Effect of simulated gastric acid on the surface degradation of dental ceramics
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abstract
Objective. The aim of this study was to compare the effect in vitro of simulated gastric acid solution on the roughness, microhardness and micro-structural topography surface of two dental ceramics: lithium disilicate glass-ceramic and monolithic zirconium dioxide (ZrO2) at baseline and after different immersion time. Materials and methods. Lithium disilicate and ZrO2 glass-ceramic discs were fabricated (40 of each one) and was evaluated under microscope the roughness (Atomic force microscopy), mi-crohardness (Vickers hardness tester) and micro-structural topography surface (Scanning electron microscopy) before immersion (baseline) and after three periods of immersion: 8 h 25 min, 46 h 2.5 min and 92 h 5 min in simulated gastric acid solution of hydrochloric acid (HCl, 0.06 M, pH 1.2) at 37 ºC. The ceramics were compared over time with a repeated measures analysis of variance (ANOVA). Results. Statistically significant changes (P<.05) were found in the microhardness values between both ceramics, which decreased after all times points of immersion in simulated gastric acid solution, ZrO2 showed higher microhardness mean values (P<.05) but lithium disilicate showed significant changes (P <.05) in the surface microhardness at baseline versus the three immersion times. Lithium disilicate had higher roughness values than ZrO2 (P<.05), which increased after 8 h 25 min of immersion; however, after 46 h 2.5 min and 92 h 5 min of immersion, the roughness decreased. More microporosities were observed in the lithium disilicate surface than with ZrO2. Conclusion. The simulated gastric acid solution of HCl affected the roughness, microhardness and micro-structural topography surface of both lithium disilicate and ZrO2, but greater surface degradation was presented lithium disilicate.
