Association between condylar asymmetry and temporomandibular disorders using 3D-CT

Selected muscle tone and asymmetry of the occlusal plane in case of intracapsular temporomandibular joint disorder

Objective: To discover the extent of the connection between occlusal plane asymmetry and the rest tone of the four muscle groups of the orofacial region with temporomandibular joint pathology.Methods: Eighty-seven subjects were divided into two groups. The following methods were applied: clinical examination, roentgenological examination, and electromyography. Data were evaluated and statistically analyzed.Results: The variability of occlusal plane inclination in relation to the porion plane was 0-4.6º.The tonus of masseter muscle was higher in the experimental group: 1.45 mV more than in the control group: 1.23 mV (p < 0.05).Conclusion: Asymmetry of the occlusal plane inclination was found for nearly all subjects in both groups. It can be compensated for by adaptation mechanisms and does not cause temporomandibular joint disorders. Undertaken research shows the existence of a proven correlation between TMJ disorders and the resting tonus of the masseter muscle.

The relationship between the size of temporomandibular joint condyle and the sagittal disc-condyle position in adults

OBJECTIVE

To explore the relationship between the size of temporomandibular joint (TMJ) condyle and the sagittal disc-condyle position and the relationship between the condylar size and craniofacial structure.

METHODS

Seventy-four subjects (23.82 ± 3.77 years) underwent cone beam computed tomography (CBCT) and lateral cephalograms for orthodontics and volunteered to undergo magnetic resonance imaging (MRI). Mimics was used to calculate the volume and surface area of the condyle. MRI was used to evaluate the sagittal disc-condyle position. The lateral cephalograms were analyzed by Jarabak analysis.

RESULTS

The condylar volume and surface area were negatively correlated with the sagittal disc-condyle position. The condylar volume and surface area were positively correlated with Ar-Go, S-Go, and S-Go/N-Me*100% (p < 0.05) and negatively correlated with ∠Ar-Go-Me and ∠N-Go-Me (p < 0.05).

CONCLUSION

Condylar size was negatively correlated with the sagittal disc-condyle position. The condylar size was correlated with the vertical skeletal pattern.

Correlations Between Mandibular Asymmetries and Temporomandibular Disorders: A Systematic Review

Objective

This systematic review aimed to investigate the correlation between mandibular asymmetry and temporomandibular disorders (TMDs).

Materials and Methods

A systematic search of the published literature was performed in electronic databases such as PubMed (MEDLINE), Scopus, Web of Science, Cochrane, Google Scholar, Clinicaltrials.gov, and Saudi Digital Library. Gray literature was searched through System for Information on Grey Literature through OpenGrey. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed in the investigation. The focussed question according to PICO format was: "does the mandibular asymmetry contribute to temporomandibular disorders"? Eligibility criteria included clinical trials (CTs), observation studies, cross-sectional and cohort studies in English that investigated mandibular asymmetries and TMD among patients. Blind and duplicate study selection, data extraction, and risk of bias assessment were carried out.

Results

The initial search resulted in 1906 articles, of which 11 (8 CTs, 1 cross-sectional, 1 retrospective, and 1 observational) studies were selected for qualitative synthesis after fulfilling the eligibility criteria.

Conclusion

Most of the studies included in this review showed either very high risk or high risk of bias. Despite the low certainty of evidence, the current study indicated a likely relationship between mandibular asymmetries and TMDs.

Skeletal Divergence and Condylar Asymmetry in Patients with Temporomandibular Disorders (TMD): A Retrospective Study

Introduction

This study was aimed at evaluating the association between vertical skeletal patterns, condylar height symmetry, and temporomandibular disorders in adults.

Methods

The study sample consisted of 200 patients (ages 18-30 years old) retrospectively recruited: 100 with temporomandibular disorders (TMD) and 100 without TMD (control), diagnosed by Diagnostic Criteria for the Temporomandibular Disorders (DC/TMD). For each subject, skeletal divergence was assessed on lateral cephalograms, and condylar height symmetry was evaluated by orthopantomography (Habets' method).

Results

Subjects with temporomandibular disorders showed a strong association with condylar asymmetry (p < 0.0001) and, for the skeletal pattern variables, hyperdivergence (p < 0.001). A correlation with the female sex was also found (p < 0.04), while there was no difference in terms of age in the 2 groups (p > 0.29).

Conclusions

Although it does not imply a direct cause-and-effect relationship, the present study suggests condylar asymmetry and hyperdivergent skeletal pattern are more likely to be associated with a higher risk of temporomandibular disorder joint diseases in adult patients.

Condylar long axis and articular eminence in MRI in patients with temporomandibular disorders

OBJECTIVE

To compare morphologic findings in MRI and skeletal divergence of a group of patients with temporomandibular joint disorders (TMD) subdivided into condylar symmetric and asymmetric.

METHODS

Fifty-nine adults (26.7 years old) with TMD were retrospectively recruited. Condylar height symmetry was evaluated by orthopantomography (Habets's method) and used to divide patients into Symmetric and Asymmetric groups; skeletal divergence was assessed on lateral cephalograms. MRI was used to evaluate the condylar long axis' angle, the glenoid fossa morphology, and the degree of disc displacement.

RESULTS

Asymmetric subjects showed a hyperdivergent skeletal pattern (p = 0.036), asymmetric condylar long axis (p = 0.018), and deeper (p = 0.025) and asymmetric (p = 0.001) glenoid fossa compared to symmetric subjects.

CONCLUSION

Patients with TMD and condylar asymmetry diagnosed with orthopantomography are more likely to show hyperdivergent skull in cephalometry, condylar asymmetry of both height and major axis, and a steeper glenoid fossa in MRI.

Positional and dimensional temporomandibular joint changes after correction of posterior crossbite in growing patients: A systematic review

OBJECTIVE

To elucidate the positional and dimensional temporomandibular joint (TMJ) changes after correction of posterior crossbite in growing patients.

MATERIALS AND METHODS

A systematic unrestricted search was done in six databases until June 27, 2017. A manual search in the reference lists of the included studies and gray literature was also performed. The eligibility criteria included randomized controlled trials and prospective nonrandomized controlled clinical trials and a sample of growing subjects with posterior crossbite that required maxillary expansion. Risk of bias assessment was performed using Cochrane's Risk of Bias Tool. The literature search, study inclusion, risk of bias assessment, evaluation of quality of evidence (GRADE), and data extraction were performed by two reviewers independently.

RESULTS

Only two articles were finally eligible to be included in the qualitative analysis. Both studies were RCTs and were assessed as having unclear risk of bias. Meta-analysis was not possible since one study used cone-beam computed tomography as an assessment tool while the other used ultrasonography. One study reported significant reduction in the condylar positional difference between centric and habitual occlusion in the treatment group, while no spontaneous correction of condylar asymmetric position occurred in the control group. The other study reported minor changes of condylar position in both treatment and control groups.

CONCLUSIONS

The current available data provide insufficient and weak evidence to form a solid and firm conclusion. There is poor, very low-quality evidence regarding the positional and dimensional effects of posterior crossbite correction on the TMJs.

TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia: a cross-sectional study

Background: Temporomandibular joint disorder (TMD) includes symptoms of pain and dysfunction in the muscles of mastication and the temporomandibular joint. Differences in vertical condylar height, observed in the assessment of mandibular asymmetry, is a structural alteration that represents a risk factor for TMD. The study aimed to evaluate the association between TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia.  Methods: The cross-sectional study included 18-25-year-old (mean ± SD, 21.9 ± 2.0 years) old orthodontic patients admitted to the Dental Hospital of Universitas Sumatera Utara, Medan, between June 2016 and March 2017. Vertical mandibular asymmetry was assessed from all 106 subjects using Kjellberg's technique from pre-treatment panoramic radiographs. The TMD symptoms were assessed by structural interviews using modified questionnaires based on Temporomandibular Disorder Diagnostic Index and Fonseca's Anamnestic Index. Results: Of the 106 subjects, 26 (24.5% of the total) with vertical mandibular symmetry and 39 (36.8%) with vertical mandibular asymmetry were positive for TMD symptoms. By contrast, 17 patients (16.0% of the total) with vertical condylar symmetry and 24 patients (22.6%) with vertical mandibular asymmetry were regarded negative for TMD symptoms. There was no significant difference (p=0.520) in TMD symptoms based on vertical mandibular symmetry. Conclusion: The results from this studied Sumatran population indicate that there are common TMD symptoms in young adult orthodontic patients, but there is no significant association between vertical mandibular asymmetry and TMD symptoms. Further study on the development of TMD, mandibular asymmetry and treatment planning for growing patients is suggested, using longitudinal and transitional approaches.

TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia: a cross-sectional study

Background: Temporomandibular joint disorder (TMD) includes symptoms of pain and dysfunction in the muscles of mastication and the temporomandibular joint. Differences in vertical condylar height, observed in the assessment of mandibular asymmetry, is a structural alteration that represents a risk factor for TMD. The study aimed to evaluate the association between TMD symptoms and vertical mandibular symmetry in young adult orthodontic patients in North Sumatra, Indonesia.  Methods: The cross-sectional study included 18-25-year-old (mean ± SD, 21.9 ± 2.0 years) old orthodontic patients admitted to the Dental Hospital of Universitas Sumatera Utara, Medan, between June 2016 and March 2017. Vertical mandibular asymmetry was assessed from all 106 subjects using Kjellberg's technique from pre-treatment panoramic radiographs. The TMD symptoms were assessed by structural interviews using modified questionnaires based on Temporomandibular Disorder Diagnostic Index and Fonseca's Anamnestic Index. Results: Of the 106 subjects, 26 (24.5% of the total) with vertical mandibular symmetry and 39 (36.8%) with vertical mandibular asymmetry were positive for TMD symptoms. By contrast, 17 patients (16.0% of the total) with vertical condylar symmetry and 24 patients (22.6%) with vertical mandibular asymmetry were regarded negative for TMD symptoms. There was no significant difference (p=0.520) in TMD symptoms based on vertical mandibular symmetry. Conclusion: The results from this studied Sumatran population indicate that there are common TMD symptoms in young adult orthodontic patients, but there is no significant association between vertical mandibular asymmetry and TMD symptoms. Further study on the development of TMD, mandibular asymmetry and treatment planning for growing patients is suggested, using longitudinal and transitional approaches.

A three-dimensional analysis of skeletal and dental characteristics in skeletal class III patients with facial asymmetry

OBJECTIVE

To evaluate the skeletal and dental characteristics in skeletal class III patients with facial asymmetry and to analyse the relationships among various parts of the stomatognathic system to provide a theoretical basis for clinical practice.

METHODS

Asymmetric cone-beam computed tomography data acquired from 56 patients were evaluated using Mimics 10.0 and 3-Matic software. Skeletal and dental measurements were performed to assess the three-dimensional differences between two sides. Pearson correlation analysis was used to determine the correlations among measurements.

RESULTS

Linear measurements, such as ramal height, mandible body length, ramal height above the sigmoid notch (RHASN), maxillary height, condylar height, buccal and total cancellous bone thickness, and measurements of condylar size, were significantly larger on the nondeviated side than on the deviated side (P < 0.05). Crown root ratio and buccolingual angle of mandibular first molar were found to be significantly smaller on the nondeviated side than on the deviated side (P < 0.05). A negative correlation was also discovered between the buccolingual angle of mandibular first molar and the ramal height (P < 0.01).

CONCLUSIONS

In patients with facial asymmetry, asymmetries in the mandible, maxilla and condylar morphology, and skeletal canting served as major components of skeletal asymmetry. Furthermore, a reduced thickness of buccal cancellous bone and a larger crown root ratio were found on the deviated side, indicating that orthodontic camouflage has limitations and potential risks. A combination of orthodontics and orthognathic surgery may be the advisable choice in patients with a menton deviation greater than 4 mm. An important association between vertical skeletal disharmony and dental compensation was also observed.

Biological predictors of mandibular asymmetries in children with mixed dentition

OBJECTIVES

The objective was to investigate the severity of skeletal mandibular asymmetry in children with mixed dentition and other factors associated with asymmetry.

METHOD

The study was cross sectional, with stratified sampling according to malocclusion type consisting of 205 subjects with mixed dentition (median 10, interquartile range 9-11 years). There were 59 subjects presenting Class II/1, 77 Class II/2, and 69 Class III. The mandibular asymmetry has been estimated from orthopantomograms using the Habets' method and the dental maturation by Demirjian's method. The sagittal skeletal relationship and facial growth pattern were assessed from lateral cephalograms.

RESULTS

Asymmetries in general, were not rare and were more present in the condylar height rather than in the height of the ramus. The highest severity of condylar asymmetry was in Class II/2 subjects (median of asymmetry index 7.3; 64% subjects exhibiting moderate and severe asymmetry), while the Class III subjects exhibited the highest severity of both ramus and total height asymmetry (2.1; 13% and 2.0; 15%, respectively). Multiple logistic regression unveiled male gender as the only predictor of moderate or significant overall asymmetry. Dental age, the difference between dental and chronological age, and facial growth pattern were not significant predictors of asymmetries.

DISCUSSION

Overall, asymmetries in mixed dentition cannot be considered rare; however, no strong relationships between asymmetry and observed biological factors were found.

The temporomandibular joint of California sea lions (Zalophus californianus): part 2-osteoarthritic changes

OBJECTIVES

Following comprehensive characterization of the temporomandibular joint (TMJ) of the California sea lion, as well demonstrating that TMJ-osteoarthritis (OA) occurs in this species, the objective of this part of the investigation was to describe the macroscopic osteologic findings associated with TMJ-OA in a large museum collection of skull specimens.

DESIGN

Museum skull specimens (n=497) of California sea lions were examined macroscopically according to defined criteria for the presence, severity, location and characteristics of TMJ-OA. The specimens, acquired from strandings, varied in age from young adults to mature adults.

RESULTS

Overall 63.5% of the specimens had findings consistent with TMJ-OA. Of these, 56.2% were from females 43.8% were from males. Moreover, 71.2% specimens were from mature adults and 28.8% from young adults. However, there was no significant association between age and sex with the presence or severity of TMJ-OA. The most prominent TMJ-OA changes were the presence of subchondral bone defects and abnormal porosity. The majority of the OA present at the mandibular head affected the entire articular surface. In contrast, the OA present on the mandibular fossa of the temporal bone was located primarily on the medial aspect (P<0.001).

CONCLUSION

The incidence of TMJ-OA in California sea lions is high and varies in severity. Although the significance of the high incidence of this disease in the California sea lion remains elusive, the occurrence and severity of TMJ-OA detected in this study may play an important role in the species' morbidity and mortality.

Osteoarthritis of the temporomandibular joint in southern sea otters (Enhydra lutris nereis)

Museum skull specimens (n = 1,008) of southern sea otters (Enhydra lutris nereis) were examined macroscopically according to defined criteria for the presence, severity and characteristics of temporomandibular joint osteoarthritis (TMJ-OA). The specimens were from stranded young adult to adult animals. Overall, 4.1% of the specimens had findings consistent with TMJ-OA. Of these, 61.0% were from females and 39.0% were from males. In addition, 85.4% of the affected specimens were from adults and 14.6% were from young adults. However, there was no significant association between age and sex with the presence or severity of TMJ-OA. Lesion severity was mild in 41.5%, moderate in 19.5% and severe in 39.0% of affected specimens. The most prominent changes were the presence of osteophytes and subchondral bone defects and porosity. The mandibular condylar process and fossa were affected equally. The lengths of the right and left mandibular heads were significantly associated with age (P = 0.002 and P = 0.003, respectively) and sex (P = 0.0009 and P = 0.001, respectively), but not with the presence of TMJ-OA. The significance of this disease in sea otters remains elusive, but this condition may play an important role in survival of these animals.