Chemical durability and microhardness of dental ceramics immersed in acidic agents

Abstract

Objective. To evaluate the microhardness and surface elemental compositions of ceramics immersed in acidic agents. Material and methods. Thirty-five ceramic disc specimens were made from each of four types of ceramic (VMK 95, Vitadur Alpha, Empress Esthetic and IPS e.max Ceram). Before immersion, baseline data of Vicker's microhardness and elemental composition were recorded. Four groups of discs (seven per group) were then immersed in acidic agents (citrate buffer solution, pineapple juice and green mango juice) and deionized water (as a control) for 168 h at 37°C. One group was immersed in 4% acetic acid at 80°C for 168 h. After immersion, specimens were evaluated and data were analyzed using two-way ANOVA with repeated measurements and a paired t-test at a significance level of 0.05. Results. The microhardness values of four types of ceramic significantly decreased after being immersed in acidic agents (p < 0.05). The elemental compositions of ceramics mainly comprise silicon, aluminium and potassium. These compositions also decreased after immersion (p < 0.05). Conclusions. The acidic agents used in this study affected the microhardness and elemental dissolution of ceramics. The main elemental compositions of ceramics (silicon, aluminium and potassium) decreased after being immersed in acidic agents.

Key Words::

• Alumina
• energy-dispersive X-ray
• fluorapatite
• leucite
• microhardness

Acknowledgements

This work was supported by the Prince of Songkla University research fund. The authors also thank Professor Dr. Peter A. Leggat, James Cook University, Australia, for reading the manuscript.