Micro-Shear Bond Strength of Indirect Composite Resin to Three Different Computer-Milled Cores After Thermocycling

Background and Aim: The aim of this study was to evaluate the micro-shear bond strength of an indirect composite resin to three different types of cores. Materials and Methods: In this in-vitro study, 14 blocks (5×5×2 mm) were designed and milled by computer from cobalt-chromium (Co-Cr) alloy, zirconia, and polyether ether ketone (PEEK). Each sample was treated according to the manufacturer’s instructions, and the appropriate primer, and a layer of Crea.lign opaquer were applied on the surface. For micro-shear bond strength test, a plastic tube with an internal diameter of 1 mm and height of 2 mm was placed on each block, and Crea.lign paste was condensed in it. The Crea.lign paste and opaquer were light-cured separately for 180 s, and finally for 360 s. All samples were placed in 37°C distilled water for 24 h and thermocycled for 5000 cycles (5 to 55°C). The microtensile tester machine was used to measure the micro-shear bond strength. The samples were also evaluated for failure modes. Data were analyzed using one-way ANOVA (P<0.05). Results: According to one-way ANOVA, the mean micro-shear bond strength (MPa) in Co-Cr alloy, zirconia, and PEEK groups was 25.19±5.53, 23.49±5.48, and 20.58±5.68 MPa, respectively. There was no significant difference in micro-shear bond strength of the three groups (P= 0.099). The most frequent mode of failure in all three groups was adhesive, followed by mixed, and cohesive. Conclusion: Applying the standard procedure, type of core material had no significant effect on the micro-shear bond strength of Crea.lign composite veneer.