A Single-center, 3-arm, Parallel-group Randomized Controlled Trial to Evaluate Bond Failures and the Effectiveness of Three Orthodontic Retention Schemes in Preventing Post-treatment Mandibular Arch Changes

There is high possibility of relapse of the lower anterior teeth after orthodontic treatment. Relapse is related with the initial orthodontic anomaly, pathology of surrounding tissues, patient's age and sex and compliance and the retention protocol applied. The options for the later are various. Permanent fixed retainers are considered of the most common ones and vastly vary based of composition. There are fixed retainers distinguished for their composition (SS, β-NiTi, fiber-reinforced composite retainers) or for their shape and dimensions (round or rectangular shape and single-strand or multi-strand respectively), and/or for the teeth they are placed on (canine and canine or canine to canine). Fixed retainers may require patient's cooperation , nevertheless debond failure rate varies between 0.1-53%.

The aim of this prospective randomized clinical study is to compare failure incidents and retention effect on lower anterior teeth after orthodontic finish between three different types of fixed retainers. There will be 3 arms studied in this research: a) single strand 0.016x0.022'' β-Ti canine to canine, b) 0.028'' SS canine to canine and c) 0.027'' multi-strand twistflex canine to canine. Variables such as repeatability of failures, and undesired tooth movements will be measured. Measurements will be repeated every 3 months after patient's recruitment in this study, for one year period (12 months in total). Intraoral scans will be collected during baseline (fixed retainer insertion) and after 12 months.