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Abstract
This study evaluated the effect of three different surface conditioning methods on
the bond strength of a Bis-GMA based luting cement to six commercial dental ceramics.
Six disc shaped ceramic specimens (glass ceramics, glass infiltrated alumina, glass
infiltrated zirconium dioxide reinforced alumina) were used for each test group yielding
a total number of 216 specimens. The specimens in each group were randomly assigned
to one of the each following treatment conditions: (1) hydrofluoric acid etching,
(2) airborne particle abrasion, (3) tribochemical silica coating. The resin composite
luting cement was bonded to the conditioned and silanized ceramics using polyethylene
molds. All specimens were tested at dry and thermocycled (6.000, 5-55 degrees C, 30
s) conditions. The shear bond strength of luting cement to ceramics was measured in
a universal testing machine (1 mm/min).
In dry conditions, acid etched glass ceramics exhibited significantly higher results
(26.4-29.4 MPa) than those of glass infiltrated alumina ceramics (5.3-18.1 MPa) or
zirconium dioxide (8.1 MPa) (ANOVA, P<0.001). Silica coating with silanization increased
the bond strength significantly for high-alumina ceramics (8.5-21.8 MPa) and glass
infiltrated zirconium dioxide ceramic (17.4 MPa) compared to that of airborne particle
abrasion (ANOVA, P<0.001). Thermocycling decreased the bond strengths significantly
after all of the conditioning methods tested.
Bond strengths of the luting cement tested on the dental ceramics following surface
conditioning methods varied in accordance with the ceramic types. Hydrofluoric acid
gel was effective mostly on the ceramics having glassy matrix in their structures.
Roughening the ceramic surfaces with air particle abrasion provided higher bond strengths
for high-alumina ceramics and the values increased more significantly after silica
coating/silanization.