title: Twelve-year follow-up of mandibular incisor stability: Comparison between two bonded lingual orthodontic retainers.
abstract: OBJECTIVE
  To compare the long-term outcome 9 years after removal of two different types of fixed retainers used for stabilization of the mandibular anterior segment.
  
  
  METHODS
  Sixty-four children who had undergone orthodontic treatment with fixed appliances in both arches were divided into two groups depending on which kind of retainer being used. Twenty-eight of the patients had a canine-to-canine retainer bonded to the canines and 36 had a bonded twistflex retainer 3-3, bonded to each tooth. Measurements were made on study models and lateral head radiographs, before and after treatment, 6 years after treatment, and 12 years after treatment, with a mean of 9.2 years after removal of the retainers.
  
  
  RESULTS
  No significant differences were found between the two groups at the long-term follow-up according to Little's Irregularity Index or available space for the mandibular incisors. The overjet and overbite were reduced after treatment in both groups and stayed stable throughout the observation period. Also, no differences in bonding failures between the two retainers were found.
  
  
  CONCLUSIONS
  Both a canine-to-canine retainer bonded only to the canines and a twistflex retainer 3-3 bonded to each tooth can be recommended. However, neither of the retention types prevented long-term changes of mandibular incisor irregularity or available space for the mandibular incisors after removal of the retainers.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schütz-Fransson
authors.forename: Rune
authors.initials: R
authors.lastname: Lindsten
authors.forename: Krister
authors.initials: K
authors.lastname: Bjerklin
authors.forename: Lars
authors.initials: L
authors.lastname: Bondemark
mesh_terms: D000293:Adolescent; D002648:Child; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor / Q000503:physiopathology*; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible; D018704:Orthodontic Retainers; D012008:Recurrence; D012307:Risk Factors; D016896:Treatment Outcome
keywords: Irregularity Index; Long-term stability; Orthodontic retainers; Relapse