Changes in soft tissue profile after mandibular setback surgery in Class III subjects

The aim of this study was to investigate changes in hard and soft tissue profile after mandibular setback surgery. Lateral cephalograms of 25 Class III subjects were assessed before and 1.5+/-0.4 years after mandibular setback surgery. Paired t test, Pearson correlation test and linear regression analysis were used to evaluate the changes in soft tissue profile. Significant changes were found in skeletal (SNB -3.6+/-0.9 degrees, ANB 3.7+/-1.0 degrees, overjet 5.0+/-1.2 and overbite 2.5+/-1.1 mm, P<0.001), soft tissue (facial convexity 5.9+/-1.6 degrees, P<0.001; labiomental fold 0.6+/-0.6 mm, P<0.001; upper and lower lip protrusion 0.5+/-0.8 mm, P<0.01; -3.3+/-1.2 mm, P<0.001), and upper and lower lip lengths (0.9+/-1.2mm, P<0.01; -1.8+/-2.1 mm, P<0.001). Correlations were found between facial convexity and SNB and ANB angles and between upper lip length and SNB and ANB angles. The change in lower lip length was correlated with SNB, ANB, overjet and overbite. Lower lip retrusion was correlated with overjet and a significant correlation was found between the retrusion of lower incisor and lower lip. Mandibular setback surgery was effective in producing an orthognathic profile in adult Class III subjects with mandibular prognathism.