Role of investment interaction layer on strength and toughness of ceramic laminates.
OBJECTIVE
The aim of this study was to test the hypothesis that the interaction of a core ceramic with investment material can significantly reduce the flexural strength and the fracture toughness of core/veneer ceramic laminates.


METHODS
Ceramic composites were prepared from experimental core and experimental veneer and Empress 2 core and Empress 2 veneer ceramics. Four divesting techniques were used for each bilayer ceramic group. Core surfaces were etched with 1% HF solution for 15 or 30 min and grit blasted with 100 microm Al2O3 particles for 15 or 30 s. The effect of treatment on strength was analyzed statistically by means of two-way ANOVA. A linear regression graph was made for each group to analyze the relationship between flexural strength and the dimensions of critical cracks.


RESULTS
The four surface divesting treatments produced no significant differences (p > 0.05) between the mean flexural strengths and the mean fracture toughnesses. However, groups with different core/veneer combinations showed statistically significant differences (p < or = 0.05) between the mean flexural strengths and between the mean fracture toughnesses. The Empress 2 core/experimental veneer combination exhibited the greatest fracture toughness values. The Empress 2 core/Empress 2 veneer combination exhibited the lowest mean fracture toughness and lowest mean flexural strength.


CONCLUSIONS
The investment interaction layer does not have a significant effect on the flexural strength and fracture toughness of the bilayer ceramic laminates for interfaces that are coherent and well bonded. However, the core/veneer combination of materials does affect the strength of bilayer ceramic laminates. The existence of global residual stress is the most likely reason for the observed strength increases.
Department of Dental Biomaterials, College of Dentistry, University of Florida, P.O. Box 100405, Gainesville, FL 32610-0405, USA. btaskonak@dental.ufl.edu
Burak
B
Taskonak
Kenneth J
KJ
Anusavice
John J
JJ
Mecholsky
D000134:Acid Etching, Dental; D020906:Air Abrasion, Dental; D000537:Aluminum Oxide / Q000737:chemistry; D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D004548:Elasticity; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D016014:Linear Models; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D018583:Pliability; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
C118557:Empress 2; D018020:Lithium Compounds; D003776:Dental Porcelain; D000537:Aluminum Oxide; D006858:Hydrofluoric Acid