Morton D, Stanford C M, Aquilino S A
Department of Prosthodontics, College of Dentistry, University of Florida, Gainesville, USA.
J Prosthet Dent. 1998 Jul;80(1):46-51. doi: 10.1016/s0022-3913(98)70090-3.
Factors that affect transmission of strain from prostheses to bone may affect the long-term success of loaded implants. Current in vitro models are theoretically predictive (finite element modeling) or facsimile (photoelastic) in nature. A more clinically relevant in vitro model for strain evaluation should be investigated.
This study attempted: (1) to validate a human cadaver bone model for vitro measurement of cortical bone strain, and (2) to evaluate the effect on cortical strain measurements of a resilient plastic component incorporated within a titanium implant in response to variable dynamic loading.
Two IMZ (Interpore International) abutment alternatives were used: the titanium Abutment Complete and the polyoxymethylene Intra-mobile Element. The model system consisted of two implants placed in unfixed human cadaver ulna bone to simulate an implant bound edentulous region. Four biaxial rosette strain gauges simultaneously recorded cortical bone strain immediately mesial and distal to each implant. During experimentation a simulated prosthetic framework supported by either titanium or polyoxymethylene abutments was dynamically loaded 6 min from the terminal abutment along a cantilever extension. Cyclic nominal peak loads were applied with a materials testing machine at 20-N intervals from 20 to 200 N at a crosshead speed of 5 mm/minute. The protocol allowed frequency of load application to vary. A Newtonian linear correlation (r2 > or = 0.98) between load application and strain output was determined for each gauge position except for the terminal gauge located opposite the cantilever.
Cortical strains recorded were within reported physiologic ranges involved in bone modeling and remodeling. Further, the polyoxymethylene abutment components did not result in reduction of peak microstrain at any gauge position. The Intra-mobile Element abutments, however, did increase the time required to complete 10 loading cycles when compared with the titanium Abutment Complete abutments for the crosshead speed and ultimate loads evaluated.
Results indicate the cadaver bone behaved in an elastic manner within the load range evaluated, and as such represents a viable in vitro experimental model. Under these conditions, polyoxymethylene abutment components do not affect measurable bone strain in response to variable loading when compared with titanium.
影响应变从假体传递至骨的因素可能会影响负重植入物的长期成功率。当前的体外模型在本质上要么是理论预测性的（有限元建模），要么是模拟性的（光弹性）。应该研究一种更具临床相关性的用于应变评估的体外模型。
本研究试图：（1）验证一种用于体外测量皮质骨应变的人体尸体骨模型，以及（2）评估钛植入物中包含的弹性塑料部件在可变动态载荷作用下对皮质应变测量的影响。
使用了两种IMZ（Interpore International）基台替代品：钛制完整基台和聚甲醛制活动内元件。模型系统由两枚植入未固定的人体尸体尺骨中的植入物组成，以模拟种植体支持的无牙区。四个双轴应变片式应变计同时记录每枚植入物近中和远中紧邻处皮质骨的应变。在实验过程中，由钛制或聚甲醛制基台支撑的模拟修复体框架沿着悬臂延伸部分从末端基台开始动态加载6分钟。使用材料试验机以5毫米/分钟的十字头速度在20至200牛的范围内以20牛的间隔施加循环名义峰值载荷。该方案允许载荷施加频率变化。除了位于悬臂相对位置的末端应变计外，为每个应变计位置确定了载荷施加与应变输出之间的牛顿线性相关性（r2≥0.98）。
记录到的皮质应变处于报道的参与骨塑形和重塑的生理范围内。此外，聚甲醛制基台部件在任何应变计位置均未导致峰值微应变降低。然而，对于所评估的十字头速度和极限载荷，与钛制完整基台相比，活动内元件基台确实增加了完成10次加载循环所需的时间。
结果表明，在评估的载荷范围内尸体骨表现为弹性行为，因此代表了一种可行的体外实验模型。在这些条件下，与钛相比，聚甲醛制基台部件在可变载荷作用下不会影响可测量的骨应变。
