Prediction of Soft Tissue Profile in Nose and Upper Lip Region following Orthognathic Surgery. Classified by Directions of Surgical Displacement of Maxilla and Evaluated with Multivariate Analysis.

The purpose of this study was to investigate the changes of soft tissue profile in the nose and upper lip region following orthognathic surgery.The subjects were 114 adult females who underwent two-jaw surgery to correct anterior reversed occlusion and were classified into four groups by the directions of surgical displacement of maxilla by cluster analysis. In addition to displacement of hard tissue, some of the soft tissue measurements in the nose and upper lip region such as height and thickness were evaluated with multiple regression analysis.The results were as follows:(1) Although the tip of the nose was displaced in the upward and forward direction, except in the group where the anterior part of the maxilla was surgically displaced downward, the displacement of the nose as a whole was minimum.(2) The displacement of the upper lip was similar to that of the front part of maxilla, except in the downward group.(3) In addition to the displacement amount of the hard tissue maxilla, thickness and height of the soft tissue in the nose and upper lip region also contributed to significant changes of the profile.By using a multiple regression analysis, acceptable prediction of the soft tissue profile in the upper lip region would be possible, but precise prediction would be difficult, because of the nose and alar base cinch suture, etc.