Dental occlusal wear and degenerative disease of the temporomandibular joint: a correlational study utilizing skeletal material from a contemporary population

The association of severely worn dentition resulting from betel nut chewing with temporomandibular disorders: a cross-sectional study

BACKGROUND

Most studies support parafunctions play an important role in temporomandibular disorders (TMD), whereas the association between tooth wear and TMD remains controversial. Betel nut chewing as a parafunction is popular in South and Southeast Asia. We therefore investigated the association of severely worn dentition resulting from betel nut chewing with TMD.

METHODS

A cross-sectional analysis of 408 control participants (male: 380, female: 28, 43.62 ± 9.54 years) and 408 participants with betel nut chewing related severely worn dentition (male: 380, female: 28, 43.73 ± 8.93 years) who received dental and TMD checkup according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) in Health Management Center, Xiangya Hospital was performed. Betel nut chewing related severely worn dentition meant all the natural teeth had moderate to severe tooth wear [Tooth Wear Index (TWI) ≥ 2)] including ≥ 2 severe wear teeth (TWI ≥ 3) due to betel nut chewing. Multivariable logistic regression analysis was used.

RESULTS

After adjusting for age, gender, betel nut chewing related severely worn dentition, oral submucosal fibrosis, number of missing teeth, number of dental quadrants with missing teeth, visible third molar and orthodontic history, variables of age, gender and betel nut chewing related severely worn dentition were significant for overall TMD. Multivariable analysis showed betel nut chewing related severely worn dentition was significantly associated with intra-articular TMD [odds ratio and 95% confidence intervals: 1.689 (1.271-2.244), P = 0.001] in a betel nut chewing dose-dependent manner.

CONCLUSION

Betel nut chewing related severely worn dentition was associated with intra-articular TMD.

Temporomandibular joint osteoarthritis at Chelechol ra Orrak, Palau

OBJECTIVE

To explore the frequency and severity of temporomandibular joint osteoarthritis (TMJ-OA) and its causative factors in a skeletal assemblage from the prehistoric site of Chelechol ra Orrak, Palau, western Micronesia.

MATERIALS

50 temporomandibular joint surfaces (mandibular condyles and articular eminences), representing a minimum of 22 adult individuals, 17 of which retain teeth.

METHODS

Joint surfaces were macroscopically evaluated for characteristics associated with TMJ-OA and joint morphology. Dental remains were scored for tooth wear and staining.

RESULTS

Nine individuals (40.1 %) displayed lesions typical of TMJ-OA. The strongest associations were between tooth wear and TMJ-OA.

CONCLUSIONS

Indirect effects of parafunctional dental activity appear to be a factor in TMJ-OA frequency at Chelechol ra Orrak. While betel nut chewing may be one of those activities, it does not appear to be solely driving the presence of TMJ-OA.

SIGNIFICANCE

This study highlights the association between a specific parafunctional use of the temporomandibular joint and the potential pathological consequences. It also reinforces the need to carefully evaluate the archaeological context of skeletal remains in order to evaluate specific etiological factors in the presence of TMJ-OA in present and past populations.

LIMITATIONS

Sample sizes are limited in this study. This will increase as excavations continue.

SUGGESTIONS FOR FURTHER RESEARCH

Because dental occlusion appears to be associated with TMJ-OA, focus on dental conditions affecting occlusal patterns, such as third molar agenesis, antemortem tooth loss, and malocclusion, and their relationship to TMJ-OA frequency, are recommended.

The association between dental wear and reduced vertical dimension of the face: a morphologic study on human skulls

OBJECTIVE

The aim of this study was to explore the relationship between dental wear and facial morphology, with particular reference to the occlusal vertical dimension, in modern human skulls.

DESIGN

One hundred and three skulls (52 men and 51 women) between the ages of 20 and 50+ years old were studied. The selected skulls were from a modern period (the 17th and the 18th centuries) and included at least one entire condyle and had at least 3 posterior teeth (premolar or molar) in each quadrant to allow for dental articulation. Occlusal wear was evaluated using ordinal scale (0-4) and vertical occlusal dimension was evaluated by measuring upper facial height (UFH), lower facial height (LFH), LFH-to-UFH ratio (L-U-R) and dental wear. Based on the occlusal wear score, two groups were defined: with and without significant wear.

RESULTS

Significant relation was observed between age and dental wear (P<0.01). No significant differences were found in the LFH (P=0.847) or UFH (P=0.108) between the two wear groups. In addition, no significant difference (P=0.132) was demonstrated in the LFH-to-UFH ratio between the groups. No difference was observed in the dental wear score between genders (P=0.321).

CONCLUSION

Within its limitations, this study demonstrated that dental wear does not influence the vertical dimension of occlusion. Our assumption is that the dento-facial complex fully compensates for the dental effects of wear throughout life.

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.

Degenerative changes in human temporomandibular joints in relation to occlusal support

OBJECTIVE

Controversy exists concerning the etiological factors behind degenerative changes in the temporomandibular joints (TMJs). Tooth attrition, occlusal support, food consistency, ageing, gender and genetics are some possible causative factors that have been discussed in the literature. The aim of this study was to examine contemporary human skull material for possible relations between degenerative form and surface changes in the TMJs in relation to occlusal support.

MATERIAL AND METHODS

The material consisted of 259 human skulls from 170 males and 89 females, with an age range of 18-100 years.

RESULTS

Dental status was in general poor, and 22% of skulls were edentulous. Form and surface changes of both the condyles and the temporal components were more common in the present material compared to that in most previous studies. In males, irrespective of age, only weak and clinically insignificant correlations could be found between degenerative TMJ changes and occlusal support. In women, however, the correlations between these variables were in general much stronger, especially at higher ages.

CONCLUSIONS

The present findings do not lend support to the hypothesis that loss of occlusal support is a causative factor for degenerative changes in the TMJs in male subjects. In women, such a correlation was obvious in the present sample, at least at higher ages. It can be speculated that hormonal factors play a role in the sex difference found.

Relationship of degenerative changes of the temporomandibular joint (TMJ) with the angle of eminentia

The purposes of this study were threefold: (i) to assess the degenerative changes of the temporomandibular joint [TMJ (condyles and articular eminence of the glenoid fossa)], (ii) to determine whether the TMJ degeneration levels differ by ethnic group and gender and (iii) to assess the association between the angles of eminentia and TMJ degeneration, while controlling for gender, ethnicity, age and number of teeth. The sample included 245 20th century dry skulls: 130 African-American (82 male and 48 female) and 115 European-American (75 male and 40 female), with a mean age of 46.4 +/- 19.9 years. The angles of eminentia were measured in a sagittal plane. The medial, central and lateral portions of the articular slope and anterior portion of the condyle were assessed for degenerative changes. Degeneration scores were calculated for the eminentia and condyles. Statistical analyses included two-way anovas, Pearson's correlation coefficients and linear regression models. There were differences in the degree of TMJ degeneration of the African-American and European-American males and females. European-American females retained fewer teeth, had the highest TMJ degeneration scores and exhibited significant relationships between the eminentia angles and degeneration. When the independent variables were entered into the regression model, only the degeneration of the eminentia was significantly associated with the angles of eminentia. Although the degeneration of the eminentia explained some of the variation of the eminentia angles, it is clear that the inclusion of multiple factors is essential to study the remodelling of the glenoid fossa.

Macroscopic osseous changes in the temporomandibular joint related to dental attrition in Japanese macaque skull

The purpose of this study was to investigate the relationship between osseous changes in the temporomandibular joint (TMJ) and dental attrition in the Japanese macaque. One hundred and thirty Japanese macaque skulls (54 male and 76 female) from animals which had been bred in the same environment, were randomly sampled from a collection at the Primate Research Institute of Kyoto University. The age at death had been recorded in all cases. TMJ osseous changes were independently evaluated by three examiners, and were defined as an irregular surface or a perforated compact bone layer with a markedly irregular surface on either the temporal or condylar components. Age was a significant factor in predicting TMJ osseous changes (P < 0.001). A strong relation was observed between age and dental attrition (P < 0.001), while dental attrition was not a significant factor in predicting TMJ osseous changes (P = 0.334). The prevalence TMJ osseous changes in male animals was slightly higher than in females (P = 0.057). The results of this study suggest that osseous changes in the macaque TMJ are mainly related to age, not to dental attrition.

Temporomandibular joint osteoarthritis in a British skeletal population

The potential role of dental function in TMJ osteoarthritis is examined in an ancient British population. Human skeletal remains from five archaeological sites in England (n = 369) were studied to assess the associations between the presence of osteoarthritis and dental function variables, in particular antemortem tooth loss and dental attrition. Individuals aged over 17 years with at least a portion of either the left or right TMJ were included in the study. Each individual was scored for the occurrence of arthritic lesions on the mandibular condyle and glenoid fossa, the level of dental attrition, and antemortem tooth loss. A loglinear analysis was performed with osteoarthritis as the dependent variable and tooth loss, attrition, sex, and age as the independent variables. Tooth loss and sex are not significantly associated with TMJ osteoarthritis when attrition and age are included in the analysis. Attrition is significantly associated with osteoarthritis even when the analysis corrects for age. The significant association of attrition with osteoarthritis suggests that dental functions may have an influence, separate from ageing, on the development of TMJ osteoarthritis.

Effect of bilateral asymmetric tooth clenching on load distribution at the mandibular condyles

The effects of balancing-side tooth contacts on temporomandibular joint loads are unclear. We used a 3-D computer model to calculate the magnitude and direction of temporomandibular reaction forces during simulated clenching on interocclusal acrylic resin shims and between natural teeth. Muscle tensions were proportioned according to the task modeled. Working-side tooth contacts included the canine alone, as well as group function, and occlusal loads were progressively shifted toward a posterior contralateral simple balancing contact. In the acrylic resin shim experiments, group function with simple balancing contact yielded the highest forces at the load point and at both temporomandibular joints. Movement of the occlusal load toward the balancing side produced greater, anteriorly oriented forces on the working condyle. For natural teeth, changes in the angle of resultant tooth force (simulating facet angulation) greatly influenced condylar forces. As the occlusal load moved toward the balancing side, greater and more laterally oriented forces were produced on the balancing condyle. Unilateral clenching on the canine produced the least condylar and bite forces. The simulation involving natural teeth offers a possible explanation for deviations in form and osteoarthrosis at the temporomandibular joints.

Axial temporomandibular joint morphology: a correlative study of radiographic and gross anatomic findings

In degenerative diseases of the temporomandibular joint the mandibular condyle demonstrates changes in contour, including flattening and enlargement, resulting in an increased diameter of the articular surface. The purpose of this study was to determine if such alterations in the shape of the mandibular condyle can be visualized in submentovertex (axial) radiographs and correlated with pathologic changes of the temporomandibular joint. Submentovertex radiographs of 18 human cadaver specimens were made. The radiographic condylar dimensions, morphologic condylar outline, and angle of the condylar axis with respect to the transmeatal line were determined. The specimens were dissected and disarticulated, and radiographic findings were compared to anatomic structure. Osseous abnormalities were found in 21 of the 36 joints studied (58%). Perforations of the disk were found in nine of 31 joints (29%) investigated. No statistically significant differences between the normal condyles and condyles displaying osseous abnormalities were found in any of the radiographic parameters studied.

Differences in the rate of molar wear between monkeys raised on different diets

The purpose of this study was to make detailed comparisons of rates and patterns of tooth wear in 15 growing vervet monkeys raised on hard vs. soft diets. Dental impressions were taken every six to eight weeks over a four-year period. Cusp heights and areas of dentin exposure on the buccal cusps of the left mandibular first molar were measured from high-resolution epoxy casts, by use of a Reflex Measuring Microscope. Areas of dentin exposure were regressed against time (by use of least-squares regression) so that the course of tooth wear in animals from both diet groups could be charted. By use of a two-sample t test and the Mann-Whitney test, slopes of the regressions and changes in cusp height were compared between diet groups. In both comparisons, animals raised on the hard diet showed more rapid tooth wear than did animals raised on the soft diet. Analyses of other parameters indicate that this was probably because of differences in dietary consistency between the two groups.