Flexural strength of fluorapatite-leucite and fluorapatite porcelains exposed to erosive agents in cyclic immersion

OBJECTIVE: The aim of this study was to evaluate the flexural strength of two porcelain materials (IPS d.SIGN and IPS e.max Ceram) exposed to erosive agents MATERIAL AND METHODS: One hundred and twenty bar-shaped specimens were made from each of fluorapatite-leucite porcelain (IPS d.SIGN) and fluorapatite porcelain (IPS e.max Ceram) and divided into 8 groups of 15 specimens each. Six groups were alternately immersed in the following storage agents for 30 min: deionized water (control), citrate buffer solution, pineapple juice, green mango juice, cola soft drink and 4% acetic acid. Then, they were immersed for 5 min in deionized water at 37°C. Seven cycles were completed, totalizing 245 min. A 7(th) group was continuously immersed in 4% acetic acid at 80°C for 16 h. The final, 8(th), group was stored dry at 37°C for 245 min. Three-point bending tests were performed in a universal testing machine. The data were analyzed statistically by 2-way ANOVA, Tukey’s HSD test and t-test at significance level of 0.05. RESULTS: The flexural strengths of all groups of each porcelain after exposure to erosive agents in cyclic immersion did not differ significantly (p>0.05). For both types of porcelain, dry storage at 37°C yielded the highest flexural strength, though without significant difference from the other groups (p>0.05). The flexural strengths of all groups of fluorapatite porcelains were significantly higher (p<0.05) than those of the fluorapatite-leucite porcelains. CONCLUSIONS: This study demonstrated that the erosive agents evaluated did not affect the flexural strength of the tested dental porcelains.