Effect of Aging on the Bond Strength between Lithium Disilicate and Preheated Composite

Abstract

Objective: investigation of the microshear bond strength (µSBS) between lithium disilicate with preheated packable composite, flowable composite and resin cement by comparison of their (µSBS) before and after aging. Material and method: Ninety samples were prepared and divided into three groups; preheated packable composite, flowable composite and resin cement. Materials were injected into plastic transparent molds (2x2mm) on the surface of lithium disilicate discs pretreated previously with hydrofluoric acid 4.5% and silane coupling agent. Then each group was divided into 2 subgroups (15 samples each). The first subgroup didn’t receive any aging procedure while the second subgroup was thermocycled (5000 cycles) to simulate aging process. µSBS test was performed for each sample by universal testing machine. Results: before aging the highest µSBS was recorded for preheated packable composite, while after aging there was no significant difference between all tested materials. Conclusions: the preheated packable composite is a reliable substitute of flowable composite and resin cement in cementation of lithium disilicate ceramic restorations.