title: Effect of mechanical cycling on the flexural strength of densely sintered ceramics.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of mechanical cycling on the biaxial flexural strength of two densely sintered ceramic materials.
  
  
  METHODS
  Disc shaped zirconia (In-Ceram Zirconia) and high alumina (Procera AllCeram) ceramic specimens (diameter: 15 mm and thickness: 1.2 mm) were fabricated according to the manufacturers' instructions. The specimens from each ceramic material (N=40, n=10/per group) were tested for flexural strength either with or without being subjected to mechanical cycling (20,000 cycles under 50 N load, immersion in distilled water at 37 degrees C) in a universal testing machine (1 mm/min). Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha=0.05).
  
  
  RESULTS
  High alumina ceramic specimens revealed significantly higher flexural strength values without and with mechanical cycling (647+/-48 and 630+/-43 MPa, respectively) than those of zirconia ceramic (497+/-35 and 458+/-53 MPa, respectively) (p<0.05). Mechanical cycling for 20,000 times under 50 N decreased the flexural strength values for both high alumina and zirconia ceramic but it was not statistically significant (p>0.05).
  
  
  CONCLUSIONS
  High alumina ceramic revealed significantly higher mean flexural strength values than that of zirconia ceramic tested in this study either with or without mechanical cycling conditions.
authors.affiliation: São Paulo State University, Department of Dental Materials and Prosthodontics, São José dos Campos, Brazil.
authors.forename: Koiti Marco
authors.initials: KM
authors.lastname: Itinoche
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.forename: Denise
authors.initials: D
authors.lastname: Oyafuso
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D018583:Pliability; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: C105314:AllCeram; C485633:In-Ceram Zirconia; D014867:Water; D003776:Dental Porcelain; D000537:Aluminum Oxide