title: Predicting lower lip and chin response to mandibular advancement and genioplasty.
abstract: The purposes of this retrospective study were to examine the multidimensional nature of soft tissue changes associated with mandibular advancement and genioplasty and to develop predictive models. Longitudinal lateral cephalograms of 62 nongrowing patients (27 men and 35 women) were taken in centric relation with the lips in repose within 4 weeks before surgery and at least 6 months postoperatively (median postsurgical duration was 11 months). The mandibular incisor and pogonion were advanced surgically approximately 6 mm and 11 mm, respectively. The lower lip lengthened slightly (2.5 +/- 3.8 mm), and its surface contour straightened because of thinning at labrale inferior (-2.8 +/- 2.0 mm); there was a slight thickening at the labiomental fold (1.0 +/- 2.3 mm) and a slight thinning at soft tissue pogonion (-0.8 +/- 2.2 mm). Multiple regression models (explaining from 80% to 94% and 66% to 82% of the variation for horizontal and vertical movements, respectively) showed that soft tissue response to advancement surgery depended on pretreatment tissue thickness, horizontal skeletal movement, vertical skeletal movement, and the position of the maxillary incisors. Similar amounts of variation were explained when the models were applied to an independent validation sample of 15 subjects. It was concluded that lower lip and chin response to mandibular advancement and genioplasty is multifactorial but can be accurately and reliably predicted.
authors.affiliation: Department of Orthodontics, Baylor College of Dentistry, The Texas A & M University System, 3302 Gaston Avenue, Dallas, TX 75246, USA.
authors.forename: Trevor
authors.initials: T
authors.lastname: Veltkamp
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buschang
authors.forename: Jeryl D
authors.initials: JD
authors.lastname: English
authors.forename: James
authors.initials: J
authors.lastname: Bates
authors.forename: Sterling R
authors.initials: SR
authors.lastname: Schow
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D002680:Chin / Q000033:anatomy & histology* / Q000601:surgery*; D005260:Female; D005544:Forecasting; D006801:Humans; D008046:Lip / Q000033:anatomy & histology*; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000601:surgery; D019186:Mandibular Advancement; D008954:Models, Biological; D011184:Postoperative Period; D012044:Regression Analysis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014716:Vertical Dimension