Chen Yi-Jane, Chen Yuan-Hou, Lin Li-Deh, Yao Chung-Chen Jane
Department of Orthodontics, School of Dentistry, College of Medicine, National Taiwan University, Taipei.
Int J Oral Maxillofac Implants. 2006 Mar-Apr;21(2):283-9.
Implant anchors such as miniscrews and miniplates have been loaded immediately for anchorage during orthodontic treatment. The purpose of this study was to measure the removal torque of immediately loaded miniscrews after clinical usage and to determine the possible factors associated with this value.
From 29 patients with malocclusions, 46 miniscrews were removed, and removal torque was measured with a torque gauge. Removal torque values were subjected to statistical analysis for possible association of different clinical characteristics.
The mean removal torque value was 1.10 kg x cm, and removal torques for 50% of the implants were greater than 0.89 kg x cm (8.7 N x cm). Removal torque values were significantly higher in the mandible than in the maxilla. The removal torques of 15-mm and 17-mm miniscrews were significantly higher than those of 13-mm miniscrews. Therefore, the site of implantation and miniscrew length were important factors associated with removal torque. However, there was no significant correlation between the removal torque value and age, gender, healing time, or time in function.
When miniscrews are used as anchorage for uprighting tipped molars, excessive torque in a counterclockwise direction may loosen them. From the measurements obtained in this investigation, miniscrews can sufficiently sustain an uprighting moment.
The removal torque values of the majority of miniscrews in this study population when loaded immediately as orthodontic anchorage were greater than 0.89 kg x cm, and this was sufficient for these implants to fulfill their purpose as anchors in 3-dimensional tooth movements.
正畸治疗期间，诸如微螺钉和微型钢板等种植支抗已被立即加载以用于锚固。本研究的目的是测量临床使用后立即加载的微螺钉的拆除扭矩，并确定与此值相关的可能因素。
从29例错牙合畸形患者中取出46颗微螺钉，并用扭矩计测量拆除扭矩。对拆除扭矩值进行统计分析，以探讨不同临床特征之间的可能关联。
平均拆除扭矩值为1.10 kg×cm，50%的种植体拆除扭矩大于0.89 kg×cm（8.7 N×cm）。下颌骨的拆除扭矩值显著高于上颌骨。15 mm和17 mm微螺钉的拆除扭矩显著高于13 mm微螺钉。因此，植入部位和微螺钉长度是与拆除扭矩相关的重要因素。然而，拆除扭矩值与年龄、性别、愈合时间或使用时间之间无显著相关性。
当微螺钉用作直立倾斜磨牙的支抗时，逆时针方向的过大扭矩可能会使其松动。从本研究获得的测量结果来看，微螺钉能够充分承受直立力矩。
本研究人群中，大多数微螺钉作为正畸支抗立即加载时的拆除扭矩值大于0.89 kg×cm，这足以使这些种植体在三维牙齿移动中发挥支抗作用。
