Comparison of the bond strength of laser-sintered and cast base metal dental alloys to porcelain

Objective 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. Methods 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 (α = 0.05) was used for statistical analysis. Fractured specimens were observed with a stereomicroscope to classify the type of failure after shear bond testing. Results 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. Conclusions 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 practice. Significance Laser sintering of Co–Cr alloy seems to be an alternative technique to conventional casting of dental alloys for porcelain fused to metal restorations.