DISCUSSION
plaque/calculus, tooth
COMPLICATION, PLAQUE
Long-term retention of mandibular incisor alignment using bonded retainers is considered safe, predictable,To the best of our knowledge, this randomized clinical trial is the first to compare Ortho-Flex-Tech™ wire and multi-strand wire retainer in terms of gingival health, plaque accumulation, tooth alignment and failure rate. Long-term retention with bonded retainers may present potential negative effects on periodontal health.No significant differences were detected between the two groups in this study in terms of PI, GI, CI, and SOHI. Even when the mean PI, GI and CI were divided into tooth surfaces, no significant differences were detected between the two groups. The gingival health and the plaque/calculus accumulation may have been affected by the subject’s oral hygiene status. Accordingly, it is important to have almost matched groups in terms of oral hygiene. In this study, baseline data for gingival parameters were considered at the time of bracket debonding, and not before orthodontic treatment or even during the active fixed orthodontic treatment. This can be considered as a limitation, since individuals with poor oral hygiene before or during treatment tend to have poor oral hygiene during retention phase. To reduce this bias, only patients with good oral hygiene were included in this study from the beginning. Also, randomization was performed to reduce the chance of unbalanced grouping. In this study, the PI (0.51) and GI (0.93), for multi-strand wire group were higher than that reported by Årtun et al.A recent systematic review with meta-analysisIn the present report, the only statistically significant difference between the two groups was related to IRI. Ortho-Flex-Tech™ wire showed better alignment retention than multi-strand wire group. However, multi-strand wire group presented clinically less than 2 mm irregularity mean score. Previous studies have tried to define acceptable levels of relapse, and suggested that irregularity less than 3.5 mm in the anterior segment may be considered an acceptable level of relapse;In the present study, the IRI of the multi-strand wire retainer group (0.69 mm) was almost similar to that reported by Årtun et al.Although the difference in the retainers’ efficiency in this study was statistically significant, the clinical significance is questionable, as the mean difference in the IRI between the two groups was less than 1 mm. Long-term follow up may be necessary in the future to clarify this issue. Failure of a bonded retainer is a relatively common complication, with prevalence ranging from 1 to 53%.The failure rate for multi-strand retainer (8%) was lower than that reported by Dahl and Zachrisson