Therefore,the structure of five composite CAD–CAM blocks was investi-gated, in particular to assess (1) the effect of sandblasting ontheir surface topography and (2) the effect of sandblasting andsilanization on their bonding receptiveness.In this study,the ultra-structure of composite CAD–CAM blocks was investigated with special attention to the effect of sandblasting on the surface topography and of silanization on the bonding performance.