title: Change of lip and occlusal cant after simultaneous maxillary and mandibular distraction osteogenesis in hemifacial microsomia.
abstract: BACKGROUND
  The purpose of this study was to investigate the lip and occlusal cant changes in hemifacial microsomia (HFM) cases after simultaneous maxilla and mandibular distraction osteogenesis (DO) of the mandible.
  
  
  METHODS
  Retrospective analysis of all HFM cases at Balaji Dental and Craniofacial Hospital were performed. Patient of either gender with all medical imaging records and pre and post-operative (6 months) facial photographs in natural head position were included in the study. The lip cant change was assessed by the angle of each labial commissure and the bi-pupillary reference line. The line joining the frontozygomatic unions and a parallel line is drawn at the level of anterior nasal spine. The occlusal plane is then traced. A vertical line is traced perpendicular to the frontozygomatic union. The deviation of the occlusal plane from the horizontal is measured as the occlusal cant and a change, between pre and post-operative records was considered as the angle and linear measurements.
  
  
  RESULTS
  With the linear measurement, the mean change in occlusal cant was 7.18 ± 1.47 mm while for the mean change in lip cant was 3.31 ± 0.52 mm (P = 0.120). For the angular measurement, the mean angle change in occlusal cant was 13.86 ± 2.69° and mean change in angle of lip cant was 8.54 ± 0.7° (P = 0.01).
  
  
  CONCLUSIONS
  For type1HFM, DO corrects the occlusal and lip cant. In present study, the lip cant change relative to occlusal cant change was 47.54 ± 10.71% in linear measurements while for angular measurements it was 63.19 ± 10.07% (P = 0.476; Pearson's correlation coefficient = -0.241).
authors.affiliation: Balaji Dental and Craniofacial Hospital, No: 30 KB Dasan Road, Teynampet, Chennai, 600018 Tamil Nadu India.
authors.forename: S M
authors.initials: SM
authors.lastname: Balaji