微型种植体植入角度对骨界面应力峰值的影响

Influence of various implanting angles of micro-implants on peak stress in peri-implant surface

背景:近几年,微型种植体骨性支抗很大地扩展了正畸治疗的范围。种植体周围合适的应力分布有助于降低种植体脱落率。目的:分析微型种植体不同植入角度对骨界面应力峰值的影响。材料:颌骨CT扫描数据依据董玉英的扫描结果。参照德国Medicon公司生产的螺纹型微型种植体(纯钛,Aarhus Screw Syst1.6型)建立种植体模型。方法:应用颌骨CT扫描图象建立三维有限元模型,在下颌第1磨牙及第2双尖牙间分别以向30°,60°,90°,近中向30°,60°植入种植体,给以水平方向1.96N加载。主要观察指标:计算种植体周围骨界面最大第1主应力(拉应力),第3主应力(压应力)及Von-Mises应力蜂值和位移峰值,分析骨界面上的应力分布特点。结果:近中30°植入的拉应力、压应力及Von-Mises应力峰值都明显小于其他模型,种植体Von-Mises应力主要集中在种植体-骨界面的颈部,并在皮质层内迅速衰减,松质骨内的Von-Mises应力很小,靠近载荷的一侧受压,另一侧受拉。结论:植入角度对应力分布有明显影响。不同加载条件下应力集中部位均出现在种植体颈部。减少植入角度及减少载荷线与种植体长轴的夹角可以降低应力峰值。

BACKGROUND： Skeletal anchorage with mini-implants has greatly broadened the treatment possibilities in orthodontics over the last few years. To reduce implant failure rates, it is advisable to obtain adequate stress distribution around implant. OBJECTIVE： To evaluate the stress distribution on bone adjacent to a mini-implant under the different implanting direction and angle. MATERIALS： Jaw data were obtained from the scanning of Dong. Implant model was established according to screwed mini-implant, titanium, Aarhus Screw Syst 1.6, Medicon, Germany. METHODS： Three-dimensional finite element mandible model was established based on the CT scanning data. The mini-implant was implanted in the region between first mola and second premolar at 30°, 60° and 90° tilted mesiolly, and 30° and 60° tilted occlusally, respectively. In addition, a force load of 1.96 N was applied horizontally to the head of implant. MAIN OUTCOME MEASURES; The maximum first （pulling） and third （pressing） stress, minimum stress, Von-mises stress and maximum strain were calculated. RESULTS： The peak pulling and pressing stress and Von-mises stress at 30° tilted mesiolly were significantly smaller than the other models. The Von-mises stress mainly located at the neck of implant-bone interface, and decreased rapidly in the lamina cortex. The Von-mises stress in cancellous bone was small, and the side adjacent to loading was pressed, while the other side was pulled. CONCLUSION： Implanting angle shows much more influence on the stress distribution. The stress is primarily located at the neck of implant under different loads. Decreased implanting angle and reduced angle between load line and implant long axis can reduce peak stress.