A computer assisted photogrammetric analysis of soft tissue changes after orthodontic treatment. Part II: Results

The purpose of this study was to use standardized facial photographs to compare the soft tissue profile changes in persons with Class II, Division 1 malocclusions who were treated with either an extraction or a nonextraction treatment modalities. Ninety-one patients (44 extraction and 47 nonextraction) were evaluated using standardized facial photographs, available at pretreatment, posttreatment and 2-years in retention. The photographs were digitized and displayed on a computer monitor. Thirty-eight landmarks (18 frontal and 20 lateral) were located. From these landmarks, 29 angular and linear dimensions (8 frontal and 21 lateral) were constructed. Descriptive and analytical statistics were used to compare the absolute dimensions, as well as the incremental changes, between the extraction and nonextraction groups. The present findings indicate: (1) After treatment the upper and lower lips were retracted significantly more in the extraction group compared with the nonextraction group. These differences persisted into retention. (2) The upper lip length increased more among subjects who were treated without extractions. (3) The upper vermilion height in male subjects and the upper and lower vermilion heights in female subjects increased among subjects who were treated without extractions and decreased among subjects who were treated with four first premolar extractions. (4) The nasolabial angle became significantly more obtuse among the female subjects who were treated with four first premolar extractions.