Quantification and validation of predictive values of occlusal variables in temporomandibular disorders using a multifactorial analysis

Exploring Temporomandibular Disorders (TMDs) and Occlusion Debate in Dentistry: Biting Into Controversy

Some conditions known as temporomandibular disorders (TMDs) affect surrounding muscles and jaw joints. In dentistry, there has been discussion and research on the connection between TMDs and occlusion, which is how the upper and lower teeth meet. Although some dental experts have proposed a direct link between TMDs and occlusion, the specifics of this relationship are still unclear and have many facets. More particularly, the research facets of "occlusion" remain one of the most contentious subjects in TMDs. This abstract aims to provide an overview of TMDs and occlusion, summarizing the key points from the literature. The etiological factors contributing to the TMDs, including occlusal, psychological, and hormonal factors, are also analyzed. The second part of the article includes the concept of malocclusion, emphasizing its significance in masticatory function and overall health. Anterior open and posterior open bites and the potential influence of occlusal factors on TMDs are elucidated.

Distinctive Anatomical Patterns of the Mandibular Coronoid Process, Condyle, and Sigmoid Notch: Cone Beam Computed Tomography (CBCT) Imaging for Advanced Personal Identification

INTRODUCTION

The human mandible plays a significant role in personal identification due to its unique morphological characteristics. The coronoid process, condyle, and sigmoid notch exhibit variations that can be utilized for forensic and anthropological purposes. This study aims to analyze the morphological diversities of these mandibular features in our ethnic group using cone beam computed tomography (CBCT) imaging.

MATERIALS AND METHODS

A retrospective analysis was conducted using 100 CBCT images obtained from the archives of the Department of Oral Medicine and Radiology. The images were captured using Carestream 9600 machines (Carestream Dental LLC, Atlanta, GA) with standard exposure parameters. Curved slicing screenshots were utilized for tracing the morphological variations of the coronoid process, condyle, and sigmoid notch.

RESULTS

Out of 100 CBCT images analyzed (corresponding to 200 sides), the shape-wise distribution of the coronoid process revealed that a triangular shape was most commonly observed in 59% (118) of cases. The condyle exhibited a predominantly round shape in 38.7% (77) of cases based on shape parameter-wise distribution. Similarly, the sigmoid notch displayed a round shape in 40.5% (81) of cases based on shape-wise distribution.

CONCLUSION

Personal identification using radiographs has gained significance in the current scenario due to its feasibility. Cone beam computed tomography imaging has become a reliable and accurate method for revealing hidden details in forensic odontology, especially when antemortem records are available. This research sheds light on the morphological variations of the mandibular coronoid process, condyle, and sigmoid notch within our ethnic cohort, enhancing personal identification practices. Further research encompassing larger sample sizes and diverse populations would enhance the applicability of these findings in forensic and anthropological contexts.

Centric relation-A biological perspective of a technical concept

BACKGROUND

Few terms and concepts have been so extensively debated in dentistry as the words 'centric relation' (CR). Debates involve its biological, diagnostic and therapeutic usefulness.

METHODS

A review of the literature on the current concepts on CR as a diagnostic or therapeutic aid in dentistry was provided. Clinical trials assessing the superiority of one CR recording method over the others to identify patients with temporomandibular disorders (diagnostic use) or to manage patients with prosthodontic or orthodontic needs (therapeutic use) were tentatively included.

RESULTS

Due to the absence of literature addressing either of the above targets, a comprehensive overview was provided. The diagnostic use of CR as a reference position to identify the correct position of the temporomandibular joint condyle within the glenoid fossa is not supported and lacks anatomical support. From a therapeutic standpoint, the use of CR can be pragmatically useful in prosthodontics as a maxillo-mandibular reference position when occlusal re-organization is warranted and/or when the position of maximum intercuspation is no longer available.

CONCLUSIONS

The derived occlusal goals from a diagnostic misuse of CR are generally the result of circular reasoning, that is a technique is based on the recording of a certain condylar position that is believed to be 'ideal' and the treatment is considered successful when such position is shown by the specific instrument that was manufactured for that purpose. The term 'Centric Relation' might be replaced with the term 'Maxillo-Mandibular Utility Position'.

Orthodontics and Temporomandibular Disorders: An Overview

The relationship between orthodontics and temporomandibular disorders (TMDs) constitutes a subject of paramount significance in dental and craniofacial health. This abstract embarks upon an in-depth examination of the intricate connection between orthodontic practices and TMD, primarily focusing on evaluating the impact of orthodontic treatment modalities on the health and functionality of the temporomandibular joint (TMJ). This exploration elucidates the multifaceted interplay between orthodontic interventions and TMD by traversing a landscape of scholarly research and empirical investigations. The review draws from a broad spectrum of studies to analyze the potential influence of orthodontic treatments, which encompass occlusal adjustments and alterations in jaw positioning, on the development and management of TMD symptoms. The inquiry delves into the diverse range of TMD conditions, considering the implications of orthodontic techniques on occlusal stability, condylar alignment, and overall TMJ function. Through a comprehensive synthesis of the available body of knowledge, this abstract aspires to equip dental practitioners, orthodontists, and researchers with a nuanced understanding of the complex dynamics that govern the relationship between orthodontics and TMD. This knowledge, in turn, offers a foundation for informed clinical decision-making and the formulation of effective treatment strategies for patients presenting with TMD symptoms. By shedding light on the intricate interactions between orthodontic procedures and TMJ health, this abstract contributes to the advancement of clinical practices, promoting improved patient outcomes and well-being in the context of both orthodontics and TMDs.

Bibliometric Analysis of Research on Temporomandibular Joint and Occlusion from 2000 to 2022

Purpose

This study conducted a bibliometric analysis that comprehensively described publications on temporomandibular joint and occlusion from 1 January 2000 to 31 October 2022, aiming to reveal hotspots and predict future research trends.

Methods

A total of 2985 articles and reviews were retrieved from Web of Science Core Collection (WoSCC). Excel 2019, VOSviewer and CiteSpace software were used for visualizing analysis of research trends, authors, journals, institutions, countries, keywords and cited references.

Results

Both the annual publication counts and citation times increased significantly. Wang MQ was the most active author. Moreover, Manfredini D and Okeson JP were the most influential two. Journal of Oral Rehabilitation was the core journal. University of Sao Paulo was the most productive institutions. "Temporomandibular disorders" (TMDs), "temporomandibular joint" and "occlusion" were the top 3 keywords with the most frequencies. Keywords and references with burst showed that the causes of TMDs, diagnosis and treatments for TMDs as well as bruxism may be hotspots currently and in the future.

Conclusion

In this study, the research trends, the most productive and influential authors, journals, institutions, countries, in addition to keywords and cited references with burst in the field of temporomandibular joint and occlusion were revealed by a bibliometric analysis, which could help scholars to understand recent hotspots and future trends.

Prevalence and severity of temporomandibular joint disorder in partially versus completely edentulous patients: A systematic review

Temporomandibular joint disorders (TMDs) following tooth loss may or may not be prevalent, but the risk of developing these disorders is always there due to changes in occlusion and vertical dimension, leading to changes in the disc-fossa relationship. The purpose of this systematic review was to evaluate the prevalence and severity of temporomandibular joint (TMJ) disorder in partially versus completely edentulous patients. An elaborated literature search was conducted in PubMed/Medline, Scopus, Web of Science, Lilacs, and Google Scholar databases including all articles about varied effects of partial and complete edentulism on the TMJ published from January 1, 2000, to January 1, 2022. After the meticulous screening, only publications which fulfilled the inclusion parameters were ultimately selected for full-text evaluation and tested for bias using the Joana Briggs Institute Appraisal tools for cross-sectional, case-control, and cohort studies. A total of 547 articles from various electronic databases and manual searches were found. After eliminating the duplicates and thorough screening, 13 studies were included for qualitative synthesis. Most of the studies demonstrated at least one or two signs of the presence of TMDs following tooth loss, the intensity/frequency of which increased in proportion to the number of missing teeth.

Evaluation of condyle-fossa relationships in skeletal Class I malocclusion with variable degrees of deep overbite and open bite

OBJECTIVE

To compare the temporomandibular joint (TMJ) position and shape between skeletal Class I subjects with different degrees of deep overbite or open bite and unaffected peers.

METHODS

Cone beam computed tomography (CBCT) images of 90 participants, equally divided into deep bite, open bite, and control groups (DBG, OBG, and CG, respectively), were analyzed. The DBG and OBG were further subdivided into three subgroups based on the severity. Linear and angular measurements were used to determine the positional and morphological characteristics of the TMJ.

RESULTS

DBG showed significantly larger superior joint space, anterior inclination of the condyle, and articular eminence inclination than CG and OBG. The severity of deep bite and open bite significantly influenced the TMJ position and morphology.

CONCLUSION

In severe deep overbite and open bite cases, there were considerable alterations in TMJ components, most likely as a result of functional demands.

Effects of Prosthetic Rehabilitation on Temporomandibular Disorders: Protocol for a Randomized Controlled Trial

Background

Loss of teeth or occlusal imbalance is one of the proposed dental risk factors for temporomandibular disorders (TMDs). Losing some non–free-end teeth cause the original occluding tooth/teeth to supraerupt from the original upright position and causes neighboring tooth/teeth to shift in an angle, causing biomechanical imbalance on the mandible. Based on these sequelae, rehabilitation of missing teeth is the first step in managing TMD in edentulous patients. Even though the prevalence of TMD in association with edentulism and in rehabilitated patients has been increasing, proper guidelines for the management of such cases have not been established. This study describes the protocol to analyze the effect of prosthetic rehabilitation on patients with TMD.

Objective

This study aims to determine the effectiveness of prosthetic rehabilitation in the reduction of pain in edentulous patients with TMD and to determine the effect of the span of edentulism, the number of quadrants involved, pathological migration, the type of Kennedy classification, and the prosthetic status on temporomandibular joint dysfunction signs and symptoms.

Methods

In this randomized controlled trial, 300 patients diagnosed with TMD will be grouped into one of the three interventional groups based on the type of their edentulous state. The interventional groups are (1) partially edentulous arch: Kennedy Class I and II (prosthetic rehabilitation without splint); (2) partially edentulous arch: Kennedy Class III and IV (prosthetic rehabilitation with a splint); and (3) completely edentulous arches (prosthetic rehabilitation without splint). All three of the mentioned interventional groups have corresponding control groups that will receive symptomatic treatment and comprehensive counseling. The measured primary outcomes are pain and electromyogram, and the secondary outcomes include pain drawing, Graded Chronic Pain Scale, Jaw Functional Limitation Scale, Oral Behaviours Checklist, depression, physical symptoms, and anxiety. The outcome measurements will be recorded at baseline and at the end of 24 hours, 7 days, 28 days, and 3 months.

Results

Ethical approval was obtained from the Institutional Review Board of Amrita Institute of Medical Sciences, Kochi, India. Study participants’ recruitment began in May 2021 and is expected to conclude in March 2023. This clinical trial protocol was developed based on the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) 2013 Statement.

Conclusions

The purpose of this study is to gather data on prosthetic rehabilitation as a treatment for TMD. Obtaining this goal will aid in the development of evidence-based therapy protocols for prosthetic rehabilitation in TMD management.

Trial Registration

Clinical Trials Registry - India CTRI/2020/06/026169; http://ctri.nic.in/Clinicaltrials/pdf_generate.php?trialid=42381

International Registered Report Identifier (IRRID)

DERR1-10.2196/33104

Safe clinical technique for increasing the occlusal vertical dimension in case of erosive wear and missing teeth

A safe method to increase the occlusal vertical dimension (OVD) in patients with mild temporomandibular symptoms (such as tenderness upon palpation) is described. After a temporomandibular joint magnetic resonance (MR), an OVD increase was sought, pursuing pure rotational movement without condyle displacement. Prior to definitive rehabilitation, an additional MR confirmed steady and healthy condyle-disc-fossa relationships.

Osteoarthritis of the temporomandibular joint: A review of aetiology and pathogenesis

The aim of this review was to assess the level of evidence for genetic, biological, and functional predictive and predisposing factors for end-stage temporomandibular joint arthritis within the published literature. A comprehensive review based upon PRISMA guidelines was performed from all literature relevant to the topic. Case series and animal studies were included given the rare nature of the disease and goal of finding root-cause predictive factors. Clinical and radiographic measures were used specifically to identify factors which may have contributed to disease onset and progression. A total of 249 abstracts were identified based on search terms of major databases. After application of exclusion and inclusion criteria, 63 full-text articles were included in the analysis of this paper. There were few factors that could be reliably used to predict end-stage temporomandibular joint disease. Limited evidence is available to adequately predict end-stage temporomandibular joint osteoarthritis. No descriptive process exists that explains how and why this process can occur in younger adults. A better understanding of the aetiology and pathogenesis of TMJ-OA may lead to prevention and more effective management strategies that may reduce the need for drastic surgical intervention, particularly in young adults.

The Prevalence of Temporomandibular Disorders and Dental Attrition Levels in Patients with Posterior Crossbite and/or Deep Bite: A Preliminary Prospective Study

Background

The prevalence of various temporomandibular disorders (TMD) and the severity of attrition in patients with either bilateral or unilateral deep bite and/or posterior crossbite has not been established, nor has the effect of one year of orthodontic treatment on TMD.

Methods

Of 310 patients presenting with suspected TMD, 160 were diagnosed with various TMD and 150 were TMD-free. Diagnosis was according to the Axis I of the Diagnostic Criteria for TMD. All participants underwent a dental examination, and 100 patients were reevaluated after one year of orthodontic treatment. Fisher's exact test and the proportion test with Bonferroni's correction were used for the categorical univariate analysis.

Results

There was a significant association (P < 0.001) between deep bite and dental attrition (wear), but not between crossbite and/or deep bite in patients diagnosed with either painful TMD or disc displacement. The risk of sustaining painful TMD when crossbite presented simultaneously on the anterior and the posterior dentition was 2.625-fold greater than when it presented with a normal bite, although this difference was not significant (P=0.286) due to the lack of statistical power. There was no significant sex-related association between the occurrence of either painful TMD or disc displacement. A reduction in TMD findings was demonstrated after one year of treatment, but no statistical power was reached due to the small sample size.

Conclusions

Deep bite may be related to dental wear but not to pain from TMD and/or disc displacement. Only crossbite that presents simultaneously on the anterior and the posterior dentition (mixed X-bite) may have some effect on the level of pain in TMD, but not on in the prevalence of disc displacement. Confirmation of these conclusions by well-designed studies on larger patient groups is warranted. There was a clinically significant improvement in TMD findings after one year of treatment.

Mapping research trends of temporomandibular disorders from 2010 to 2019: A bibliometric analysis

BACKGROUND

Because of various clinical manifestations and complicated courses, temporomandibular disorders (TMDs) are difficult to treat. Current knowledge about this disease remains insufficient for precise treatment after diagnosis.

OBJECTIVES

The objective of this study is to obtain and map the overall literature trends and most cited keywords in TMDs research.

METHODS

Many indicators, including annual number of publications, country distribution, global cooperations, author contributions, original journals, cited references and keywords, were calculated and evaluated using VOSviewer v.1.6.13, which visualised many results, from the WoSCC database.

RESULTS

A total of 3121 papers on TMDs research were retrieved from 2010 to 2019. The United States produced the most articles published, but the most productive institution was the University of Sao Paulo (Brazil). Researchers and institutions conducting TMDs research have shown a very widespread and close connection. TMDs have been studied worldwide by many research centres. Professor Svensson P was the most published researcher in TMDs research and the Journal of Oral Rehabilitation published the most TMDs research articles. The top cited references mainly presented diagnostic criteria of TMDs. The most cited keywords formed clusters: (a) Anatomical factor of TMDs, (b) Symptoms of TMDs and (c) RDC/TMD, the risk factors, biopsychosocial factors and epidemiology of TMDs.

CONCLUSIONS

The research results provide very valuable data for a thorough understanding of the research status of TMDs and demonstrated international cooperation.

Occlusion and Temporomandibular Disorders: A Long-Standing Controversy in Dentistry

The relationship between temporomandibular disorders (TMDs) and occlusion remains controversial. Some authors believe that occlusion is the primary factor in the onset of TMD symptoms, whereas others feel that occlusion has no role in this at all. The majority of reasoning behind causation is based upon anecdotal rather than scientific evidence. Existing evidence in the literature supports the absence of a disease-specific association. This article describes this controversy and provides the reader with findings from contemporary literature.

The prevalence of posterior crossbite, deep bite, and sleep or awake bruxism in temporomandibular disorder (TMD) patients compared to a non-TMD population: A retrospective study

Objective: To assess the prevalence of posterior crossbite and/or deep bite among patients diagnosed with temporomandibular disorders (TMD) compared to a non-TMD population.Methods: Four hundred ninety-four patients were enrolled: 345 with TMD according to the diagnostic criteria for TMD and 149 without TMD (control group). The chi-square test was used for statistical analysis.Results: A statistically significant association was found between sleep and awake bruxism and painful TMDs (p < .001 for both), but not with disc displacement. There was no association between posterior crossbite and/or deep bite with either painful TMD or disc displacement.Conclusion: Within the study limitations, sleep bruxism and awake bruxism may be related to pain in the TMD, and the severity of a deep overbite and presence of a unilateral or bilateral posterior crossbite should not be considered risk factors or as having any effect on the pain associated with TMD and/or disc displacement.

Masticatory behaviour and chewing difficulties in young adults with temporomandibular disorders

BACKGROUND

Difficulties and limitations on masticatory function are among the main reasons why patients with temporomandibular disorder (TMD) seek care.

OBJECTIVE

To evaluate the masticatory behaviour and perception of chewing difficulties in adults with mild TMD of recent onset, considering the presence of malocclusion.

METHODS

Eighty-one young adults were divided into groups according to the presence of TMD and malocclusion: Non-TMD Normal Occlusion (n = 18), Non-TMD Malocclusion (n = 22), TMD Normal Occlusion (n = 18) and TMD Malocclusion (n = 23). TMD was assessed using the TMD Research Diagnostic Criteria and volunteers also answered questionnaires regarding their perception about jaw functional limitation and difficulty to chew foods of different textures. Masticatory and swallowing behaviours were assessed using the Orofacial Myofunctional Evaluation with Scores (OMES) protocol. Chewing time and chewing frequency taken to ingest the test-food were also obtained. Two-way-ANOVA was used to analyse the TMD, occlusion and TMD × occlusion interaction effects.

RESULTS

Temporomandibular disorder effect was observed on vertical jaw mobility and jaw function limitation total scores, meaning that groups differed in the perception of opening limitation and mandibular limitation according to TMD status with a medium effect size. Also, more changes in chewing function (OMES-chewing score) and higher chewing frequency was observed in the presence of TMD (P < 0.05). Occlusion effect was only observed on OMES-swallowing score and no TMD × occlusion interaction effect was observed.

CONCLUSION

Changes in chewing behaviour, frequency and perception of mandibular limitation was observed in the presence of TMD, pointing out the importance of functional evaluation when planning and establishing a treatment plan.

Association between posterior crossbite and/or deep bite and temporomandibular disorders among Palestinian adolescents: A sex comparison

Objective: To assess the prevalence of temporomandibular disorders (TMDs) and posterior crossbite and/or deep bite and any possible association between them. Methods: One thousand-nineteen adolescents responded to a questionnaire regarding oral habits and TMD symptoms. Afterwards, they were diagnosed according to the Axis I of the DC/TMD and underwent a dental examination. The chi-square test was used for statistical analysis. Results: A significant association  was found between posterior crossbite and some TMD diagnosis, but no association was found between deep bite and TMD, nor between occlusal diagnosis and bruxism. TMDs were more prevalent in girls. There was a significant sex difference (more among females) in the prevalence of painful TMDs. Conclusion: Posterior crossbite in the adolescent population analyzed may be related to TMDs, in contrary to deep-bite. The presence of posterior crossbite may have different impact on TMD findings between the sexes.

Methadone maintenance treatment may be associated with bruxism in male prisoners

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Methadone treatment, bruxism, and temporomandibular disorders among male prisoners. Enguelberg-Gabbay JV, Schapir L, Israeli Y, Hermesh H, Weizman A, Winocur E. Eur J Oral Sci 2016;124(3): 266-71.

SOURCE OF FUNDING

None TYPE OF STUDY/DESIGN: Cross-sectional study.

Tooth loss and craniofacial factors associated with changes in mandibular condylar morphology

Objective: To investigate the association between tooth loss and craniofacial factors with changes in mandibular condylar morphology. Methods: A total of 123 patients participated in this cross-sectional study. The mandibular condylar morphology was evaluated using digital panoramic radiography. The exposure variables included gender, age group, molar relationship, facial growth pattern, facial asymmetry, dental midline, posterior crossbite, presence of fixed dental prosthesis, and tooth loss. Results: Unilateral and bilateral mandibular condyle structural alterations were found in 20.3% and 28.5% of the sample, respectively. After the adjustment analysis, posterior crossbite (adjusted OR = 3.34, 95% CI = 1.23-9.06) and tooth loss (adjusted OR = 4.08, 95% CI = 1.72-9.64) were associated with the outcome. The tooth type associated with mandibular condyle structural alterations were premolars and upper molars. Conclusion: The findings suggest that posterior crossbite and tooth loss are associated with mandibular condyle structural alterations.

The role of occlusion in temporomandibular disorders (TMD) in the Northern Finland Birth Cohort (NFBC) 1966

OBJECTIVE

To investigate the role of occlusion in temporomandibular disorders (TMDs) in the Northern Finland Birth Cohort 1966 (NFBC 1966).

METHODS

Subjects (n = 1962) participated in clinical medical and dental examinations. The association between TMD signs and diagnoses with occlusal disturbances, i.e. malocclusions and occlusal interferences, was examined. Pearson's chi-square test, as expressed by odds ratios (OR) and 95% confidence intervals (CI) and logistic regression models, were used in the analysis.

RESULTS

A statistically significant association was found between myalgia and lateral scissor bite and also between arthralgia and lateral deviation in the retruded contact position and intercuspal contact position (RCP-ICP) slide. Pain in the masticatory muscles was associated with negative overjet and the amount of RCP-ICP slide.

DISCUSSION

Occlusal factors showed a statistically significant association with TMD. The TMD signs were associated with unstable occlusion, especially the amount and lateral deviation in RCP-ICP slide, as well as negative overjet.

Prevalence of temporomandibular symptoms and parafunctional habits in a university dental clinic and association with gender, age, and missing teeth

Objective To assess the prevalence of symptoms of temporomandibular disorder (TMD) and parafunctional habits as well as to investigate their association with age, gender, and number of missing teeth. Methods This retrospective study is based on 4204 randomly selected patients who were examined to determine their symptoms of TMD, such as clicking, difficulty chewing, difficulty opening/closing, as well self-reported joint pain and parafunctional habits. Results Clenching/grinding was reported by 26.5% of the examined population, clicking by 14.8%, and difficulty chewing and closing by 3.6%. Significant associations between the number of missing teeth with clenching/grinding (p = 0.05) and difficulty chewing (p < 0.001) were detected. Age and gender showed significant effects on the examined parameters (p < 0.05). Discussion Understanding the TMD subjective symptoms in relation to age, gender, and tooth loss would be of great value for treatment planning and could provide other perspectives to establish preventive measures.

A Study to Determine the Prevalence of Temporomandibular Disorders in a Young Adult Population and its Association with Psychological and Functional Occlusal Parameters

PURPOSE

To determine the prevalence of temporomandibular disorders (TMD) in medical university students and to analyze the relationship of TMD with psychological and functional occlusal parameters.

MATERIALS AND METHODS

200 students (mean age 21.81 ± 1.99) were screened for TMD with the TMD Pain Screener. Clinical examinations identified the participants with TMD. Based on their diagnostic criteria for TMD (DC/TMD) axis I diagnosis, participants were divided into three groups: group 1- non-TMD, group 2- pain related TMD and headaches, and group 3- intra-articular joint disorders. Further study was continued involving patients diagnosed with TMD as the study group, and an equal number of age- and sex-matched participants were selected in control group. Among these, emotional distress was evaluated using the "hospital anxiety and depression scale" (HADS). Occlusal evaluations were done by using the T-Scan computerized occlusal analysis system. Occlusion time, left lateral disclusion time, right lateral disclusion time, and protrusion disclusion time were measured with T-Scan III. These parameters were compared among the groups with ANOVA test at a significance level of 0.05.

RESULTS

17% of the population were affected by TMD. The mean HADSd (depression) and HADSa (anxiety) scores were significantly higher (p < 0.05) in group 2 (7.67 ± 3.68; 10.60 ± 3.33) and group 3 (6.89 ± 3.23; 9.26 ± 4.05) as compared to group 1 (3.18 ± 2.33; 5.29 ± 3.21). The mean values of occlusion time, left lateral disclusion time, right lateral disclusion time, and protrusion-disclusion time were also higher for group 2 and group 3 as compared to group 1.

CONCLUSIONS

This study found that the prevalence of TMD in this university student population was 17%. There were significant associations of TMD with psychological parameters and functional occlusal parameters.

Osteoarthrosis of Temporomandibular Joint Related to the Defects of Posterior Dentition: A Retrospective Study

Osteoarthrosis (OA) of temporomandibular joint (TMJ) is a progressive degenerative disease, gradually affecting cartilage, synovial membrane and bone structures. OA of TMJ clinically manifests with joint noises, pain and restricted mouth opening. In late stages, it results in severe damage of TMJ structures and development of ankylosis. Osteoarthrosis is a multifactorial disease; the occurrence is associated with TMJ overloading. The cohort included 619 patients [538 women (87%) and 81 men (13%), with average age 40.6 years (age range 8-89 years)] with TMJ disorder, who were examined in the year 2014 in Department of Dental Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic. The aim of this retrospective study was to analyse, if the lack of posterior teeth (supporting teeth zones) is the main etiologic factor of osteoarthrosis of TMJ. Diagnosis of OA was established on the clinical signs and the panoramic X-ray signs. Simultaneously other etiologic factors of OA were assessed. The presence of OA changes on X-ray had 171 patients (i.e. 27.6% of the total number of 619). 17.5% from these patients with OA had defect in posterior dentition. Other aetiological factors (stress, skeletal or vertebrogenous disorders) showed higher incidence of OA changes on X-ray. Defect of posterior dentition is not negligible, but it is not the main aetiological factor for osteoarthrosis of TMJ.

Overbite and Overjet are not Related to Self-report of Temporomandibular Disorder Symptoms

Overbite and overjet, especially high or low values, have been found in some studies to be associated with temporomandibular disorders (TMD). This study evaluates the relationship between overbite/overjet and three TMD self-report measures (pain, joint noises, limited mouth-opening). Subjects were from two population-based cross-sectional studies (3033 subjects). After adjustment for age and gender, high or low values of overbite were not associated with an increased risk of self-reported TMD pain as compared with a reference category of a normal overbite of 2 to 3 mm (-8 to -1 mm, odds ratio = 0.36, 95% confidence interval = 0.05-2.76; 6 to 15 mm, odds ratio = 1.08, 95% confidence interval = 0.68-1.72). Similar non-significant results were found for overjet and TMD pain, and for the association of overjet/overbite and joint noises or limited mouth-opening. This study provides the strongest evidence to date that there is no association between overbite or overjet and self-reported TMD.

Implications of Vertebrate Craniodental Evo-Devo for Human Oral Health

Highly processed diets eaten by postindustrial modern human populations coincide with higher frequencies of third molar impaction, malocclusion, and temporomandibular joint disorders that affect millions of people worldwide each year. Current treatments address symptoms, not causes, because the multifactorial etiologies of these three concerns mask which factors incline certain people to malocclusion, impaction, and/or joint issues. Deep scientific curiosity about the origins of jaws and dentitions continues to yield rich insights about the developmental genetic mechanisms that underpin healthy craniodental morphogenesis and integration. Mounting evidence from evolution and development (Evo-Devo) studies suggests that function is another mechanism important to healthy craniodental integration and fit. Starting as early as weaning, softer diets and thus lower bite forces appear to relax or disrupt integration of oral tissues, alter development and growth, and catalyze impaction, malocclusion, and jaw joint disorders. How developing oral tissues respond to bite forces remains poorly understood, but biomechanical feedback seems to alter balances of local bone resorption and deposition at the tooth-bone interface as well as affect tempos and amounts of facial outgrowth. Also, behavioral changes in jaw function and parafunction contribute to degeneration and pain in joint articular cartilages and masticatory muscles. The developmental genetic contribution to craniodental misfits and disorders is undeniable but still unclear; however, at present, human diet and jaw function remain important and much more actionable clinical targets. New Evo-Devo studies are needed to explain how function interfaces with craniodental phenotypic plasticity, variation, and evolvability to yield a spectrum of healthy and mismatched dentitions and jaws.

Dental Angle class asymmetry and temporomandibular disorders

OBJECTIVES

The aim of this study was to determine whether there is an association between the presence of asymmetric molar or canine Angle classes on the two sides and the presence of temporomandibular joint dysfunction (TMD).

MATERIALS AND METHODS

Participants to the study were divided into two groups: TMD group (90 patients) or a control group (58 patients). In the TMD group, clinical assessment for TMD was performed according to the Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) guidelines by the same two trained examiners. In both groups, all subjects underwent an assessment of dental occlusion, focusing on the assessment of bilateral canine and molar Angle class relationship. The study protocol was reviewed and approved by the Institutional Review Board of the University of Padova, and each participant gave written consent to take part in the investigation.

RESULTS

TMJ pain was diagnosed in 58, disk displacement in 96, arthrosis in 17, and muscle pain in 46 individuals. Molar Angle class was symmetrical in 86 individuals and asymmetrical in 62 subjects. Molar Angle class was not correlated with any of the TMD diagnoses. Canine Angle class was correlated with TMJ arthrosis. Correlation values with the other TMD diagnoses were low and were not significant.

CONCLUSIONS

It can be suggested that an association between dental Angle class asymmetry and TMDs does not exist and that the role of dental asymmetries as a factor correlated with the presence of TMD signs and symptoms is minimal.

Influence of generalized joint hypermobility on temporomandibular joint and dental occlusion: a cross-sectional study

Purpose

To evaluate the dental occlusion and temporomandibular joint in women with and without generalized joint hypermobility.

Methods

Generalized joint hypermobility was assessed by the Beighton score. Individuals were divided into two groups: with and without hypermobility. The Research Diagnostic Criteria for Temporomandibular Disorders was used to evaluate the temporomandibular joint. Dental occlusion was assessed according to Angle classification, overjet and overbite measures, presence of open bite or crossbite, pattern of disocclusion, and occlusal interference.

Results

Forty-three women participated voluntarily in the study: 17 in the group with hypermobility and 26 in the group without hypermobility. The frequencies of joint noise and deviation during mouth opening were greater in the hypermobility group (52.9% vs. 38.5% and 76.5% vs. 50%, respectively), but without statistical significance. None of the volunteers presented ideal occlusion and no significant difference was found in Angle Class between the groups. The hypermobility group presented a higher percentage of changes in occlusion (29.4% of overbite, 47.1% of overjet, and 17.6% of crossbite), with crossbite showing statistical difference between the groups.

Conclusion

Hypermobility does not influence occlusion and range of mandibular motion in the women assessed. Nevertheless, the higher percentage of articular noise and uncorrected deviation during mouth opening shown by the group with hypermobility, even without statistical difference, may constitute evidence of correlation between hypermobility and temporomandibular disorder.

Factors involved in the etiology of temporomandibular disorders - a literature review

BACKGROUND AND AIM

This review aims at presenting a current view on the most frequent factors involved in the mechanisms causing temporomandibular disorders (TMD).

METHOD

We conducted a critical review of the literature for the period January 2000 to December 2014 to identify factors related to TMD development and persistence.

RESULTS

The etiology of TMD is multidimensional: biomechanical, neuromuscular, bio-psychosocial and biological factors may contribute to the disorder. Occlusal overloading and parafunctions (bruxism) are frequently involved as biomechanical factors; increased levels of estrogen hormones are considered biological factors affecting the temporo-mandibular-joint. Among bio-psychosocial factors, stress, anxiety or depression, were frequently encountered.

CONCLUSIONS

The etiopathogenesis of this condition is poorly understood, therefore TMDs are difficult to diagnose and manage. Early and correct identification of the possible etiologic factors will enable the appropriate treatment scheme application in order to reduce or eliminate TMDs debilitating signs and symptoms.

Orthodontics is temporomandibular disorder-neutral

OBJECTIVES

To assess if subjects with a clinical diagnosis of temporomandibular disorders (TMDs) have a similar prevalence of orthodontic history as a population of TMD-free individuals and to assess if those subjects who have a history of ideal orthodontics have fewer symptoms than those with a history of nonideal orthodontics.

MATERIALS AND METHODS

Two groups of age- and sex-matched individuals belonging to either a study ("TMD") or a control group were recruited. Subjects who underwent orthodontic treatment were classified as having a history of ideal or nonideal orthodontics based on the current presence of normal values in five reference occlusal features.

RESULTS

The correlation with a history of orthodontic treatment was not clinically significant for any of the TMD diagnoses (ie, muscle pain, joint pain, disc displacement, arthrosis), with Phi (Φ) coefficient values within the -0.120 to 0.058 range. Within the subset of patients with a history of orthodontics, the correlation of ideal or nonideal orthodontic treatment with TMD diagnoses was, in general, not clinically relevant or was weakly relevant.

CONCLUSIONS

Findings confirmed the substantial absence of clinically significant effects of orthodontics as far as TMD is concerned. The very low correlation values of a negative or positive history of ideal or nonideal orthodontics with the different TMD diagnoses suggest that orthodontic treatment could not have a true role for TMD.

Do changes in oral health-related quality-of-life, facial pain and temporomandibular disorders correlate after treatment of severe malocclusion?

INTRODUCTION

The aim was to evaluate the relationships of changes in facial pain, temporomandibular disorders (TMDs) and oral health-related quality-of-life (OHRQoL) in adults who underwent orthodontic or orthodontic/surgical treatment.

METHODS

Sixty-four patients (46 women, 18 men, range 18-64 years) with severe malocclusion and functional problems were treated in Oulu University Hospital. Of these, 44 underwent orthodontic-surgical and 20 orthodontic treatment. Data were collected with questionnaires and clinical stomatognathic examinations before and on average 3 years after treatment. The OHRQoL was measured with OHIP-14 (The Oral Health Impact Profile), the intensity of facial pain with the Visual Analogue Scale (VAS) and the severity of TMD with the Helkimo's anamnestic (Ai) and clinical (Di) dysfunction indices.

RESULTS

A significant improvement was found in facial pain, signs and symptoms of TMD and OHRQoL after the treatment (p < 0.05). The decrease in VAS was associated with improvement in OHIP-14 severity (r = 0.296, p = 0.019). The correlations between changes in OHIP-14 severity and Ai and Di were not statistically significant.

CONCLUSION

Treatment of severe malocclusion seemed to improve OHRQoL via decreased facial pain. Decreased facial pain was associated especially with improved OHRQoL dimensions of physical pain, physical disability and social disability.

Treating temporomandibular disorders with permanent mandibular repositioning: is it medically necessary?

In this paper, the authors review the rationale and history of mandibular repositioning procedures in relation to temporomandibular disorders (TMDs) as these procedures have evolved over time. A large body of clinical research evidence shows that most TMDs can and should be managed with conservative treatment protocols that do not include any mandibular repositioning procedures. Although this provides a strong clinical argument for avoiding such procedures, very few reports have discussed the biologic reasons for either accepting or rejecting them. This scientific information could provide a basis for determining whether mandibular repositioning procedures can be defended as being medically necessary. This position paper introduces the biologic concept of homeostasis as it applies to this topic. The continuing adaptability of teeth, muscles, and temporomandibular joints throughout life is described in terms of homeostasis, which leads to the conclusion that each person's current temporomandibular joint position is biologically "correct." Therefore, that position does not need to be changed as part of a TMD treatment protocol. This means that irreversible TMD treatment procedures, such as equilibration, orthodontics, full-mouth reconstruction, and orthognathic surgery, cannot be defended as being medically necessary.

Associação entre funções estomatognáticas, oclusão dentária e sinais de disfunção temporomandibular em mulheres assintomáticas

OBJETIVO: verificar a associação entre funções estomatognáticas de mastigação e deglutição, oclusão dentária e sinais de disfunção temporomandibular em mulheres assintomáticas. MÉTODOS: as funções estomatognáticas foram avaliadas pelo exame miofuncional orofacial; o exame da oclusão dentária compreendeu: classificação de Angle; medidas de sobrepasse horizontal e vertical; presença de mordida aberta e cruzada; e a avaliação da articulação temporomandibular foi realizada pelo instrumento Critérios de Diagnóstico para Pesquisa de Desordens Temporomandibulares. RESULTADOS: foram avaliadas 43 mulheres com idade média de 23,7 anos. O exame miofuncional orofacial demonstrou alterações no padrão de mastigação (30,2%) e contrações atípicas na mastigação (18,6%) e deglutição (58,1%). Quanto à oclusão dentária, houve predomínio de classe I de Angle (74,4%), porém nenhuma voluntária apresentou uma oclusão ideal. A avaliação da articulação temporomandibular apresentou amplitude de movimento dentro da normalidade, presença de desvio na abertura da boca (60,5%) e diagnóstico de disfunção temporomandibular (16,3%). Houve associação significante entre presença de ruídos articulares e diagnóstico de disfunção temporomandibular e contrações atípicas na deglutição; padrão de abertura e contrações atípicas na mastigação; e não houve associação entre a Classe Oclusal de Angle, padrão de mastigação e disfunção temporomandibular. CONCLUSÃO: voluntárias assintomáticas apresentaram alterações das funções estomatognáticas, como contrações atípicas durante a deglutição e mastigação, as quais foram associadas com a presença de ruídos articulares e padrão de abertura da boca. Tais achados podem ser atribuídos a desequilíbrios e incoordenação dos músculos envolvidos nessas funções. Nenhuma voluntária apresentou oclusão ideal e não foram encontradas associações com esta condição.

Clinical issues in occlusion - Part I

Good occlusal practise provides an important cornerstone to optimal patient care. Occlusal problems can manifest in different areas of dentistry but these are more apparent when there are restorative aspects to the patient׳s problem. This review highlights areas of restorative dentistry where the appreciation of occlusal aspects can optimise diagnosis and follow up care.

Dentofacial characteristics in orthodontic patients with centric relation-maximum intercuspation discrepancy

INTRODUCTION

To investigate dentofacial characteristics of orthodontic patients with centric relation (CR)-maximum intercuspation (MI) discrepancy and to analyze changes in dentofacial characteristics between CR and MI positions in these patients using lateral cephalograms.

MATERIALS AND METHODS

Adult female patients were classified into two groups: large CR-MI discrepancy (greater than 2.0 mm horizontal or vertical mandibular incisor movements during CR to MI change, n  =  20) and small CR-MI discrepancy (less than 1.0 mm horizontal and vertical mandibular incisor movements during CR to MI change, n  =  22). All subjects underwent temporomandibular joint (TMJ) magnetic resonance imaging prior to treatment. Gnathological stabilizing splints were used to find a reliable CR position in patients with large CR-MI discrepancy. Sixteen variables from lateral cephalograms were analyzed to identify differences in cephalometric variables between CR and MI positions in patients with large discrepancy. Differences in dentofacial cephalometric variables at MI positions between patients with large and small CR-MI discrepancies were also analyzed.

RESULTS

Patients with large CR-MI discrepancy had backward positioning and rotation of the mandible at the MI position compared to the norm. In addition, the mandible moved more posteriorly and rotated more in a clockwise direction during MI to CR change. Interestingly, all patients with large CR-MI discrepancy had TMJ disk displacement. There were no significant differences in the cephalometric variables of the MI positions between patients with small and large CR-MI discrepancies.

CONCLUSIONS

This study suggests that adult patients with backward positioning and rotation of the mandible should be carefully evaluated as a result of the potential CR-MI discrepancy.

The role of occlusal factors on the occurrence of temporomandibular disorders

AIMS

The aim of this study was to investigate the relationship between occlusal factors and temporomandibular disorders (TMD).

METHODOLOGY

One hundred patients were selected among those who sought medical or dental care in public practice in Recife, Brazil. The presence of malocclusions and absence of five or more posterior teeth were evaluated by the clinical exam. TMD diagnosis was given using Research Diagnostic Criteria (RDC/TMD). Statistics were carried out using Fisher and Mann-Whitney methods with 5% significance level, as well as multiple logistic regression analysis.

RESULTS

The sample was mainly comprised of women (83%), individuals over 30 years old (57%) and singles (53%). The percentage of TMD and malocclusion in total sample was 42% and 50%, respectively, while in TMD subjects, malocclusion was present in 38.1%. There was no association between TMD and the occlusal factors studied.

CONCLUSION

It can be concluded that malocclusion and loss of five or more posterior teeth does not contribute to TMD.

Are occlusal features associated with different temporomandibular disorder diagnoses in bruxers?

AIMS

The present study was designed to test the hypothesis that dental occlusion may have a role in mediating the effects of bruxism in temporomandibular disorders (TMD) patients. It aimed to answer the clinical research question: in a population of TMD patients with clinically diagnosed clenching-type bruxism, are the different TMD diagnoses associated with different occlusal features?

MATERIALS AND METHODS

A total of 294 TMD patients (73% females, mean age 38·3±9·2 years) who were positive for a clinical diagnosis of clenching-type bruxism underwent an assessment in accordance with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I, as well as a recording of nine occlusal features. Statistical analyses were performed to test the null hypotheses that: (1) no differences existed between the patients with or without the various occlusal features as for the prevalence of the various single and combined RDC/TMD group diagnoses (single variable analysis), and (2) having any specific occlusal feature makes no difference in distinguishing within the RDC/TMD diagnoses (multiple variable analysis).

RESULTS

The distribution of the different combination of RDC/TMD axis I diagnoses was significantly different in patients with laterotrusive interferences with respect to those without such interferences (chi-square = 15·209; P = 0·033) as well as in patients with a slide from retruded contact position (RCP) to maximum intercuspation (MI) >2 mm with respect to those without such slide (chi-square = 4·029; P = 0·012) and in those with or without molar class asymmetry (chi-square = 17·438; P = 0·015). Multinomial regression analysis showed that the model including the various occlusal features account for 20·4% of the variance for RDC/TMD diagnoses (Nagelkerke R(2) = 0·204) and allowed the rejection of the null hypothesis that having such specific occlusal features makes no difference in distinguishing within the RDC/TMD diagnoses.

CONCLUSIONS

Within the limitations of this study, it can be suggested that in a population of patients with TMD and clinically-diagnosed clenching-type bruxism, the patterns of TMD diagnoses may be influenced, at least in part, by the presence of some features of dental occlusion, namely, slide RCP-MI, laterotrusive interferences, and molar asymmetry.