Long-term assessment of condyle-fossa relationship in skeletal Class II patients with idiopathic condylar resorption after combined orthodontic and orthognathic treatment

Objectives: To assess the relationship between the condyle and fossa in idiopathic condylar resorption (ICR) patients with severe Class II skeletal deformities who achieved stable functional and esthetic outcomes. Materials and Methods: ICR patients receiving orthodontic-orthognathic treatment with more than 2 years of follow-up were included in this retrospective study. Post-treatment changes in Y-axis-B of less than 2 mm were considered indicative of achieving a stable treatment outcome. Anterior joint space (AJS), superior joint space (SJS), and posterior joint space (PJS) on computed tomography (CT) and magnetic resonance images (MRI) were measured. Results: After screening, a total of 20 patients with 40 condyles were included. 12 patients were included in the Stable group and eight patients were included in the Relapse group. In the Stable group, mean AJS, SJS, and PJS linear measurements during follow-up on CT images were 1.82 ± 0.34, 1.78 ± 0.38, and 1.81 ± 0.33 mm, respectively. Ratio of AJS:SJS:PJS was 1.0:0.97:1.0. Mean AJS, SJS, and PJS linear measurements on MRI images were 1.71 ± 0.50, 1.82 ± 0.50, and 1.70 ± 0.51 mm, respectively. Ratio of AJS:SJS:PJS was 1.0:1.06:1.0. In the Relapse group, no constant ratio of joint spaces was found on CT or MRI images. Conclusions: A relationship exists between the condyle and fossa in ICR patients with stable treatment outcomes, as the AJS:SJS:PJS ratio was close to 1:1:1. This condyle-fossa relationship provides clinicians with an assessment criterion and may be an alternative treatment goal for patients with ICR.