title: Effects of two grading techniques of zirconia material on the fatigue limit of full-contour 3-unit fixed dental prostheses.
abstract: This study evaluated the effects of two grading techniques of zirconia material on the fatigue limit of full-contour 3-unit fixed dental prostheses (FDPs).
  
  
  
  Presintered blocks of 3Y-TZP were milled to obtain sixty-nine 3-unit FDPs, which were divided into three groups (n=23). The control group (CTL) was sintered and glazed following manufacturer's instructions. In the two experimental groups presintered FDPs received a surface silica/glass infiltration treatment before the sintering process. Silica sol-gel group (SSG) was graded by the sol-gel processing route, while the glass-zirconia-glass group (GZG) was graded by an enameling technique. Graded groups did not receive a glaze layer after sintering. All FDPs were then luted with a dual-curing resin cement on composite abutments, embedded in polyurethane and stored in water for five days. The initial load of the fatigue test was calculated based on the results of the monotonic testing applied on three specimens of each group. To determine the fatigue limit, 20 samples of each group were subjected to staircase testing (100,000 cycles/5Hz).
  
  
  
  The fatigue limits (in Newtons) were CTL=1607.27, SSG=1824.31, and GZG=2006.57, and the Dixon and Mood test indicated statistically significant differences among groups (95% confidence interval) (GZG > SSG > CTL).
  
  
  
  The infiltration of silica and glass on bulk zirconia, by two different grading methods, increased the fatigue limits of monolithic zirconia FDPs.
authors.affiliation: PhD Graduate Program in Restorative Dentistry, Prosthetic Dentistry Unit, School of Dentistry, São Paulo State University, Av. Eng Franscisco José Longo, 777, São José dos Campos, SP 12245-000, Brazil. Electronic address: reginavillefort@gmail.com.
authors.forename: Regina Furbino
authors.initials: RF
authors.lastname: Villefort
authors.affiliation: PhD Graduate Program in Restorative Dentistry, Prosthetic Dentistry Unit, School of Dentistry, São Paulo State University, Av. Eng Franscisco José Longo, 777, São José dos Campos, SP 12245-000, Brazil. Electronic address: marinamaral_85@yahoo.com.br.
authors.forename: Marina
authors.initials: M
authors.lastname: Amaral
authors.affiliation: PhD Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria, R. Floriano Peixoto, 1184, Santa Maria, RS 97015-372, Brazil. Electronic address: gabrielkrpereira@hotmail.com.
authors.forename: Gabriel Kalil Rocha
authors.initials: GK
authors.lastname: Pereira
authors.affiliation: Department of Physics, Technological Institute of Aeronautics, São José dos Campos, São Paulo, Brazil. Electronic address: moreiratiago22@gmail.com.
authors.forename: Tiago Moreira Bastos
authors.initials: TM
authors.lastname: Campos
authors.affiliation: Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA. Electronic address: yz21@nyu.edu.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: PhD Graduate Program in Restorative Dentistry, Prosthetic Dentistry Unit, School of Dentistry, São Paulo State University, Av. Eng Franscisco José Longo, 777, São José dos Campos, SP 12245-000, Brazil. Electronic address: mmbottino@uol.com.br.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.affiliation: PhD Graduate Program in Restorative Dentistry, Prosthetic Dentistry Unit, School of Dentistry, São Paulo State University, Av. Eng Franscisco José Longo, 777, São José dos Campos, SP 12245-000, Brazil; PhD Graduate Program in Oral Science, Prosthetic Dentistry Unit, Federal University of Santa Maria, R. Floriano Peixoto, 1184, Santa Maria, RS 97015-372, Brazil. Electronic address: lfvalandro@hotmail.com.
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
authors.affiliation: PhD Graduate Program in Restorative Dentistry, Prosthetic Dentistry Unit, School of Dentistry, São Paulo State University, Av. Eng Franscisco José Longo, 777, São José dos Campos, SP 12245-000, Brazil. Electronic address: marquesdemelo@gmail.com.
authors.forename: Renata Marques
authors.initials: RM
authors.lastname: de Melo
mesh_terms: D003764:Dental Materials; D003776:Dental Porcelain; D017266:Dental Prosthesis; D008422:Materials Testing; D019279:Resin Cements; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003764:Dental Materials; D019279:Resin Cements; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: Fatigue; Fixed dental prostheses; Mechanical; Silicon dioxide; Stress; Zirconium