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The purpose of this study was to compare shear bond strengths of cast Ni-Cr and Co-Cr
alloys and the laser-sintered Co-Cr alloy to dental porcelain.
Dental porcelain was applied on two cast and one laser-sintered base metal alloy.
Ten specimens were prepared for each group for bond strength comparison. ANOVA followed
by Tukey HSD multiple comparison test (alpha=0.05) was used for statistical analysis.
Fractured specimens were observed with a stereomicroscope to classify the type of
failure after shear bond testing.
While the mean shear bond strength was highest for the cast Ni-Cr metal-ceramic specimens
(81.6+/-14.6 MPa), the bond strength was not significantly different (P>0.05) from
that for the cast Co-Cr metal-ceramic specimens (72.9+/-14.3 MPa) and the laser-sintered
Co-Cr metal-ceramic specimens (67.0+/-14.9 MPa). All metal-ceramic specimens prepared
from cast Ni-Cr and Co-Cr alloys exhibit a mixed mode of cohesive and adhesive failure,
whereas five of the metal-ceramic specimens prepared from the laser-sintered Co-Cr
alloy exhibited the mixed failure mode and five specimens exhibited adhesive failure
in the porcelain.
The new laser-sintering technique for Co-Cr alloy appears promising for dental applications,
but additional studies of properties of the laser-sintered alloy and fit of castings
prepared by this new technique are needed before its acceptance into dental laboratory
Laser sintering of Co-Cr alloy seems to be an alternative technique to conventional
casting of dental alloys for porcelain fused to metal restorations.