Computed tomography-based findings and severity of temporomandibular joint osteoarthritis are associated with the development of skeletal mandibular retrusion.

The aim of this study was to clarify the relationship between the severity of condylar osteoarthritis (OA) and skeletal mandibular retrusion. Three-dimensional cephalometric characteristics of skeletal mandibular retrusion were analysed using computed tomography scans from 15 patients with OA and 15 without OA. Mandibular, dental, and condylar-related factors were evaluated. Severity was scored by counting findings of cysts, erosion, atrophy, osteophytes, and sclerosis (score of 1 for the presence of each). The OA group was further divided into mild and moderate OA according to the total severity score of both condyles. The mean condylar volume was significantly lower in OA (851.1 mm³) than in non-OA (1151.3 mm³) (P < 0.001). A decrease in volume was significantly correlated with the number of radiographic OA findings (P = 0.012). Findings seen in mild OA were mostly cysts and erosion, while all findings were identified in moderate OA. The measured factors did not differ significantly between the mild OA and non-OA groups, whereas many mandible-related factors differed significantly between the moderate OA and non-OA groups. A significantly lower volume of the condyle was observed in moderate OA compared to non-OA (P < 0.001), suggesting that the appearance of atrophy, osteophytes, and sclerosis worsened OA from mild to moderate, and correspondingly, mandibular retrusion became apparent.