Three-dimensional analysis of the horizontal condylar angle in the temporomandibular joint: morphology and surgical implications

Objectives. This study aimed to develop a three-dimensional method for measuring the horizontal condylar angle (HCA) of the temporomandibular joint (TMJ) and to investigate its distribution across different skeletal patterns, as well as its changes following orthognathic and disc repositioning surgeries. Materials and Methods. Using a novel 3D model reconstruction approach, 90 non-surgical patients (180 TMJs) were included to evaluate the natural distribution of HCA. To evaluate surgical effects, 50 patients (100 TMJs) undergoing orthognathic surgery were analyzed at three time points: preoperatively, immediately postoperatively, and at follow-up (>6 months). Additionally, 30 patients (60 TMJs) treated with disc repositioning were assessed before surgery and more than one year postoperatively.Results. HCA differed significantly among skeletal patterns, with the highest mean value in Class II (23.97 ± 11.81°), intermediate in Class I (19.05 ± 11.03°), and lowest in Class III (13.61 ± 7.35°). Mandibular advancement caused no immediate change but showed a reduction at follow-up, whereas mandibular setback resulted in a significant immediate increase that remained stable over time. In the disc repositioning group, HCA decreased significantly after surgery.Conclusions. These findings demonstrate that HCA exhibits a skeletal pattern–specific distribution under natural conditions and undergoes adaptive changes following surgical interventions.