[The differential diagnostic value of skeletal, dental and soft-tissue analyses in the planning of orthodontic-oral surgical therapy. A retrospective study of treated patients with skeletal Angle class III].

The study evaluated the orthodontic documentation gathered in the course of conducting combined surgical-orthodontic therapy on 45 skeletal angle class III patients. In 15 of the patients Le Fort I osteotomy of the maxilla was performed, in 15 sagittal split osteotomy of the mandible, and in the last 15 patients bimaxillary surgery. The purpose of the study was to evaluate by means of a retrospective analysis of cephalograms taken prior to surgery the role hard tissue, soft tissue, and dental cephalometric variables play in the choice of the type of surgery to be performed. Discriminate analysis was used to determine the ability of the individual parameters to predicate accurately the type of the surgery that had been carried out. The study revealed that the skeletal relationship diagnosed in the x-rays was suitable primarily in the differentiation of the monomaxillary and bimaxillary patients who had undergone surgery. Using discriminate analysis the accuracy to predict group membership was 75.6% for the skeletal parameters of the McNamara analysis and 67.5% for those of the Bergen analysis. Differentiation between the cases where surgery had been performed solely in the maxilla and those where surgery had been performed only in the mandible was most successful using the soft tissue parameters describing the position of the subnasale and the position of the lower lip in relation to the aesthetic line according to Ricketts. In addition, the arrangement of the lower incisors was more retrusive in the cases with isolated surgery in the maxilla. Discriminate analysis applying a combination of skeletal, dental, and soft tissue parameters had a capability to predict accurately in 93.3% of the patients the form of the chosen surgical procedure.