Leung Michael T C, Rabie A Bakr M, Wong Ricky W K
Orthodontics, Faculty of Dentistry, The University of Hong Kong, SAR, China.
Eur J Orthod. 2008 Oct;30(5):483-9. doi: 10.1093/ejo/cjm124. Epub 2008 May 4.
The aim of this study was to examine the primary stability of connected mini-implants and miniplates. Three different skeletal anchorage systems were investigated: (1) two 1.5 mm diameter cylindrical mini-implants connected with a 0.021 x 0.025 inch stainless steel (SS) wire, (2) two 1.6 mm diameter tapered mini-implants connected with a 0.021 x 0.025 inch SS wire, and (3) two 2.0 mm diameter cylindrical mini-implants connected by a titanium locking miniplate. Fifteen standardized bovine bone specimens were prepared, five specimens for each experimental group. The connected mini-implants were fixed on the bone specimens. The systems underwent uniaxial pull-out tests at the midpoint of the connecting wire or miniplate using a mechanical testing machine. One-way analysis of variance was used to determine the difference of the pull-out test results between the groups. Both the titanium miniplate and SS wire connection systems showed severe deformation at the screw head, which broke before the mini-implants failed. The 2.0 mm miniplate system showed the highest pull-out force (529 N) compared with the other two wire connection systems (P < 0.001). The 2.0 mm system was also stiffer than the 1.6 and 1.5 mm systems (P < 0.001). The yield force of the 2.0 mm miniplate (153 N) was significantly higher than the 1.5 mm (88 N) and 1.6 mm (76 N) systems (P < 0.001). This in vitro study demonstrated that the connection of two mini-implants with a miniplate resulted in higher pull-out force, stiffness, and yield force to resist pulling force and deformation. Such a set-up could thus provide a stable system for orthodontic skeletal anchorage.
本研究的目的是检测连接式微型种植体和微型钛板的初始稳定性。研究了三种不同的骨锚固系统：（1）两根直径1.5 mm的圆柱形微型种植体通过一根0.021×0.025英寸的不锈钢（SS）丝连接；（2）两根直径1.6 mm的锥形微型种植体通过一根0.021×0.025英寸的SS丝连接；（3）两根直径2.0 mm的圆柱形微型种植体通过一个钛制锁定微型钛板连接。制备了15个标准化牛骨标本，每个实验组5个标本。将连接式微型种植体固定在骨标本上。使用机械试验机在连接线或微型钛板的中点对这些系统进行单轴拔出试验。采用单因素方差分析来确定各组拔出试验结果的差异。钛制微型钛板和SS丝连接系统在螺钉头部均出现严重变形，在微型种植体失效之前就断裂了。与其他两种丝连接系统相比，2.0 mm微型钛板系统显示出最高的拔出力（529 N）（P < 0.001）。2.0 mm系统也比1.6 mm和1.5 mm系统更硬（P < 0.001）。2.0 mm微型钛板的屈服力（153 N）显著高于1.5 mm（88 N）和1.6 mm（76 N）系统（P < 0.001）。这项体外研究表明，用微型钛板连接两个微型种植体可产生更高的拔出力、刚度和屈服力，以抵抗拉力和变形。这样的设置因此可以为正畸骨锚固提供一个稳定的系统。
