ABSTRACT
Objective To evaluate changes from the front in morphology and improvement degree of smiling lip after orthognathic surgery with class Ⅲ skeletal malocclusion.Methods Adult males in experiment were divided into two groups,orthognathic surgery group and the normal group,25 in each group.Experimental subjects in orthognathic surgery group and the normal group were taken positive images before and after the surgery,respectively,and the 35 marks were labelled in every photoes.The mark points were put in the coordinate system of XY,where apophysiary point was original.Test was used to compare changes of lip shape in static and smiling situation before and after treatment and differences between groups.Results Position of upper and lower lip were lower than the normal group when smiling before treatment in orthognathic surgery group,and the upward amplitude of upper lip and angulus oris less than normal group.Between bilateral corner of mouth it was obviously wider than before horizontally when smiling after the treatment.After the surgery,the patient's smile characteristics were significantly improved,but there was still difference comparing with the normal group.Conclusions The lip shape of patients with Class Ⅲ skeletal malocclusion are significantly improved after orthognathic surgery.