror of the body”.1,2

Saliva is a multi-component oral fluid which contains approximately 99% water as well as minerals, nucleic acids, electrolytes, mucus, and proteins that originate from multiple local and systemic sources.1-3

In addition to molecules synthesized in salivary glands [mucins, cystatins, and proline-rich peptides (PRPs)...], saliva also contains constituents that do not originate from salivary glands (including gingival crevicular fluid, serum transduate from oral mucosae and sites of inflammation, epithelial and immune cells, and many microorganisms). It also contains molecules that are present in blood. Depending on their size and charge, some molecules enter into saliva via diffusion, filtration, and/or active transportation, rendering saliva a diagnostic medium.

SALIVA PROTEOME Proteomic studies of human saliva target the

identification and characterization of new peptides and proteins that display biological activity at glandular

Saliva as a potential tool for cancer diagnosis and prognosis: A clinical reminder and mini-review.Nisrine El Arrouf Bisbis 1, Dr. Med. Dent., CES Dent. Biomat., CES Endo./Conservat. Dent., CES Pain Treatment,Souad Nechad 2, Dr. Med. Dent., CES Oral. Biol., CES Endo./Conservat. Dent., DEA Nutrition

AbstractSalivary analysis is nowadays an important mean for evaluating physiological and pathological conditions in

humans. The use of saliva has many advantages, including simplicity and non-invasiveness of collection. Recent scientific and technological advances have produced continued improvements in many areas, such as saliva proteomic content and new saliva biomarkers.

Saliva testing may be an effective modality for diagnosis and prognosis prediction of oral cancer, as well as for monitoring post-therapy status; it has been shown to be a useful diagnostic tool also for distant malignancies such as breast cancer. This paper examines the scientific literature addressing saliva as a potential diagnostic tool for cancer.

1. Assistant Professor, Department of Conservative Dentistry, Mohammed V University, Faculty of Dental Medicine, Rabat, Morocco.2. Professor, Department of Conservative Dentistry, Mohammed V University, Faculty of Dental Medicine, Rabat, Morocco.

Oral Medicine



level and/or under various pathological conditions.3

Based on advanced mass spectrometry technologies, the capability of saliva protein identification has been greatly enhanced by combining different protein separation technologies.4

The Saliva Proteome Knowledge Base* is the first database in the world that centralizes proteomic data and annotates identified saliva proteins; it is accessible to the general public.4,7,8,18

Recent work by many laboratories has catalogued a total of 2290 proteins in whole saliva, and approximately 27% of plasma proteins are found in human saliva.5 It is an encouraging indicator for the clinical use of saliva as a diagnostic fluid.12,20,21

SALIVA AS A DIAGNOSTIC FLUIDFor the last decade, salivary science proved to

be a dynamic field using molecular diagnostics and nanotechnology for the diagnosis of oral and systemic diseases20.

Clinical development of salivary biomarkers Comprehensive analysis and identification of the

proteomic content in human saliva is the first step toward discovering novel saliva biomolecules associated with human health and disease status.3 In fact, oral and systemic diseases may directly or indirectly affect salivary glands; they may influence the quantity and composition of saliva that they produce.6

These phenomena have significant impact on biomarker discovery for disease by utilizing proteomic methodologies.

When comparing protein compositions (or proteomes) found in human salivary and plasma fluids, there are 2290 proteins found in whole saliva while 2698 are found in plasma. Approximately 27% of the whole-saliva proteins are found in plasma and nearly 40% of the proteins considered as candidate markers for cancer, cardiovascular disease, and stroke, can be detected in whole saliva.8

This composition suggests that detecting biomolecules of clinical sensitivity and specificity in saliva is feasible and easier than in blood.9

Although proteomic constituents are a logical first choice as salivary diagnostic analytes, genomic targets have emerged as highly informative and discriminatory

biomarkers.3

The future of saliva diagnostics relies on combinations of biomarker panels used as screening tools to improve diagnostic accuracy and specificity. One biomarker alone may not suffice as a reliable source to enable investigators define the pathogenesis of an underlying disease. The use of combinations of biomarkers may provide additive and powerful diagnostic information.3,21,22

Saliva as a tool for cancer diagnosis and prognosisThe increasing worldwide incidence of cancer

urgently demands the discovery of new biomarkers, since diagnosis has always been based on clinical and histopathological criteria.

In recent years, there have been many studies of disease diagnosis using salivary biomarkers in lung, breast, pancreatic, and oral cancers.14-18

Streckfus and co-workers17 compared salivary levels of a breast cancer marker (HER2/neu) in healthy women, women with benign breast lesions, and women with breast cancer; they found that salivary as well as serum levels of this marker were significantly higher in women with breast cancer than in healthy women and women with benign breast lesions; they concluded that HER2/neu may have a potential use in the initial detection and/or follow-up screening for the recurrence of breast cancer in women.17

Zhang and associates14 demonstrated that researchers were able to detect pancreatic cancer with high sensitivity and specificity (90.0% and 95.0%, respectively) by screening saliva for four specific mRNA biomarkers (KRAS, MBD3L2, ACRV1, and DPM1).

Hamada and Shimosegawa15 studied pancreatic cancer biomarkers and concluded that novel transcriptonic or metabolomic biomarkers in clinical samples collected by non-invasive methods (such as saliva samples) are applied for the diagnosis of pancreatic cancer.

Emekli-Alturfan and co-workers16 compared saliva of breast cancer patients to that of healthy individuals and observed that breast cancer patients’ samples contained dysplastic cells and reduced lipid peroxides.

Jou and associates18 found that patients diagnosed with oral squamous cell carcinoma had elevated

* http://www.skb.ucla.edu


levels of transferrin in saliva compared to healthy controls; they also discovered that salivary transferrin measurement using ELISA technique was “highly specific, sensitive, and accurate for the early detection of oral cancer.”

Advantages and disadvantages of saliva as a diagnostic fluid

Saliva is easy to collect, store, and transport; it does not require highly trained personnel, and it is safer for hospital staff to handle, compared to blood and other body fluids. In addition, saliva is a “real-time” fluid because salivary glands are exocrine glands that produce protein profiles indicative of an individual’s health at the moment of collection. It also offers a cost-effective approach for the screening of large populations.3,10,12,19,20 These characteristics (Fig. 1) make it possible to monitor several biomarkers in infants, children, elderly, and uncooperative patients, as well as in circumstances in which blood and urine sampling are difficult to obtain.

As a diagnostic medium, saliva has disadvantages (Fig. 1): for example, owing to the diurnal/circadian variations of certain biomolecules present in saliva, it does not always reliably reflect the concentrations of these molecules in serum. Salivary composition can also be influenced by the method of collection and the degree of stimulation of salivary flow.11,12 In addition, saliva contains analytes in concentrations that are 1000-fold less than those in blood.13

Sensitive detection systems are thus needed before we can unveil the utility of saliva as a diagnostic medium.

Technological advancements in salivary diagnosticsSome of the current nanotechnologies have been

demonstrated to have the analytical sensitivity required for the use of saliva as a diagnostic medium to detect and predict disease progression. However, these technologies have not yet been integrated into current clinical practice.3

The vision of the U.S. National Institute of Dental and Craniofacial Research (NIDCR) toward translational and clinical maturation of salivary diagnostics includes a parallel and timely development of point-of-care technology platforms that can enable the measurements of multiple salivary constituent

targets for early detection and/or risk-assessment applications (Fig. 2).19

CONCLUSIONFor decades, dental healthcare professionals have

measured the buffering capacity and bacterial content of saliva to assess patient’s risk of developing tooth decay.

Nowadays, scientific and technological advances in biochemistry, microbiology, immunology, and molecular biology are leading to the discovery of new saliva biomarkers that can be used to detect systemic illnesses such as cancer. This growing recognition of the association between an individual’s oral and overall health has led to renew interest in using saliva as a diagnostic fluid.

According to Jasim and associates21, the variable nature of the salivary proteome suggests that different

Fig. 1. The advantages and disadvantages of saliva as a diagnostic fluid (C Punyadeera, 2013).

Fig. 2. The Oral Fluid NanoSensor Test (OFNASET) is a UCLA-developed point-of-care platform optimized for salivary diagnostics (DTW Wong, 2012).


approaches have to be adopted when studying its composition or its possible role as an indicator for particular physiological states.

It is now established22 that salivary genomic, transcriptomic, proteomic, metabolomic, and microbial biomarkers have an important role in the detection of systematic cancers. Dental profession should be a first-line of primary healthcare by helping diagnosis, early detection, screening, and monitoring progression of cancer.

Human DNA has been shown to be useful as a biological marker and its utilization has been studied for the detection of some types of neoplasia. But most of the specimens used for this type of investigation are collected through biopsies and, generally, when analysis is possible, the tumor is already settled. This suggests a need for the development of new diagnosis tools that may possibly lead to an early detection of the disease.

REFERENCES 1. De Almeida PV, Gregio AM, Machado MA, De Lima AA, Azevedo LR. Saliva composition and functions: a comprehensive review. J Contemp Dent Pract 2008; 9:72-80. 2. Wang Q, Gao P, Wang X, Duan Y. Investigation and identification of potential biomarkers in human saliva for the early diagnosis of oral squamous cell carcinoma. Clinica Chimica Acta 2014;427:79-85. 3. Pfaffe T, Cooper-White J, Beyerlein P, Kostner K, Punyadeera C. Diagnostic potential of saliva: current state and future applications. Clin Chem 2011;57:675-687. 4. Xiao H,Wong DT. Proteomics and its applications for biomarker discovery in human saliva. Bioinformation 2011;5:294-296.5. Miller CS, Foley JD, Bailey AL, Campell CL,Humphries RL, Christodoulides N, et al. Current developments in salivary diagnostics. Biomark Med 2010;4:171-189.6. Kaufman E, Lamster IB. The diagnostic applications of saliva: a review. Crit Rev Oral Biol Med 2002;13(2):197-212. 7. Schulz BL, Cooper-White J, Punyadeera CK. Saliva proteome research: Current status and future outlook. Crit Rev Biotechnol 2013;33(3):246-259. 8. Loo JA, Yan W, Ramachandran P, Wong DT. Comparative human salivary and plasma proteomes. J Dent Res 2010;89(10):1016-1023.9. Punyadeera C. Saliva: an often forgotten but convenient diagnostic fluid. Clinical Laboratory News 2013 Jan.10. Liu J, Duan Y. Saliva: a potential media for disease diagnostics and monitoring. Oral Oncol 2012;48(7):569-577. 11. Hofman LF. Human saliva as a diagnostic specimen. J Nutr 2001;131:1621S-1625S.

12. Chiappin S, Antonelli G, Gatti R, de Palo EF. Saliva specimen: A new laboratory tool for diagnostic and basic investigation. Clinica Chimica Acta (Int J Clin Chemistry Diag Lab Med) 2007;383(Issues 1-2):30-40. 13. Christodoulides N, Mohanty S, Miller CS, Langub MC, Floriano PN, Dharshan P, et al. Application of microchip assay system for the measurement of C-reactive protein in human saliva. Lab Chip 2005;5(3):261-269. 14. Zhang L, Farrell JJ, Zhou H, Elashoff D, Akin D, Park N-H, Chia D, Wong DT. Salivary transcriptomic biomarkers for detection of resectable pancreatic cancer. Gastroenterology 2010 Mar; 138(3):949-957. 15. Hamada S, Shimosegawa T. Biomarkers of pancreatic cancer. Pancreatology 2011;11 Suppl 2:14-19. 16. Emekli-Alturfan E, Demir G, Kasikci E, Tunali-Akbay T, Pisiriciler R, Caliskan E, Yarat A. Altered biochemical parameters in the saliva of patients with breast cancer. Tohoku J Exp Med 2008;214(2):89-96. 17. Streckfus C, Bigler L, Dellinger T, Dai X, Kingman A, Thigpen JT. The presence of soluble c-erbB-2 in saliva and serum among women with breast carcinoma: a preliminary study. Clin Cancer Res 2000 Jun;6(6):2363-2370. 18. Jou YJ, Lin CD, Lai CH, Chen CH, Kao JY, Chen SY, Tsai MH, Huang SH, Lin CW. Proteomic identification of salivary transferrin as a biomarker for early detection of oral cancer. Analytica Chimica Acta 2010;681(1-2):41-48.19. Wong DTW. Saliva Diagnostics: "Build It and They Will Come". Inside Dentistry 2012 May; Volume 8: Issue 5. 20. Malamud D, Rodriguez-Chavez IR. Saliva as a diagnostic fluid. Dent Clin North Am 2011 Jan;55(1):159-178.21. Jasim H, Olausson P, et al. The proteomic profile of whole and glandular saliva in healthy pain-free subjects. Scientific Reports 2016 Dec 15;1-10. DOI:10.1038/srep39073.22. Wang X, Kaczor-Urbanowicz KE, Wong TW. Salivary biomarkers in cancer detection. Med Oncol 2017 Jan;34(1):7.

Corresponding author:Nisrine El Arrouf [email protected]

75

INTRODUCTIONNowadays, dentistry requires practical,

uncomplicated, and minimally invasive methods to restore lost tooth structures affecting esthetics and functions. Restoration of endodontically-treated teeth conventionally takes the indirect full-coverage pathway; furthermore, teeth with minimal remaining coronal structure warrant a clear necessity for indirect crowns.

However, some authors reported that the consideration of direct cuspal coverage of endodontically-treated teeth leads to acceptable clinical performance without compromising the long-term survival of restored tooth.1,2 As a matter of fact, a good alternative would be semi-direct approach, which is essentially a direct resin composite restoration with the advantage of extra-oral fabrication on a model carried out chairside. Therefore, since there is no significant difference between direct/indirect restoration in case of minimal-to-moderate coronal damage of non-vital teeth, semi-direct restorative technique offers a fast, low-cost, and clinically acceptable treatment modality.

In this paper, we address a case report of semi-direct restoration of a maxillary right second premolar in

addition to a mini-review of the literature on different restorative techniques.

CASE REPORTA 23-year-old female patient consulted our office

for regular dental treatment. Based on clinical findings and diagnosis, her maxillary right second premolar necessitated root canal therapy.

A week after endodontic treatment, patient returned for subsequent restoration of the tooth. A full-coverage porcelain-fused-to-metal crown (PFM) was advised; however, the patient could not afford the cost of a PFM crown and asked for a lower cost treatment. We suggested the semi-direct restoration as a low-priced option; and after explaining this treatment to her in details along with its advantages and disadvantages, she agreed.

At first, A2-A3 tooth shades were recorded using VITA classical A1-D4® shade guide (Zahnfabrik, Germany); the temporary filling (Cavit™ G, 3M, Germany) was removed, coronal structure was thoroughly inspected to rule out any remaining decay, and a liner was placed over the root canal entries (TheraCal LC®, Bisco Inc., Schamburg, IL, USA). Then, pulp chamber was etched with 37% phosphoric acid (PA), adhesive was

Semi-direct restoration as a potential alternative for endodontically-treated posterior teeth: A case report and mini-review.

Abbass El-Outa1, BDS, DES Clin. Dent. Manag., MEAOM,Lara Nasr2, BDS

AbstractRestoration of endodontically-treated teeth remains a challenge in general dental practice, with the major opinion

advocating indirect full-coverage restorations as the treatment of choice. However, recent studies suggest there is no enough evidence against direct restorations of such teeth, given that enough coronal structure exists. In this paper, we address a case report of a semi-direct restoration of an endodontically-treated maxillary second premolar along with a mini-review of the literature on indications and limitations of directly restoring endodontically-treated posterior teeth. Usefulness of considering the semi-direct technique a good alternative modality is discussed as well.

1. Private practice, Beirut, Lebanon.2. Private practice, Kfarchima, Lebanon.


Restorative and Esthetic Dentistry


applied to dentin (Tetric® N-Bond, Ivoclar Vivadent, Schaan, Liechtenstein) in pulp chamber, and it was partially filled with Tetric® N-Flow and Tetric® N-Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) composite resins (using A1 shade to allow maximum light access for polymerization). Following that step, tooth was prepared for a modified onlay (Fig. 1). An impression was taken of the right maxillary semi-arch with c-silicone putty and light materials (Zetaplus; Zhermack Spa, Badia Polesine, Italy).

The impression was poured with elastic material (flexible die technique13) (Fig. 2). Consequently, the restoration was built-up on the obtained model using A2 and A3 composite resin shades (Fig. 3). After multiple polymerizations from different angles (20-second-each), the restoration was transferred into mouth for a try-in.

Correct seating was confirmed and proper contact points were verified; no occlusal adjustment or finishing was done at this stage. Restoration was removed to prepare it for cementation; restoration treatment included the creation of slight rigorous internal texture

of the surface using an 801.012 diamond medium round bur (to maximize available surface for adhesion), then 37% phosphoric acid was applied for 20 seconds to clean restoration surfaces; 9% hydrofluoric acid (HF) was used for 30 seconds to etch these surfaces, and a silane-coupling agent (Bisco® Inc., Schamburg, IL, USA) was applied to improve adhesion. On the other hand, and after rubber dam placement, tooth treatment included cleansing with 2% chlorhexidine gluconate solution for 60 seconds, followed by carefully etching the composite resin placed in pulp chamber with 9% HF for 30 seconds. Both restoration and tooth were dried (preserving dentine humidity), and a dual-cured self-etch and self-adhesive resin cement (BisCem®, Bisco Inc., Schaumburg, IL, USA) was applied in prepared tooth and restoration was seated. Light curing using Dr’s Light (GoodDoctors Co., Seoul, Korea) for 5 seconds was done to allow removal of excessive cement. Then, 20-second light curing from multiple sides was done (Fig. 4). Following rubber dam removal, occlusion was recorded and adjusted and proximal margins finishing carried on (Fig. 5). Restoration was polished using

Fig. 1. Tooth 15 after preparation. Fig. 2. Impression taken and poured.

Fig. 3. Left: Fabricating restoration; right: intaglio (interior) surface of finished restoration.


Fig. 4. The restoration immediately after cementation and rubber dam removal.

Fig. 6. Final aspect of the restoration.

Fig. 5. Occlusal and proximal finishing.


OptiDisc (Kerr, Orange, California, USA) and rubber Spiral SofLex disk (3M, Germany) (Fig. 6). Total time of the session from preparation to final polishing was around 45 minutes.

A two-week follow-up of the restoration revealed proper aspect and function.

DISCUSSIONRestoration methods of endodontically-treated teeth

remain a subject of controversy; these teeth generally undergo severe structure loss, they can be restored indirectly by full-coverage crowns, ceramic inlays/onlays, directly by resin composite restorations, or semi-directly with cuspal coverage.1,12

Indirect restorations are indicated for extensively damaged teeth when direct restorations cannot offer reliable long-term preservation of tooth structure, anatomy, and function. Nevertheless, PFM or all-ceramic indirect restorations unfavorably increase costs for patient and require several sessions for laboratory and clinical workflow, making it time-consuming.1,3 Despite the fact that computer-aided design / computer-aided manufacturing system (CAD/CAM) and chairside milling systems offer the benefit of reduced time, costs related to these technologies are significantly greater than those of conventional approaches, making such modalities unaffordable for many patients and practitioners alike.3

Moreover, it is important to note that the choice of a restorative material should rely also on opposing teeth condition; given that the wear resistance of ceramic is highly superior to that of enamel or composite resins, practitioners may favor composite restorations over ceramics when facing virgin teeth or teeth restored with composite resin in opposing dentition.4

Polymerization shrinkage is perhaps the most crucial problem of direct composite restorations leading to microleakage, secondary caries, postoperative sensitivity, pulpal irritation (when facing vital teeth), marginal discoloration, and stress at the tooth-restoration interface.4 Low wear resistance is another important problem of direct composite restorations: it is due to an improper degree of conversion of their monomers, compromising their mechanical and physical properties and affecting their efficiency under masticatory forces.1,5

In a comparative study, Dejak and Młotkowski6

showed that teeth with direct restorations are more prone to damage compared to those with indirect ones; an additional struggle affecting posterior direct composite restorations is reproducing tight and anatomically appropriate interproximal contact, as dental separation sponsored by wedges is not always sufficient to counteract metallic matrix thickness.6

Problems of direct composite restorations are avoided by indirect inlays/onlays/overlays; however, cost and time needed for indirect techniques remain a burden for some patients. Consequently, the chairside semi-direct technique presents as a potentially reliable method to surpass indirect techniques in terms of cost and time, while providing good esthetic and functional outcomes.1,3,5 Indeed, semi-direct technique limits polymerization shrinkage while the restoration is made outside the mouth on a model; as a result, problems resulting from shrinkage are reduced because additional polymerization in all directions can be made, including the restoration’s inner surface, enhancing, then, the conversion degree; thus, no stress is transmitted to the remaining tooth structure.7

In small and medium cavities, there is no significant difference regarding short-term marginal adaptation when comparing direct to semi-direct restorations; yet, semi-direct restorations surpass direct ones regarding their long-term clinical outcomes, which makes it the treatment of choice for restoring large cavities with unfavorable configurations for patients in need of proper extensive reconstructions in posterior teeth in a short period of time and at a lower cost. Another advantage of the semi-direct technique is that interproximal contact areas are adequately reconstructed, along with a good occlusal morphology and an appropriate marginal adaptation since better visualization and control during resin insertion and sculpture are obtained when work is implemented outside the mouth.1

It is generally agreed upon that endodontically-treated teeth require restorations with full-coverage crowns; yet, controversy remains when it comes to restore teeth with minimal coronal destruction. Regardless of the fact that extensively damaged teeth should conventionally be restored by full-coverage crowns, there is some evidence that direct cusp coverage of endodontically-treated posterior teeth contributes to


acceptable clinical performance in a 5-year period.2,8

Sequeira-Bryon and co-workers8 have shown, after conducting a Cochrane systematic review, that there is not enough evidence to evaluate the outcomes of crowns correlated to conventional fillings for the restoration of endodontically-treated teeth; authors concluded that practitioners should persist on founding decisions (about restoring endodontically-treated teeth) on their own clinical experience, while taking into account patient’s desires.8

Angeletaki and associates5 conducted a systematic review and meta-analysis and concluded that there exists evidence, though weak, to favor direct over indirect inlay/onlay composite restorations; results evolved from studies with high risk of bias. Therefore, further long-term studies are warranted in the interest of making more significant comparisons between both techniques.

In their systematic review, Suksaphar and co-workers9 deducted that in endodontically-treated posterior teeth with minimal to moderate loss of coronal structure, survival rates facing fracture with either full-coverage crowns or direct resin composite restorations were not considerably different9; same authors have shown again, in a retrospective study10, that survival rate facing fracture of endodontically-treated premolars restored with full-coverage crowns is higher than those restored with composite resins. However, endodontically-treated teeth with 1 or 2 lost surfaces and 2 proximal contacts restored with resin composite presented a high survival rate that was similar to that of endodontically-treated teeth indirectly restored with crowns.10

Another systematic review and meta-analysis conducted by Shu and associates11 has shown that there is a poor recommendation for indirect restorations to reconstruct endodontically-treated teeth, especially for those with extensive coronal deterioration. Indirect restorations with crowns have a higher short-term (5-year) and medium-term (10-year) survival than direct restorations using composite resins or amalgam, but no considerable difference was noticed in short-term (<5-year) restorative success. Indirect and direct restorations did not show any significant difference in endodontic success (rate of apical periodontitis), based on a very low quality of evidence. Future studies

relying on high-quality clinical trials are to be pursued, especially well-designed randomized clinical trials.11

CONCLUSIONIn the light of current evidence, the semi-direct

method with cuspal coverage can be an applicable and more conservative treatment option for patients who cannot afford indirect restorations, whether the tooth was endodontically-treated or not. Indeed, semi-direct restorations surpass direct ones on the long-term outcome and constitute an acceptable alternative to indirect restorations when time or cost is problematic.

REFERENCES1. Torres CRG, Zanatta RF, Huhtala MFRL, Borges AB. Semidirect posterior composite restorations with a flexible die technique: A case series. J Am Dent Assoc 2017;148(9):671–676. 2. Deliperi S, Bardwell DN. Direct cuspal-coverage posterior resin composite restorations: a case report. Operative Dentistry 2006; 31(1):143-150.3. Alharbi A, Rocca GT, Dietschi D, Krejci I. Semidirect composite onlay with cavity sealing: A review of clinical procedures. J Esthet Restor Dent 2014;26(2):97–106. 4. Deliperi S. Functional and Aesthetic Guidelines for Stress-Reduced Direct Posterior Composite Restorations. Oper Dent 2012;37(4):425–431. 5. Angeletaki F, Gkogkos A, Papazoglou E, Kloukos D. Direct versus indirect inlay/onlay composite restorations in posterior teeth. A systematic review and meta-analysis. J Dent 2016 Oct;53:12–21.6. Dejak B, Młotkowski A. A comparison of stresses in molar teeth restored with inlays and direct restorations, including polymerization shrinkage of composite resin and tooth loading during mastication. Dent Mat 2015 Mar;31(3):e77–87. 7. Restrepo M, Santos-pinto L, Ricci WA. Onlay restoration using semi-direct technique. A case report. Revista CES Odontología 2012;25(2):66–72. 8. Sequeira-Byron P, Fedorowicz Z, Carter B, Nasser M, Alrowaili EF. Single crowns versus conventional fillings for the restoration of root-filled teeth. Cochrane Database Syst Rev 2015 Sep 25;(9):CD009109.9. Suksaphar W, Banomyong D, Jirathanyanatt T, Ngoenwiwatkul Y. Survival rates against fracture of endodontically treated posterior teeth restored with full-coverage crowns or resin composite restorations: a systematic review. Restor Dent Endod 2017;42(3):157-167. 10. Suksaphar W, Banomyong D, Jirathanyanatt T, Ngoenwiwatkul Y. Survival Rates from Fracture of Endodontically Treated Premolars Restored with Full-coverage Crowns or Direct Resin Composite Restorations: A Retrospective Study. J Endod 2018 [Epub ahead of print].


11. Shu X, Mai Q-Q, Blatz M, Price R, Wang X-D, Zhao K. Direct and Indirect Restorations for Endodontically Treated Teeth: A Systematic Review and Meta-analysis, IAAD 2017 Consensus Conference Paper. J Adhes Dent 2018 [Epub ahead of print].12. Sequeira-Byron P, Fedorowicz Z, Carter B, Nasser M, Alrowaili EF, McReynolds D, et al. Insufficient evidence on whether to restore root-filled teeth with single crowns or routine fillings. Evidence Based Dentistry 2016;17(2):50-51. 13. Papazoglou E, Diamantopoulou S. The Modified Semidirect Onlay Technique with Articulated Elastic Model. Eur J Prosth Restor Dent 2015 Dec;23(4):207-212.

Corresponding author:Abbass [email protected]

81

INTRODUCTIONEdward Kennedy’s classification is most commonly

used when designing partial dentures; Kennedy Class I indicates a patient with bilateral free-end saddles (edentulous posterior areas bilaterally).

In the mandible, Kennedy’s Class I situations are problematic due to the difference in displacement between mucosa and teeth. The amount of mucosal displacement can be up to 20 times more than that of teeth1. Indeed, the majority of authors agree on the disharmonic physiological behavior of these two tissues; periodontal ligament allows axial movement more or less close to the tenth of a millimeter, while compressibility of oral mucosa ranges from 0.4 to 1 millimeter2. When an occlusal load is applied, displacement of oral soft tissues is 13 times higher than abutment teeth3.

Several techniques are used to compensate for this difference and reduce the damage on remaining teeth: at the impression level when making an altered cast technique4 or at the design phase with many possibilities (such as using a stress breaker partial denture5).

In cases of free-end saddles, the use of a non-

rigid mechanism is advocated in order to distribute forces between abutment teeth and tissue-supporting prosthetic saddles.6-9

The stress breaker design of Tourtet10,14 is another option to treat partially edentulous cases; its principle is based on the disjunction of the saddle relative to the frame of the prosthesis; this is, in fact, an evolution of the rigid frame, and it is characterized by distal shifting of the point of connection between frame and saddle11.

According to Jourda6,9,14, stress breaker design improves preservation of abutment teeth, vertical dimension of occlusion, and alveolar and basal bone heights; consequently, denture relining is avoided12,13.

Published studies12-18 were inspired by produced stress breaker design without comparison with conventional one. This article addresses a case report where two different designs (conventional semi-rigid frame and stress breaker design) were used on the same partial denture (Kennedy Class I mandibular).

CASE REPORTA 40-year-old female with no medical problems,

having all her natural teeth in the maxilla and a Kennedy Class I edentulism in the mandible, consulted us for a removable partial denture (RPD) to replace her missing teeth (Fig. 1). After obtaining her consent, it was

Conventional semi-rigid frame and stress breaker designs on the same partial denture for a mandibular Kennedy Class I: A case report.

Naji Hayek1, Dr. Chir. Dent., CES Remov. Prostho., CES Fixed Prostho.Ghassan Masri2, Dr. Chir. Dent., DES Remov. Prostho., DU Oral Pathol.

AbstractA removable partial denture (RPD) intended to restore physiological and esthetic functions must be integrated in

the masticatory system to protect oral supporting tissues. In Kennedy’s Class I and II situations, the specific problem of RPD metal frame is the duality of hard and soft tissues when dentures are supported by both remaining teeth and soft tissues covering edentulous ridges. This problem is usually resolved at impression level (altered cast technique) or at design level (stress breakers).

This case report addresses a clinical situation where two different designs (conventional semi-rigid frame and stress breaker design) were used on the same partial denture (Kennedy Class I, mandibular). A recall visit after one year showed that the stress breaker design was better than the semi-rigid one.

1,2. Chief of Clinical Services, Department of Prosthodontics, Lebanese University Faculty of Dental Medicine, Beirut, Lebanon

Removable Prosthodontics



decided to try an experimental type of RPD in which we implemented two techniques in order to reduce the leverage effects of the mandibular Kennedy Class I. An RPD was fabricated with a conventional semi-rigid partial denture on the right side and a “Tourtet stress breaking framework” on the other side14 (Fig. 2).

The originality of Tourtet’s concept is due to the particular design of the framework with the shape of a safety pin where the loop is located distally and the free part mesially (Fig. 3). The stress breaker framework allows the disconnection between saddle and framework (Fig. 4): displacement of saddle takes place only when masticatory forces are applied on prosthetic teeth.6,19

This clinical technique allows the patient to try both systems at the same time and comment on the difference in terms of comfort and masticatory efficiency between right and left sides10,20-24.

On the first year recall visit, patient claimed that both designs were satisfactory; however, she reported that Tourtet’s shape proved to be more comfortable and more efficient than the conventional one.

Acknowledgment:We thank Mr. Georges Sayegh* who performed the

laboratory work.

REFERENCES1. Manderson RD, Wills DJ, Picton DCA. Biomechanics of denture-supporting tissues. In: Lefkowitz W. (Ed). Proceedings of the Second International Prosthodontic Congress. St Louis, Mosby.1979. p. 98-101.2. Hansen CA, Singer MT. The segmented framework removable partial denture. J Prosthet Dent 1987 Jun;57(6):765-768.3. Igarashi Y, Ogata A, Kuroiwa A, Wang Ch. Stress distribution and abutment tooth mobility of distal-extention removable partial dentures with different retainers: An in vivo study. J Oral Rehabil 1999;26:111-116.4. Feit DB. The altered cast impression technique revisited. J Am Dent Assoc 1999;130:1476-1481.5. Watt DM, MacGregor AR (Ed). Connectors. In: Designing Partial Dentures. Bristol, Wright. 1984. p. 110-121. 6. Jourda G. Le châssis à selle amortie ou châssis amorti. Principes. Cahiers de Prothèse 1990 juin;70:68-76.7. Augereau D, Renault P, Pierrisnard L, Loir F, Fornaro C. Contraintes et déplacements dentaires en prothèse adjointe partielle: analyse par la méthode des éléments finis. Cahiers de Prothèse 1997 juin;98:89-100.8. Jin X, Sato M, Nishiyama A, Ohyama T. Influence of loading positions of mandibular unilateral distal extension removable partial dentures on movements of abutment tooth and denture base. J Med Dent Sci 2004 Sep;51(3):155-163.

Fig. 1. Clinical presentation at first appointment. Fig. 2. Removable partial denture with a semi-rigid design on right side of the RPD and a stress breaker design on its left one.

Fig. 3. Tourtet’s stress breaker design1: Tourtet’s stress breaker shape2: Distal loop with free mesial end3: Acrylic resin embedded inside the Tourtet's shape (no contact between acrylic saddle and the premolar's clasp).

Fig. 4. The disconnexion between the Nally-Martinet clasp and the saddle on buccal and lingual sides.

* Dental laboratory technician and Instructor at Antonine University, Department of Dental Laboratory Technology, Baabda, Lebanon.


9. Jourda G. Le châssis à selle amortie: résultats cliniques. Cahiers de Prothèse 1991 mars; 73:35-38.10. Cosme DC, Baldisserotto SM, Fernandes Ede L, et al. Functional evaluation of oral rehabilitation with removable partial dentures after five years. J Appl Oral Sci 2006 Apr;14(2):111–116. 11. Sajjan C. An altered cast procedure to improve tissue support for removable partial denture. Contemp Clin Dent 2010 Apr;1(2):103-106. 12. Wada S, Wakabayashi N, Tanaka T, Ohyama T. Influence of abutment selection in maxillary Kennedy Class II RPD on elastic stress distribution in oral mucosa: an FEM study. J Prostho 2006 Mar-Apr;15(2):89-94. 13. Yanagawa M, Fueki K, Ohyama T. Influence of length of food platform on masticatory performance in patients missing unilateral mandibular molars with distal extension removable partial dentures. J Med Dent Sci 2004 Jun;51(2):115-119. 14. Tourtet LC, Jourda G, Gaillard J. Le châssis amorti en prothèse adjointe partielle. Revue d’Odonto-Stomatologie 1989;18(3):233-244.15. Williams RJ, Bibb R, Eggbeer D, Collis J. Use of CAD/CAM technology to fabricate a removable partial denture framework. J Prosthet Dent 2006 Aug;96(2):96-99. 16. Williams RJ, Bibb R, Rafik T. A technique for fabricating patterns for removable partial denture frameworks using digitized casts and electronic surveying. J Prosthet Dent 2004 Jan;91(1):85-88. 17. McCracken WL. Contemporary partial denture designs. J Prosthet Dent 2004 Nov;92(5):409-417.18. Pienkos TE, Morris WJ, Gronet PM, Cameron SM, Looney SW. The strength of multiple major connector designs under simulated functional loading. J Prosthet Dent 2007 May;97(5):299-304.19. Thompson WD, Kratochvil FJ, Caputo AA. Evaluation of photoelastic stress patterns produced by various designs of bilateral distal-extension removable partial dentures. J Prosthet Dent 2004 Feb;91(2):105-113.20. Koyama S, Sasaki K, Yokoyama M, Sasaki T, Hanawa S. Evaluation of factors affecting the continuing use and patient satisfaction with removable partial dentures over 5 years. J Prosthodont Res 2010 Apr;54(2):97-101.21. LaVere AM, Krol AJ. Selection of a major connector for the extension-base removable partial denture. J Prosthet Dent 2005 Sep;94(3):207-208.22. Avant WE. Indirect retention in partial denture design. J Prosthet Dent 2003 July;90(1):1-5.23. Ozhayat EB, Stoltze K, Elverdam B, Owall B. A method for assessment of quality of life in relation to prosthodontics. Partial edentulism and removable partial dentures. J Oral Rehabil 2007 May;34(5):336-344. 24. Bilhan H, Erdogan O, Ergin S, et al. Complication rates and patient satisfaction with removable dentures. J Adv Prosthodont 2012 May;4(2):109-115.

Corresponding Author:Ghassan [email protected]

associate editors for research - lda€¦ · professor of restorative dentistry and endodontics,...

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