Comparison Physiological Tooth Mobility and Retention Success in Patients Using Different Retainers

The purpose of this prospective clinical study is to comparatively evaluate the long-term stability of teeth, physiological tooth mobility, and effects on periodontal tissues of three different fixed lingual retainer materials used to prevent relapse following orthodontic treatment. A total of 80 participants whose orthodontic treatment is completed will be randomly and equally distributed into four groups as one control (n=20) and three study groups (n=20 each): Group 1 will receive CAD/CAM-fabricated 0.016-inch Nitinol wire; Group 2 will receive manually bent multi- strand 0.0215-inch stainless steel wire; and Group 3 will receive 0.030-inch stainless steel chain retainers. Control group will be 20 samples. Clinical and radiographic measurements will be performed at the day of debonding (T0) and at a 6-month follow-up (T1). Physiological tooth mobility will be measured objectively using a Periotest device. Relapse amounts will be assessed by superimposing intraoral digital scans via Nemocast software using Little's Irregularity Index, and the 6-month failure/breakage rates of the retainers will be recorded. The null hypothesis states that there is no statistically significant difference among the different retainer materials regarding tooth stability, relapse, and physiological mobility.

Inclusion Criteria: 1. Patients who have undergone fixed orthodontic treatment at the Department of Orthodontics, Faculty of Dentistry, Marmara University, and whose treatment is nearing completion 2. Patients whose treatment duration is between 2 and 3 years 3. Patients with healthy periodontal tissue (plaque index and gingival index \