Effect of Sintering Technique on Shade and Shear Bond Strength of CAD/CAM Monolithic Translucent Zirconia

Introduction: The fabrication of zirconia dental restoration is a time-consumingprocess due to traditional slow sintering schemes. A speed sintering protocol hasbeen developed to meet the demand for time and cost-effective chair-side CAD/CAM-produced restorations, as well as to control ceramic microstructures for bettertranslucency. Fast heating and cooling rates, as well as shorter sintering dwell timesare known to affect the microstructure and properties of zirconia. Aim of study: Thisstudy aimed to investigate and compare between three types of monolithic translucentzirconia in terms of the shade and the shear bond strength of the zirconia samples toadhesive resin cement after conventional and speed sintering. Material and Methods:Three types of zirconia discs were cut into 20 square shaped samples, 10 large squareshaped and 10 small square shaped and bonded to each other. Bonded samples weredivided according to type of zirconia into 3 groups: Group 1: Dental direct ZX2,Group 2: Dental Direct ZW iso, Group 3: Zolid HT+. Each group was subdividedaccording to sintering technique into 2 subgroups. Shade and shear bond test weremeasured. Results: The speed sintering of the three types of zirconia showed a lowerΔE values than that showed with the conventional sintering, and among the speed andconventional sintering subgroups Dental Direkt Bio ZX2 showed the lowest ΔE valueand highest shear bond strength value followed by Dental Direct Bio ZW iso and ZolidHt+. Conclusion: The speed sintering technique of the monolithic translucent zirconiagave better color shade reproduction and higher shear bond strength to resin cementthan that of the conventional sintering technique. Dental Direkt ZX2 produced bettercolor shade reproduction and higher shear bond strength to resin cement than that ofthe Dental Direkt ZW iso and Zolid Ht+ in speed and conventional sintering technique.