Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.
OBJECTIVE
This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions.


METHODS
Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05).


RESULTS
Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic.


CONCLUSIONS
Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.
Mesquita
A M M
AM
Department of Dental Materials and Prosthodontics, São Paulo State University at São José dos Campos, Brazil.
Ozcan
M
M
Souza
R O A
RO
Kojima
A N
AN
Nishioka
R S
RS
Kimpara
E T
ET
Bottino
M A
MA
D002516:Ceramics; D001840:Dental Bonding; D003776:Dental Porcelain; D003801:Dental Veneers; D004868:Equipment Failure; D005898:Glass; D006358:Hot Temperature; D006813:Humidity; D066298:In Vitro Techniques; D008422:Materials Testing; D011897:Random Allocation; D033081:Shear Strength; D013997:Time Factors
C483026:In-Ceram Alumina; C485633:In-Ceram Zirconia; C556625:VITA VM7; D003776:Dental Porcelain