title: Hyrax appliance opening and pattern of skeletal maxillary expansion after surgically assisted rapid palatal expansion: a computed tomography evaluation.
abstract: OBJECTIVE
  The objective of this study was to evaluate, using computed tomography, correlations between Hyrax appliance opening and post-SARPE skeletal changes.
  
  
  METHODS
  Fifteen patients underwent SARPE according to a specific protocol and were followed. Linear and angular measurements of the anterior, intermediate, and posterior portions of the maxilla were evaluated. The correlation between maxillary expansion and appliance opening was investigated.
  
  
  RESULTS
  Significant overall expansion was observed. In the anterior and intermediate portions of the maxilla, the increase in maxillary width was greater than that observed in the posterior portion. The degree of appliance opening was significantly greater than that of the skeletal expansion. Also, no linear correlation between appliance opening and regional maxillary expansion was established.
  
  
  CONCLUSIONS
  The transverse expansion of the maxilla was less than uniform. The lack of linear correlation between appliance opening and skeletal expansion is attributable to multiple factors, including those related to the device, the surgical technique, and the craniofacial deformity itself.
authors.affiliation: Division of Plastic Surgery, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil. drdov@terra.com.br
authors.forename: Dov C
authors.initials: DC
authors.lastname: Goldenberg
authors.forename: Fernanda C
authors.initials: FC
authors.lastname: Goldenberg
authors.forename: Nivaldo
authors.initials: N
authors.lastname: Alonso
authors.forename: Eloisa S
authors.initials: ES
authors.lastname: Gebrin
authors.forename: Theresinha S
authors.initials: TS
authors.lastname: Amaral
authors.forename: Marco A
authors.initials: MA
authors.lastname: Scanavini
authors.forename: Marcus C
authors.initials: MC
authors.lastname: Ferreira
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000601:surgery*; D008437:Maxilla / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000473:pathology; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D019340:Osteotomy, Le Fort; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D021362:Palate, Hard / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D055815:Young Adult