Evaluation of bond strength of two porcelain types to base metal alloy after different surface treatments

One of the most common problems in metal ceramic restorations is the loss of porcelain‒metal bond. The aim of this study was to evaluate the bond strength of two porcelain types to base metal alloy after different surface treatments. In this experimental research, 64 wax sheets were selected and after casting with base metal alloy were randomly divided into 8 groups. Surface treatment in each group was randomly accomplished by one of the four different methods to improve metal‒porcelain bonding. After surface treatment, porcelain application was carried out with Ceramco porcelain in half of the samples and Noritake porcelain in the remaining half. All the samples underwent 3-point bending test and the force at failure of each sample was recorded. Kruskal-Wallis test was used to compare 4 surface preparation techniques in the two porcelain groups and Mann-Whitney test was used to compare Ceramco and Noritake porcelains (α=0.05). There were significant differences between the means of four methods of surface treatment in Ceramco porcelain (p value = 0.022); there were significant differences between the four methods of surface treatment in Noratike porcelain (p value = 0.012). There were no significant differences between the two porcelain group (p value = 0.412). In this study, degassing increased the metal‒ceramic bond strength and steam- cleaning before degassing decreased it. There were no significant differences in the bond strength of the two types of porcelain with different surface treatments of base metal alloy.