Is it ok to grind or sandblast the internal surface of a zirconia-based restoration to improve bonding with resin cements?

Grinding the internal surface of a zirconia-based restoration with a bur does improve the bond strength compared to the as-sintered surface, but the best procedure is to sandblast with alumina. Use 50-um alumina powder at a pressure of 1.5 bars (22 psi or 0.15 MPa).