title: Factors associated with orthodontic stability: a retrospective study of 209 patients.
abstract: OBJECTIVE
  To assess the long-term stability of orthodontic treatment and some factors associated to posttreatment changes.
  
  
  METHODS
  Six hundred twenty-seven dental casts of 209 patients were examined with the PAR Index at pretreatment (T1), end of treatment (T2), and at long-term follow-up (T3, mean 8.5 years posttreatment). Friedman test and multiple regression analysis at P < .05 were used to evaluate changes among the time points and factors associated with stability.
  
  
  RESULTS
  After orthodontic treatment, the PAR Index improved by 94.2%. No significant change was observed between T2 and T3 (P>.05). However, when the sample was divided into a well- (PAR Index ≠ 3) and a less well-finished (PAR Index >3) group, it was observed that well-finished patients experienced some deterioration (P<.001), whereas the less well-finished ones showed some improvement (P<.05). Even with the deterioration, the well-finished patients still had a better PAR Index at T3 compared to the less well-finished ones. Regression analysis showed that PAR Index at T1 and T2, age at T1, and length of retainer wear had a slight association with occlusal stability (R(2)=0.27). No significant association was observed between stability and length of treatment, length of follow-up, sex, extraction, or third molar status on the other side.
  
  
  CONCLUSIONS
  Orthodontic treatment is quite stable. Not so well-finished treatments tend to show some improvement and well-finished ones deteriorate some. Well-finished patients still have better occlusal characteristics. Retention contributes to maintenance of the final orthodontic results.
authors.affiliation: Federal University of Rio Grade do Norte, Brazil.
authors.forename: Nair Galvão
authors.initials: NG
authors.lastname: Maia
authors.forename: Antonio David Corrêa
authors.initials: AD
authors.lastname: Normando
authors.forename: Francisco Ajalmar
authors.initials: FA
authors.lastname: Maia
authors.forename: Maria Angêla Fernandes
authors.initials: MA
authors.lastname: Ferreira
authors.forename: Maria Socorro Costa Feitosa
authors.initials: MS
authors.lastname: Alves
mesh_terms: D000293:Adolescent; D000367:Age Factors; D003766:Dental Occlusion; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000628:therapy; D008964:Molar, Third / Q000473:pathology; D018704:Orthodontic Retainers; D009971:Orthodontics, Corrective / Q000706:statistics & numerical data; D057887:Overbite / Q000628:therapy; D012008:Recurrence; D012189:Retrospective Studies; D012737:Sex Factors; D014081:Tooth Extraction / Q000706:statistics & numerical data; D016896:Treatment Outcome; D055815:Young Adult