The Effect Of Sandblast On All-ceramic Core Material

Sandblast is a most useful surface technology in denture processing, which can remove impurities, increase surface roughness and change characters of material surface. Meanwhile it can also cause damage to material. It is very important to investigate the surface damage of dental all-ceramics caused by sandblast because of the brittleness of dental ceramics that make it sensitive to the surface micro crack. In this study, using an all-ceramic core material (MIC), we investigate the change of strength caused by sandblast under different grain size, pressure and time. We also research the strength change of MIC sintering with its veneering porcelain that has been sandblasted before. Meanwhile, we analyze the erosion mechanism of MIC and junction between MIC and its veneering porcelain by Scanning-Electrical-Machine (SEM). The results show as following: 1. Sandblast can decrease the strength of MIC significantly; under the denture processing condition, grain size effect is the mostprominent among the three factors: grain size, pressure and time. That is the larger the grain size, the more significant of the effect of decrease.2. After sintering the veneering porcelain, the bending strength of specimens that have been sandblasted with smaller grain size granule increases while those sandblasted with larger grain size granule decrease. The effect of pressure and time are not prominent.3. The major erosion mechanism of MIC is fatigue fracture. Erosion cause surface crack system developing, thus pits and micro crack emerge on the surface of MIC.4. After sandblast, MIC and its veneering porcelain fused to each other, which showed a good junction.