Abstract
BACKGROUND: The association between occlusion and temporomandibular disorders (TMD) remains obscure. The present purpose was to explore the asymmetrical occlusion feature(s) potentially linked to TMDs. METHODS: This study enrolled 148 patients with a chief complaint of malocclusion. Of those, 84 had no signs of TMD (Group-ORD1), and 64 had signs of TMD (Group-ORD2). An additional 84 patients with a chief complaint of TMD symptoms and a history of orthodontic therapy were included (Group-TMD). All patients in the study were female. Asymmetry of six occlusion variables was measured on plaster study casts and recorded as 1 for asymmetry and 0 for symmetry. The variables contain the sagittal asymmetry: the first molar mesial-distal relationship (F1), canine mesial-distal relationship (F2); the horizontal asymmetry: anterior overjet and overbite relationship (F3), posterior overjet and overbite relationship (F4); missing teeth (F5), and the weight of the asymmetrical occluding pair (F6). And logistic regression model was used for data analyses. RESULTS: In the analyses for Group-ORD2 versus Group-ORD1, the F6 variable and the interactions of F1*F2 and F1*F2*F6 were entered into the model (all OR > 2.68). For Group-TMD versus Group-ORD1, the variables were F1, F5, and F6 (all OR > 2.39) and F4 (OR = 0.28), and the interactions were F5*F6, F1*F2*F6, F1*F5*F6, and F1*F2*F5*F6 (all OR > 2.78) and F2*F4, F3*F5, and F2*F4*F6 (all OR < 0.13). For Group-TMD versus Group-ORD2 the variables and interactions were F5, F5*F6, and F1*F5*F6 (all OR > 4.03) and F4, F4*F6 and F2*F4*F6 (all OR < 0.21) (all P < .05). CONCLUSIONS: Patients with sagittal asymmetry, asymmetrical missing teeth, or asymmetrical weight of contact have a higher prevalence of TMD.