title: Predictors of postretention stability of mandibular dental arch dimensions in patients treated with a lip bumper during mixed dentition followed by fixed appliances.
abstract: OBJECTIVE
  To identify which dental and/or cephalometric variables were predictors of postretention mandibular dental arch stability in patients who underwent treatment with transpalatal arch and lip bumper during mixed dentition followed by full fixed appliances in the permanent dentition.
  
  
  METHODS
  Thirty-one patients were divided into stable and relapse groups based on the postretention presence or absence of relapse. Intercuspid, interpremolar, and intermolar widths; arch length and perimeter; crowding; and lower incisor proclination were evaluated before treatment (T0), after lip bumper treatment (T1), after fixed appliance treatment (T2), and a minimum of 3 years after removal of the full fixed appliance (T3). Logistic regression analyses were performed to evaluate the effect of changes between T0 and T1, as predictive variables, on the occurrence of relapse at T3.
  
  
  RESULTS
  The model explained 53.5 % of the variance in treatment stability and correctly classified 80.6 % of the sample. Of the seven prediction variables, intermolar and interpremolar changes between T0 and T1 (P = .024 and P = .034, respectively) were statistically significant. For every millimeter of increase in intermolar and interpremolar widths there was a 1.52 and 2.70 times increase, respectively, in the odds of having stability. There was also weak evidence for the effect of sex (P = .047).
  
  
  CONCLUSIONS
  The best predictors of an average 4-year postretention mandibular dental arch stability after treatment with a lip bumper followed by full fixed appliances were intermolar and interpremolar width increases during lip bumper therapy. The amount of relapse in this crowding could be considered clinically irrelevant.
authors.forename: Gaetana
authors.initials: G
authors.lastname: Raucci
authors.forename: Camila
authors.initials: C
authors.lastname: Pachêco-Pereira
authors.forename: Maryam
authors.initials: M
authors.lastname: Elyasi
authors.forename: Fabrizia
authors.initials: F
authors.lastname: d'Apuzzo
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Mir
authors.forename: Letizia
authors.initials: L
authors.lastname: Perillo
mesh_terms: D002508:Cephalometry; D002648:Child; D003724:Dental Arch / Q000503:physiopathology*; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy*; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible; D052280:Orthodontic Anchorage Procedures; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D012008:Recurrence; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D016896:Treatment Outcome
keywords: Cephalometry; Dental arch; Lip bumper; Malocclusion; Relapse and mixed dentition