[The images of osteoarthrosis associated with anterior disc displacement without reduction detected by cone-beam CT].

Objective: To analyze the radiological characteristics of the condylar bone in patients with anterior disc displacement without reduction of temporomandibular joint using cone-beam CT (CBCT), and to further investigate the clinical factors possibly associated with the early-stage osteoarthritic changes. Methods: Two hundred and four individuals (≤30 years old) diagnosed as unilateral anterior disc displacement without reduction (disease duration≤1 year) were recruited. CBCT images of bilateral condyles were independently evaluated by two assessors and documented. Correlation between the early-stage osteoarthritic (OA) changes and gender, age, disease duration and mouth opening were analyzed using SPSS 21.0 software. Results: About sixty percent were presented with OA changes in the symptomatic joints, and most of them (47.1%) (96/204) were early-stage OA changes characterized by loss of continuity of articular cortex (Ⅰ) and/or surface erosion (Ⅱ). Logistics regression analyses indicated that disease duration (P =0.000) and mouth opening (P =0.002) were correlated significantly with early-stage OA changes. Conclusions: Disc displacement without reduction was closely related to OA occurrence. OA changes occurred in more than half of the patients after one month of the joint locked and more possibly in patients with increased mouth opening.