Influence of irradiation seguence on physical properties of dual-cured resin cements.

据报道，双固化树脂胶结物的粘结强度受到通过树脂材料的光能的影响。本研究的目的是研究双固化树脂水泥的光活化顺序与树脂水泥的粘结强度之间的关系。并从临床角度评价不同照射方式下的凝固时间和膜厚度。设计了三个实验来研究以下因素的影响：(1)预拌活化（混合前仅对液体进行活化），(2)按厂家说明进行后拌活化，(3)无光活化。预拌活化水泥的凝结时间比未活化水泥的凝结时间短。预拌活化与未活化的水泥混合料的膜厚无显著差异。抗压强度和抗折强度受辐照顺序的影响。随着预混料活化，纵向截面表面的努氏硬度值增大。在水泥搅拌前对液体进行预拌辐照，即使在水泥浇筑后不进行辐照，也是有效的。通过活化将液体中的樟脑醌置于反应状态。这种情况显然会产生自由基，并在处理期间持续下去。这种活性状态使得预混合粘结剂在放置后无需辐照即可增强。樟脑醌固化体系的动力学和机理有待进一步研究。

IT has been reported that the bond strength of dual-cured resin cements is influenced by the light energy through the resin materials. The purpose of this study was to examine the relationship between the order in which a dual-cured resin cement is light activated and the bond strength of the reshin cement. Also, the setting time and film thickness with various irradiation procedures were evaluated from the clinical perspective.Three experiments were designed to study the influence of the following factors : (1) pre-mix activation (activation of only the liquid prior to mixing), (2) post-mix activation according to the manufacturer's instructions, (3) no-light activation.The setting time of cement mix with pre-mix activation was shorter than that with no activation. No difference was observed between the specimen with pre-mix activation and that with no activation regarding the film thickness of the cement mix. The compressive strength and flexural strength were influenced by irradiation sequences. The Knoop Hardness Number on the longitudinally sectioned surface increased with the pre-mix activation. The pre-mix irradiation to the liquid before cement mixing is effective even without irradiation to the cement after placement. Camphoroquinone in the liquid is placed in a reactive condition by activation. This condition apparently generates free radicals and continues during handling time. This active condition makes the pre-mixed bond strength without irradiation after placement.Further studies are needed to define the kinetics and mechanisms of the camphoroquinone curing system.