Investigation of the effect of zirconia acid etching time on the shear bond strength between porcelain veneer and a type of zirconia block

Abstract

In this study, we used 60 zirconia block samples whose standards were checked and then their surface was prepared. In fact, the standards of the zirconia sample, including the correct size, the absence of bubbles and nodules, the correct thickness and diameter, were controlled and followed. The acid solution of zircos-e etching solution was considered in three etching times of half, one and two hours and was compared with the control group (without etching). After surface preparation, porcelain was baked on the samples and its thickness was measured by micrometer. To measure the bond strength of each sample, the area between porcelain and zirconia was subjected to shear stress using a universal test machine at a speed of 1 mm/min until breaking. The maximum breaking force was recorded in Mpa. In fact, the criterion for examining fractures was the blind color difference between zirconia and porcelain veneers. At the end, the best etching time to prepare the surface of the zirconia block was selected and introduced based on the bond strength. The test results were reported as mean and standard deviation. The median was not used to establish normality. Graphs were used to show the value of resistance among groups. First, the normality of the data was tested with the Kolmogorov Smirnov test. To compare the average resistance between the two groups, T-test was used to establish normality, and Mann-Whitney's test was not used. Analysis of variance was used to compare the average resistance among the four groups. Due to the significance of the analysis of variance, the amount of resistances was compared in pairs among the groups. Bonferroni's test was used to compare two groups. Due to the establishment of normality, the Kruskal-Wallis test and its follow-up tests were not used. Two-way analysis of variance was also used to evaluate the interaction effect of time and band type. A probability value of less than 0.05 was considered as a significant level. SPSS version 19 software was used for data analysis.