title: Loading frequencies up to 20Hz as an alternative to accelerate fatigue strength tests in a Y-TZP ceramic.
abstract: Considering the interest of the research community in the fatigue behavior of all-ceramic restorations and the time consumed in low-frequency cyclic fatigue tests, this study aimed to investigate the influence of the loading frequency on the zirconia fatigue strength. The biaxial flexural fatigue strength of Y-TZP discs was determined by the staircase approach after 500,000 cycles. The investigated frequencies were 2Hz (control-simulation of the chewing activity; n=20), 10Hz (n=20), 20Hz (n=20), and 40Hz (n=21). The fatigue strength data were analyzed using one-way ANOVA and post-hoc Tukey׳s test (α=0.05). Pearson coefficient (r) was calculated to assess the existence of a correlation between fatigue strength and loading frequency. X-ray diffraction analysis was used to determine the relative amount of monoclinic phase under each fatigue test condition. The fatigue strength was significantly higher for 40Hz group (630.7±62.1MPa) and did not differ among the groups 2Hz (550.3±89.7MPa), 10Hz (574.0±47MPa) and 20Hz (605.1±30.7MPa). Pearson correlation coefficient indicated a significantly moderate correlation (r=0.57) between fatigue strength and loading frequency. The percentage of monoclinic phase was similar among the groups. Therefore, the use of loading frequencies up to 20Hz seems a good alternative to expedite the cycling strength fatigue tests in polycrystalline ceramics without significantly changing the fatigue behavior showed by zirconia in tests employing the frequency of the masticatory cycle.
authors: Post Graduate Program in Dental Science (Prosthodontics Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: sara.odonto@yahoo.com.br.
authors: Sara
authors: S
authors: Fraga
authors: Post Graduate Program in Dental Science (Prosthodontics Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: gabrielkrpereira@hotmail.com.
authors: Gabriel Kalil Rocha
authors: GKR
authors: Pereira
authors: Dentistry College, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: m4riana.freitas@gmail.com.
authors: Mariana
authors: M
authors: Freitas
authors: Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands. Electronic address: c.kleverlaan@acta.nl.
authors: Cornelis Johannes
authors: CJ
authors: Kleverlaan
authors: Post Graduate Program in Dental Science (Prosthodontics Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: lfvalandro@gmail.com.
authors: Luiz Felipe
authors: LF
authors: Valandro
authors: Post Graduate Program in Dental Science (Prosthodontics Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: liligmay@gmail.com.
authors: Liliana Gressler
authors: LG
authors: May
mesh_terms: D003799:Dental Stress Analysis; D006801:Humans; D008409:Mastication; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium
keywords: Fatigue; Load frequency; Mechanical cycling; Zirconium oxide partially stabilized by yttrium