title: Dentoalveolar effects induced by a removable expansion plate.
abstract: OBJECTIVE
  The aim of this article was to analyze the changes in the transverse dimensions of the dental arches produced by a removable expansion plate (Removable Spring Expander, RSE) in subjects with unilateral posterior crossbite.
  
  
  METHODS
  The treated group (TG) comprised of 17 subjects (5 males and 12 female) with unilateral posterior crossbites. Dental casts were available at pre-treatment (T1) and at a post-retention observation period (T2). The mean age at T1 was 6 years +/- 1 year and 4 months, and 7 years 11 months +/- 1 year and 5 months at T2. Seventeen subjects (7 males, 10 females) with an untreated unilateral posterior crossbite were used as the control group (CG). The mean age was 5 years 11 months +/- 1 year and 2 months at T1 and 7 years 9 months +/- 1 year and 4 months at T2. Post-retention changes in the transverse dimensions of the dental arches were evaluated statistically by means of a t-test for independent samples.
  
  
  RESULTS
  The TG showed statistically significant increments when compared with untreated controls in maxillary intermolar widths (4.5 mm), intercanine widths (3.6 mm), and there were significant improvements in the posterior transverse interarch discrepancy (4.2 mm) and in the anterior transverse interarch discrepancy (3.3 mm). No statistically significant differences were found for the mandibular intermolar and intercanine widths between TG and CG.
  
  
  CONCLUSIONS
  The expansion plate is a simple and effective device for the expansion of the upper arch in the deciduous and early mixed dentitions.
authors.affiliation: Department of Orthodontics, University of Florence, Italy.
authors.forename: Efisio
authors.initials: E
authors.lastname: Defraia
authors.forename: Andrea
authors.initials: A
authors.lastname: Marinelli
authors.forename: Giulia
authors.initials: G
authors.lastname: Baroni
authors.forename: Isabella
authors.initials: I
authors.lastname: Tollaro
mesh_terms: D002648:Child; D002675:Child, Preschool; D003724:Dental Arch / Q000033:anatomy & histology*; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008437:Maxilla; D016382:Orthodontic Appliance Design; D009968:Orthodontic Appliances, Removable; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D014094:Tooth, Deciduous