Department of Biomedicine, School of Dentistry, University of Trieste, Italy.
Eur J Orthod. 2012 Feb;34(1):1-9. doi: 10.1093/ejo/cjq093. Epub 2010 Nov 1.
The present comparative study aimed to evaluate the surface corrosion and fracture resistance of two commercially available nickel-titanium (NiTi)-based archwires, as induced by a combination of fluoride, pH, and thermocycling. One hundred and ten rectangular section NiTi-based archwires were used, 55 of each of the following: thermally activated Thermaloy® and super-elastic NeoSentalloy® 100 g. Each of these was divided into five equal subgroups. One of these five subgroups did not undergo any treatment and served as the control, while the other four were subjected to 30 days of incubation at 37°C under fluoridated artificial saliva (FS) at 1500 ppm fluoride treatment alone (two subgroups) or combined with a session of thermocycling (FS + Th) treatment at the end of incubation (two subgroups). Within each of the Thermaloy® and NeoSentalloy® groups, the FS and FS + Th treatments were performed under two different pH conditions: 5.5 and 3.5 (each with one subgroup per treatment). Analysis of the surface topography and tensile properties by means of scanning electron microscopy (a single sample per subgroup), atomic force microscopy, and a universal testing machine for ultimate tensile strength were carried out once in each of the control subgroups or immediately after the treatments in the other subgroups for 10 of the archwires. Non-parametric tests were used in the data analysis. Significant effects in terms of surface corrosion, but not fracture resistance, were seen mainly for the Thermaloy® group at the lowest pH, with no effects of Th irrespective of the group or pH condition. Different NiTi-based archwires can have different corrosion resistance, even though the effects of surface corrosion and fracture resistance appear not to be significant in clinical situations, especially considering that thermocycling had no effect on these parameters.
本比较研究旨在评估两种市售镍钛（NiTi）基弓丝在氟化物、pH 值和热循环联合作用下的表面腐蚀和抗断裂性能。使用了 110 根矩形截面 NiTi 基弓丝，每种弓丝 55 根，分别为：热激活 Thermaloy®和超弹性 NeoSentalloy® 100 g。这些弓丝分为五等份，其中一份未经任何处理作为对照组，而其他四份则在 37°C 下用含氟人工唾液（FS）孵育 30 天，单独（两组）或在孵育结束时进行热循环（FS + Th）治疗（两组）。在 Thermaloy®和 NeoSentalloy®组内，FS 和 FS + Th 治疗在两种不同的 pH 值条件下进行：5.5 和 3.5（每组各有一个亚组）。用扫描电子显微镜（每组一个样本）、原子力显微镜和万能试验机对表面形貌和拉伸性能进行分析，以测量极限拉伸强度。每个对照组只进行一次分析，其他亚组则在处理后立即进行分析，共对 10 根弓丝进行了分析。数据分析采用非参数检验。主要在 pH 值最低的 Thermaloy®组中观察到表面腐蚀的显著影响，但在考虑到热循环对这些参数没有影响的情况下，断裂阻力没有显著影响，无论组或 pH 值条件如何。即使在临床情况下，表面腐蚀和抗断裂性能的影响似乎不显著，但不同的 NiTi 基弓丝可能具有不同的耐腐蚀性。
