Oral Technology, School of Dentistry, University of Bonn, Germany.
Eur J Orthod. 2011 Aug;33(4):381-7. doi: 10.1093/ejo/cjq088. Epub 2010 Nov 9.
Mini-implants are widely utilized as anchorage units in orthodontic treatment. Nevertheless, there are factors that interfere with their clinical performance. The aim of this study was to examine the impact of length and diameter on the primary stability of two different types of orthodontic mini-implants loaded with two force levels. A total of 90 self-drilling mini-implants were inserted in bovine ribs in vitro, 62 of which were used in data analysis. The mini-implants were of two types, Aarhus (n=29) and Lomas (n=33), of two lengths (7 and 9 mm, n=26 and n=28, respectively), and of two diameters (1.5 and 2 mm, Lomas only, n=6 and n=8, respectively). A closed nickel-titanium (NiTi) coil spring was attached to each mini-implant. Half of the preparations were loaded with a low force of 0.5 N and the other half with a force of 2.5 N. Mini-implant deflections during force application were non-invasively registered using a three-dimensional (3D) laser-optical system. The results were analysed with analysis of variance for the effects of implant type, implant length, and force level, and with a t-test for the study of the effect of diameter in two different diameter variants of the same (Lomas) implant. In the low-force group, implant displacements were not statistically significant difference according to the investigated parameters. In the high-force group, the 9 mm long mini-implants displaced significantly less (10.5±7.5 μm) than the 7 mm long (22.3±11.3 μm, P<0.01) and the 2 mm wide significantly less (8.8±2.2 μm) than the 1.5 mm implants (21.9±1.5 μm, P<0.001). The force level at which significance occurred was 1 N. The rotation of the Lomas mini-implants in the form of tipping was significantly higher than that of the Aarhus mini-implants at all force levels. Implant length and diameter become statistically significant influencing parameters on implant stability only when a high force level is applied.
微型种植体被广泛用作正畸治疗的锚固单位。然而，有一些因素会影响其临床性能。本研究旨在探讨两种不同类型的正畸微型种植体在两种力水平下的长度和直径对其初始稳定性的影响。总共在牛肋骨上体外植入了 90 个自攻微型种植体，其中 62 个用于数据分析。微型种植体分为两种类型，奥胡斯（Aarhus）（n=29）和洛马斯（Lomas）（n=33），两种长度（分别为 7 毫米和 9 毫米，n=26 和 n=28），两种直径（Lomas 仅为 1.5 毫米和 2 毫米，n=6 和 n=8）。每个微型种植体上都附有一个闭合的镍钛（NiTi）螺旋弹簧。一半的准备工作以 0.5 N 的低力加载，另一半以 2.5 N 的力加载。微型种植体在力作用下的挠度使用三维（3D）激光光学系统进行非侵入式记录。使用方差分析研究了种植体类型、种植体长度和力水平的影响，并使用 t 检验研究了同一（洛马斯）种植体两种不同直径变体的直径的影响。在低力组中，根据研究的参数，种植体位移没有统计学上的显著差异。在高力组中，9 毫米长的微型种植体的位移明显小于 7 毫米长的（10.5±7.5μm）（22.3±11.3μm，P<0.01），2 毫米宽的微型种植体的位移明显小于 1.5 毫米宽的（8.8±2.2μm）（21.9±1.5μm，P<0.001）。发生显著性的力水平为 1N。在所有力水平下，洛马斯微型种植体的倾斜形式的旋转都明显高于奥胡斯微型种植体。只有当施加高力水平时，种植体长度和直径才成为影响种植体稳定性的统计学显著参数。
