title: Arch width changes with a rapid maxillary expansion appliance anchored to the primary teeth.
abstract: OBJECTIVE
  To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage.
  
  
  METHODS
  Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3).
  
  
  RESULTS
  Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3.
  
  
  CONCLUSIONS
  To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.
authors.affiliation: Department of Orthodontics, University of Ferrara, Italy. maurocozzani@libero.it
authors.forename: Mauro
authors.initials: M
authors.lastname: Cozzani
authors.forename: Antonio
authors.initials: A
authors.lastname: Guiducci
authors.forename: Stefano
authors.initials: S
authors.lastname: Mirenghi
authors.forename: Sabrina
authors.initials: S
authors.lastname: Mutinelli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Siciliani
mesh_terms: D016022:Case-Control Studies; D002508:Cephalometry; D002648:Child; D003724:Dental Arch / Q000033:anatomy & histology*; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D052280:Orthodontic Anchorage Procedures; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013997:Time Factors; D014094:Tooth, Deciduous