A Cephalometric Analysis for Evaluation of Changes in Soft Tissues in the Regions of the Upper and Lower Lips and Chin due to Orthognathic Maxillary Advancement Surgery

Introduction There is currently no consensus regarding the best method for predicting the changes in soft tissues due to the modification of hard tissues in orthognathic surgery. Objective To measure the changes in soft tissues of the upper lip, lower lip, and chin regions due to the modifications of hard tissues caused by orthognathic maxillary advancement surgery using a cephalometric methodology. Methods The study was conducted on 35 patients with dentoskeletal and facial deformities submitted to orthognathic maxillary advancement surgery. Two teleradiographs were taken: one during the preoperative period and the other 1 year after the surgery, on which the cephalometric tracing was drawn. Results A strong correlation (r = 0.747) was demonstrated in the horizontal analysis between the hard A (Ah) point (located in the deepest point of the anterior curvature of the maxilla) and the soft A (As) point in the advancement of the maxilla, with a mean variation of 0.859% occurring in As with each 1% variation of the Ah point. A mean variation of 0.698% occurred in the superior soft prostion point (prolongation of the superior hard prostion point to its corresponding point on soft tissue) for each 1% variation in the superior hard prostion point (bone point located at the junction of the alveolar process with the crown of the upper incisors). Conclusion The cephalometric methodology applied here revealed that the soft tissues of the upper lip accompanied 70 to 80% of the movement of hard tissues in maxillary advancement and that the soft tissues of the lower lip did not change or showed no significant changes.