Twenty-year follow-up of patients with permanently bonded mandibular canine-to-canine retainers

Introduction: Many orthodontists believe permanent retention is the only way to maintain ideal tooth alignment after treatment. Fixed bonded retainers are now routinely left in place for many years, even decades. The purpose of this study was to examine the health effects and effectiveness of very long-term retention. Methods: Sixty patients who had had bonded canine-to-canine retainers placed a minimum of 20 years previously were recalled. Results: Forty-five still had the retainers still in place, and, of these, only 1 had an irregularity index score >2 mm. In this group, the retainers of 28 patients had never broken, and the retainers were repaired once for 8 patients and more than once for 9. The other 15 patients had had their retainers removed outside the orthodontic practice 5 to 25 years previously. In 13 of these patients, the irregularity index score was >3 mm, and 5 of them had scores >4 mm. Gingival index scores for all teeth from first molar to first molar in both arches demonstrated no detrimental effects to the mandibular anterior gingiva from leaving these retainers in place, and the mean score for the maxillary incisor area was better in the patients with a retained mandibular retainer, suggesting better hygiene in the group with retainers. Conclusion: Long-term retention of mandibular incisor alignment is acceptable to most patients and quite compatible with periodontal health.