Effect of mechanical cycling on the flexural strength of densely sintered ceramics.
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.
Itinoche
Koiti Marco
KM
São Paulo State University, Department of Dental Materials and Prosthodontics, São José dos Campos, Brazil.
Ozcan
Mutlu
M
Bottino
Marco Antonio
MA
Oyafuso
Denise
D
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
C105314:AllCeram; C485633:In-Ceram Zirconia; D014867:Water; D003776:Dental Porcelain; D000537:Aluminum Oxide