A non-invasive method has recently been introduced to remove osseo-integrated palatal implants by using the implantation ratchet which is designed to screw in or unscrew the implants. Although a proof of concept has been published, the torque involved to successfully explant have not been investigated so far. The aim of this study was to assess the removal torque required to explant osseo-integrated and orthodontically utilized palatal implants, and to identify potentially influencing variables. Thirty-one consecutive patients (15 females, 16 males; mean age 24.1 ±7.4 years) with fully osseo-integrated and previously orthodontically loaded palatal implants (Orthosystem®: diameter 4.1mm/length 4.2mm/sandblasted with large grits (SLA) surface) were randomly assigned to either clockwise or counter-clockwise non-invasive explantation. The respective explantation tool with an electric torque control was placed on the abutment connection of the implant and secured by an occlusal screw. The primary outcome studied was maximal removal torque (MRT) needed to detach the implant from its socket which was recorded individually together with other potentially influencing secondary outcomes (gender, age, orthodontic loading time, use of local anaesthetics). Student’s t-test was used to contrast MRT difference for the gender, type of suprastructure, use of local anaesthetics, and rotational direction. Spearman correlations was used to investigate associations between MRT and patient’s age or duration loading time. Average MRT (148.6 ± 63.2N/cm) using ratchet as a non-invasive removal method of palatal implant was considered safe. The triangular head fractured of palatal implant at a torque level of 300.1 Ncm. Significantly higher explantation were recorded for male patients compared to female patients (182.0 ± 63.0 Ncm vs 112.8 ± 40.8 Ncm; P=0.001). On the other side, the mean removal torque for palatal removal in clockwise direction was non-significantly different (158.3 ± 58.6 Ncm) compared to counter-clockwise direction (139.4 ± 67.9 Ncm). Neither patient’s age (p=0.324) nor loading time (p=0.214) were significantly correlated with removal torque values. Pertinent literature on this subject is practically non-existent, as orthodontics is presumably the only discipline where implant removal represents a treatment success. Mean MRT for successful palatal implant removal was 148.6±63.2Ncm, but a large spectrum was observed (minimum 31.5Ncm, maximum 272.8Ncm). This obvious heterogeneity underlines the importance to investigate possible influencing factors. The safe and simple non-invasive method for palatal implant removal necessitates moderate, but not high torque MRTs, independently of the torque direction. The necessary MRT seems clearly influenced by gender, but less so by patient’s age or loading time.

中文翻译：

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影响正畸支抗用腭种植体移除扭矩的因素

最近引入了一种非侵入性方法，通过使用旨在拧入或拧下植入物的植入棘轮来移除骨整合性腭部植入物。尽管已经发表了概念证明，但到目前为止还没有研究成功外植所涉及的扭矩。本研究的目的是评估外植骨整合和正畸使用的腭部种植体所需的移除扭矩，并确定潜在的影响变量。连续 31 名患者（15 名女性，16 名男性；平均年龄 24.1 ±7.4 岁）具有完全骨整合和先前正畸加载的腭部种植体（Orthosystem®：直径 4.1 毫米/长度 4.2 毫米/喷砂大砂粒 (SLA) 表面） ) 被随机分配到顺时针或逆时针非侵入性外植。将带有电动扭矩控制的相应拔除工具放置在种植体的基台连接处，并通过咬合螺钉固定。研究的主要结果是将种植体与牙槽窝分离所需的最大移除扭矩 (MRT)，该扭矩与其他可能影响次要结果（性别、年龄、正畸加载时间、局部麻醉剂的使用）一起单独记录。学生 t 检验用于比较 MRT 在性别、上部结构类型、局部麻醉剂的使用和旋转方向方面的差异。Spearman 相关性用于研究 MRT 与患者年龄或持续负荷时间之间的关联。使用棘轮作为腭植入物的非侵入性移除方法的平均 MRT (148.6 ± 63.2N/cm) 被认为是安全的。腭植入物的三角头在 300.1 Ncm 的扭矩水平下断裂。与女性患者相比，男性患者的外植率明显更高（182.0 ± 63.0 Ncm vs 112.8 ± 40.8 Ncm；P=0.001）。另一方面，与逆时针方向 (139.4 ± 67.9 Ncm) 相比，顺时针方向上腭移除的平均移除扭矩没有显着差异 (158.3 ± 58.6 Ncm)。患者的年龄 (p=0.324) 和加载时间 (p=0.214) 均与移除扭矩值没有显着相关性。关于这个主题的相关文献实际上是不存在的，因为正畸可能是唯一一个种植体移除代表治疗成功的学科。成功去除腭部种植体的平均 MRT 为 148.6±63.2Ncm，但观察到的范围很大（最小 31.5Ncm，最大 272.8Ncm）。这种明显的异质性强调了调查可能的影响因素的重要性。安全和简单的非侵入性腭部植入物移除方法需要中等但不是高扭矩的 MRT，与扭矩方向无关。必要的 MRT 似乎明显受性别影响，但受患者年龄或加载时间的影响较小。