Changes in soft tissue chin resulting from premolar extraction and incisor retraction in adult female patients.

Kim, Yang Hee; Son, Woo Sung

Abstract

The purpose of this study was to evaluate changes in soft tissue chin thickness and to investigate correlations between hard and soft tissues measurements after orthodontic treatment conducted by premolars extraction and incisor retraction. The sample consisted of 35 female adults with Angle classification class I or class II division 1 malocclusion. Using lateral cephalometric radiographs taken before and after treatment, hard and soft tissue structures were measured and reproducible six landmark on soft chin tissue were used to locate the various points of soft tissue contour of the chin. The results were as follows : 1. There were signigicant correlations between pretreatment B-B', Pm-Pm' and pretreatment vertical skeletal measurements such as angle of MP & HP, angle of MP & PP, ALFH and between a-a', b-b', Me-Me' and measurements of symphyseal morphology such as SL, SW, PL. 2. There were significant decreases at B-B', Pm-Pm' and significant increases at a-a', b-b' between pre-and posttreatment measurements. 3. There were significant correlations among soft tissues changes and hard tissue changes except for changes at B-B' and the range of correlation coefficient was about 0.3-0.4. 4. There were significant differences at deltaUI-VP, angle of LI &