title: Immediate effects of rapid maxillary expansion on the naso-maxillary facial soft tissue using 3D stereophotogrammetry.
abstract: BACKGROUND
  Rapid maxillary expansion (RME) is used to expand the narrow maxilla. Dental and skeletal affects have previously been reported but few studies have reported on the overlying soft tissue changes. This study reports on the immediate effects of RME on the naso-maxillary facial soft tissue using 3D stereophotogrammetry.
  
  
  METHODS
  Fourteen patients requiring upper arch expansion using RME as part of their full comprehensive orthodontic plan were recruited. Cone beam CT scans and stereophotogrammetry images were taken for each patient; pre-RME activation (T0) and immediately post-RME expansion (T1). Based on twenty-three landmarks, 13 linear and 3 angular measurements were made from each of the stereophotogrammetry images. A linear measurement at ANS was taken from each CBCT image. Using a Wilcoxon signed rank test, the pre-RME and post-RME measurements were compared.
  
  
  RESULTS
  The mean separation of the anterior nasal spine was 3.8 mm ± 1.2 mm. The largest median increase was in nasal base width (1.6 mm), which was statistically significant (p = 0.001). Changes in the nasal dorsum height, nasal tip protrusion, philtrum width, and upper lip length were not statistically significant (p < 0.05). No significant differences were observed in the nostril linear measurements, expect for columella width (p = 0.009). Naso-labial angle decreased but was not statistically significant (p = 0.276). The only statically significant angular change was an increase in the nasal tip displacement angle (p = 0.001).
  
  
  CONCLUSIONS
  Rapid maxillary expansion produces subtle changes in the naso-maxillary soft tissue complex. There is an increase in nasal base width, retraction and flattening of the nasal tip. These changes are small, less than 2 mm and variable between patients.
authors.affiliation: Orthodontic Department, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Altorkat
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, Hong Kong University, Hong Kong. Electronic address: bkhambay@hku.hk.
authors.forename: B S
authors.initials: BS
authors.lastname: Khambay
authors.affiliation: Orthodontic Department, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: McDonald
authors.affiliation: Orthodontic Department, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Cross
authors.affiliation: Radiology Department, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: L M
authors.initials: LM
authors.lastname: Brocklebank
authors.affiliation: Medical Devices Unit, NHS Greater Glasgow and Clyde, Glasgow, UK.
authors.forename: X
authors.initials: X
authors.lastname: Ju
mesh_terms: D002648:Child; D054893:Cone-Beam Computed Tomography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008437:Maxilla; D009295:Nasal Bone; D010155:Palatal Expansion Technique; D010159:Palate; D010780:Photogrammetry / Q000379:methods*; D012189:Retrospective Studies
keywords: 3D imaging; Facial; Rapid maxillary expansion; Rapid palatal expansion; Soft tissue; Stereophotogrammetry