Long-Term Effects of Distraction Osteogenesis of the Mandible

1) To assess the fate of the permanent teeth in and adjacent to the regenerate in pediatric patients who underwent mandibular distraction osteogenesis (DO) and 2) to compare the postoperative growth of the distracted mandible with age- and gender-matched controls. This was a retrospective cohort study of children who underwent mandibular DO during the primary or mixed dentition period and before completion of somatic growth (boys aged ≤14 years and girls aged ≤12 years) at Massachusetts General Hospital from 1996 to 2014. From the DO registry, patients were selected who had complete clinical and radiographic records and at least 1 year of follow-up. Patients with disorders of dental development (eg, ectodermal dysplasia) were excluded. Panoramic radiographs were used to assess changes in morphology, eruption, and orientation of the dentition. Standardized digital lateral cephalograms were used to assess the mandible (sella–nasion–B point, mandibular unit length, ramus height, body length) preoperatively, at the end of distraction, at 1 year after device removal, and at longest follow-up. A total of 118 patients of all ages in the registry underwent some form of DO during the study period. For assessment of the effects on dentition, 26 subjects, who had 36 osteotomies and distraction wounds, met the inclusion criteria. In this sample, 22 of 26 subjects (85%) had 52 adverse effects in 38 of 90 permanent teeth (42.2%) assessed. Cephalometric measurements indicated that there was net mandibular growth at longest follow-up, after a period of skeletal relapse from the end of distraction to 1 year after device removal; however, only 2 of 25 subjects (8%) regained a growth rate in the vector of DO that matched or exceeded normal age- and gender-matched controls. DO commonly results in adverse effects on the dentition within and adjacent to the DO gap, with only a minority resolving over time. Net growth of the mandible occurs after DO but at a slower rate and lesser magnitude than that of age- and gender-matched controls.