Abstract
BackgroundThe long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers.Trial designRetrospective cohort study.MethodsEighty-eight patients in retention 10–15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients’ clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival.Results and conclusionsIn the mandible, 47 (53.4%) .016″ × .022″ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027″ β-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016″ × .022″ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10–15 years after debonding. No adverse torque changes were observed.LimitationsPotential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.
Highlights
Today, most patients treated orthodontically expect an attractive smile for life
The aim of this study is to assess the survival and risk of failure 10 and 15 years after treatment of a maxillary retainer (.016′′ × .022′′ braided stainless steel (SS) wire bonded to all four anterior teeth) and two different mandibular retainers (I) .016′′ × .022′′ braided steel retainers (SS) wire bonded to all six mandibular anterior teeth and (II) .027′′ round Beta titanium (TMA) wire bonded to mandibular canines only
TMA retainers bonded only to canines have never been assessed long-term. This could be due to the fact that TMA retainers are rarely used by orthodontists as stainless steel retainers of various dimensions seem to be the retainers of choice [1]
Summary
In order to meet the patients’ expectations, lifelong retention is frequently recommended [1]. Extended wear of retainers is not free of failures and adverse effects. Depending on the Failures of bonded retainers range from relatively easy to fix detachments of the wire from an individual tooth. Kocher et al Progress in Orthodontics (2019) 20:28 to detachment of the wire from several/all teeth resulting in retainer loss. Failures at the adhesive-wire interface are less frequent. The tooth detached from the retainer can move causing esthetic problems and the need for retreatment. The long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers.
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