Accelerated development of the first and second mandibular molars after distraction osteogenesis of the mandible in patients with hemifacial microsomia.

Although distraction osteogenesis of the mandible in patients with hemifacial microsomia (HFM) before the mixed dentition period is widely performed, long-term follow-up information on dental problems is limited. We evaluated the long-term effect of distraction osteogenesis on dental development by comparing Nolla's developmental stages of the first and second molars between the affected and unaffected sides of the mandible. Forty-five patients with unilateral HFM who received distraction osteogenesis of the mandible between the ages of 5 and 8 years and whose dental status was followed for more than 2 years were selected for this study. The patients were divided into 2 groups: group I (n = 28) consisted of patients with Pruzansky types I and IIA and group II (n = 17) consisted of patients with types IIB and III. Panoramic radiographs at T0 (1 month before distraction), T1 (6 months to 1 year after distraction), T2 (2-3 years after distraction) were reviewed. Nolla's stages for the first and second molars were compared at each of the abovementioned times between the affected and unaffected sides using Wilcoxon signed-rank test. In group I, there was no differences observed in Nolla's stages of the first and second molars in comparisons between the affected and unaffected sides of the mandible. However, in group II, at T0, there was a significant difference in Nolla's stage of the first and second molars in comparisons between the affected and unaffected sides. Over time, tooth development was accelerated, and eventually, there was no difference in Nolla's stage between the affected and unaffected sides at T1 and T2. Patients with severe HFM can benefit from distraction osteogenesis of the mandible. The results of this study showed that this procedure could normalize the delayed development and eruption of the first and second molars.