The overbite and intraoral mandibular distraction osteogenesis

Purpose: The purpose of this study was to quantify the overbite reduction in skeletal Angle Class II malocclusions and discuss the management of the overbite during and after intraoral distraction of the mandible, and during orthodontic treatment with fixed appliances. Material and Methods: Cephalograms of 26 patients with an Angle Class II occlusion and orthodontic appliances and distraction osteogenesis of the horizontal part of the mandible before (T0) and at least 1 year after treatment (T1) were evaluated. Mean age of the patients at the time of distraction wag 14.6 years (range 12.8-15.9 years) and at the final registration 17.3 years (range 14.6-20.4 years). Results: The overbite decreased significantly and the SpP/MP value increased significantly. The increase in the value of the Y-axis and the MP/SN angle before and after treatment was statistically insignificant. Conclusion: Opening of the bite during distraction of the mandible can be expected. The use of the 'floating bone' technique did not correct the overbite permanently. The patients in whom an open bite has already been treated are not ideal for mandibular lengthening by means of distraction osteogenesis. (C) 2003 European Association for Cranio-Maxillofacial Surgery.