Fracture behavior of lithia disilicate- and leucite-based ceramics.
OBJECTIVE
This study was designed to characterize the fracture behavior of ceramics and test the hypothesis that variation in strength is associated with a variation in fracture toughness.


METHODS
The following four groups of 20 bar specimens (25 x 4 x 1.2 mm) were fabricated (ISO standard 6872): E1, a hot-pressed leucite-based core ceramic (IPS Empress); E2, a hot-pressed lithia-based core ceramic (IPS Empress 2); ES, a hot-pressed lithia-based core ceramic (Experimental); and GV, a glass veneer (IPS Empress2 body). Specimens were subjected to four-point flexure loading in 37 degrees C distilled water. Fractographic analysis was performed to determine the fracture origin (c) for calculation of fracture toughness (KIC). Weibull analysis of flexure strength (sigma) data was also performed.


RESULTS
Differences in mean sigma and KIC were statistically significant for E1 and GV (p<0.05). These differences are associated with processing effects and composition.


CONCLUSIONS
The higher mean sigma and KIC values of E2 and ES core ceramics suggest potentially improved structural performance compared with E1 although the Weibull moduli of E1 and E2 are the same.
Della Bona
Alvaro
A
School of Dentistry, The University of Passo Fundo, P.O. Box 611/613, Passo Fundo, RS 99001 970, Brazil. dbona@upf.br
Mecholsky
John J
JJ
Anusavice
Kenneth J
KJ
D000538:Aluminum Silicates; D000704:Analysis of Variance; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D004548:Elasticity; D019544:Equipment Failure Analysis; D005898:Glass; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D016019:Survival Analysis
D000538:Aluminum Silicates; C075815:IPS-Empress ceramic; C493120:lithia disilicate; D003776:Dental Porcelain; C078519:leucite