title: Facial soft tissue changes following maxillomandibular advancement for treatment of obstructive sleep apnea.
abstract: OBJECTIVE
  The goal of this retrospective study was to evaluate the horizontal and vertical facial soft tissue changes occurring after maxillomandibular advancement (MMA) surgery to treat obstructive sleep apnea (OSA).
  
  
  METHODS
  The study group comprised 31 consecutive adult patients with OSA who underwent MMA through Le Fort I osteotomy and bilateral sagittal split ramus osteotomies. Adjunctive maxillary procedures, consisting of piriformplasty, anterior nasal spine recontouring, alar base cinch, and V-Y closure of the upper lip, were used for all patients. A "best-fit" templating cephalometric technique was used to assess dentoskeletal movements and corresponding soft tissue changes.
  
  
  RESULTS
  Maxillary movements (measured at point A) averaged 8.77 +/- 2.34 mm horizontally and 2.20 +/- 2.42 mm vertically. Mandibular movements (measured at point B) averaged 11.16 +/- 2.56 mm horizontally and 2.25 +/- 3.02 mm vertically. The horizontal upper lip soft tissue-to-hard tissue ratios averaged >0.90:1 (SLS/A, 0.97:1; Ls/U1fac, 0.96:1; Stm(s)/ls, 0.86:1). Upper lip length (Sn-Ls) increased by a clinically insignificant amount (0.37 mm). The nasolabial complex rotated in a counterclockwise rotation, with the nasolabial angle decreasing (3.87 degrees) due primarily to forward movement of the upper lip. Horizontal lower lip and chin soft tissue-to-hard tissue ratios averaged >0.90:1 (Stm(i)/li, 0.90:1; Li/Ii, 0.89:1; Pg'/Pg, 0.92:1; Me'/Me, 0.91:1).
  
  
  CONCLUSIONS
  This study demonstrated that MMA in this selected group of OSA patients results in soft tissue movements producing a soft tissue-to-hard tissue ratio of about 0.90:1 for most anatomic sites of the upper lip, lower lip, and chin.
authors.affiliation: Division of Orthodontics, Department of Orthodontics and Pediatric Dentistry, University of Michigan School of Dentistry, Ann Arbor, MI 48109-1078, USA. rsconley@umich.edu
authors.forename: R Scott
authors.initials: RS
authors.lastname: Conley
authors.forename: Scott B
authors.initials: SB
authors.lastname: Boyd
mesh_terms: D000328:Adult; D002508:Cephalometry; D002680:Chin / Q000033:anatomy & histology; D005145:Face / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008046:Lip / Q000033:anatomy & histology; D008297:Male; D019186:Mandibular Advancement; D008875:Middle Aged; D009666:Nose / Q000033:anatomy & histology; D056948:Orthognathic Surgical Procedures; D019340:Osteotomy, Le Fort; D012016:Reference Values; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000601:surgery*