Comparison of stability and outcomes of surgery-first bimaxillary surgery for skeletal class III deformity between unilateral and bilateral cleft lip and palate

Objectives: Some adults with cleft lip and palate (CLP) require orthognathic surgery due to skeletal deformity. This prospective study aimed to (1) compare skeletal stability following bimaxillary surgery for correction of class III deformity between patients with unilateral CLP (UCLP) and bilateral CLP (BCLP), and (2) identify risk factors of stability. Materials and methods: Adults with CLP and skeletal class III deformities who underwent surgery-first bimaxillary surgery were divided into two groups according to cleft type: UCLP (n = 30) and BCLP (n = 30). Skeletal stability was assessed with measures from cone beam computed tomography images of the maxilla and mandible taken before treatment, 1-week and ≥ 1 year postsurgery for translation (left/right, posterior/anterior, superior/inferior) and rotation (yaw, roll, pitch); multiple regression analysis examined risk factors. Results: At follow-up, the maxilla moved upwards in both groups, and backwards in the UCLP group. The mandible moved forward and upward, shifted to the cleft (deviated) side, and rotated upward in both groups. The amount of surgical advancement was a risk factor for sagittal stability in the maxilla (ß = −0.14, p < 0.05). The mandible had three risk factors for sagittal stability: age (ß = −0.23, p < 0.05), surgical team (ß = −1.83, p < 0.05), and amount of surgical setback (ß = −0.32, p = 0.001). Conclusions: Two years after bimaxillary surgery, patients with UCLP had a higher sagittal relapse of the maxilla compared with patients with BCLP, which was due to a greater surgical advancement in the patients with UCLP. Clinical relevance: Surgery-first bimaxillary surgery results in favorable treatment outcomes for correction of cleft-related class III deformity. Severity of jaw discrepancy and surgeons should be considered in the surgical design of overcorrection.