复合树脂收缩应力测量系统初探

目的 探讨复合树脂聚合收缩应力的测试方法及树脂基质对收缩应力的影响.方法 使用模拟临床条件下的聚合收缩应力测量系统,测量两种以新型单体为基质的复合树脂(P 90、维纳斯钻石)和传统基质复合树脂(Z350和卡瑞斯玛)光照开始后收缩力值变化情况,并测得复合树脂在光照后300 s时的聚合收缩应力值.结果 两种采用新型基质的复合树脂在光照后300 s时的收缩应力显著低于传统基质复合树脂,4种被测复合树脂收缩应力的大小依次为Z350 (4.08 ±0.12)MPa]＞卡瑞斯玛(1.92 ±0.10)MPa]＞维纳斯钻石(1.16 ±0.03)MPa] ＞P90(0.94±0.04)MPa] (P ＜0.05).且两种新型复合树脂的聚合收缩反应速率较缓慢.结论 本测量系统可实时有效监测复合树脂固化过程中收缩应力的变化过程；以新型单体代替传统树脂基质是开发低收缩复合树脂的有效途径.

Development and application of a new testing system of contraction stress of composite materials

Objective The aim of this study was to compare the contraction stress of a new low-shrinkage silorane-based composite (P 90 ) and a new low-shrinkage nanohybrid composite (Venus Diamond) with two conventional dimethacrylate-based composites using new measuring systems.Methods The materials tested were P 90 (3M ESPE),Venus Diamond (Heraeus),Z 350 (3M ESPE),and Charisma Opal(Heraeus).Shrinkage stress was assessed using a stress-strain analyzer consisting of two opposing attachments,one connected to a load cell and the other fixed to the device.All specimens were light-cured and the contraction stress (MPa) generated during polymerization was continuously recorded for 300 s.The contraction stress after 30,60,300 s were recorded.Results The silorane-based composite (P 90) and new low-shrinkage nanohybrid composite (Venus Diamond ) exhibited significantly lower contraction stress and very slowly cure rate than the conventional dimethacrylate-based composites.Contraction stresses after 300 s were:Z 350 (4.08 ±0.12) MPa] ＞ Charisma Opal ( 1.92 ±0.10) MPa]＞ Venus Diamond ( 1.16 ± 0.03 ) MPa] ＞ P 90 ( 0.94 ± 0.04 ) MPa],and significant differences among groups were observed ( P ＜ 0.05).Conclusions A new test system can continuously record the contraction stress during polymerization.The low-shrinkage composites ( P 90 and Venus Diamond) tested in the study show an improvement in terms of reducing contraction stress and reducing cure rate.Some new monomer comoositions of the resin matrix can be valid alternatives to dimethacrylates.