Complexity of the relationships between the sintering-temperature-dependent grain size, airborne-particle abrasion, ageing and strength of 3Y-TZP ceramics

Objectives. This study was designed to explore the complex relationships between the sintering-temperature-dependent grain size, airborne-particle abrasion, ageing and strength of 3Y-TZP ceramics. Methods. Biomedical grade 3Y-TZP powder was used to fabricate 180 discs. Half of them were sintered at 1400 degrees C for 2 h and half at 1500 degrees C for 2 h. A total of 18 groups of 10 were formed and subjected to the fully crossed experimental protocol of airborne-particle abrasion with Al2O3 at 2.5 bar (no abrasion, 50 mu m, 110 mu m) and accelerated ageing at 134 degrees C (no ageing, 12 h, 48 h). The relative amount of monoclinic phase was determined with XRD. The biaxial flexural strength was measured and statistically analyzed using the three-way ANOVA followed by predetermined contrasts and Tukey's HSD test (alpha = 0.05). Results. The low-temperature-sintered, fine-grained ceramic exhibited an excellent ageing resistance, while the high-temperature-sintered, coarse-grained ceramic experienced a higher surface strengthening and a substantially improved ageing resistance with respect to the airborne-particle abrasion. The overall performance of this material was superior. Significance. Our results show that the sintering temperature has a minor effect on the flexural strength, but it plays a crucial role in the surface strengthening and the ageing behaviour of 3Y-TZP dental ceramics. (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.