Flexural strength of glass-infiltrated zirconia/alumina-based ceramics and feldspathic veneering porcelains.
OBJECTIVE
To compare the flexural strength of two glass-infiltrated high-strength ceramics and two veneering glass-ceramics.


METHODS
Four ceramic materials were tested: two glass-infiltrated high-strength ceramics used as framework in metal-free restorations [In-Ceram Zirconia IZ (Gr1) and In-Ceram Alumina IA (Gr2)], and two glass-ceramics used as veneering material in metal-free restorations [Vita VM7 (Gr3) and Vitadur-alpha (Gr4)]. Bar specimens (25 x 5 x 2 mm3) made from core ceramics, alumina, and zirconia/alumina composites were prepared and applied to a silicone mold, which rested on a base from a gypsum die material. The IZ and IA specimens were partially sintered in an In-Ceram furnace according to the firing cycle of each material, and then were infiltrated with a low-viscosity glass to yield bar specimens of high density and strength. The Vita VM7 and Vitadur-alpha specimens were made from veneering materials, by vibration of slurry porcelain powder and condensation into a two-part brass Teflon matrix (25 x 5 x 2 mm3). Excess water was removed with absorbent paper. The veneering ceramic specimens were then removed from the matrix and were fired as recommended by the manufacturer. Another ceramic application and sintering were performed to compensate the contraction of the feldspar ceramic. The bar specimens were then tested in a three-point bending test.


RESULTS
The core materials (Gr1: 436.1 +/- 54.8; Gr2: 419.4 +/- 83.8) presented significantly higher flexural strength (MPa) than the veneer ceramics (Gr3: 63.5 +/- 9.9; Gr4: 57.8 +/- 12.7).


CONCLUSIONS
In-Ceram Alumina and Zirconia were similar statistically and more resistant than VM7 and Vitadur-alpha.
São José dos Campos Dental School, Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, Brazil.
Marco Antonio
MA
Bottino
Susana M
SM
Salazar-Marocho
Fabiola P P
FP
Leite
Vanessa C
VC
Vásquez
Luiz Felipe
LF
Valandro
D000538:Aluminum Silicates / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D005898:Glass / Q000737:chemistry*; D005899:Glass Ionomer Cements; D008422:Materials Testing; D018583:Pliability; D017680:Potassium Compounds / Q000737:chemistry*
D000538:Aluminum Silicates; D003764:Dental Materials; D005899:Glass Ionomer Cements; C483026:In-Ceram Alumina; C485633:In-Ceram Zirconia; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar