Aim: Bonding to zirconia still represents a challenge due to being chemically inert. In an attempt to overcome this problem, we aimed to demonstrate the effect of newly introduced bioactive calcium aluminate-based cement versus MDP-containing resin cement on the shear bond strength of zirconia to human dentin; and detect their mode of failure.
Subjects and methods: Twenty caries-free human maxillary first molars were flattened and mounted in acrylic resin. Twenty super high translucent zirconia discs (Zolid fx Zirconia ML) were obtained and air-abraded. Teeth and zirconia discs were randomly equally distributed into two groups (n=10) according to the cement type; Groups CB; bioactive cement (Calibra bio), Group TH; MDP-containing resin cement (TheraCem). Both groups were cemented according to their manufacturer instructions under a uniform vertical load of 5-kg and subjected to thermocycling. Shear bond strength was tested using a universal testing machine. After testing for normality, data sowed parametric distribution and were expressed as mean and SD. Data were statistically analyzed using independent t-test at a level of significance (P≤0.05). Failure modes were assessed visually, using scanning electron microscope and Energy dispersive x-ray spectroscopy analysis.
Results: Groups CB showed statistically insignificant higher bond strength (19.06MPa ±2.76) than Group TH (17.85MPa ±3.57). All specimens in both groups showed mixed failure mode, with change in surface elemental compositions in both zirconia and dentin.
Conclusion: Bioactive Calibra Bio and MDP-containing TheraCem cements showed comparable shear bond strength to super high translucent zirconia after six-month aging simulation, which was higher than clinical acceptable values.