A comparative assessment of failures and periodontal health between 2 mandibular lingual retainers in orthodontic patients. A 2-year follow-up, single practice-based randomized trial

Abstract

Introduction:The objective of this study was to compare the survival rates and periodontal health in patients with 3-strand round twisted (RT) vs 8-strand rectangular braided (RB) fixed retainers bonded to all 6 anterior teeth in the mandible. Methods: A total of 133 patients completing orthodontic treatment (median age, 24.6 years; 25th percentile, 17.2 years; 75th percentile, 32.4 years; minimum, 15.1 years; maximum, 49.8 years) were randomly allocated in a 1:1 ratio to receive either an RT or RB wire retainer. Inclusion criteria were all mandibular permanent incisors and canines present, no active caries, no restorations, no fractures on the mandibular incisors and canines, no periodontal disease. Patients with poor oral hygiene before debonding were excluded from the trial. The primary outcome was any first-time retainer failure. Secondary outcomes were periodontal index, bleeding on probing, plaque index, gingival index, and probing depth. Randomization was accomplished with random permuted blocks of size 4, 6, or 8 with allocation concealed in sequentially numbered, opaque, sealed envelopes. Blinding was not possible in this trial. Patients were evaluated at baseline, 3, 6, 12, 18, and 24 months after placement of the retainer. Retainer survival was assessed using Cox regression. Periodontal parameters were reported at each time point and generalised estimating equations were used to assess the effect of treatment, time, tooth and treatment X time interaction on the indices. Results: Baseline characteristics were similar between groups; in 1 patient, the intervention was discontinued. During 2-year follow-up 37 of 66 (56.1%, RT group) and 32 of 66 (48.5%, RB group) retainers failed at least once (log-rank test, P 5 0.55). The adjusted hazard ratio was 0.69 (95% confidence interval, 0.42-1.12; P 5 0.13). Neither age nor gender was a predictor of failure. All periodontal parameters (periodontal index, bleeding on probing, plaque index, gingival index, and pocket depth) were comparable between groups and remained relatively stable during follow-up. Conclusions: The overall risk for first-time failure was high and amounted to 52.3% (56.1% in the RT group and 48.5% in the RB group). There was no difference in terms of survival or periodontal health between the examined retainers.

CAD/CAM nitinol bonded retainer versus a chairside rectangular-chain bonded retainer: A multicentre randomised controlled trial

“…These failure rates, although lower than the upper arch, are still disappointingly high. It is interesting that these higher failure rates are consistent with some other recent prospective controlled research ( Naraghi et al, 2021 ; Wegrodzka et al, 2021 ), which tend to show higher failure rates than those measured in retrospective trials.…”

Orthodontic Retainers—A Critical Review

“…Particular wire properties do not appear to be contributory to any noteworthy deterioration of the periodontium [101]. According to Bucur et al (2022) [102], plaque accumulation is significantly lower in removable compared to fixed retainer bearers, but in Hawley appliance wearers, interdental plaque may also be prominent.…”

Missing data, part 1. Why missing data are a problem

“…This example was created using data from an orthodontic randomised controlled trial comparing how probing depth evolves over time when using two types of lower lingual retainers. 2 In this example, probing depth (the outcome) is measured on six teeth (lower left canine to lower right canine) per individual at six time points. Table 1 presents an example of data on treatment, gender and age at baseline, and mean probing depth across six teeth at six time points, for five individuals.…”