ABSTRACT
The purpose of this study was to evaluate the amount and interrelationship of hard and soft tissue changes after mandibular setback osteotomy and reduction genioplasty in mandibular prognathism with long anterior facial height. The control group (Group A) consisted of 20 patients who had severe horizontal discrepancy. They experienced presurgical orthodontic treatment and orthognathic surgery via mandibular setback. The experimental group (Group B) consisted of 20 patients who had severe horizontal and vertical discrepancy. They experienced presurgical orthodontic treatment and orthognathic surgery via mandibular setback and reduction genioplasty. The presurgical and postsurgical lateral cephalograms were valuated. The computerized statistical analysis was carried on with EXCEL 97 program. The results were as follows : 1. The correlation of hard and soft tissue horizontal changes in lower 2/3 of lower anterior facial height were high for both groups. The correlation coefficients of hard tissue changes and Ls, Stm, Li changes in group B were moderately higher than Group A. 2. The correlation of hard and soft tissue vertical changes in Group B were lower than Group A. (except for pointB-Ils, Me-Me') 3. The ratio for soft tissue to Pog in Group B was lower than Group A. The ratios of hard and soft tissue vertical changes were 32% at Ils, 54% at Pog', and 60% at Me'. 4. The ratio of lower anterior facial height to total anterior facial height was reduced for both group. But ratio of upper 1/3 of lower anterior facial height to total anterior facial height did not changed significantly in Group B. 5. Reduction genioplasty combined with mandibular setback procedure showed no change in upper one third(Sn-Stm) and significant decrease(Stm-Me') in the lower two thirds of the soft-tissue anterior lower facial height.
Subject(s)
Humans , Genioplasty , Orthognathic Surgery , Osteotomy , PrognathismABSTRACT
The chin is one of the factors which express human character, and appropriately protruding chin is very important to harmonious profile. the purpose of genioplasty is to reshape the chin and improve the facial esthetics which is one of the purposes of orthodontic treatment. It can be classified as augmentation genioplasty which enlarge the chin vertico-horizontally and reduction genioplasty which smallen it. The examples to apply this procedure are as follows. 1. advancement of retruded chin 2. reduction of chin prominence 3. control of chin vertical dimension 4. correction of asymmetry