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In Vitro Study of Structural Changes of Glazed and Unglazed Feldspathic Ceramic after Immersion in Corrosive Medium by Atomic Force Microscopy

Ceramics are attractive dental materials owing to their superior aesthetic and biocompatibility. However, they are brittle and are inclined to premature failure, especially in repeated contact loading and moist environment. Chemical stability of dental ceramics is important because it directly affects mechanical properties and aesthetic value of restorations. The aim of this in vitro study was to investigate the effects of a corrosive agent, 4% acetic acid, on the surface of glazed and unglazed feldsphatic ceramic. Metal- ceramic discs (diameter 8 mm, thickness 1.2 mm) composed of Ni-Cr alloy (Wiron 99, Bego Germany) and glazed and unglazed feldspathic ceramics (IPS Classic, Ivoclar-Vivadent, Schaan, Liechtenstein) were prepared according to the manufacturer's instructions. The samples were immersed in 4% acetic acid at 80°C and kept there for 16 h (ISO 6872). The surfaces of the samples before and after immersion in the corrosive medium were examined by atomic force microscopy (AFM). The pre-corrosion and post-corrosion AFM images of the surfaces of the feldspathic ceramic samples clearly show a dense surfaces, with very little open porosity. After corrosion, the surface displays an obvious surface deterioration, which is dominated by differently sized porosities and voids especially at unglazed ceramics sample.

structural changes; ceramic; corrosive; AFM

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