A systematic review on soft-to-hard tissue ratios in orthognathic surgery part I: maxillary repositioning osteotomy.

INTRODUCTION: Changes occurring in facial soft tissues after orthognathic surgery have been studied over the past 45 years. In this systematic review, we analyzed soft-to-hard tissue ratios regarding maxillary repositioning surgery. METHODS: We searched major online databases according to the guidelines of the CONSORT/QUORUM flowchart, and selected studies based on their inclusion and exclusion criteria. RESULTS: Our search identified 27 articles, and 10 additional articles were found in the reference sections. Of these, six were evidence level IIIb, three were evidence level IIb, and the rest were evidence level IV. Only three articles were prospective. A high variability of soft-to-hard tissue ratios regarding Le Fort I surgery seemed to vanish if data were stratified according to confounding factors. With the available data, a ratio of 0.6:1 (labrale superius to upper incisor tip) could be used in Le Fort I advancement surgery if alar base cinch suture is not performed, and a ratio of 0.9:1 if it is performed. CONCLUSION: Although there are many publications on soft tissue changes after orthognathic surgery, more prospective studies are needed that stratify by confounding factors such as type of osteotomy technique, magnitude of the movement, age, sex, race, quantity, and quality of the soft tissues.