Evaluation of bond strength of CAD/CAM zirconia blocks with different resin cements, using atmospheric pressure plasma and conventional surface modification methods

Interest in monolithic zirconia restorations has increased with the development of CAD-CAM systems. The long-term clinical success of zirconia restorations depends on the adhesion between the zirconia and the resin cement. The aim of this thesis is to evaluate the effects of atmospheric pressure plasma and different surface modification methods applied to increase the bond strength between zirconia and resin cement on the surface properties of zirconia and bond strength to adhesive resin cement systems. 9 different surface treatments including control, sandblasting, laser, plasma, primer, sandblasting+primer, laser+primer, plasma+primer, laser+plasma+primer on the surface of 180 zirconia samples obtained from Vita YZ HT monolithic zirconia disc has been applied. Surface roughness and contact angle values of 10 samples from each group were measured, SEM-EDS and AFM analyzes were performed on one sample from each group. Rely X Ultimate Clicker adhesive resin cement was applied to half of the samples and Theracem self-adhesive resin cement was applied to the other half. The specimens were kept in distilled water at 37ºC for 24 hours and then subjected to the shear test. Failure types were examined with a stereomicroscope and SEM images were made. Ra values of sandblasting, primer, sandblasting+primer, plasma+primer and laser+plasma+primer surface treatments were significantly higher than the control group. The contact angle values of the sandblasting, plasma and laser groups were significantly lower than the control group. The highest shear bonding value was observed in the sandblasting+primer group in the Theracem cement group, followed by plasma+primer and laser+plasma+primer groups, respectively. In the Rely X Ultimate Clicker cement group, the highest shear bond value was observed in the laser+plasma+primer group, followed by the sandblasting+primer, plasma+primer and laser+primer groups, respectively. Primer application after surface treatment significantly increased the shear bond values in both cement groups. Atmospheric pressure plasma significantly increased the wettability of zirconia when applied alone, but when used in combination with primer, it could significantly increase the shear bond strength values compared to the control group. There was no significant effect of laser application before plasma+primer application. Sandblasting+primer and plasma+primer applications are effective procedures in increasing the zirconia-resin cement bond strength. Keywords: bond strength, CAD/CAM, laser, monolithic zirconia, plasma, resin cement