Orthodontics Department, School of Dentistry, University of Genova, Genova, Italy.
Private Practice, Gallarate, Italy.
Orthod Craniofac Res. 2021 Aug;24(3):386-395. doi: 10.1111/ocr.12449. Epub 2020 Dec 14.
To compare torque recordings of immediately loaded orthodontic miniscrews between insertion time and different post-placement timepoints (2 weeks, 4 weeks and removal time, respectively).
Parallel trial with an allocation ratio of 1:1. Eligibility criteria were needs of fixed orthodontic treatment, no systemic disease and absence of using drugs altering bone metabolism.
Patients received miniscrews, 2.0 mm diameter and 10 mm length. All miniscrews underwent inter-radicular placement, and they were placed in the maxilla or in the mandible, palatally or buccally. No pre-drilling was performed. Miniscrews were loaded immediately after the insertion and were used for distalization, intrusion, extrusion, mesialization or indirect anchorage. Patients were randomly divided into three groups. For each patient, Maximum Insertion Torque (MIT) was evaluated at baseline. MIT was measured again after 2 weeks and after 4 weeks by tightening the screw a quarter of turn in Groups 1 and 2, respectively. At the end of the treatment, maximal removal torque was evaluated in Group 3. Torque variation with respect to insertion time was considered as the primary outcome. Baseline and longitudinal differences were tested using the linear mixed-effects (LME) model.
Forty seven patients and 74 miniscrews were followed up. An association existed between maximum insertion torque and the observation time. A torque decrease of 26.9% and 30% after 2 weeks was observed for mandibular and maxillary miniscrews, respectively. After 1 month, torque values were similar to the baseline records. The overall success rate was 79.7%. No serious harm was observed.
Maximum insertion torque undergoes a loss during the first 2 weeks, and its values may depend on the insertion site and the anchorage purpose. Removal torque value is almost the same as the initial torque after 1 month.
比较即刻加载正畸微螺钉在插入时间和不同放置时间点（分别为 2 周、4 周和取出时间）的扭矩记录。
1:1 分配比例的平行试验。入选标准为需要固定正畸治疗、无系统性疾病且未使用影响骨代谢的药物。
患者接受直径 2.0mm、长 10mm 的微螺钉。所有微螺钉均行根间放置，放置在上颌或下颌，腭侧或颊侧。未行预钻孔。微螺钉插入后立即加载，用于远移、压低、伸长、近中移动或间接锚固。患者随机分为三组。对于每位患者，在基线时评估最大插入扭矩（MIT）。第 1 组和第 2 组分别在第 2 周和第 4 周将螺钉拧紧四分之一圈，再次测量 MIT。治疗结束时，在第 3 组评估最大取出扭矩。将相对于插入时间的扭矩变化视为主要结局。使用线性混合效应（LME）模型检验基线和纵向差异。
47 名患者和 74 枚微螺钉得到随访。最大插入扭矩与观察时间之间存在关联。下颌和上颌微螺钉在第 2 周后观察到的扭矩分别下降了 26.9%和 30%。1 个月后，扭矩值与基线记录相似。总体成功率为 79.7%。未观察到严重危害。
最大插入扭矩在最初的 2 周内会损失，其值可能取决于插入部位和锚固目的。1 个月后取出扭矩值几乎与初始扭矩相同。
