Effect of Bonding Agent on Metal‐Ceramic Bond Strength between Co‐Cr Fabricated with Selective Laser Melting and Dental Feldspathic Porcelain

Abstract

Purpose:To investigate the effect of bonding agent on the bonding strength between Co-Cr dental alloy, prepared by selective laser melting (SLM), and feldspathic porcelain. Materials and Methods:The experiments were conducted according to ISO 9693 and the conventional protocols for the production of metal-ceramic dental restorations. After Al 2 O 3 air-particle abrasion, metal substrates of Co-Cr dental alloy specimens were bonded, using bonding agent (25 specimens), with dental porcelain positioned in layers (opaque, dentin, enamel). Control specimens (25) were also produced without bonding agent. Bonding strength was measured using 3-point bending tests, and the results were statistically analyzed using the t-test and Weibull statistics. Elemental (by SEM/EDS) and crystallographic analyses (by XRD) were conducted on the bonding agent, along cross sections of alloy-porcelain interfaces, and on fracture surfaces. Results: Cohesive fracture occurred (on the porcelain side). The application of the bonding agent decreased the average bonding strength (from 42.27 ± 5.85 to 36.25 ± 3.26 MPa, P = 0.00006), attributed to the nonexisting reaction between the TiO 2rich bonding agent and the Co-Cr alloy, but it increased the Weibull modulus (from 7.84 to 12.16), which reflects the reliability of the bond in the tested metal-ceramic specimens. Conclusions: Although the application of bonding agent slightly decreased the bonding strength, all the measured values of the metal-ceramic specimens produced by the SLM technique, with or without the bonding agent, are markedly higher than the minimum value required by ISO 9693 (25 MPa). Moreover, the use of bonding agent favors the increase of the Weibull modulus.

Effects of Bonding Agents on Metal-Ceramic Bond Strength of Co-Cr Alloys Fabricated by Selective Laser Melting

“…This supports the suggestion of the manufacturers that metal bonding agents affect bond strength by reducing the thickness of the oxide layer and compensating for differences in coefficient of temperature expansion between ceramic and Co-Cr alloy. A previous study reported that use of a metal bonding agent increased the Weibull modulus [ 37 ]. This means that the presence of bonding agent narrowed the scatter of values of bond strength; in other words, a more reliable interface between ceramic and metal was produced.…”

Glass‐ceramics in the CaO–MgO–Al2O3–SiO2 system as potential dental restorative materials

“…The results of three‐point bending strength tests (Autograph AGS‐H; Shimadzu), carried out with a crosshead speed of 1.0 mm/min and a span of 25 mm between the supporting rods, allowed the calculation of the flexural strength ( σ ) and the modulus of elasticity ( E ) by using the following Equations () and (3), 2,12 respectively:andwhere, F is the load at fracture load, and L , w , and h are the span between the supporting rods, and the specimen width and thickness (25, 4, and 3 mm), respectively. The slope of the load versus displacement is denoted with m. Ten specimens for each composition (i.e., n = 10, for each group) were used.…”

Simplified Acid Treatment Technique in Cobalt-Chromium Alloys: Effect on Metal-Ceramic Bond Strength

“…Mechanical bonding is related to compressive forces from the difference in the coefficients of thermal expansion of metal and ceramics 10 , or to the surface roughness and retentive edges in the metal structure, which may favor wettability 12 . Chemical bond occurs when the elements of dental alloys, such as cobalt, chromium, and molybdenum 13 , undergo surface oxidation forming ion channels, where the diffusion of atoms present in metal-ceramic interface occurs 13 . The composition and morphology of this oxide layer depends on the type of surface treatment performed 14 as well as interaction among atoms from both metal and ceramic 12 , which may interfere in MCBS [13][14][15] .…”

“…Chemical bond occurs when the elements of dental alloys, such as cobalt, chromium, and molybdenum 13 , undergo surface oxidation forming ion channels, where the diffusion of atoms present in metal-ceramic interface occurs 13 . The composition and morphology of this oxide layer depends on the type of surface treatment performed 14 as well as interaction among atoms from both metal and ceramic 12 , which may interfere in MCBS [13][14][15] . If the thickness of this film reduces in the sintering process, the MCBS decreases 3 .…”

“…For this reason, Co-Cr alloy manufacturers usually recommend the use of a bonding agent 13 to improve the chemical affinity between metal and ceramic.…”