Long-term skeletal and dental stability after orthognathic surgery of the maxillo-mandibular complex in Class II patients with transverse discrepancies.

INTRODUCTION: Two-jaw surgery has become the standard procedure for correcting skeletal maxillo-mandibular discrepancies in adults. However, only a few studies have reported on the long-term stability of bimaxillary orthognathic surgery in patients with Class II malocclusion and transverse discrepancies. In this study, the long-term outcome of two-piece maxillary treatment during bimaxillary surgery in patients with skeletal Class II malocclusion was examined and the results are discussed. MATERIAL AND METHODS: Dental plaster casts and lateral cephalograms of 47 patients were collected in five phases of treatment: baseline (t1), preoperatively (t2), postoperatively (t3), at the end of orthodontic treatment (t4), and at the time of long-term follow-up (t5), and were retrospectively analyzed. RESULTS: At follow-up all patients showed a Class I occlusion. The maxillary width was, on average, enlarged by 2.7 mm surgically. During the following 8.8 years after treatment, 1.7 mm were lost. The cephalometric analyses showed no severe changes in the sagittal maxillary position for the duration of follow-up. The sagittal mandibular position (SNB) was changed significantly by the mandibular advancement from 75.4 degrees to 77.8 degrees and remained stable for 8.8 years postoperatively. CONCLUSION: Bimaxillary surgery with two-piece maxillary treatment in patients with Class II malocclusion leads to stable long-term occlusal results in the sagittal plane. The transverse enlargement achieved by intraoperative widening does not remain stable over the years. A relapse of about 60% of the surgically expanded transverse width is seen. In Class II deformities without an open bite, where extended transverse enlargement is necessary, a two-step procedure with primary surgically-assisted rapid palatal expansion followed by one-piece surgery should be planned.