title: Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging.
abstract: 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.
authors.affiliation: MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil; Department of Dental Material Sciences, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands. Electronic address: gabrielkrpereira@hotmail.com.
authors.forename: G K R
authors.initials: GK
authors.lastname: Pereira
authors.affiliation: Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: taissilvestri@yahoo.com.
authors.forename: T
authors.initials: T
authors.lastname: Silvestri
authors.affiliation: Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: rosanedecamargo@hotmail.com.
authors.forename: R
authors.initials: R
authors.lastname: Camargo
authors.affiliation: MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: mariliarip@hotmail.com.
authors.forename: M P
authors.initials: MP
authors.lastname: Rippe
authors.affiliation: MDS-PhD Graduate Program in Dentistry, University of Taubaté, Taubaté, São Paulo, Brazil. Electronic address: marinamaral_85@yahoo.com.br.
authors.forename: M
authors.initials: M
authors.lastname: Amaral
authors.affiliation: Department of Dental Material Sciences, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands. Electronic address: c.kleverlaan@acta.nl.
authors.forename: C J
authors.initials: CJ
authors.lastname: Kleverlaan
authors.affiliation: MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: lfvalandro@hotmail.com.
authors.forename: L F
authors.initials: LF
authors.lastname: Valandro
mesh_terms: D003080:Cold Temperature; D018130:Diamond / Q000737:chemistry; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D013997:Time Factors; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D018130:Diamond; D015040:Zirconium
keywords: Dental materials; Dental prosthesis; Flexural strength; Low-temperature degradation; Mechanical properties; Surface treatments; Zirconium oxide partially stabilized by yttrium