Intermolar Mandibular Distraction Osteogenesis-A Preliminary Report

Background: Dental Class II is the most common indication for combined orthodontic-orthognathic treatment. Intermolar mandibular distraction osteogenesis (IMDO) treatment was performed during the growth spurt, to avoid surgery at a later age. The aim of this study is to present our first experience with IMDO. Methods: This is a retrospective case series of patients who underwent an IMDO. All patients showed mandibular retrognathism, and orthodontic treatment with functional appliances was not successful. Results: In total, 20 patients (mean age of 14.8 years (SD = 0.9 ys) were included. All patients achieved a Class I occlusion. An average length gain of 9.6 mm (SD = 3.7 mm) was reached. In one patient an abscess occurred. Nine patients presented with root fractures of the second molar; three were lost, one treated endodontically. The average time between insertion and removal of the distractors was 4.6 months (SD = 1.5 mths). In one case a premature consolidation was seen. Conclusion: We achieved satisfactory results with IMDO, although undesirable effects occurred. An advantage is the manageable overall treatment time. Open questions concern the occurrence of root fractures. Furthermore, the question of long-term stability is open. The question of dynamic distraction treatment in relation to temporomandibular joint changes can only be answered in the long term.