Comparison of occlusal condition and prevalence of bone change in the condyle of patients with and without temporomandibular disorders

The Relationship between Bony Changes of the Mandibular Condyle and Eichner Index

INTRODUCTION

The aim of this study was to evaluate whether degenerative bone changes in the mandibular condyle on cone beam computed tomography images are associated with the Eichner index.

METHODOLOGY

336 cone beam computed tomography images condyle images of 168 patients were analyzed for degenerative bone changes. These changes were named as condyle flattening, osteophytes, erosions, subchondral sclerosis, generalized sclerosis and subchondral cysts. The edentulous status of the patients was classified as group A-B-C and subtypes according to the Eichner index. Categorical variables were evaluated with chi-square test and p < 0.05 was considered statistically significant.

RESULTS

According to the results of the study, the most common degenerative condyle change was flattening of the condyle. Among the Eichner index groups, the most common group was A and the least common group was C. Condyle changes on the right and left sides were most commonly observed in group A patients. The statistically significant majority of patients with right-sided condyle flattening and erosion were in group C. No significant difference was found between all other condyle changes and Eichner index groups. There was no significant relationship between Eichner index and gender.

CONCLUSION

Degenerative bone changes (flattening and erosion of the condyle) in the condyle region were more common in group C patients with more tooth loss. There is a significant relationship between condyle changes and posterior toothlessness.

Effect of transcutaneous electrical nerve stimulation therapy on condylar position and myofascial pain in patients with temporomandibular joint disorders-A pilot clinical trial

OBJECTIVE

Temporomandibular joint disorders (TMD) are a type of disorder that affects the temporomandibular joint, muscles, and nerves leading to persistent facial pain. Transcutaneous electrical nerve stimulation (TENS) therapy is an alternative treatment for pain relief in TMD patients. The aim of the study was to assess the condylar position changes and pain levels occurring in TMD patients after TENS therapy.

MATERIALS AND METHODOLOGY

According to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) criteria, a total of seven patients with TMD were included in this study. Routine diagnostic investigations were taken for each patient along with joint vibration analysis (JVA), electromyography (EMG), and a cone beam computed tomography (CBCT) at rest position. Using the Dolphin software (version 11.95), the temporomandibular joint spaces were measured on the CBCT for the right and left sides individually for each patient. These patients were then subjected to TENS therapy, and an EMG reading was taken post-TENS therapy to evaluate the effect on muscle strain. A CBCT was taken after the TENS therapy to assess its effect on the condylar position. The statistical significance of the pre- and post-temporomandibular joint spaces and the EMG readings post-TENS therapy were assessed using paired t-tests, respectively.

RESULTS

There was a change in the anterior, middle, and posterior dimensions observed radiographically, before and after TENS. However, the results were found to be statistically significant only in the anterior region on the right joint space (P = 0.03) and posterior region of the left joint space (P = 0.04).

CONCLUSION

TENS therapy has been found to bring about a change in the condylar position and pain intensities by relieving inadvertent muscle activity in the temporomandibular region. Therefore, further studies with larger sample sizes and control are required to fully ascertain the role of inadvertent muscle activity on the TMJ.

Dental Attrition and its Association With the Signs and Symptoms of TMJ Dysfunction and Radiographic Condylar Changes - An Observational Study

To determine the level of dental attrition and its relation to signs of TMJ dysfunction adding to condylar alterations analyzed by conventional TMJ Tomography and to propose the correlation between dental attrition and signs of TMJ dysfunction and condylar changes. Patients for the study were selected from the regular outpatient Department of Oral Medicine, Diagnosis and Radiology, Rajah Muthiah Dental College and Hospital, Annamalai University, Chidambaram, with performed criteria. The radiographic examination of TMJ is performed by the PLANMECA OPG machine using the tomographic program. Statistical analysis was performed using a Chi-square test to determine the relation between attrition and temporomandidular disorders [TMD] signs and symptoms. The study group comprises 60 subjects who are having dental attrition, and they are divided into three groups according to their age: Group I, 20-40 age; Group II, 41-60 age; Group III, more than 60 age 80% of the samples had one or more tooth with significant attrition with grades of two or more on a 0-4 scale The prevalence of changes in condylar morphology was more in individuals above 40 yrs (33.33%) as compared to those below the age of 40 with a total prevalence of 41.67%. The most common symptom reported is tooth sensitivity, joint sounds, and muscle tenderness. The last reported are scalloped tongue, buccal mucosa ridging, referred pain, and limitation of mouth opening. Out of the 25 subjects who showed condylar changes, 10 subjects had symptoms of TMD. The symptoms reported are strain in the mouth opening, tenderness in jaw movements, and TMJ clicking sounds. Attrition is not a predictable sign of TMJ dysfunction, yet a finite association was defined between attrition and signs and symptoms of TMJ dysfunction. Studies involving larger samples compared with additional radiographic modalities are recommended.

Relationship between Posterior Permanent Dentition Pattern and Radiographic Changes of the Mandibular Condyle

This study assessed the relationship between posterior permanent dentition and radiographic changes of the mandibular condyle. This descriptive, cross-sectional study was conducted on 300 panoramic radiographs of patients over 40 years of age (188 females and 112 males). Panoramic radiographs were evaluated for condylar changes such as flattening, subcortical sclerosis, subcortical cyst, erosion, osteophytes, and generalized sclerosis. Presence of muscle pain and temporomandibular joint (TMJ) pain and sounds, and history of TMJ trauma were also assessed. The occlusal scheme of posterior teeth was analyzed according to the Eichner's index. The frequency of condylar changes was calculated in the right and left sides, and their association with posterior permanent dentition was analyzed by the Chi-square test (alpha = 0.05). The frequency of flattening, muscle pain, TMJ sounds, and erosion was 11.7%, 9.7%, 5.7%, and 3.7% in the right side, respectively. The frequency of flattening, muscle pain, erosion, and subcortical cyst was 12%, 9.3%, 5%, and 5% in the left side, respectively. The frequency of bilateral muscle pain, flattening, TMJ sounds, and TMJ pain was 18%, 16.7%, 11.7%, and 9.3%, respectively. Cases with TMJ trauma, generalized sclerosis, and osteophytes were few. According to the Eichner's index, most patients with condylar changes had classes A and B, and a smaller percentage had class C. No significant difference was noted between healthy individuals and those with condylar changes regarding dentition patterns. No relationship existed between condylar changes and posterior permanent dentition pattern.

The impact of occlusal support on temporomandibular disorders: a literature review

Temporomandibular disorders are a multifactorial disease. Occlusal support and the number of teeth in dentition have significant effects on the masticatory system. The current study aims to review the role of occlusal support in association with findings of temporomandibular disorders. Data sources were PubMed, Web of Science and Google Scholar, with 1411 citations published over the period 1992–2019. The selection criteria stipulated that articles must have reported the association between the number of teeth, occlusal unit, occlusal support and temporomandibular disorders. A total of 15 full-text articles was finally accessed for eligibility in the current review. The studies on temporomandibular disorders were collected from various sources, including articles reporting temporomandibular disorder symptoms ( n=1), temporomandibular disorder signs ( n=5), temporomandibular joint osseous changes ( n=1), temporomandibular joint dysfunction using the Helkimo index ( n=2), and temporomandibular disorder classification ( n=6). Of these articles, significant associations were found between: the number of missing teeth and temporomandibular disorders ( n=5); the number of occlusal units and occlusal supports and temporomandibular disorders ( n=3); the position of the lost occlusal units and temporomandibular disorders ( n=1). Loss of the occlusal unit has more impact on temporomandibular disorders than the loss of posterior teeth. The total loss of unilateral occlusal support seems to be an aetiological factor for temporomandibular disorders, and maintenance of balanced posterior occlusal support has a role in the prevention and management of temporomandibular disorders.

Morphological Assessment of TMJ Spaces, Mandibular Condyle, and Glenoid Fossa Using Cone Beam Computed Tomography (CBCT): A Retrospective Analysis

Background  The temporomandibular joint (TMJ) is included in the category of ginglymoarthrodial synovial joints. The mandibular condyle plays a vital part in the development of the craniofacial complex. Hence, the evaluation and assessment of the condylar volume and its morphology are of utmost importance.

Aim  The aim of this research was to use cone beam computed tomography (CBCT) imaging modality to evaluate the morphology of the mandibular condyle and glenoid fossa in a selected population and document any morphometric changes.

Setting and Design  It is an observational study.

Materials and Methods  A retrospective CBCT analysis was performed on 119 patients. The length, width, height, linear measurements of the joint spaces (anterior, posterior, and superior), volume of the condyle, and roof of glenoid fossa thickness were evaluated on both the left and right sides in both males and females.

Results  The height, width, and length of mandibular condyle were significantly increased in males on both sides. Except for the left anterior space, all other spaces were significantly larger in males. Overall, the volume of the condyles in males was significantly increased on both sides.

Conclusion  CBCT can be a valuable diagnostic aid in the evaluation of various dimensions, joint spaces, and condylar volume in different planes and thus, can be a useful predictor in the assessment of treatment outcomes of disorders affecting the TMJ.

Evaluation of the influence of mandibular condylar contour, height, and asymmetry in subjects with myalgia presenting with or without clicking among south coastal Karnataka population - A descriptive cross-sectional study

Aim:

The purpose was to evaluate the morphological variations of the condyle in patients presenting with myalgia associated with and without clicking of temporomandibular joint (TMJ) and its possible effect on the contour and height.

Setting and Design:

Cross sectional study.

Material and Methods:

A total of 60 patients comprising of 20 patients with myalgia, 20 patients with myalgia associated with clicking of TMJ, and a control group of 20 patients without any signs and symptoms of temporomandibular disorder were selected for purpose of the study. Using a digital panoramic radiograph, the contour of the condyle was evaluated for shape, condylar height (CH), and condylar asymmetry.

Statistical Analyses Used:

Chi-square test, One- way ANOVA.

Results:

Rounded contour of the condyle was the most prevalent shape of the condyle amongst the three groups. There was a significant decrease in mean right and left CH in subjects with myalgia (0.71 cm and 0.73 cm) and subjects with myalgia associated with clicking (0.65 cm and 0.62 cm) compared to control group subjects. There was also an increase in the mean asymmetry index in subjects with myalgia presenting with clicking (2.362 ± 1.4) and without clicking (1.388 ± 2.1) (P < 0.05).

Conclusion:

Within the limitations of the current study, round contour of the condyle is the most common variant. Subjects with myalgia showed a significant reduction in condyle height. Condyle contour, height, and asymmetry may not predispose the joint for clicking.

Identification of Biomechanical Properties of Temporomandibular Discs

Material

Experimental and model tests were conducted on ten fresh porcine temporomandibular joint discs. The average thickness of disc tissue was, accordingly, 2.77 mm for the anterior zone, 3.98 mm for the posterior, and 1.54 mm for the intermediate. The selection of research material in the form of porcine discs was due to the similarity to human discs.

Methods

Discs were loaded in cycles, a temporary course with the amplitude 3 N and frequency 0.07 Hz, and growth in the load was 1 N/s. The selection of load frequency was due to real conditions of temporomandibular joint functioning during mastication. The necessary experimental research was conducted on a testing machine with a measurement range of 2.5 kN.

Results

The obtained numeric calculation results indicate that the number of load cycles has a decisive impact on the limitation of energy dispersion capacity through disc tissue. This phenomenon was observed in all the studies on the disc areas. Along with the growth in load cycles, discs are stiffened, and the most significant stiffness was observed in the intermediate area.

Conclusions

Based on the conducted research, it should be concluded that excessive load affecting temporomandibular joints caused by the act of mastication and occlusal forces generated during parafunction and in people with defined long-term bruxism has crucial importance on biomechanical disc properties and hence the course of temporomandibular joint conditions.

Evaluation of Normal Morphology of Mandibular Condyle: A Radiographic Survey

Objectives

The temporomandibular joint (TMJ) is a complex, highly specialized joint. Along with the teeth, these joints are considered to be a "tri-joint complex." Mandibular condyle morphology is characterized by a rounded bone projection with an upper biconvex and oval surface in axial plane. Anatomical knowledge of the TMJ is one of the basic foundations of clinical practice, allowing the understanding of TMJ pathologies and fabrication of condylar prostheses. The cross-sectional descriptive study was undertaken to evaluate normal variation in the condylar morphology on radiographs in persons without TMJ symptomatology and its relation to age, gender, dentition status, chewing habits, parafunctional habits, history of orthodontic treatment, and denture wearing was assessed.

Material and Methods

A total of 350 subjects without TMJ symptomatology included in the study were further grouped by age, gender, dentition status, chewing habits, parafunctional habits, history of orthodontic treatment, and denture wearing history. Panoramic radiograph was taken for the assessment of condylar morphology.

Results

A significant association between dentition status and bilaterally similar condylar morphology was noticed. Bilaterally similar condyles were seen in 81.4% of subjects. Round-shaped condyles were seen in 176 (62%) persons. Loss of bilateral occlusion tends to alter the condylar morphology. Association between normal chewing habits and bilaterally similar condyle shapes was significant.

Conclusion

The study describes the normal morphology of mandibular condyles in a population attending the tertiary dental care center, Kozhikode. The dentition status and chewing habits of individuals had a significant role in determining condylar morphology.

Association of radiographic and clinical findings in patients with temporomandibular joints osseous alteration

OBJECTIVES

To characterize the relationship between radiographic and clinical characteristics of patients with temporomandibular joint (TMJ) osseous changes.

MATERIALS AND METHODS

TMJ cone beam computed tomography (CBCT) images of 73 patients (142 joints) with changes in osseous component of TMJ were included in this study. Based on both clinical and radiographic findings, each TMJ was diagnosed as either non-degenerative joint disease (non-DJD) or degenerative joint disease (DJD) according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) criteria. The DJD group was further classified into two subgroups of osteoarthritis and osteoarthrosis. The data were analyzed using t test and Pearson's correlation. Level of statistical significance was set at 0.05.

RESULTS

Statistically significant relationships were found between TMJ crepitation sound and 4 radiographic characteristics of DJD. DJD group demonstrated statistically significant higher CBCT bone change score (BCS) and age. In contrast, there was no significant difference of BCS between osteoarthrosis and osteoarthritis groups within the DJD group.

CONCLUSIONS

Crepitation sounds and osseous changes in TMJ radiograph are confirmed to be important diagnostic criteria for TMJ DJD. However, degree of TMJ osseous changes does not correlate significantly with clinical pain symptom.

CLINICAL RELEVANCE

For TMJ DJD diagnosis, dentists should consider both clinical examination for TMJ crepitation and radiographic assessment for TMJ bony changes.

Comparison of condylar size among different anteroposterior and vertical skeletal patterns using cone-beam computed tomography

OBJECTIVES

To compare condylar size among different anteroposterior and vertical skeletal patterns using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The study included 166 subjects (61 men, mean age: 27.2 ± 7.6 years; 105 women, mean age: 27.4 ± 9.2 years). The anteroposterior skeletal patterns of the subjects were classified into Classes I (-1° ≤ A point-nasion-B point angle [ANB] < 4°), II (ANB ≥ 4°), and III (ANB < -1°). The vertical skeletal patterns were classified into hypodivergent (mandibular plane [MP] ≤ 23°), normodivergent (23° < MP < 30°), and hyperdivergent (MP ≥ 30°) groups. The condylar length, height, and width were examined using CBCT images. Analysis of covariance was used to compare three condylar size measurements among the three anteroposterior groups and the three vertical groups using sex as a covariate. Both left and right sides were examined. Nine groups were further divided according to the anteroposterior and vertical groups, and two-way analysis of covariance (ANCOVA) was applied to estimate the composite effect of skeletal patterns in both directions.

RESULTS

Sex as a covariate showed statistical significance in most examinations. The condylar height on both sides had statistically different anteroposterior skeletal patterns ( P < .001). The condylar width on both sides also had statistically different vertical skeletal patterns ( P < .001). After adjusting for sex, the condylar height and width on both sides increased from Class II, Class I, and Class III. The condylar width on both sides increased from the hypodivergent group, the normodivergent group, and the hyperdivergent group. No composite effect of skeletal patterns in both directions was observed.

CONCLUSIONS

Condylar height and width considerably differed among subjects with different anteroposterior or vertical skeletal patterns. The anteroposterior or vertical skeletal patterns independently affected the condylar size.

Effect of Shortened Dental Arch on Temporomandibular Joint Intra-articular Disorders

AIMS

To investigate whether a shortened dental arch (SDA), as identified by reduced posterior occlusal contacts, is a risk factor for the progression of temporomandibular joint (TMJ) intra-articular disorders (ID), as identified using imaging techniques.

METHODS

This multisite, prospective observational study with a mean follow-up period of 7.9 years had a sample of 345 participants with at least 1 temporomandibular disorder (TMD) diagnosis at baseline. SDA was defined as reduced occlusal posterior support due to lack of occlusal intercuspal contacts in the molar region on the left and/or right side. SDA was assessed at baseline and at follow-up with metalized Mylar Tape. The presence or absence of a TMJ ID and the specific TMJ ID diagnoses for baseline and follow-up images were established by a calibrated, blinded radiologist at each of three sites by using bilateral magnetic resonance imaging for soft tissue imaging for disc displacement and by bilateral multidetector computed tomography or cone beam computed tomography for hard tissue imaging for degenerative joint diseases. Wilcoxon rank sum test and linear regression analyses were used to test for an impact of SDA on TMJ ID status.

RESULTS

At baseline, TMJ ID status of either side was not significantly affected by the presence of SDA on the ipsilateral or contralateral side of the jaw (all P > .05). Furthermore, the presence or absence of SDA at baseline was also not a significant predictor for progression of the TMJ ID status between baseline and follow-up (all P > .05).

CONCLUSION

The findings of this study suggest that there is no significant effect of SDA on progression of TMJ ID.

Three-dimensional mandibular motion in skeletal Class III patients

OBJECTIVE

The aim of the study was to analyze the characteristics and changes in mandibular condylar motion in patients with skeletal Class III malocclusion.

METHODS

Using a 3D motion analyzer, mandibular movements were recorded in 9 patients with skeletal Class III malocclusion and 22 control subjects with Angle Class I jaw relationships.

RESULTS

Class III patients had a similar interincisor point displacement but a significantly reduced displacement of both condyles on the sagittal and frontal planes, with smaller translation paths than control subjects (right -9.4 mm; left -4.8 mm). The overall condylar rotation component was larger in Class III patients (right +8.8%; left +7.3%). The largest inter-group significant differences were observed in the first 10% of mouth opening, in which Class III patients had a larger rotating component than control subjects (+20%, p < 0.01).

CONCLUSIONS

Condylar motion was reduced in skeletal Class III patients, in particular in the translational path.

A controversy with respect to occlusion

There are very little controversies on occlusion in healthy individuals, where centric relation is regarded as the criterion for assessing the present occlusion and also for establishing a new occlusal relationship between the upper and the lower jaws. On the other hand, the occlusal position in patients with deformed condyles still remains to be clarified. In this review, the effectiveness and limits of centric relation in these patients are discussed. In addition, the muscle induced occlusal positions, such as the muscular position and the terminal positions of habitual closing movements, are suggested as a substitution for centric relation. Finally, the importance of a stable intercuspal position, where the habitual closing movements terminate without any premature tooth contact, is emphasized.

Age changes in horizontal condylar angle: a clinical and cephalometric study

Determination of condylar inclination is important when restoring the occlusal surfaces of teeth. It is important to know the changing trends in horizontal condylar inclination with age so as to have an idea about the cuspal morphology.

AIMS AND OBJECTIVES

a) to determine the effect of age changes in horizontal condylar inclination using articulator method and radiographic method (cephalometry) b) to compare the values of horizontal condylar inclination obtained using articulator method with that of cephalometric method c) to ascertain the symmetry of horizontal condylar angle on both right and left side on an articulator. 40 dentulous individuals with Angle's class I occlusion were selected for the study. They were divided into four groups Group I: 20-29 years, Group II: 30-39 years, Group III: 40-49 years, Group IV: 50-59 years. Horizontal condylar inclination was determined on right and left side for each individual using protrusive interocclusal record in a Dentatus (ARL) semiadjustable articulator. Cephalometric recording was carried out twice on the left side, once in centric occlusion position and then in protrusive position. The two radiographs were superimposed to draw a line connecting the shifting position of condylion on an acetate tracing paper. This line when joined with Frankfurt horizontal plane gives the horizontal condylar inclination. Analysis of variance (ANOVA) revealed that there was a significant difference in horizontal condylar angle values in all the four groups which were statistically significant. There is a decrease in horizontal condylar angle values from Group I to Group IV. Horizontal condylar values obtained by articulator method and cephalometric method showed no significant difference for all the four groups tested. When horizontal condylar values obtained on right and left sides of Dentatus articulator were compared there was not much of a significant difference. Horizontal condylar values showed a decreasing trend with increasing age, i.e, as age advances there is a flattening of condylar head. Both articulator and cephalometric method yielded no significantly different values and hence both the methods can be used for determining condylar inclination. The difference in values of horizontal condylar angle on right and left sides were insignificant.

Osteoarthritic changes and condylar positioning of the temporomandibular joint in Korean children and adolescents

Purpose

To investigate the prevalence of osteoarthritic changes and condylar positioning of the temporomandibular joint (TMJ) in Korean children and adolescents with or without temporomandibular disorders (TMDs).

Materials and Methods

A total of 101 asymptomatic and 181 symptomatic children and adolescents aged 10 to 18 years old were included in the study. Osteoarthritic changes such as flattening, sclerosis, osteophytes, or erosion, and the parasagittal positioning of the condyle were assessed using cone-beam computed tomography (CBCT) images.

Results

The overall prevalence of osteoarthritic changes was higher in symptomatic (26.8%) than in asymptomatic adolescents (9.9%) (p<0.05). In the symptomatic group, the frequency was higher in males (33.3%) than in females (23.0%) (p<0.05). Erosion was the most common change for the symptomatic group (15.6%), whereas sclerosis was the most common change for the asymptomatic group (5.4%). Posterior condylar position was more frequently observed in the symptomatic group (p<0.05). Erosion was more common in the samples with TMJ pain or mouth opening limitations as compared to those without them (p<0.05).

Conclusion

This study showed that osteoarthritic changes in TMJ were common in children and adolescents, with a much higher prevalence in symptomatic patients.

TMJ osteoarthritis: a new approach to diagnosis

Disorders of the temporomandibular joint (TMJ), including TMJ osteoarthritis (TMJ OA), are the topic of intensive clinical research; however, this is not the case in the archaeological literature, with the majority of work on the subject ceasing with the early 1990s. The methods employed in the diagnosis of TMJ OA within the archaeological work appear nonrepresentative of the disease and may have led to erroneous assumptions about the pattern and prevalence of OA. This current work presents a new method for evaluating OA specifically for the TMJ, considering both the biomechanics of the joint and the mechanisms of the disease. Totally, 496 specimens (including a group of modern documented specimens) were analyzed for the presence of TMJ OA using the following criteria: eburnation, osteophytes (marginal and new bone on joint surface), porosity, and alteration to joint contour. The results suggest that eburnation occurs rarely in the TMJ, so should not be used as an exclusive criterion. Rather a combination of at least two of the other criteria should be used, with osteophytes and porosity occurring the most frequently on both the mandibular condyle and articular eminence. Additionally, the prevalence of TMJ OA in the modern assemblage was similar to that observed in current clinical research, suggesting that the method employed here was able to produce a reasonable approximation of what is found in contemporary living populations.

Condylar Changes and Its Association with Age, TMD, and Dentition Status: A Cross-Sectional Study

The present study was undertaken to evaluate the prevalence of radiographic changes in the condylar morphology and its association with age, clinical signs and symptoms of temporomandibular dysfunction and dentition status and also to evaluate the intra examiner and inter examiner reliability in assessing condylar changes using panoramic radiographs. A total of 75 subjects were recruited for the study. They were divided into 3 age groups. 20–40 yrs (Group A), 41–60 yrs (Group B) and 61 yrs and above (Group C). In each age group 25 subjects were evaluated both clinically and radiographically. The prevalence of radiographic changes in condylar morphology and symptoms of temporomandibular dysfunction was 81.3% and 18.6%, respectively. Radiographic abnormalities in the mandibular condylar morphology increased with age. They were seen more frequently in patients with clinical signs and symptoms of temporomandibular dysfunction and in patients with loss of teeth. Intra examiner and inter examiner reliability was high indicating a good reliability in assessing the condylar changes using panoramic radiograph.

A preliminary anatomical study on the association of condylar and occlusal asymmetry

The aim of this study was to test the hypothesis that condylar and occlusion asymmetry are not associated. For each of 22 skulls, the asymmetry of condyles was graded by one examiner and the asymmetry of occlusion by another examiner, both blinded to each other's evaluation, as 0 = symmetrical, 1 = mild asymmetrical and 2 = severe asymmetrical. There were 18 condyles graded the same as to their occlusion, but in four, the grades differed by one degree. Nine were graded symmetrical, seven were mild, and six were graded severely asymmetrical condyles. The corresponding figures for occlusion were: 10 were graded symmetrical, seven were graded mildly asymmetrical, and five were graded severely asymmetrical occlusion. The relation between occlusion and condylar asymmetry was tested using Goodman-Kruskal's gamma and was found to be 0.970 (p < 0.001). The null hypothesis was not supported. The results indicate that asymmetry of occlusion and condyles are associated, which indicates the need for further studies on larger samples, and in vivo studies.

The role of occlusal factor in the etiology of temporomandibular dysfunction

INTRODUCTION

The influence of occlusal condition at the onset of temporomandibular disorders (TMD) has been strongly debated for many years and still is the source of controversy. Up to the eighties in the last century, the occlusal factors such as the presence of uncured malocclusions, discrepancies between intercuspal position and retruded contact position greater than two millimeters, retrusive and nonworking side interferences and loss of posterior teeth were considered to be the primary causes of TMD.

OBJECTIVE

The aim of this study was to estimate the role of occlusal factor in the etiology of craniomandibular dysfunction and therapeutic effects of irreversible occlusal therapy (occlusal equilibration) in patients with TMD.

METHODS

In the investigation we studied a group of 200 men and women. The average age of the selected patients was between 18 and 25 years. The purpose of TMD signs and symptoms was confirmed in every patient using a special functional analysis and evaluating the craniomandibular index (CMI) according to Fricton and Schiffman. The value of craniomandibular index was determined in the group of 15 patients with signs and symptoms of temporomandibular dysfunction. In the study groups occlusal equilibration (selective grinding) was performed according to Okeson using the central position of the mandible as the referent position in the occlusal therapy. The value of CMI was determined before and 30 days after occlusal equilibration.

RESULTS

The results of this study confirmed the significant reduction in the signs and symptoms of TMD after occlusal equilibration. The statistical elaboration of the differences between the values of CMI I (before treatment) and CMI II (30 days after treatment) revealed highly significant differences. The CMI I values in the group ranged between 0.076 and 0.346 with the mean value of 0.188 +/- 0.082.The values of CMI II ranged between 0.038 and 0.19 with the mean value of 0.038 +/- 0.053.

CONCLUSION

The study conformed the validity of irreversible occlusal therapy (selective grinding) in patients with TMD.

Histological investigation of osseous changes of mandibular condyles with backscattered electron images

OBJECTIVES

This study aims to confirm the radiographic morphology of mandibular condyles with microscopic observation and to investigate the mechanism of osseous changes of adult human mandibular condyles.

METHODS

Following the radiographic examinations of ten temporomandibular joints (TMJs) from five cadavers using conventional tomography, helical CT and limited cone beam CT for dentistry (limited CBCT), ten mandibular condyles were removed. Micro CT images were made of the undecalcified dissected joints in the sagittal plane, perpendicular to the long axis of the condyles, to produce images similar in orientation to the radiographic images. Tissue morphology was observed through backscattered electron images and elemental analysis using electron probe microanalysis (EPMA). The microscopic findings were compared with the radiographic findings.

RESULTS

Limited CBCT images most accurately depicted erosive change of the bone cortex of the mandibular condyle. EPMA indicated bone remodelling in all mandibular condyles analysed, which showed cartilage calcification different from typical enchondral ossification. No finding of dissolution or disruption of the superficial soft tissue was observed in all specimens, including those presenting radiographic findings of osteoarthrosis. Active bone remodelling with hypertrophic changes of superficial soft tissue was observed in mandibular condyles, which implied radiographic findings of osteoarthrosis.

CONCLUSIONS

The high detectability of limited CBCT images on bony morphology of mandibular condyles was confirmed. It is speculated that bone remodelling of adult human mandibular condyles is brought about by cartilage calcification. It was suggested that the osseous changes classified as osteoarthrosis with radiographic images are normal bone remodelling.