Distraction Osteogenesis Normalizes Mandibular Body-Symphysis Morphology in Infants With Robin Sequence.

PURPOSE: To evaluate changes in mandibular morphology in infants with Robin sequence (RS) after mandibular distraction osteogenesis (MDO) and compare the post-distraction morphology with that in infants without RS and infants with RS who had not undergone MDO. MATERIALS AND METHODS: Infants with RS treated with MDO were retrospectively evaluated over a 12-year period. All patients had pre-distraction and end-consolidation maxillofacial computed tomograms. Morphologic features of the mandible were divided into ramus and condyle, body and symphysis, and composite measurements. Post-distraction RS mandibular morphology was compared with pre-distraction morphology, as well as to age-matched infants without RS and age-matched infants with RS who had not undergone MDO. Comparisons were done using nonparametric paired-samples analyses. RESULTS: During the study period, 17 patients with RS treated with MDO met the inclusion criteria for the study. The mean ages at distraction and end-consolidation were 1.95 ± 3.24 and 8.46 ± 5.99 months, respectively. The post-MDO mandible was significantly different from the pre-MDO mandible with regard to the ramps-condyle unit and body-symphysis measurements, including development of a more parabolic mandibular arch form (P ≤ .001). Compared with age-matched non-RS infant mandibles, the post-distraction RS mandibles had similar morphologies. Compared with age-matched non-MDO RS mandibles, the post-distraction mandibles had significantly different morphologies anterior to the gonial angle, including a more parabolic arch form (P ≤ .006). CONCLUSIONS: MDO normalized mandibular morphology in infants with RS, with the greatest effect on measurements anterior to the gonial angle.