A comparison of profile changes between ramus and anterior mandibular subapical osteotomies in class III Chinese...

The purpose of this study was to compare cephalometrically the differences in soft-tissue profile changes produced by intraoral ramus and anterior subapical osteotomies for the treatment of Chinese patients with class III malocclusion. Thirty-seven Chinese adults whose class III malocclusion was treated either with an intraoral ramus (group A) or an anterior subapical (group B) osteotomy were selected for the study. Serial lateral cephalograms taken presurgically (T1) and at least 6 months postrentention (T2), showed marked improvement in the soft-tissue profile in both groups. Although the percentage response of soft- to hard-tissue movement was similar at lebrale inferius, the response at soft-tissue point B was found to be statistically less in group B than in group A (P less than .05). Although the correlation between the upper lip response to mandibular ramus setback in group A was weak (r = 0.11), there appeared to be a relatively strong correlation between posterior movement of the upper lip and the magnitude of the lower segmental setback (r = 0.65). The differences in soft- to hard-tissue response with the two osteotomy procedures appear to vary with those reported in whites. This study emphasizes the need for different prediction ratios of soft- to hard-tissue movement in different racial types.