Melbourne Dental School, Faculty of Medicine, Dentistry, and Health Sciences, University of Melbourne, Melbourne, Australia.
Division of Orthodontics, School of Dentistry, University of Geneva, Geneva, Switzerland.
Am J Orthod Dentofacial Orthop. 2022 Aug;162(2):152-161.e1. doi: 10.1016/j.ajodo.2022.03.014. Epub 2022 May 9.
This 2-arm parallel trial aimed to assess the number of failures of mandibular fixed retainers bonded with direct and indirect bonding methods at a 5-year follow-up and investigate the stability of intercanine and interpremolar distances.
Consecutive patients from the clinic of the University of Geneva (Switzerland) were randomly allocated to either direct or indirect bonding of a mandibular fixed retainer at the end of orthodontic treatment. Inclusion criteria included the presence of all mandibular incisors and canines; and the absence of active caries, restorations, fractures, or periodontal disease of these teeth. The patients were randomized in blocks of 4 using an online randomization service, with allocation concealment secured by contacting the sequence generator for assignment. Two and 5 years (T5) after bonding the retainers, the patients were recalled, and impressions were taken. The primary outcome was the 5-year survival of the mandibular fixed retainer bonded with both bonding methods. The secondary outcomes were the intercanine and interpremolar distances and the assessment of unexpected posttreatment changes (ie, changes in torque and/or rotations of the mandibular incisors and canines). Blinding was applicable for outcome assessment only. Kaplan-Meier curves were generated, and a Cox proportional hazard regression model was fitted for bonding type, age, and treatment. Linear mixed models were fitted to intercanine and interpremolar distances: bonding type, time, age, and treatment were modeled as outcomes.
Sixty-four patients were randomized in a 1:1 ratio. At T5, 6 patients without previous failure were lost to follow-up from each group. At T5, the fixed retainer was debonded in 14 patients (54%) for each group. The hazard ratio of indirect bonding to direct bonding was 1.09 (95% confidence interval, 0.26-4.60; P = 0.91); there was no statistically significant difference in survival between the groups. Regarding intercanine and interpremolar distances, none of the tested prognostic factors reached statistical significance. Unexpected posttreatment changes were observed in 6 failure-free patients, all bonded with the direct bonding method. Only 1 patient required debonding of the fixed retainer. No other serious harms were observed.
The 5-year survival rate for both direct and indirect bonding methods was 46%, without a statistically significant difference between bonding methods. Bonded retainers were effective in maintaining intercanine and interpremolar distances. Unexpected posttreatment changes were only observed with retainers bonded with the direct bonding method.
The trial was not registered.
The protocol was not published before trial commencement.
No funding or conflict of interest to be declared.
本项 2 臂平行试验旨在评估 5 年随访时直接和间接粘结下颌固定保持器的失败数量，并研究尖牙间和磨牙间距离的稳定性。
来自瑞士日内瓦大学（瑞士）诊所的连续患者在正畸治疗结束时被随机分配至直接或间接粘结下颌固定保持器。纳入标准包括所有下颌切牙和尖牙存在；并且这些牙齿无活跃龋坏、修复体、折裂或牙周病。患者以 4 例为一组进行随机分组，使用在线随机服务进行分组，通过联系序列发生器进行分配来确保分配隐藏。在粘结保持器后 2 年和 5 年（T5），召回患者并取印模。主要结局是两种粘结方法粘结的下颌固定保持器的 5 年存活率。次要结局是尖牙间和磨牙间距离以及意外治疗后变化的评估（即下颌切牙和尖牙转矩和/或旋转的变化）。仅对结局评估进行盲法。生成 Kaplan-Meier 曲线，并拟合 Cox 比例风险回归模型以评估粘结类型、年龄和治疗。使用线性混合模型拟合尖牙间和磨牙间距离：将粘结类型、时间、年龄和治疗作为结局进行拟合。
64 名患者以 1:1 的比例随机分组。在 T5 时，两组各有 6 名无先前失败的患者失访。在 T5 时，两组各有 14 名患者（54%）因各种原因拆除了固定保持器。间接粘结与直接粘结的危险比为 1.09（95%置信区间，0.26-4.60；P=0.91）；两组之间的存活率无统计学差异。关于尖牙间和磨牙间距离，未发现任何测试的预后因素具有统计学意义。6 名无失败的患者观察到意外的治疗后变化，所有患者均采用直接粘结法粘结。只有 1 名患者需要拆除固定保持器。未观察到其他严重的危害。
直接和间接粘结方法的 5 年存活率均为 46%，两种粘结方法之间无统计学差异。粘结保持器有效维持尖牙间和磨牙间距离。仅在直接粘结法粘结的保持器中观察到意外的治疗后变化。
试验未注册。
试验方案在试验开始前未公布。
无资金或利益冲突需要声明。
