Kapila S, Haugen J W, Watanabe L G
Department of Growth and Development, School of Dentistry, University of California San Francisco.
Am J Orthod Dentofacial Orthop. 1992 Aug;102(2):120-6. doi: 10.1016/0889-5406(92)70023-4.
The desirable mechanical properties of nickel-titanium alloy wires and their relatively high cost has prompted many clinicians to recycle these wires. Clinical recycling exposes the wires to several weeks or months of mechanical stresses and elements of the oral environment, as well as sterilization between uses. In a previous study it was noted that clinical recycling combined with cold sterilization alters the load-deflection characteristics and surface topography of nickel-titanium wires. Whether similar changes in mechanical properties occur in wires subjected to repeated clinical use and dry heat sterilization is not yet clear. The purpose of this investigation was to determine the effects of in vivo recycling interposed by dry heat sterilization (together referred to as clinical recycling, CR) on the load-deflection characteristics of nickel-titanium alloy wires. To differentiate the effects of dry heat sterilization (DHS) from those of CR on the behavior of these wires, a series of wires were also subjected to DHS only. Two types of nickel-titanium wires, namely Nitinol and NiTi were subjected to a three-point bending test in an as-received condition (T0), after one cycle (T1), and two cycles (T2) of DHS or CR. Ten wires comprised each subsample. Statistical analyses were done by one-factor repeated measures analysis of variance and Scheffe F test. Both DHS alone, as well as CR, produced significant changes in the loading and unloading characteristics of Nitinol and NiTi wires. However, the changes in the load-deflection characteristics of these wires after DHS only were relatively small, and the clinical significance of these changes is open to question.(ABSTRACT TRUNCATED AT 250 WORDS)
镍钛合金丝理想的机械性能及其相对较高的成本促使许多临床医生对这些丝进行再利用。临床再利用使这些丝暴露于数周或数月的机械应力、口腔环境因素以及使用期间的消毒过程中。在之前的一项研究中发现，临床再利用结合冷消毒会改变镍钛丝的载荷-挠度特性和表面形貌。对于经过反复临床使用和干热消毒的丝是否会出现类似的机械性能变化尚不清楚。本研究的目的是确定干热消毒（统称为临床再利用，CR）介入的体内再利用对镍钛合金丝载荷-挠度特性的影响。为了区分干热消毒（DHS）和CR对这些丝性能的影响，还对一系列丝仅进行了DHS处理。两种镍钛丝，即镍钛诺和NiTi，在接收状态（T0）、经过一个循环（T1）和两个循环（T2）的DHS或CR处理后进行三点弯曲试验。每个子样本包含10根丝。通过单因素重复测量方差分析和谢费F检验进行统计分析。单独的DHS以及CR均使镍钛诺和NiTi丝的加载和卸载特性产生了显著变化。然而，仅经过DHS处理后这些丝的载荷-挠度特性变化相对较小，这些变化的临床意义尚存在疑问。（摘要截选于250词）
