Stevenson J S, Kusy R P
Department of Biomedical Engineering, University of North Carolina, Chapel Hill 27599.
Angle Orthod. 1994;64(6):455-64; discussion 465-7. doi: 10.1043/0003-3219(1994)064<0455:FAADCO>2.0.CO;2.
In this study the effects of prestressing, environmental acidity, oxygen content, and temperature on mechanical properties were measured for three polyurethane-based orthodontic elastomeric chains. Specimens of each chain were treated for 10 and 100 days, and their mechanical properties were compared with those of the untreated specimens via stress-relaxation tests. Conditioning treatments were determined to affect the magnitude of residual load after relaxation, with the largest effect due to prestressing. Among the other variables studied, an increase in temperature of the environment appeared to significantly influence the degradation mechanism responsible for the deterioration of the mechanical properties of polyurethane elastomers (p < 0.001); acidity and oxygen content had no significant effects. Force decay profiles from the specimens were derived using a Maxwell-Weichert model consisting of springs and dashpots. This model allows the orthodontist to predict load magnitude supplied by the chain at activation and at any time during treatment.
在本研究中，对三种基于聚氨酯的正畸弹性链，测量了预应力、环境酸度、氧含量和温度对其力学性能的影响。每种链的样本分别处理10天和100天，并通过应力松弛试验将其力学性能与未处理样本的力学性能进行比较。已确定调节处理会影响松弛后残余负荷的大小，其中预应力的影响最大。在所研究的其他变量中，环境温度的升高似乎会显著影响导致聚氨酯弹性体力学性能劣化的降解机制（p<0.001）；酸度和氧含量没有显著影响。使用由弹簧和阻尼器组成的麦克斯韦-魏歇特模型得出样本的力衰减曲线。该模型可让正畸医生预测链在激活时以及治疗期间任何时间提供的负荷大小。
