Effect of sintering temperature on aging resistance and mechanical properties of 3Y-TZP dental.docVIP

PAGE  PAGE 7 Effect of sintering temperature on aging resistance and mechanical properties of 3Y-TZP dental ceramics ZHANG Jingchao1,2, LIAO Yunmao1,2, LI Wei1,2,*, JIANG Li1,2, ZHAO Yongqi1,2, YUN Xiaofei1,2 (1. West China College of Stomatology, Sichuan University, Chengdu, 610041, China; 2. State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, 610041, China) Abstract：In order to investigate the effect of sintering temperature on aging properties and mechanical properties of 3Y-TZP dental ceramics in a simulated oral environment, 3Y-TZP nanopowder compacts were prepared by pressureless sintering at 1350℃，1400℃，1450℃，1500℃, respectively, then treated by soaking in artificial saliva (65℃，pH=7) for two months. The treated specimens sintered at 1350℃showed no phase transformation but significantly improved strength and toughness（P0.05）, while those sintered at 1400℃-1500℃ revealed a small amount of phase transformation and insignificant mechanical reinforcement (P0.05). No micro-cracks were detected but increase in lattice volume was found in all specimens. Lowering sintering temperature favors aging resistance and mechanical reinforcement of 3Y-TZP in simulated oral environment. Key words：3Y-TZP; dental ceramic; sintering temperature; simulated oral environment; low temperature agingdegradation 1 Introduction All-ceramic dental restorations have become more and more important due to their favorable esthetics and outstanding biological compatibility when compared with metal and resin restorations. In particular, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) attracts the most attention due to exceptionally high strength and toughness, which provides the base for applications in multi-unit fixed partial dentures and dental implant abutments. The superior mechanical properties of 3Y-TZP are related to the stress-induced phase transformation of tetragonal zirconia into monoclinic symmetry (t-ZrO2→m-ZrO2) accompanied by an volume