CONDYLAR REMODELING AND RESORPTION AFTER LE-FORT-I AND BIMAXILLARY OSTEOTOMIES IN PATIENTS WITH ANTERIOR OPEN BITE - A CLINICAL AND RADIOLOGICAL STUDY

A sample of 259 patients with vertical maxillary hyperplasia, mandibul ar hypoplasia and anterior vertical open bite, collected from three di fferent institutions, was analysed regarding temporomandibular joint ( TMJ) sounds, condylar remodelling, and condylar resorption. All patien ts underwent Le Fort I osteotomies, and bilateral sagittal split advan cement osteotomies were performed in 117 patients. Intraosseous wire f ixation was used in 149 and rigid internal fixation in 110 patients. C ephalometric and orthopantomographic radiographs were available before surgery, immediately after surgery, one year postoperatively and at t he latest follow up. The mean follow up was 69 months (range 20-210 mo nths). The number of patients with TMJ sounds decreased from 38% to 31 %. At the latest follow up 23.6% of the patients showed condylar remod elling, 7.7% unilateral condylar resorption and 7.7% bilateral condyla r resorption. Condylar contours, as assessed on orthopantomographic ra diographs, were classified as five different types. Condyles with pree xisting radiological signs of osteoarthrosis or having a posterior inc lination were at high risk for progressive resorption. Female patients with severe anterior open bite, high mandibular plane angle and a low posterior-to-anterior facial height ratio, who underwent a bimaxillar y osteotomy, were prone to condylar resorption. Bone loss was predomin antly found at the anterior site of the condyle. The incidence of cond ylar resorption was significantly higher after bimaxillary osteotomies (23%) than after only Le Fort I intrusion osteotomies (9%). Avoidance of intermaxillary fixation by using rigid internal fixation tended to reduce condylar changes, in particular in patients who underwent only a Le Fort I osteotomy. Rigid internal fixation in bimaxillary osteoto mies resulted in condylar remodelling in 30% and progressive condylar resorption in 19% of the patients. Condylar changes were not significa ntly different after using either miniplate osteosynthesis or position al screws in bilateral sagittal split osteotomy procedures.