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Abstract：
OBJECTIVE: To examine the effect of clinical use on both force retention and the deactivation of closed-coil nickel-titanium (NiTi) springs in a 16-week trial.
METHODS: The force-activation curves for NiTi springs were determined before and after clinical use. The rate of tooth movement and maximum force (MF), hysteresis between activation and deactivation, and mean force of the deactivation plateau (MDF) were examined and correlated as a function of 4, 8, 12 and 16 weeks of clinical use. To recover the force properties, the springs were heat treated at 100°C and the results were compared with the preceding data.
RESULTS: A total of 36 springs were analysed. The MF loss after use was 60, 74, 55, and 48 g for the 4-, 8-, 12- and 16-week springs, respectively. Heat treating had little effect on the MF. Clinical use lowered hysteresis by a mean of 180 g*mm compared with the pre-clinical use data, and heat treating increased the hysteresis by a mean of 59 g*mm above the post clinic testing data. The MDF was nominally 100 g less than the MF. Teeth moved approximately 1 mm/month, independent of the force loss.
CONCLUSIONS: The loss of MF and the lowering of the MDF was not time dependent. Heat treating can partially recover the mechanical properties of the used springs.
METHODS: The force-activation curves for NiTi springs were determined before and after clinical use. The rate of tooth movement and maximum force (MF), hysteresis between activation and deactivation, and mean force of the deactivation plateau (MDF) were examined and correlated as a function of 4, 8, 12 and 16 weeks of clinical use. To recover the force properties, the springs were heat treated at 100°C and the results were compared with the preceding data.
RESULTS: A total of 36 springs were analysed. The MF loss after use was 60, 74, 55, and 48 g for the 4-, 8-, 12- and 16-week springs, respectively. Heat treating had little effect on the MF. Clinical use lowered hysteresis by a mean of 180 g*mm compared with the pre-clinical use data, and heat treating increased the hysteresis by a mean of 59 g*mm above the post clinic testing data. The MDF was nominally 100 g less than the MF. Teeth moved approximately 1 mm/month, independent of the force loss.
CONCLUSIONS: The loss of MF and the lowering of the MDF was not time dependent. Heat treating can partially recover the mechanical properties of the used springs.
摘要：
目的：在一项为期16周的试验中，研究临床使用对闭式线圈镍钛（NiTi）弹簧的力保持和失活的影响。
方法：在临床使用前后测定NiTi弹簧的力激活曲线。牙齿移动速率和最大力（MF），激活和去激活之间的滞后，检查了失活平台（MDF）的平均力，并将其与临床使用4、8、12和16周的功能相关联。要恢复力属性，在100°C下对弹簧进行热处理，并将结果与先前的数据进行比较。
结果：共分析了36个弹簧。对于4-，使用后的MF损失为60、74、55和48g，8-,12周和16周的弹簧，分别。热处理对MF影响不大。与临床前使用数据相比，临床使用将滞后现象平均降低了180g*mm，和热处理使滞后现象比临床后测试数据平均增加了59g*mm。MDF名义上比MF少100g。牙齿移动约1毫米/月，独立于力的损失。
结论：MF的损失和MDF的降低不是时间依赖性的。热处理可以部分地恢复所使用的弹簧的机械性能。
方法：在临床使用前后测定NiTi弹簧的力激活曲线。牙齿移动速率和最大力（MF），激活和去激活之间的滞后，检查了失活平台（MDF）的平均力，并将其与临床使用4、8、12和16周的功能相关联。要恢复力属性，在100°C下对弹簧进行热处理，并将结果与先前的数据进行比较。
结果：共分析了36个弹簧。对于4-，使用后的MF损失为60、74、55和48g，8-,12周和16周的弹簧，分别。热处理对MF影响不大。与临床前使用数据相比，临床使用将滞后现象平均降低了180g*mm，和热处理使滞后现象比临床后测试数据平均增加了59g*mm。MDF名义上比MF少100g。牙齿移动约1毫米/月，独立于力的损失。
结论：MF的损失和MDF的降低不是时间依赖性的。热处理可以部分地恢复所使用的弹簧的机械性能。
