Gender differences in dentofacial characteristics of adult patients with temporomandibular disc displacement.

PURPOSE: The purpose of this study was to assess gender differences in dentofacial characteristics of adult patients according to temporomandibular joint (TMJ) disc displacement (DD) status. MATERIALS AND METHODS: The sample consisted of 293 adult patients (80 male and 213 female). Male and female patients were divided into 3 groups based on magnetic resonance images of bilateral TMJs: bilateral normal disc position (BN), bilateral DD with reduction (DDR), and bilateral DD without reduction (DDNR). Seventeen variables from lateral cephalograms were analyzed by 2-way analysis of variance to identify differences in dentofacial morphologies with respect to gender and TMJ DD status. RESULTS: Patients with TMJ DD had short ramus height, short mandibular body length, and backward positioning of the ramus and mandible. These dentofacial characteristics became more severe as TMJ DD progressed to DDNR. In addition, dentofacial characteristics associated with TMJ DD were not significantly different between men and women except for effective mandibular length (Articulare to pogonion). Effective mandibular length even tended to decrease as TMJ DD progressed, but male patients showed a larger difference in effective mandibular length between BN and DDR than female patients. CONCLUSIONS: This study's findings suggest that dentofacial morphology is strongly associated with TMJ DD status and that skeletal Class II hyperdivergent pattern with a short ramus and mandible may be a potential indicator of TMJ DD regardless of gender.