title: Long-term stability of combined rapid palatal expansion-lip bumper therapy followed by full fixed appliances.
abstract: BACKGROUND
  The purpose of this study was to evaluate the long-term postretention stability of rapid palatal expansion-lip bumper therapy followed by full fixed appliances.
  
  
  METHODS
  The sample included 20 treated patients (11 women and 9 men) who were recalled to obtain postretention records. The subjects were out of retention for a minimum of 4 years and an average of 7.9 years. They had begun treatment in the late mixed dentition at a mean age of 11.1 with considerable incisor crowding but, on average, no tooth size-arch length discrepancies. Pretreatment, posttreatment (mean age, 13.6 years), and postretention (mean age, 24.3 years) models were digitized, and the computed measurements were compared with untreated reference data.
  
  
  RESULTS
  The majority of treatment increases in maxillary and mandibular arch dimensions were statistically significant (P < .05) and greater than expected for untreated controls. Although many measurements decreased postretention, net gains were maintained for 21 of the 30 measurements evaluated. The notable exception was arch perimeter, which decreased to less than pretreatment values. Postretention incisor irregularity increased 0.5 +/- 1.2 mm in the maxillary arch and 1.1 +/- 1.5 mm in the mandibular arch.
  
  
  CONCLUSIONS
  Based on the good long-term stability observed in this study, we concluded that use of rapid palatal expansion-lip bumper expansion therapy in the late mixed dentition followed by full fixed appliances is an effective form of treatment for patients with up to moderate tooth size-arch length discrepancies.
authors.forename: Tyler
authors.initials: T
authors.lastname: Ferris
authors.forename: R G
authors.initials: RG
authors.lastname: Alexander
authors.forename: Jimmy
authors.initials: J
authors.lastname: Boley
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buschang
mesh_terms: D002648:Child; D003724:Dental Arch / Q000033:anatomy & histology; D005115:Extraoral Traction Appliances; D005260:Female; D006801:Humans; D007180:Incisor / Q000503:physiopathology; D008046:Lip; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible; D009811:Odontometry; D009967:Orthodontic Appliances; D018704:Orthodontic Retainers; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D012008:Recurrence; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016896:Treatment Outcome