Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging

• Published in: Materials Science & Engineering C Vol. 63; pp. 70 - 77
• Main Authors: Pereira, G.K.R., Silvestri, T., Camargo, R., Rippe, M.P., Amaral, M., Kleverlaan, C.J., Valandro, L.F.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2016
• Subjects: Ceramics; Coarsening; Cold Temperature; Dental materials; Dental prosthesis; Diamond - chemistry; Flexural strength; Low-temperature degradation; Materials Testing; Mechanical properties; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Restoration; Roughness; Surface Properties; Surface treatments; Tetragonal zirconia polycrystals; Time Factors; Topography; X-Ray Diffraction; Yttria stabilized zirconia; Yttrium - chemistry; Zirconium - chemistry; Zirconium oxide partially stabilized by yttrium; Low-temperature degradation; Zirconium oxide partially stabilized by yttrium; Dental materials; Dental prosthesis; Flexural strength; Mechanical properties; Surface treatments
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2016.02.049

This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped specimens (Zirlux FC, Ivoclar Vivadent) were manufactured according to ISO 6872 (2008) and divided in accordance with two factors: “grinding — 3 levels” and “LTD — 2 levels”. Grinding was performed using a contra-angle handpiece under constant water-cooling with different grit-sizes (extra-fine and coarse diamond burs). LTD was simulated in an autoclave at 134°C, under a pressure of 2 bar, over a period of 20h. Surface topography analysis showed an increase in roughness based on surface treatment grit-size (Coarse>Xfine>Ctrl), LTD did not influence roughness values. Both grinding and LTD promoted an increase in the amount of m-phase, although different susceptibilities to degradation were observed. According to existing literature the increase of m-phase content is a direct indicative of Y-TZP degradation. Weibull analysis showed an increase in characteristic strength after grinding (Coarse=Xfine>Ctrl), while for LTD, distinct effects were observed (Ctrl<Ctrl LTD; Xfine=Xfine LTD and Coarse=Coarse LTD). Weibull moduli were statistically similar between all tested groups. Within the limits of this current study, it was feasible to notice that both aging in autoclave for 20h (LTD) and grinding showed not to be detrimental to the mechanical properties of Zirlux FC Y-TZP ceramic. •Two stimuli that Y-TZP monolithic restoration is submitted clinically were studied.•Grinding showed not to be detrimental to biaxial flexure strength of Y-TZP.•Low temperature aging did not promote deleterious impact at biaxial flexure strength of Y-TZP.•An increase in m-phase content was observed for control group (notable increase) and ground groups (less intense increase).•Low temperature aging did not affect roughness, while grinding promoted increase as function of grit size.