Bonding to densely sintered alumina surfaces: Effect of sandblasting and silica coating on shear bond strength of luting cements

Purpose: An important determinant of the clinical success of ceramic restor ations is the bond strength of the luting agent to the seating surface and the prepared tooth structures. Manufacturers of ceramic systems frequently specify both the luting agent and preluting treatment of the seating surfac e of the crown. Procera AllCeram is an all-ceramic crown comprising a porce lain-veneered coping of densely sintered, high-purity aluminum oxide. This study evaluated the shear bond strength of 4 luting agents: zinc-phosphate, glassionomer, resin-modified glass-ionomer, and resin cement (dual cured) to Procera aluminum oxide coping material. The luting agents were subjected to different surface treatments: untreated, sandblasted, or silica coated by the Rocatec system. Materials and Methods: Cylindric and cubic specimens of the coping material were luted together, and the shear force necessary to separate the cylinder from the cube was measured with a universal testin g machine. The surfaces of the specimens were also analyzed. Results: No si gnificant differences were recorded for the shear bond strengths of the lut ing agents to the untreated aluminum oxide. Class-ionomer and the resin-mod ified glass-ionomer cements had the highest values (4.2 +/- 2.5 MPa and 4.3 +/- 1.9 MPa, respectively), acid the lowest were 3.3 +/- 2.3 MPa for the r esin cement and 3.2 +/- 1.0 MPa for the zinc phosphate cement. Similar resu lts were recorded for the sandblasted aluminum oxide surfaces, except with the glass-ionomer, which was significantly higher (12.9 +/- 2.4 MPa). For a ll 4 luting agents, the highest shear bond strength values were recorded fo r the silicacoated specimens; the highest was for the resin cement, at 36.2 +/- 7.8 MPa. Conclusion: The bond strengths between resin cement and alumi num oxide specimens treated by the Rocatec system were significantly higher than those of the other materials and surface treatments evaluated.