Flexural strength of fluorapatite-leucite and fuorapatite 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 7th group was continuously immersed in 4% acetic acid at 80°c for 16 h. the final,8th,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.