Effect of different magnitudes of shock and vibrationto bone metabolism -using shock absorbing Ti-Ni alloy wire in in-vino experiment

目的：钛镍合金（Ti-Ni合金）具有超弹性和形状记忆特性，近年来，高阻尼合金也成为研究的热点。材料：采用0.016 × 0.022和0.018 × 0.025英寸正畸不锈钢丝及不同规格的超弹性钛镍合金丝进行实验。用激光应变传感器对实验用的铝合金正畸丝施加预定的冲击力，记录其阻尼性能的变化。结果：钛镍合金丝的阻尼曲线突然下降，而不锈钢丝的阻尼曲线逐渐下降。特别是比阻尼能力（SDC）表明，与不锈钢丝相比，超弹性Ti-Ni合金丝具有更高的阻尼能力。结论：根据钛镍合金丝的阻尼曲线和SDC值可知，超弹性钛镍合金丝具有较高的阻尼能力。研究还表明，阻尼能力在调节正畸治疗过程中外力（如咬合力）向其他牙齿的传递中发挥作用。

AIM : Titanium-nickel alloy (Ti-Ni alloy) is known to possess super-elasticity and shape memory properties, and the recent focus has also produced a high damping alloy. This study investigated the damping capacity of the super-elastic Ti-Ni alloy wire in comparison with traditional stainless steel wire.MATERIALS : Experiment was performed with both 0.016x0.022 and 0.018x0.025 inch orthodontic stainless steel wires and varied super-elastic Ti-Ni alloy wires.METHODS: Predetermined impact was imposed on experimental orthodontic wire with aluminum rod and the damping capacity phases of the wire were recorded by laser strain sensor. In the meantime, loading of 500gf or 1000gf was added onto the wire.RESULTS : The damping curve of the Ti-Ni alloy wire was found to decrease abruptly, while that of the stainless steel wire decreased gradually. It was especially shown from the specific damping capacity (SDC) that the super-elastic Ti-Ni alloy wire possessed elevated damping capacity compared with that of the stainless steel wire. SDC for stainless steel wire was 83-86%, while super-elastic Ti-Ni alloy wire was 90-98%.CONCLUSION : It has been obvious that super-elastic Ti-Ni alloy wire owns high damping capacity according to its damping curve and SDC. It also suggested that damping capacity played a role in modulating the transmission of external forces, such as occlusal forces, to other teeth during orthodontic treatment.