Private practice, New York, NY.
Assistant professor, Department of Orthodontics and Dentofacial Orthopedics, Tufts University School of Dental Medicine, Boston, Mass.
Am J Orthod Dentofacial Orthop. 2014 Aug;146(2):215-26. doi: 10.1016/j.ajodo.2014.05.017.
The manufacturing process for copper-nickel-titanium archwires is technique sensitive. The primary aim of this investigation was to examine the interlot consistency of the mechanical properties of copper-nickel-titanium wires from 2 manufacturers.
Wires of 2 sizes (0.016 and 0.016 × 0.022 in) and 3 advertised austenite finish temperatures (27°C, 35°C, and 40°C) from 2 manufacturers were tested for transition temperature ranges and force delivery using differential scanning calorimetry and the 3-point bend test, respectively. Variations of these properties were analyzed for statistical significance by calculating the F statistic for equality of variances for transition temperature and force delivery in each group of wires. All statistical analyses were performed at the 0.05 level of significance.
Statistically significant interlot variations in austenite finish were found for the 0.016 in/27°C (P = 0.041) and 0.016 × 0.022 in/35°C (P = 0.048) wire categories, and in austenite start for the 0.016 × 0.022 in/35°C wire category (P = 0.01). In addition, significant variations in force delivery were found between the 2 manufacturers for the 0.016 in/27°C (P = 0.002), 0.016 in/35.0°C (P = 0.049), and 0.016 × 0.022 in/35°C (P = 0.031) wires.
Orthodontic wires of the same material, dimension, and manufacturer but from different production lots do not always have similar mechanical properties. Clinicians should be aware that copper-nickel-titanium wires might not always deliver the expected force, even when they come from the same manufacturer, because of interlot variations in the performance of the material.
铜镍钛弓丝的制造工艺对技术要求很高。本研究的主要目的是检验来自 2 家制造商的铜镍钛丝的力学性能的批间一致性。
对来自 2 家制造商的 2 种尺寸（0.016 和 0.016×0.022 英寸）和 3 种公称奥氏体完成温度（27°C、35°C 和 40°C）的线材进行相变温度范围和力传递测试，分别使用差示扫描量热法和三点弯曲试验。通过计算相变温度和力传递在每组线材中的方差相等的 F 统计量，对这些性能的变异性进行统计显著性分析。所有统计分析均在 0.05 的显著性水平上进行。
发现 0.016 英寸/27°C（P=0.041）和 0.016×0.022 英寸/35°C（P=0.048）线材类别中的奥氏体完成温度以及 0.016×0.022 英寸/35°C 线材类别的奥氏体起始温度存在统计学显著的批间差异（P=0.01）。此外，在 0.016 英寸/27°C（P=0.002）、0.016 英寸/35.0°C（P=0.049）和 0.016×0.022 英寸/35°C 线材之间发现力传递在 2 家制造商之间存在显著差异。
同一材料、尺寸和制造商的正畸丝，但来自不同的生产批次，并不总是具有相似的机械性能。临床医生应该意识到，即使来自同一制造商，由于材料性能的批间差异，铜镍钛丝也可能无法始终提供预期的力。
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