Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
Am J Orthod Dentofacial Orthop. 2010 Jan;137(1):73-9. doi: 10.1016/j.ajodo.2008.03.024.
In this study, we aimed to determine the effect of bone mineral density (BMD), cortical bone thickness (CBT), screw position, and screw design on the stability of miniscrews.
Ninety-six miniscrews of both cylindrical and tapered types were placed in 6 beagle dogs. The BMD and CBT were measured by computerized tomography and correlated with the placement and removal torque and mobility. A regression equation to predict the placement torque was calculated based on BMD, CBT, screw type, and screw position.
The placement torque showed a positive correlation in the order of removal torque (0.66), BMD of the cortical bone (0.58), and CBT (0.48). Placement and removal torque values were significantly higher in the mandible compared with the maxilla. Tapered miniscrews had higher placement torque than did the cylindrical type (P <0.001). However, the removal torque was similar in both groups. Placement torque was affected by screw position, screw type, and BMD of cortical bone, in that order.
BMD of cortical bone, screw type, and screw position significantly influence the primary stability of miniscrews.
本研究旨在确定骨密度（BMD）、皮质骨厚度（CBT）、螺钉位置和螺钉设计对微螺钉稳定性的影响。
将 96 枚圆柱形和锥形微螺钉分别植入 6 只比格犬体内。通过计算机断层扫描测量 BMD 和 CBT，并将其与植入和去除扭矩及微动性相关联。基于 BMD、CBT、螺钉类型和螺钉位置，计算出预测植入扭矩的回归方程。
植入扭矩与去除扭矩（0.66）、皮质骨 BMD（0.58）和 CBT（0.48）呈正相关。与上颌骨相比，下颌骨的植入和去除扭矩值明显更高。与圆柱形相比，锥形微螺钉的植入扭矩更高（P<0.001）。然而，两组的去除扭矩相似。植入扭矩受螺钉位置、螺钉类型和皮质骨 BMD 的影响，按此顺序排列。
皮质骨 BMD、螺钉类型和螺钉位置显著影响微螺钉的初始稳定性。
