Effect of different thickness hybrid and leucite reinforced glass ceramic CAD/CAM restorative materials on polymerization of resin based luting materials

The aim of this study was to evaluate the effect of 4 different resin based luting materials on polymerization by using Vicker's microhardness measurement after 1 hour, 24 hours, 7 days and 30 days under different thicknesses of hybrid ceramic and leucite reinforced glass ceramic CAD / CAM restorative materials. Blocks of 1mm and 2mm thickness were obtained from A2 color different CAD / CAM indirect restorative materials. Four different types of luting materials were used: Flowable composite resin, self adhesive resin cement, light cure resin cement and dual cure resin cement. Luting materials were polymerized for 40 seconds with an LED light unit over indirect restorative materials in different thicknesses without any restorative material. After the polimerization of test specimens, test specimens stored at 37ºC'de oven for 1 hour, 24 hour, 7 days and 30 days and after each storage times, Vicker's hardness measurements were performed from the upper and lower surfaces of the test specimens. The statistical analysis of the obtained data were completed with the SPSS 25 program and at a 95% confidence level. Friedman test, Wilcoxon test, Kruskal Wallis test and Mann Whitney test were used for the analysis of the data. Bonferroni correction was applied for multiple comparisons. There was no difference between the upper and lower surface measurements of the test samples without indirect restorative material (p> 0.05). The upper surface hardness values of the samples with indirect restorative materials are higher than the lower surface hardness values (p <0.05). However, no difference was observed between the upper and lower surfaces at the self-adhesive resin cement samples with the increase in measurement time (p> 0.05). As an indirect restorative material and increasing the material thickness, a decrease was observed in the surface hardness values of the test samples (p <0.013). When the surface hardness values of all test samples examined; the flowable composite resin and light cure composite resin cement showed the highest hardness values, and self adhesive resin cement showed the lowest hardness values (p <0.013), when the hardness values from the lower surfaces of the test specimens examined, the flowable composite resin showed the highest hardness values and it was followed by light cure composite resin cement. While self adhesive resin cement showed the lowest values at 1 hour and 24 hours measurements, dual cure composite resin cement showed lower values at 7 day and 30 day measurements (p <0.013).