Long-term bonded retention after closure of maxillary midline diastema.

INTRODUCTION: The objectives of this study were to evaluate fixed bonded palatal surface retainers between the maxillary central incisors that were placed to maintain midline diastema closure and record their longevity, proclivity for damage, and periodontal health of the central incisors in patients 5 or more years after treatment. METHODS: Twenty-nine subjects were contacted and interviewed by phone concerning the status of their bonded retainer and midline diastema. Eleven subjects with intact retainers came for a periodontal health evaluation of the maxillary central incisors. The measures used were the plaque index, the periodontal screening and recording score, and the gingival index. A split-mouth design was used. Statistical analyses of retainer duration, damage probability, and gingival health were performed. RESULTS: Of the 29 subjects, 52% of the initial retainers were in place for an average of 23 years. For the total of 34 bonded retainers, the mean longevity was 17 years. The risk of breakage for any particular year the retainer was in place was 2%. The mean differences in scores between the maxillary central incisors and the control teeth were -0.06 for the plaque index, -0.14 for the periodontal screening and recording score, and -0.11 for the gingival index. Statistical tests on the differences indicated no evidence that the long-term presence of the bonded palatal surface retainer adversely affected the periodontal health of the maxillary central incisors. CONCLUSIONS: The study's sample demonstrated that a bonded retainer for maintaining closure of a maxillary midline diastema can last an average of 17 years or more, with a yearly 2% chance of breakage and with no expected adverse effects on the periodontal health of the maxillary central incisors.