Relationship between TMJ internal derangement, BMI, Bone mineral density, craniofacial morphology in young females
Date Issued
2008
Date
2008
Author(s)
Lai, Jung-Pin
Abstract
Objectives: Prevalence of TMJ internal derangement (ID) in general population is relatively high (up to 32%). TMJ ID is often associated with joint noise, pain during mouth opening, and difficulty in chewing. Problems in TMJ ID possibly include changes in craniofacial morphology and malocclusion. From our previous study, disc displacement without reduction (DDNR) is significantly correlated with low bone mineral density and low body mass index. Therefore, high prevalence rate of TMJ ID and other associated changes may cause major health problems and needs our attention. Diagnosis rate of TMJ ID is under estimated because there is no general physical examination which can evaluate TMJ ID precisely. MRI, being used for correct diagnosis of TMJ ID, costs much and therefore, is not practical to apply on every patient. Thus, an easier and convenient method but with less cost should be developed for diagnosis of TMJ ID. The aim of this study was to explore correlations of TMJ ID and morphological differences of craniofacial structure, and to explore systemic risk factors of TMJ ID. A screening method for TMJ ID with different variables was derived for three populations of patients. aterials and methods: A total of 156 young females (18 to 28 years old) participated in this cross-sectional study. Samples were collected from: 1) TMD department, 2) orthodontic department of NTUH, and 3) general young females without any symptoms of TMD. Both static and dynamic TMJ MRI was used for the correct diagnosis of TMJ ID. Condylar head area (CHA) and ascending ramus height (ARH) were measured on the images from static TMJ MRI. The craniofacial morphology of the subjects was assessed by using both lateral and PA cephalograms. The bone mineral density in the lumbar spines was obtained by using dual energy X-ray absorptiometry (DXA). BMI was calculated using the body height and weight (height/weight2). Chi square and multivariate regression analysis were used for the statistical analyses.esults: There was significant difference in diagnosis and distributions TMJ ID among three populations. In orthodontic department, 64.10% of population was diagnosed with ID at either side of TMJ and 50% of total condyles were diagnosed as TMJ ID. In TMD department, 96.43% of population was diagnosed with ID at either side of TMJ and 83.04% of total condyles were diagnosed as TMJ ID. In general young female population, 45.45% was diagnosed with ID at either side of TMJ and 34.85% of total condyles were diagnosed as TMJ ID. Prevalence of TMJ ID was highest in the population from TMD department, subsequently followed by the population from orthodontic department. The prevalence of TMJ ID in general young females were the lowest but still with one third of the joints affected. Multivariate regression model showed that small condyle head area, narrow condyle width, and short condyle length were associated with higher risks for TMJ ID. The smaller the condyle head was with higher possibility for TMJ ID. Patients with class II and class III skeletal jaw relationships were much prone to have TMJ ID than those with normal one. Especially, asymmetry in upper and lower jaws was with higher risks for TMJ ID. In addition, skeletal class II with large overjet was highly associated with disc displacement without reduction. onclusion: There were significant differences in diagnosis and distribution of TMJ ID among three populations. TMJ ID was associated with specific changes in craniofacial morphology. Therefore, the characteristics of craniofacial morphology associated with higher risks for TMJ ID should be notified in different clinics for patient health benefits.
Subjects
TMJ internal derangement
BMI
Bone mineral density
craniofacial morphology
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