Advancement of mandibular symphysis with distraction osteogenesis

Abstract

This case report demonstrates the effects of mandibular symphysis advancement with distraction osteogenesis (DO) in a 21-year-old man with a Class I molar relationship, protrusive maxillary incisors, crowding in both arches, and increased overjet and overbite. Treatment consisted of maxillary arch leveling, mandibular incisor repositioning through mandibular symphysis advancement with DO, and subsequent mandibular arch leveling. The osteotomy line, between the canine and the first premolar, was extended from the interdental area to the lower border of the mandibular symphysis bilaterally. The distraction device was cemented after mobilization of the mandibular symphysis. The screws were activated (0.8 mm per day) after a latent period of 1 week. The amount of activation per side was 6.4 mm. After an 8-week consolidation period, the distraction appliance was removed. At the end of treatment, increases of SNB angle, effective mandibular length, SN/GoGn, anterior facial height, mandibular incisor inclinations, and labiomental angle were observed. Decreases of ANB angle, overjet, and distance from the lower lip to the esthetic line were noted. Even though this patient's long-term results are not yet available, the results so far are encouraging. Mandibular symphysis advancement with DO seems to be an effective method for correcting mandibular anterior crowding and an increased overjet. (Am J Orthod Dentofacial Orthop 2009; 135: 232-40)