The Impact of Neonatal Mandibular Distraction on Long-Term Mandibular Growth and Morphology

Abstract

Introduction: Mandibular distraction osteogenesis (MDO) is the gold standard treatment for upper airway obstruction associated with Robin Sequence (RS). The long-term effects of MDO on mandibular morphology approaching or at skeletal maturity remain unknown. The objective of this study was to morphologically characterize the mandibles of MDO and conservatively managed (CM) RS patients at or approaching skeletal maturity. Methods: Mandibular morphometric analysis was performed on MDO and CM patient mandibles via 3D-rendered computed tomographic (CT) images. Age- and sex-matched unaffected controls were used for comparison. Mean ± standard deviation was reported, Mann Whitney U Test was utilized, and a P-value of .05 or less was considered statistically significant. Results: RS patients (57.1% female, mean age 16.9 ± 2.6) treated with either CM (n = 5) or MDO (n = 7) were included. Age at latest CT was 17.3 ± 2.3 years for the CM group and 16.5 ± 2.9 for the MDO group. When compared to controls, CM patient mandibular body length was shorter, volumetrically smaller, and the anterior symphyseal angle was more obtuse ( P = .008, P = .06, and .008, respectively). When compared to controls, the MDO patient ramus height and body length were shorter ( P = .01 and <.001, respectively), the gonial angle and anterior symphyseal angle were more obtuse ( P = .02 and <.001, respectively), and mandibular volume was less ( P = .05). Conclusion: Neonatal MDO was associated with morphologic changes unique to the RS mandible at or approaching skeletal maturity. This study provides further insight into the long-term effects of MDO on mandibular morphology.