Savoldi F, Visconti L, Dalessandri D, Bonetti S, Tsoi J K H, Matinlinna J P, Paganelli C
Department of Orthodontics, Dental School, University of Brescia, Brescia, Italy.
Dental Materials Science, Faculty of Dentistry, Prince Philip Dental Hospital, The University of Hong Kong, Hong Kong.
Orthod Craniofac Res. 2017 May;20(2):119-125. doi: 10.1111/ocr.12156.
Of the variables used by in vitro studies of resistance to sliding (RS) in orthodontics, sliding velocity (SV) of the wire is often the one farthest from its clinical counterpart. We investigated whether velocity influences the RS at values approximating the orthodontic movement.
A SS self-ligating bracket with a NiTi clip was fixed onto a custom-made model. Different shaped orthodontic SS wires of four sizes and two types (round, 0.020″ and 0.022″; rectangular, 0.016″×0.022″ and 0.017″×0.025″) were tested using an Instron testing machine. Wires were pulled at four velocities (1×10 mm/s, 1×10 mm/s, 1×10 mm/s, 1×10 mm/s). Shapiro-Wilk test was used to evaluate the normal distribution of the data; two-way ANOVA was performed to compare means in the RS with wire characteristics and SV. Significance level was set at P<.05.
RS was higher for rectangular wires, and for those with larger diameters. Lower SV was associated with lower RS, with wire type and size having an interaction effect. The RS relatively to SV can be represented as: RS ∝ α[ln(SV)]+β, where α and β are constants.
At very low SV and low normal forces, SV influences the RS of SS archwires in orthodontic brackets, and the proportionality is logarithmic. Although respecting these parameters in vitro is challenging, quantitative evaluations of RS should be carried out at clinically relevant velocities if aiming at translational application in the clinical scenario.
在正畸学中，用于体外抗滑动（RS）研究的变量中，弓丝的滑动速度（SV）往往与临床实际情况相差最远。我们研究了在接近正畸移动的值时，速度是否会影响抗滑动性能。
将带有镍钛夹的不锈钢自结扎托槽固定在定制模型上。使用英斯特朗测试机对四种尺寸和两种类型（圆形，0.020英寸和0.022英寸；矩形，0.016英寸×0.022英寸和0.017英寸×0.025英寸）的不同形状正畸不锈钢弓丝进行测试。以四种速度（1×10毫米/秒、1×10毫米/秒、1×10毫米/秒、1×10毫米/秒）拉动弓丝。采用夏皮罗-威尔克检验评估数据的正态分布；进行双向方差分析以比较抗滑动性能与弓丝特性和滑动速度之间的均值。显著性水平设定为P<0.05。
矩形弓丝以及直径较大的弓丝的抗滑动性能更高。较低的滑动速度与较低的抗滑动性能相关，弓丝类型和尺寸具有交互作用。抗滑动性能与滑动速度的关系可表示为：RS ∝ α[ln(SV)]+β，其中α和β为常数。
在极低的滑动速度和低法向力下，滑动速度会影响正畸托槽中不锈钢弓丝的抗滑动性能，且比例关系为对数关系。尽管在体外遵循这些参数具有挑战性，但如果旨在在临床场景中进行转化应用，则应在临床相关速度下对抗滑动性能进行定量评估。
