In vitro shear bond strength evaluation of resin cements between zirconia and titanium

This study aimed to evaluate the Shear Bond Strength (SBS) and durability of different resin cements used for cement-retained restorations between zirconia crowns and titanium abutments. A total of 36 zirconia cubes and 324 titanium cylinders were employed in this study. Accordingly, 6 groups were assigned according to the used resin cement: three self-etching types (RU, AI, GMP), two self-adhesive types (IS, GM) and one unfilled type (SB). Each group was further divided into 3 sub-group based on storage condition (n = 10): 24-hour water storage at 37 °C, 5,000 thermocycles, and 10,000 thermocycles respectively. SBS testing employed a universal testing machine to quantify the force required for material fracture at the interface, followed by failure mode analysis. Two-way ANOVA showed significant influences of storage conditions and bonding agents on SBS values (p < 0.05), except for IS and GMP (p > 0.05). The SBS values of AI and RU showed a downward trend, while SB and GM showed an upward trend after 10,000 thermocycles. The SBS values of GM and GMP were significantly different in the 24-hour water storage but not after thermocycles. Within the limitations of the current study and based on the findings, the following can be concluded: (1) SBS was significantly influenced by both bonding agent type and storage condition; (2) Bonding systems containing HEMA and 10-MDP exhibited high initial strength but declined significantly after thermocycling; (3) IS, GM, and GMP demonstrated stable bond durability.