3D-CT measurements of facial symmetry in severe CFM patients: A comparative study between mandibular ascending ramus distraction osteogenesis and bone grafting

This study aims to compare the effects of mandibular distraction osteogenesis (MDO) and bone grafting on the facial symmetry of children with Pruzansky-Kaban type IIB and III craniofacial microsomia (CFM). Medical records and three-dimensional computed tomography (3D-CT) data of CFM patients who had primarily undergone MDO and bone grafting were collected. A retrospective analysis of pre-and post-operative 3D imaging data was conducted to compare the improvement rate in facial symmetry between the two groups based on occlusal cant, affected/unaffected ramus height ratio and chin point deviation. The data were tested for normality using the Shapiro-Wilk test. When the data followed a normal distribution, a paired sample t -test was employed for the comparison between preoperative and postoperative data. When the data did not follow a normal distribution, the Wilcoxon signed-rank test for paired samples was used for preoperative and postoperative comparison. The study included 18 children with type IIB and III CFM, 11 in the MDO group and 7 in the bone grafting group. In the MDO group, postoperative Gn-FH and Gn-Cor distances increased significantly, whereas the postoperative Gn-Mid distance decreased significantly. Occlusal cant decreased significantly and ramus height affected/unaffected ratio increased significantly after MDO. In the bone graft group, there was no statistically significant difference in the postoperative ratios of chin deviation, occlusal cant, and ramus height affected/ unaffected compared to the preoperative values. Compared to bone grafting, MDO can significantly enhance ramus height ratio, level occlusal plane, and centralize the chin point among patients with CFM. Furthermore, MDO achieves superior enhancements in facial symmetry.