The vertical changes of the lip and perioral soft tissue resulting from incisor retraction

Kang, Chang Soo; Kim, Kyung Ho; Choy, Kwang Chul

Abstract

Patients who want to reduce their lip protrusion usually estimate the severity of the lip protrusion on the frontal aspect. Most orthodontists have a perplexed experience of a reduced thin line of vermilion border on the frontal aspect as incisors are retreated, even though the lip protrusion is thought to be reduced favorably on the sagittal aspect. Some patients, also look older after orthodontic treatment because of severe lip thinning. This unaesthetic reduction of vermilion border urges us to study the vertical lip change during orthodontic procedure. The purpose of this study was to evaluate the vertical lip and perioral soft tissue changes in respect to incisor retraction in an effort to analyze which factors might be responsible for their vertical changes, using the multiple regression analysis. The results were as follows. 1. Upper and lower lip philtrum length(SnLs, LiB') were increased after retraction of anterior teeth, were as upper and lower vermilion height(LsStms, StmiLi), and vermilion length(LsLi) were decreased. 2. Upper and lower lip length(SnStms, StmiB'), and soft tissue lower anterior facial height(SnMe') did not show any significant difference after treatment. 3. The increase of the upper lip philtrum length was mainly influenced by the extrusion of upper anterior teeth(U1V), and the increase of the lower lip philtrum length was mainly influenced by the initial overjet before treatment. 4. The decrease of the upper and lower lip vermilion height was mainly influenced by the decrease of upper lip thickness.