CAD–CAM blocks to fabricate semi-direct and indirect restorations are available in different sorts of ceramics as well as composite. In order to bond restorations prepared out of composite blocks into tooth cavities, it is recommended to gently sandblast the surface prior to the application of a primer/adhesive. Today, the effect of sandblasting composite block surfaces has notthoroughly been investigated. 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.