Statement of problem
Although palladium-silver alloys have been marketed for over 3 decades for metal-ceramic restorations, understanding of the corrosion behavior of current alloys is incomplete; this understanding is critical for evaluating biocompatibility and clinical performance.
The purpose of this in vitro study was to characterize the corrosion behavior of 3 representative Pd-Ag alloys in simulated body fluid and oral environments and to compare them with a high-noble Au-Pd alloy. The study obtained values of important electrochemical corrosion parameters, with clinical relevance, for the rational selection of casting alloys.
Material and methods
The room temperature in vitro corrosion characteristics of the 3 Pd-Ag alloys and the high-noble Au-Pd alloy were evaluated in 0.9% NaCl, 0.09% NaCl, and Fusayama solutions. After simulated porcelain firing heat treatment, 5 specimens of each alloy were immersed in the electrolytes for 24 hours. For each specimen, the open-circuit potential (OCP) was first recorded, and linear polarization was then performed from –20 mV to +20 mV (versus OCP) at a rate of 0.125 mV/s. Cyclic polarization was subsequently performed on 3 specimens of each alloy from –300 mV to +1000 mV and back to –300 mV (versus OCP) at a scanning rate of 1 mV/s. The differences in OCP and corrosion resistance parameters (zero-current potential and polarization resistance) among alloys and electrolyte combinations were compared with the 2-factor ANOVA (maximum-likelihood method) with post hoc Tukey adjustments (α=.05).
The 24-hour OCPs and polarization resistance values of the 3 Pd-Ag alloys and the Au-Pd alloy were not significantly different (P=.233 and P=.211, respectively) for the same electrolyte, but significant differences were found for corrosion test results in different electrolytes (P<.001 and P=.032, respectively). No significant interaction was found between the factors of alloy and electrolyte (P=.249 and P=.713, respectively). The 3 Pd-Ag silver alloys appeared to be resistant to chloride ion corrosion, and passivation and de-alloying were identified for these alloys.
The Pd-Ag alloys test results showed excellent in vitro corrosion resistance and were equivalent to those of the high-noble Au-Pd alloy in simulated body fluid and oral environments. Passivation, de-alloying, and formation of a AgCl layer were identified as possible corrosion mechanisms for Pd-Ag alloys.
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- Metal selection.in: Rosenstiel S.F. Land M.F. Fujimoto J. Contemporary fixed prosthodontics. 5th ed. Mosby/Elsevier, St. Louis2016: 529-541
- Palladium-silver alloys: a review of the literature.J Prosthet Dent. 1989; 62: 34-37
- Evaluation of high-temperature distortion of high-palladium metal-ceramic crowns.J Prosthet Dent. 2001; 85: 133-140
- Porcelain adherence vs force to failure for palladium-gallium alloys: a critique of metal–ceramic bond testing.Dent Mater. 1998; 14: 112-119
- The corrosion behavior of palladium-silver-ceramic alloys.Dent Mater. 1989; 5: 97-100
- In vitro corrosion behavior of 13 prosthodontic alloys.Quintessence Int. 1992; 23: 279-287
- Cerium oxide as a silver decolorizer in dental porcelains.Dent Mater. 1998; 14: 365-369
- Electrochemical characteristics of high-Pd alloys in relation to Pd-allergy.Dent Mater. 2000; 16: 266-273
- Dealloying and electroformation in high-Pd dental alloys.Dent Mater. 2000; 16: 374-379
- In vitro corrosion and tarnish analysis of the Ag-Pd binary system.J Dent Res. 1981; 60: 707-715
- Standard potential of the silver-silver chloride electrode.Pure and Appl Chem. 1978; 50: 701-706
- Atlas of electrochemical equilibria in aqueous solution.Pergamon Press, Oxford, UK1966: 258-363 (393-405, 428-35, 436-42, 475-84)
- The mechanism of corrosion of palladium-silver binary alloys in artificial saliva.Biomaterials. 2005; 26: 1605-1611
- Effect of mucin on the corrosion behaviour of dental casting alloys.J Oral Rehabil. 1989; 16: 589-596
- Corrosion resistance of cobalt-chromium and palladium-silver alloys used in fixed prosthetic restorations.Eur J Oral Sci. 2005; 113: 90-95
- Influence of shape and finishing on the corrosion of palladium-based dental alloys.J Adv Prosthodont. 2015; 7: 56-61
- In vitro cytotoxicity of metallic ions released from dental alloys.Odontology. 2016; 104: 136-142
- New high-palladium casting alloys: Part 1. Overview and initial studies.Int J Prosthodont. 1991; 4: 265-275
- Potentiodynamic polarization study of the in vitro corrosion behavior of high-palladium alloys in five media.J Prosthet Dent. 2002; 87: 86-93
- Corrosion of gold and amalgam placed in contact with each other.J Dent Res. 1963; 42: 1183-1197
- Maximum-likelihood estimation for the mixed analysis of variance model.Biometrika. 1967; 54: 93-108
- Corrosion testing by potentiodynamic polarization in various electrolytes.Dent Mater. 1992; 8: 241-245
Published online: September 28, 2017
Supported by National Institute of Dental and Craniofacial Research (grant DE10147).
This study was based on a portion of a dissertation submitted by D.S., in partial fulfillment of the PhD degree, Graduate School of The Ohio State University.
© 2017 by the Editorial Council for The Journal of Prosthetic Dentistry.