Department of Biomedical Engineering, Technical Federal University of Parana, Brazil.
Eur J Orthod. 2013 Aug;35(4):414-20. doi: 10.1093/ejo/cjr062. Epub 2011 Jul 21.
The purpose of this study was to examine the mechanical behaviour of orthodontic delta retraction springs. Twelve titanium-molybdenum (0.016 × 0.022 inch) delta loops were studied. The springs were analysed by means of the finite element (FE) method and experimental tests using a platform transducer. Each spring was activated from 0 to 6 mm. Statistical analysis of the data was carried out by one-way analysis of variance and Games-Howell parametric multiple comparison test for heterogeneous variances. FE analysis revealed that the stress level varied from 277 to 1273 MPa. At 6.1 mm (773 MPa), the springs were still in the elastic range. Force levels varied from 0.1 N (10 g) to 2.2 N (224 g) at 1.4-8.1 mm of activation for the numerical study and from 0.44 N (45 g) at 1 mm to 2.02 N (206 g) at 6 mm of activation in the experimental study. The spring rate was within the levels that are appropriate for clinical use (34 g/mm). Vertical forces (Fy) showed constancy and were of low magnitude. The anterior moment/force ratio from the experimental tests was 14 at 3 mm of activation decreasing to 10.7, 8.7, and 7.2, for 4, 5, and 6 mm of activation, respectively. The springs could be activated up to 7 mm without exceeding the elastic limit.
本研究旨在探讨正畸 delta 回拉弹簧的力学行为。研究了 12 个钛钼（0.016×0.022 英寸）delta 环。采用有限元（FE）方法和平台换能器进行实验测试对弹簧进行了分析。每个弹簧从 0 激活至 6mm。采用单因素方差分析和 Games-Howell 参数多重比较检验对数据进行了统计学分析。FE 分析表明，应力水平从 277 至 1273MPa 不等。在 6.1mm（773MPa）处，弹簧仍处于弹性范围内。数值研究中，在 1.4-8.1mm 的激活范围内，力水平从 0.1N（10g）变化至 2.2N（224g），而在实验研究中，在 1mm 处为 0.44N（45g），在 6mm 处为 2.02N（206g）。弹簧的弹性系数在临床应用的适宜范围内（34g/mm）。垂直力（Fy）表现出恒定且幅度较小。从实验测试中得出的前力矩/力比在 3mm 激活时为 14，在 4mm、5mm 和 6mm 激活时分别降至 10.7、8.7 和 7.2。弹簧可以激活至 7mm 而不超过弹性极限。
