Bonded versus vacuum-formed retainers: a randomized controlled trial. Part 2: periodontal health outcomes after 12 months.

BACKGROUND: Retainer have the potential to compromise periodontal health. OBJECTIVES: Evaluate the periodontal health implications of upper and lower bonded retainers (BRs) versus upper and lower vacuum-formed retainers (VFRs) over 12 months. TRIAL DESIGN: Two-arm parallel group multicentre randomized controlled clinical trial. METHODS: Sixty consecutive patients completing upper and lower fixed appliance therapy and requiring retainers were recruited from three hospital orthodontic departments. They were randomly allocated to either upper and lower labial segment BRs (n = 30) or upper and lower full-arch VFRs (n = 30). Periodontal health was assessed using the plaque and gingival indices of Silness and Loe, and the calculus index of Greene and Vermillion. Data were collected at debond and placement of the retainers (T0), 3 months (T1), 6 months (T2), and 12 months (T3). A random sequence of treatment allocation was computer-generated and implemented by sealing in sequentially numbered opaque sealed envelopes independently prepared in advance. Patients, operators, and outcome could not be blinded due to the nature of the intervention. RESULTS: Thirty patients received BRs (median age 16 years, interquartile range [IQR] = 2, 50% female, 50% male) and 30 received VFRs (median age 17 years, IQR = 4, 60% female, 40% male). Gingival inflammation decreased from baseline for both types of retainer. There was significantly less plaque and calculus accumulation and better gingival health with VFRs than BRs over the evaluated 12 months. No serious harm was observed. LIMITATIONS: It is not known how much the patients chose to wear their removable retainers. The results reported are after 1 year only. CONCLUSIONS: After 1 year, BRs were associated with greater accumulation of plaque and calculus than VFRs and minimally worse gingival inflammation than VFRs, but this did not appear to produce any clinically significant, adverse periodontal health problems. TRIAL REGISTRATION: This trial was not registered. FUNDING: There was no funding.