Fatigue Behavior of the Resinous Cement to Zirconia Bond
Seto, K. B., McLaren, E. A., Caputo, A. A. and White, S. N. (2013),
Fatigue Behavior of the Resinous Cement to Zirconia Bond. Journal of
Prosthodontics. doi: 10.1111/jopr.12053
Abstract
Purpose
Resinous
cements are widely used for luting zirconia restorations. Adhesive
failures have occurred at the cement/zirconia interface, rather than at
the cement/dentin interface, suggesting that the cement/zirconia bond
may lack durability; however, few comprehensive, comparative evaluations
of fatigue effects have been reported. The rate of fatigue-induced loss
of bond strength may be a more important predictor of long-term success
than a single snapshot of bond strength after an arbitrary number of
thermocycles. Previous studies have failed to identify trends by
investigating bond strengths at several different numbers of cycles.
This may result in invalid conclusions about which cements have superior
bond strengths. The purpose of this study was to investigate the
effects of artificial aging by thermocycling and resinous cement type on
bond strengths to zirconia.
Materials and Methods
The
effect of the number of thermocycles (0, 1, 10, 100, 1000, and 10,000)
on the bond strengths of five resinous cements, two of which were used
with and without a primer, and an oxygen-inhibiting gel, was studied.
Specimens were randomly assigned to thermocycle number/cement-type test
groups. Because zirconia has a very low thermal diffusivity,
exceptionally long thermocycle dwell times were used. Cylinders of
zirconia were bonded end-to-end. One end of each bonded specimen was
insulated, specimens were thermocycled and tested in shear, and bond
strengths were calculated and analyzed.
Results
Two-way
ANOVA revealed that the effects of cement type, the number of
thermocycles, and their interaction all significantly affected bond
strength (p < 0.0001). By 10,000 cycles, most cements had
lost at least half of their initial bond strengths, and two cements
effectively recorded zero bond strengths. Failure modes were cement
specific, but adhesive modes predominated. Fatigue resistance of two
cements was greatly improved by use of a primer and an oxygen-inhibiting
gel, as recommended by their respective manufacturers.
Conclusions
Both
the type of resin cement and the number of thermocycles influenced bond
strength. Fatigue through thermocycling affected different cement types
in different ways. Some materials displayed more rapid loss of bond
strength than others. Cements differed in their failure modes.
Comments