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

OBJECTIVES: To develop a 3D measurement for horizontal condylar angle (HCA) and investigate its distribution across skeletal patterns and changes following orthognathic and disc repositioning sur-geries. MATERIALS AND METHODS: Using a 3D reconstruction approach, 90 non-surgical patients were analyzed for HCA distribution. Surgical effects were evaluated in 50 orthognathic patients (preoperative, post-operative, and follow-up) and 30 disc repositioning patients (preoperative and >1 year postoperative). RESULTS: HCA differed significantly among skeletal patterns (Class II: 23.97±11.81°; Class I: 19.05±11.03°; 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: HCA exhibits a skeletal pattern-specific distribution and adaptive changes following surgery. HCA serves as a simple and reproducible imaging descriptor for documenting morphological adaptation.