Soft Tissue Alar Base Width Changes in Patients Submitted to Surgically Assisted Rapid Palatal Expansion (SARPE): A Meta-Analysis

Background: During Le Fort I osteotomies, manipulation of both skeletal and soft tissues is believed to secondarily alter nasolabial physiognomy and esthetics. A major objective of orthognatic surgery is the esthetic outcome. Treatments only correcting for dentoskeletal deformities are not sufficient for optimal facial results because undesirable soft tissue changes may accompany skeletal manipulations. Quantifying the soft tissue changes accompanying surgically assisted rapid palatal expansion (SARPE) will aid in understanding these dynamic connections. The primary objective of this study was to investigate alar base width (ABW) changes a minimum of 6 months following SARPE. Because the power of past studies is limited by their enrollments, this meta-analysis attempted to pool individual study results and test the statistical significance of an overall pooled effect. Methods: The following electronic databases and citation indices were searched: PubMed, Cochrane Library, Scopus, Web of Science, Embase, and Virtual Health Library. The search included articles published until September 2015 without language restriction. The general search term was: (palatal expansion OR maxillary expansion OR SARPE OR SARME) AND (alar base OR nasal width). The intervention was SARPE with maxillary vestibular incision from first molar to contralateral first molar, a modified Le Fort I osteotomy with or without pterygomaxillary disjunction, and a V-Y closure. The primary outcome was the unstandardized mean difference between pre- and postoperative ABW. A random effects meta-analysis was performed to combine study results with the ReviewManager software (Version 5.2, The Cochrane Collaboration 2015). Included studies were assessed for statistical heterogeneity using a χ2 test for independence. A pooled estimate of ABW change was calculated using inverse-variance weighting. Results: The authors identified 7 pertinent studies investigating ABW changes following SARPE (Fig1). Studies where mean differences were presented and where data for every period assessed were not available were not included in the analysis. The results of this meta-analysis (N=41) showed a significant +1.74mm ABW increase in patients submitted to SARPE (Fig2). Widening of the alar base was observed despite including cinched patients in the analysis. There was no statistical heterogeneity among included studies (χ2=0.03; df=2; p=0.98). Discussion: None of the 3 included studies was completely free of bias. The most prominent flaws were measurement bias, limited sample size, and patient recruitment. Measurements of the 3 studies were obtained from either 3-dimensional landmarks or digital calipers. All 3 studies failed to blind outcome assessors, and because the measurement of ABW partially relies on individual judgment, results may have been affected. Soft tissue migration following SARPE is likely a function of muscular foreshortening from subperiosteal dissection, loosening or resorption of cinch sutures, and osseous base expansion at the anterior piriform aperture. Future studies should compare the magnitude of expansion with the magnitude of changes to the soft tissue envelope. Doing so will reveal how much change is contributed by surgery (or prevented by cinching) versus orthopedic movement in SARPE. Careful preoperative clinical examinations may shed light as to whether these nasolabial changes would enhance or detract from the final esthetic outcome. Conclusions: Following meta-analysis, a statistically significant increase (+1.74mm) in mean ABW was observed a minimum of 6 months postoperatively in patients submitted to SARPE. ABW increases were observed despite including cinched patients in the analysis. 1. de Assis DS, Duarte MA, Goncales ES: Clinical evaluation of the alar base width of patients submitted to surgically assisted maxillary expansion. Oral Maxillofac Surg 14(3):149-154, 2010 2. Metzler P, Geiger EJ, Chang CC, Steinbacher DM: Surgically assisted maxillary expansion imparts three-dimensional nasal change. J Oral Maxillofac Surg 72(10):2005-2014, 2014