Surface corrosion of dental ceramics in vitro.

The objective of this study was to evaluate possible structural surface changes in different dental ceramic materials in a provocative corrosive environment in vitro. On the basis of compositional and microstructural differences, seven dental ceramic materials were selected for the test. After sintering and autoglazing, the surface roughness of the specimens was evaluated by confocal laser profilometry. A specially designed specimen holder made it possible to locate the same surface area before and after contact with the corrosive solution. The surface topography was additionally analysed using scanning electron microscopy. All the ceramic materials displayed evidence of surface structural changes on the exposed surfaces, but to varying degrees. Traditional leucite-containing feldspathic porcelains displayed an increase in surface roughness compared with baseline conditions when kept in 4% acetic acid at 80 degrees C for 18 h. Micro-crystalline and non-crystalline ceramic materials, on the other hand, demonstrated a smoother surface or just a minor increase in surface roughness. Whether or not the smoother post-corrosion appearance of certain ceramic materials is indicative of a true increase in corrosion resistance or is merely the result of an uniformly progressive corrosive process will be the object of future studies.