光固化复合树脂凝胶玻璃化后固化收缩量评价

Evaluation of laser triangulation method for measurement of post-gel shrinkage and post-vitrifi-cation shrinkage in composite resins

目的评价光固化复合树脂在凝胶点后特别是玻璃化后的固化收缩量，以期为深入研究光固化复合树脂的固化收缩特性提供新的评价方法。方法利用本实验室自主研制开发的一种基于激光测距技术的固化收缩测量仪，获得5种光固化复合树脂自光照开始后300s内的固化收缩量一时间曲线和固化收缩速率．时间曲线，并通过收缩速率-时间曲线计算凝胶点和转变点V以及凝胶点后及玻璃化后的固化收缩量。结果5种光固化复合树脂的凝胶点为0．77—1．59s，差异有统计学意义（P〈0．01）；转变点V为1．99～6．33s，差异有统计学意义（P〈0．01）；凝胶点后收缩量为33．35～53．18μm，差异有统计学意义（P〈0．01）；玻璃化后收缩量为16．43—30．58μm，差异有统计学意义（P〈0．01）；总收缩量为39．25～64．84μm，差异有统计学意义（P〈0．01）。5种光固化复合树脂凝胶点后收缩量及玻璃化后收缩量的顺序与总收缩量的顺序有所不同。结论通过动态测量光固化复合树脂固化收缩量，可推测凝胶点和转变点V，从而获得更具有实用意义的复合树脂固化收缩特性评价参考值。

Objective To employ a laser triangulation method for measuring post-gel and postvitrifi-eation polymerization shrinkage of composite resins. Methods A novel experimental set-up capable of measuring real-time shrinkage strain was utilized. Total shrinkage of the five composite resins was measured. The measurements of post-gel and post-vitrification linear shrinkage as a function of the gel-point and vitrification transition point were also carried out in the study. Results Gel point of the five composite resins ranged from 0. 77 s to 1.59 s, while vitrification transition point ranged from 1.99 s to 6. 33 s. Postgel shrinkage ranged from 33.35 μm to 53.18 μm and post-vitrification shrinkage ranged from 16.43 μm to 30. 58 μm. Total shrinkage ranged from 39. 25 p,m to 64. 84 μm. Significant differences in the gel point and vitrification transition point among the five composite resins were found（ P 〈 0. 01 ）. Significant differences in the post-gel shrinkage, post-vitrification shrinkage and total shrinkage among the five composite resins were found（P 〈0. 01 ）. The ranking of post-gel and post-vitrification shrinkage of these composite was different from that of their total shrinkage. Conclusions Laser triangulation method is suitable for measuring clinically significant post-gel and post-vitrification shrinkage.