The Relationship Between Occlusion and TMD: An Evidence-Based Discussion

Occlusal Features and Temporomandibular Joint Disorder: A Cross-Sectional Study

Background

Understanding the correlation between temporomandibular joint disorder (TMD) parameters and various occlusal features can play a significant role in diagnosing and treating occlusal problems and their potential consequences on TMD.

Objectives

To investigate the relationship of occlusal features and some of the TMD parameters. Study Design and Sampling. The current cross-sectional study was conducted on 200 TMD patients seeking dental treatment at different dental centers in Baghdad city, aged 18-35 years. All participants underwent assessment for occlusal features, which were molar and canine classifications, overjet, posterior buccal or lingual crossbites, and overbites, and TMD parameters (muscle pain, TMJ pain, and clicking) using the Chi-square test for statistical analysis.

Results

Regarding molar classification, there were strong positive correlations between subjects with TMD and having different molar classifications (class I, II, and III) bilaterally or unilaterally; furthermore, there were strong positive correlations between subjects with TMD and having different canine classifications. Moreover, there were significant correlations between subjects with increased, normal, or decreased overjet and the TMD parameters. In addition, there were weak positive correlations between TMD occurrence and buccal or lingual posterior crossbite. On the other hand, there were significant correlations between subjects with a decreased overbite and the presence of TMD parameters.

Conclusion

TMD had a multifactorial background rather than dependability on a specific molar or canine classification type. There was also a correlation between overjet and TMD muscle pain, while decreased overbite was correlated to muscle and TMJ pain. Conversely, there is no vital correlation between posterior buccal or lingual crossbite occurrence and TMD parameters.

What is occlusion? Part 2

Some dentists choose to ignore the subject of occlusion, while others propose a set of doctrinal rules. It is of little wonder therefore that it can become a source of confusion and even controversy. This series of two papers aims, firstly, to answer the very simple question of 'what is occlusion?'. It will put occlusion into the context of the articulatory system because that is the bio-mechanical environment where the majority of dentists do their work. The concept of jaw relation will also be discussed but within the context of this locomotive system. Ideal occlusion will be described but only after answering the question: for whom or what might an occlusion be considered ideal? Although, in the book of which this is the first chapter, he presents what has worked for him during many years as a general dental practitioner, university lecturer and specialist in restorative dentistry, he has tried not to be didactic because he feels that, in a profession, there are no right answers, only the right questions.

Relationship between natural or iatrogenic malocclusions and temporomandibular disorders: A case control study

OBJECTIVE

To investigate the link between malocclusions and temporomandibular disorders (TMD) with a focus on iatrogenic malocclusion. Other etiologies of TMD (oral parafunctions) were also assessed.

METHODS

The prevalence of malocclusions was correlated in two groups: patients with TMD (case group) and patients without TMD (control group). Malocclusions involving dental care were specified. Parafunctions in the case group were assessed.

RESULTS

A statistically significant association between TMD and overbite >4 mm, interferences in laterotrusion, and absence of Angle Class I was shown. A potential deleterious effect of iatrogenic malocclusions was highlighted.

CONCLUSION

The multifactorial etiology of TMD was confirmed because an association between TMD and three malocclusions was found, and all case patients had parafunction(s). Current recommendations advising first a reversible treatment, TMD care should start with a behavioral re-education to remove parafunctions. However, it is essential to avoid creating iatrogenic malocclusion during dental care.

Temporomandibular disorders: knowledge, competency, and attitudes of predoctoral dental students

OBJECTIVE

To evaluate knowledge, competency, and attitudes related to temporomandibular disorders (TMD) among predoctoral dental students, and to investigate the curricular organization of contents related to TMD and occlusion.

METHODS

Predoctoral dental students (n = 147) answered a questionnaire with topics related to TMD. Another questionnaire evaluated the organization of TMD and occlusion courses.

RESULTS

Contents related to TMD and occlusion were taught in the same course in all dental schools. The students' responses showed low agreement with the current gold standards pertaining to TMD. Most students declared that they did not feel confident to treat patients with TMD (62.6%), were not satisfied with the content pertaining to TMD (55.8%), and considered a lack of clinical practice to be the primary limitation in their training (59.2%).

DISCUSSION

Students' knowledge of basic concepts related to TMD was limited, highlighting the need for readjustment of the dental curriculum to increase clinical experience.

Occlusion: is there a third way? A discussion paper

This paper does not set out to describe the reasons why a new concept of dental care should be deemed as acceptable and recognised as mainstream. Rather, the starting point of this paper is the belief that some dentists who are increasing the overall vertical dimension for worn dentition patients are not using the protocols of the traditional 're-organised approach'. If adhesive direct restorations are used, there seems to be anecdotal indication that despite not restoring in the terminal hinge axis, it can have a successful outcome.So, while not criticising this approach simply because it does not follow orthodoxy, the paper has two objectives. It hopes to stimulate some debate and research on this subject. Furthermore, by suggesting some parameters for what might be considered a new approach, it aims to improve patient outcome.

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.

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.

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.

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.

Vertical Craniofacial Morphology and its Relation to Temporomandibular Disorders

Objectives

This study investigated the association between craniofacial morphology and temporomandibular disorders in adults. The influence of different craniofacial morphologies on painful temporomandibular disorders was also evaluated.

Material and Methods

A total of 200 subjects were selected, including 100 with temporomandibular disorders (TMD) and 100 without TMD (control), diagnosed by research diagnostic criteria for temporomandibular disorders. All subjects were submitted to lateral cephalometric radiographs, and classified as brachyfacial, mesofacial, or dolichofacial by Ricketts’ analysis. Data were analysed by Tukey-Kramer and Chi-square tests.

Results

No association between craniofacial morphology and TMD was found (P = 0.6622). However, brachyfacial morphology influences the presence of painful TMD (P = 0.0077).

Conclusions

Craniofacial morphology is not related to temporomandibular disorders in general.

Intrusion of supraerupted maxillary molar using a high interim restoration on the defective opposing tooth: a clinical report

Wear, extraction, or fracture of all or part of a mandibular first molar can lead to the supraeruption of the opposing maxillary molar, resulting in occlusal interference and lack of restoration space. This report describes a method to gain sufficient vertical space for permanent restoration. A direct composite resin restoration was placed on the occlusal surface of a lower molar, intentionally making the interim restoration high and intruding the maxillary molar. After 6 weeks, the extruded tooth returned to the desired position, and functional occlusion was restored, enabling a ceramic restoration on the mandibular molar. No marked adverse sensory reaction was reported in this therapeutic process, and no deleterious signs were detected in the teeth, periodontium, or temporomandibular joints. The simple treatment type was effective, noninvasive, and time saving, while also preserving maximum tooth structures.

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.

Skeletal malocclusion: a developmental disorder with a life-long morbidity

The likelihood of birth defects in orofacial tissues is high due to the structural and developmental complexity of the face and the susceptibility to intrinsic and extrinsic perturbations. Skeletal malocclusion is caused by the distortion of the proper mandibular and/or maxillary growth during fetal development. Patients with skeletal malocclusion may suffer from dental deformities, bruxism, teeth crowding, trismus, mastication difficulties, breathing obstruction and digestion disturbance if the problem is left untreated. In this review, we focused on skeletal malocclusion that affects 27.9% of the US population with different severity levels. We summarized the prevalence of class I, II and III of malocclusion in different ethnic groups and discussed the most frequent medical disorders associated with skeletal malocclusion. Dental anomalies that lead to malocclusion such as tooth agenesis, crowding, missing teeth and abnormal tooth size are not addressed in this review. We propose a modified version of malocclusion classification for research purposes to exhibit a clear distinction between skeletal vs. dental malocclusion in comparison to Angle’s classification. In addition, we performed a cross-sectional analysis on orthodontic (malocclusion) data through the BigMouth Dental Data Repository to calculate potential association between malocclusion with other medical conditions. In conclusion, this review emphasizes the need to identify genetic and environmental factors that cause or contribute risk to skeletal malocclusion and the possible association with other medical conditions to improve assessment, prognosis and therapeutic approaches.

Neuromuscular dentistry: Occlusal diseases and posture

Neuromuscular dentistry has been a controversial topic in the field of dentistry and still remains debatable. The issue of good occlusion and sound health has been repeatedly discussed. Sometimes we get complains of sensitive teeth and sometimes of tired facial muscles on getting up in the morning. Owing to the intimate relation of masticatory apparatus with the cranium and cervico-scapular muscular system, the disorders in any system, draw attention from concerned clinicians involved in management, to develop an integrated treatment protocol for the suffering patients. There may be patients reporting to the dental clinics after an occlusal restoration or extraction, having pain in or around the temporomandibular joint, headache or neck pain. Although their esthetic demands must not be undermined during the course of treatment plan, whenever dental treatment of any sort is planned, occlusion/bite should be given prime importance. Very few dentist are able to diagnose the occlusal disease and of those who diagnose many people resort to aggressive treatment modalities. This paper aims to report the signs of occlusal disease, and discuss their association with TMDs and posture.

Skeletal pattern in subjects with temporomandibular joint disorders

INTRODUCTION

To establish the skeletal pattern in subjects with malocclusions and temporomandibular disorders (TMD); to assess the relationship between craniofacial skeletal structures and TMD in subjects with malocclusions.

MATERIAL AND METHODS

Sixty-four subjects with malocclusions, over 18 years of age, were included in the study. Temporomandibular disorders were clinically assessed according to the Helkimo Anamnestic Index. Subjects underwent a lateral cephalogram. Subjects were grouped according to the sagittal skeletal pattern (ANB angle) into class I, II and III. Parametric Student tests with equal or unequal variations were used (variations were previously tested with Levene test).

RESULTS

Twenty-four patients with TMD (experimental sample); 40 patients without TMD (control group); interincisal angle was higher in class I and II (p < 0.05) experimental subjects; overjet was larger in experimental subjects; midline shift and Wits appraisal were broader in the experimental group in all three classes. In class III subjects, the SNB angle was higher in the experimental group (p = 0.01). Joint noises followed by reduced mandible mobility, muscular pain and temporomandibular joint (TMJ) pain were the most frequent symptoms in subjects with TMD and malocclusions.

CONCLUSIONS

Temporomandibular joint status is an important factor to consider when planning orthodontic treatment in patients with severe malocclusions; midline shift, large overjet and deep overbite have been associated with signs and symptoms of TMD.

Profiling the clinical presentation of diagnostic characteristics of a sample of symptomatic TMD patients

BACKGROUND

Temporomandibular disorder (TMD) patients might present a number of concurrent clinical diagnoses that may be clustered according to their similarity. Profiling patients' clinical presentations can be useful for better understanding the behavior of TMD and for providing appropriate treatment planning. The aim of this study was to simultaneously classify symptomatic patients diagnosed with a variety of subtypes of TMD into homogenous groups based on their clinical presentation and occurrence of comorbidities.

METHODS

Clinical records of 357 consecutive TMD patients seeking treatment in a private specialized clinic were included in the study sample. Patients presenting multiple subtypes of TMD diagnosed simultaneously were categorized according to the AAOP criteria. Descriptive statistics and two-step cluster analysis were used to characterize the clinical presentation of these patients based on the primary and secondary clinical diagnoses.

RESULTS

The most common diagnoses were localized masticatory muscle pain (n = 125) and disc displacement without reduction (n = 104). Comorbidity was identified in 288 patients. The automatic selection of an optimal number of clusters included 100% of cases, generating an initial 6-cluster solution and a final 4-cluster solution. The interpretation of within-group ranking of the importance of variables in the clustering solutions resulted in the following characterization of clusters: chronic facial pain (n = 36), acute muscle pain (n = 125), acute articular pain (n = 75) and chronic articular impairment (n = 121).

CONCLUSION

Subgroups of acute and chronic TMD patients seeking treatment can be identified using clustering methods to provide a better understanding of the clinical presentation of TMD when multiple diagnosis are present. Classifying patients into identifiable symptomatic profiles would help clinicians to estimate how common a disorder is within a population of TMD patients and understand the probability of certain pattern of clinical complaints.

Risk factors for the occurrence and prevention of temporomandibular joint and muscle disorders: lessons from 2 recent studies

INTRODUCTION

Our objectives were to demonstrate how standard epidemiologic measurements can assist in evaluating the risk factors for tempormandibular joint and muscle disorders (TMJMD) and to determine whether prevention is feasible.

METHODS

We reviewed 2 recent studies that examined third-molar extractions and severe mandibular retrognathia as risk factors for TMJMD. Cumulative incidences were available from these studies. By using these values, standard epidemiologic measurements of risk, including population attributable risk (PAR), attributable risk (AR), population attributable risk percent (PAR%), and attributable risk percent (AR%), were calculated. (PAR and AR are reported as the numbers of cases per 10,000 per year.)

RESULTS

In the third-molar extraction study, PAR, AR, PAR%, and AR% were 5, 10, 25%, and 40%; in the severe mandibular retrognathia study, they were 0.5, 17.5, 10%, and 80%, respectively.

CONCLUSIONS

This review supports the current consensus that most risk factors explain only a small portion of TMJMD in the population. However, some factors might explain a significant portion of TMJMD in persons exposed to particular risk factors. This review supports the current consensus that prevention, by screening the population for risk factors and intervening, is probably not justified. Modification of certain risk factors among exposed persons to prevent TMJMD might be warranted. Incidence data and epidemiologic measurements of risk are needed to evaluate the importance of risk factors for the occurrence and prevention of TMJMD, in both the population and exposed persons.