Bond Strength of Ce-TZP/Alumina Nanocomposite Frameworks with Press Ceramics

Objectives: Zirconia has been opening up the possibilities of all ceramic restorations. A newly developed ceria-stabilized tetragonal zirconia/alumina (Ce-TZP/Alumina) nanocomposite is promising material as frameworks of all ceramic restorations, because of its very high toughness and complete resistance to low temperature aging degradation compared to the currently used yttria-stabilized tetragonal zirconia polycrystal (Y-TZP）. The objective of this in-vitro study is to investigate the bond strength of Ce-TZP/Alumina nanocomposite frameworks with five different press ceramics. Materials and Methods: Ce-TZP/Alumina nanocomposite frameworks (25 x 3 x 0.5 mm) were fabricated and divided into five groups. The framework surfaces were sandblasted with 50 µm alumina particles and air-fired (1000°C). Five press ceramics - Cerabien ZR press (Noritake), Cercon ceram press (DeguDent), NobelRondo Press (Nobel), Vintage ZR Press Over (SHOFU), and VITA PM9 (VITA) - were applied and adjusted to a final thickness of 1.5mm including the frameworks according to the ISO 9693 specifications. The specimens were subjected to a three-point bending test using a universal testing machine (AUTOGRAPH AGS-H, Shimadzu). The bond strengths (mean±SD, MPa) were calculated and compared with the standard strength specified by ISO9693 (25 MPa). The differences between ceramics were analyzed by one-way ANOVA and Tukey HSD test (p<0.05). Results: The bond strengths of Ce-TZP/Alumina nanocomposite frameworks with Cerabien ZR press, Cercon ceram press, NobelRondo Press, Vintage ZR Press Over, and VITA PM9 were 28.8±1.3, 35.7±3.5, 26.6±0.5, 28.9±1.9 and 39.8±3.3 MPa respectively. The all bond strengths were greater than 25 MPa. And Cercon ceram press and VITA PM9 showed greater bond strength than Cerabien ZR press, NobelRondo Press, and Vintage ZR Press Over. Conclusion: The bond strengths of Ce-TZP/Alumina nanocomposite frameworks with Cerabien ZR press, Cercon ceram press, NobelRondo Press, Vintage ZR Press Over, and VITA PM9 were greater than 25 MPa, the standard strength specified by ISO9693.