Compressive Strength Evaluation of Core-Build-up Systems for Onlay Restorations

Objectives: To evaluate the influence of two types of core-build-up systems on the compressive strength of CEREC-3-onlay restorations. Methods: Twenty anatomically similar human third molars were selected. The lingual cusp of each tooth was removed to simulate a tooth with fractured cusp. Teeth were prepared for ceramic onlay restorations with shoulder margin 1.0mm above the cemento-enamel junction. Prepared teeth were randomly assigned into two groups (n=10): G1: conventional composite core-build-up (control) and G2: composite core-build-up with Dentin Anchor® (DA) placement. DA is a 4.0mm length fiber reinforced composite insert patented by The Ohio State University. Holes of 2.0mm depth were prepared 1.5mm from the dentin-enamel junction for the DA placement. Nexus (Kerr) dual-cured resin cement was used to cement anchors and Prodigy (Kerr) composite resin was used to fabricate the cores. CEREC-3 ceramic onlays were fabricated and cemented with Nexus (Kerr). After 24h in water at 37°C, a compressive loading test (0.5mm/min) was performed using a universal testing machine. The data were analyzed by one-way ANOVA at p<0.05. Results: No statistic significant difference was observed between the two groups (p=0.1632). The compressive strength means (SD) in Newtons were: G1: 1148.7(406.74); G2: 1319.8(328.41). Conclusion: The use of DA for composite core-build-up had better performance compared with the conventional core-build-up on the compressive strength of CEREC-3-onlay restorations, although not statistically significant different.