Dental asymmetry in temporomandibular disorders

In our previous study, it was reported that facial asymmetry due to mandibu lar lateral displacement (MLD) was significant in patients with temporomand ibular disorders (TMD). In this study, dental asymmetry in TMD patients was investigated by means of PA cephalogram and study model. Lateral deviation of the midline of the mandibular occlusal table (PA-mid) and right-left di fference of the molar relationship (Molar-Diff.) were examined, and their r elationship with MLD was studied. PA-mid and Molar-Diff. were significantly correlated with MLD. In most cases, displaced side of the midline of the l ower occlusal table was coincident with that of the mandibular skeletal mid line. These results suggest that in TMD patients asymmetries in occlusal re lationship of the midline of the mandibular teeth and molars were mainly du e to a mandibular skeletal asymmetry and not merely due to a dental malposi tion on the alveolar basal bone. Many cases had a more distal occlusal rela tionship of the first molar on mandibular displaced side compared with that on the opposite side. A high incidence of Class II relationship was found (61.8% as a whole) and more remarkable on the mandibular displaced side. Mi dline discrepancy and right-left difference of the molar relationship seem to be important occlusal characteristics in patients with TMD.