Department of Orthodontics, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
Department of Oral Surgery and Implantology, Carolinum, Goethe University, Frankfurt, Germany.
Clin Oral Implants Res. 2019 Dec;30(12):1179-1189. doi: 10.1111/clr.13531. Epub 2019 Sep 26.
Whereas stationary stability of implants has been postulated for decades, recent studies suggested a phenomenon termed implant migration. This describes a change in position of implants as a reaction to applied forces. The present study aims at employing image registration of in vivo micro-CT scans from different time points and to assess (a) if migration of continuously loaded implants is possible and (b) migration correlates with the force magnitude.
Two customized machined implants were placed in the dorsal portion of caudal vertebrae in n = 61 rats and exposed to standardized forces (0.5 N, 1.0 N, and 1.5 N) applied through a flat nickel-titanium contraction spring, or no forces (control). Micro-CT scans were performed at 0, 1, 2, 4, 6, and 8 weeks after surgery. The baseline image was registered with the forthcoming scans. Implant migration was measured as the Euclidean distance between implant tips. Bone remodeling was assessed between the baseline and the forthcoming scans.
The findings confirmed a positional change of the implants at 2 and 8 weeks of healing, and a linear association between applied force and velocity of movement (anterior implant: χ = 12.12, df = 3, and p = .007 and posterior implant: χ = 20.35, df = 3, and p < .001). Bone apposition was observed around the implants and accompanied by formation of load-bearing trabeculae and a general cortical thickening close and also distant to the implants.
The present analysis confirmed that implants can migrate in bone. The applied forces seemed to stimulate bone thickening, which could explain why implants migrate without affecting stability.
尽管几十年来一直假设植入物具有静止稳定性，但最近的研究表明存在一种称为植入物迁移的现象。这描述了植入物作为对施加力的反应而改变位置的现象。本研究旨在采用来自不同时间点的体内微 CT 扫描的图像配准，并评估(a)连续加载的植入物是否可能发生迁移，以及(b)迁移与力的大小是否相关。
将两个定制加工的植入物放置在 61 只大鼠尾部背侧的椎骨中，并通过扁平的镍钛收缩弹簧施加标准化的力（0.5N、1.0N 和 1.5N），或不施加力（对照）。在手术后 0、1、2、4、6 和 8 周进行微 CT 扫描。将基线图像与随后的扫描进行配准。测量植入物尖端之间的欧几里得距离来表示植入物的迁移。在基线和随后的扫描之间评估骨重塑。
研究结果证实了在愈合的 2 周和 8 周时植入物位置发生了变化，并且施加的力与运动速度之间存在线性关联（前植入物：χ²=12.12，df=3，p=0.007，后植入物：χ²=20.35，df=3，p<.001）。在植入物周围观察到骨附着，并伴随着承重小梁的形成以及靠近和远离植入物的皮质普遍增厚。
本分析证实植入物可以在骨中迁移。施加的力似乎刺激了骨增厚，这可以解释为什么植入物迁移而不影响稳定性。
