Effects of Maxillary Movements on Lips Following Orthognathic Surgery: A Retrospective Non-Randomized Clinical Trial.

Introduction  Lips play a fundamental role in facial attractiveness and in decisions pertaining to orthognathic surgery. Objective  To assess the upper lip changes following Le Fort I osteotomy for maxillary advancement and/or impaction. Methods  In the present retrospective non-randomized clinical trial, we evaluated 3 groups of patients who underwent Le Fort I osteotomy of the maxilla. Group 1 (n = 35) underwent maxillary advancement, group 2 (n = 14), maxillary impaction, and group 3 (n = 11) was submitted to both maxillary advancement and impaction. The lip thickness of all patients was measured preoperatively, and the participants in each group were categorized into two subgroups: thin (< 12 mm) and thick (> 12 mm) lip. The primary (before orthognathic surgery) and final (after orthodontic bracket removal) lateral cephalograms of the patients were analyzed using the Dolphin software. Comparisons were made using the paired t -test and linear regression in the IBM SPSS Statistics for Windows software. Results  The length of the upper lip increased by 1 mm ( p  = 0.012) on average following maxillary advancement, and it decreased by 0.43 mm ( p  = 0.24) on average following maxillary impaction. In the maxillary advancement group, the change in angulation of the incisors predicted the incisal display ( p  = 0.03). In the maxillary impaction group, skeletal changes in the vertical dimension predicted changes in upper lip length ( p  = 0.033). Conclusions  Le Fort I osteotomy for maxillary advancement significantly increases the length of the upper lip. The assessment of lip thickness prior to surgery can help predict the postoperative results. Changing the angulation of the incisors can predict the incisal display. In maxillary impaction, skeletal changes in the vertical dimension can predict the changes in the length of the upper lip.