A method for masking the appearance of a support structure underlying a highly translucent ceramic dental restoration is provided. The porous form of a zirconia ceramic dental restoration is treated with a liquid masking composition comprising 0.4 wt % to 50 wt % of one or more masking agents. The masking composition is applied to the internal surface of a restoration and a region of the facial surface of the restoration that is opposite the internal surface. After application of the masking compositions, treated zirconia restoration is sintered to greater than 98% theoretical density.