Purpose: To test the bond strength of one-piece zirconia implants with either standard or reduced height using different luting agents and pretreatments of the inner surfaces of ceramic crowns.
Materials and Methods: A total of 20 monolithic zirconia CAD/CAM–fabricated single crowns per luting agent group were cemented onto 20 one-piece zirconia implants with either 5-mm (n = 10) or 4-mm (n = 10) abutment height using 13 different luting agents. After water storage, the crowns were removed using a specially developed test fixture in a universal testing machine. The maximum force (N) was recorded, and the force per area (MPa) was calculated. The statistical evaluation was performed using univariate analysis of variance.
Results: A mean of 4.19 MPa (SD 2.90) at 5-mm height and 3.89 MPa (SD 2.85) at 4-mm height was obtained for all luting agents. The highest values were achieved for a resin-modified glass-ionomer cement, with 12.37 MPa (4 mm) and 12.00 MPa (5 mm). The lowest values were shown for a long-term temporary material, with 0.73 MPa (4 mm) and 1.07 MPa (5 mm). Only a polycarboxylate cement (P < .001) and a glassionomer cement (P = .006) showed statistically significant differences in favor of the reduced abutment height. Reduced abutment height did not significantly reduce bond strength for any of the materials examined.
Conclusion: Implants with a reduced abutment height are clinically suitable. Pretreatment of the crowns’ inner surfaces with ceramic primer showed to be advantageous.
