Cooperation of phosphate monomer and silica modification on zirconia

Ceramic restorations with resin-based adhesive systems have been the focus of recent attention in clinical dentistry. Yttrium-oxide-partially-stabilized zirconia (YPSZ) ceramics have optimized physical properties and exhibit favorable fracture toughness, though their bonding properties are problematic. Although functional phosphate monomers and silica-coating by tribochemical modification were expected to improve the bonding properties between YPSZ ceramics and resin-based adhesives, these two methods remain controversial. This study evaluated the efficiency of silica-coating by tribochemical modification of YPSZ ceramics. The application of phosphate monomer and a silane coupling agent on silica-coated YPSZ was also investigated. The silica-coating of YPSZ ceramics by tribochemical modification was not efficient, given the higher mechanical toughness of the densely sintered ceramics. Stable shear bond strength was achieved on silica-coated YPSZ ceramics with the cooperative interaction of phosphate monomer and silane coupling.