Ceramic Pressed to Metal Versus Feldspathic Porcelain Fused to Metal: A Comparative Study of Bond Strength

Purpose: The aim of this study was to compare the debond/crack initiation strength (D/CIS) of a leucite-based low-fusing ceramic pressed (PC) to metal and feldspathic porcelain (FP) fused to metal. Materials and Methods: Forty rectangular metal specimens, 20 noble alloy (NA; gold-palladium) and 20 base metal alloy (BA; cobalt-chromium) were fabricated per ISO 9693:1999 standards (25.0 mm 3 0.5 mm 3 3.0 mm). Ten samples in each group received FP and the remaining 10 received PC. The samples in the PC group underwent wax pattern build-ups and subsequent investing and casting. The ceramic dimensions in all four groups were 8.0 mm 3 1.0 mm 3 3.0 mm. The final metal-ceramic specimen thickness was 1.5 mm. All specimens were subject to the Schwickerath crack-initiation three-point bending test at a crosshead speed of 1.5 mm/min. Metal-ceramic fracture loads were recorded in Newtons and D/CIS was calculated using the formula: tb = k × Ffail. Results: Mean D/CIS were as follows: BA-FP: 36.11 ± 2.31 MPa, NA-FP: 42.64 ± 1.94 MPa, BA-PC: 37.47 ± 6.02 MPa, and NA-PC: 47.94 ± 3.92 MPa. A 2-way ANOVA revealed no significant difference in D/CIS values between the four groups. A statistically significant difference was noted when comparing the mean D/CIS values obtained between the two metal alloys used (NA: 45.29 MPa and BA: 36.79 MPa). Conclusion: No differences (P > .05) in mean D/CIS were found between the low-fusing ceramic pressed to metal and the FP fused to metal. A higher mean D/CIS (P > .05) was found for the NA compared to the BA, with both ceramics tested.