Aim: To evaluate how yttria content and different 10-MDP utilization affect the shear bond strength between resin cements and zirconia. 

Materials and methods: 120 pairs of cubical and cylindrical specimens were manufactured from yttria-stabilized zirconia blocks. The specimens were divided into 12 groups (n=10) according to yttria content (3-YSZ, 4-YSZ and 5-YSZ) and cement system. Two adhesive cements (Panavia FTM2.0 and Panavia V5) and two primers (Clearfil Ceramic Primer Plus and Alloy Primer) were included. The cementation surfaces were air-abraded with aluminum oxide particles, treated with a primer and cemented. After 72 hours of storage in a heating cabinet in a humid environment at 37°C and subsequent artificial aging for 5000 thermocycles, shear bond strength test and failure mode analysis were conducted. 

Results: No statistical differences in shear bond strength were found between different yttria containing zirconia, nor within each zirconia group, irrespective of cement and primer. 

Conclusion: Within the limitations of the study, it can be concluded that the bond strength between resin cements used in combination with MDP-containing primers and 3-YSZ, 4-YSZ or 5-YSZ, are sufficient. Thus, the yttria content of zirconia does not seem to affect the adhesion. Furthermore, it was found that a universal silane and MDP-primer gives the same bond strength as an MDP-primer. Lastly, similar bond values can be achieved regardless of MDP-primers being used together with non-MDP or MDP-containing resin cements.