Prediction of the change of soft tissue profile on the lower face following retraction of incisors

Lee, Jang Seop; Sung, Jae Hyun

Abstract

The purpose of this study was to evaluate the change of soft tissue profile on lower face following retraction of incisors through orthodontic treatment. 31 Korean women with bialveolar protrusion who were treated with 4 first bicuspid extraction were selected. All of samples were treated from above 17 years of age. Lateral cephalometric head films taken before and after treatment were analyzed statistically. The results were obtained as follows. The ratio of upper incisor retraction to upper lip retraction and lower incisor retraction to lower lip retraction were 1.54 : 1(r=0.746) and 0.92 : 1(r=0.584) respectively. It appeared during orthodontic treatment that UIS-LS was increased considerably and the others in soft tissue thickness measurements were slightly decreased. Analysis of correlation showed that the change of the upper lip(LS) with th change of maxillary central incisor(UIS) and the change of lower lip with the change of B point were most strongly correlated. The multiple regression equations were obtained to predict soft tissue profile change of lower face according to retraction of incisors.