title: Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic.
abstract: This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Gabriela Scatimburgo
authors.initials: GS
authors.lastname: Polli
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Gabriel Rodrigues
authors.initials: GR
authors.lastname: Hatanaka
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Filipe de Oliveira
authors.initials: Fde O
authors.lastname: Abi-Rached
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Lígia Antunes Pereira
authors.initials: LA
authors.lastname: Pinelli
authors.affiliation: UNILA - Universidade Federal da Integração Latino-Americana, Foz do Iguaçu, PR, Brazil.
authors.forename: Márcio de Sousa
authors.initials: Mde S
authors.lastname: Góes
authors.affiliation: Department of Biomaterials and Oral Biology, Dental School, USP - Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Paulo Francisco
authors.initials: PF
authors.lastname: Cesar
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: José Maurício Dos Santos Nunes
authors.initials: JM
authors.lastname: Reis
mesh_terms: D002516:Ceramics; D008422:Materials Testing; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium