Abstract
The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.
Highlights
Corrosion can be described as the deterioration of materials by aggressive action of the atmosphere and/or oral fluids
The potential slightly increased as soon as the samples were immersed in the Fusayama’s solution and stabilized after 30 min, except for the Ni-Cr-4Ti that the potential decreased versus time
50 mL of of artificial solution (AS) was subjected to chemical analysis using an atomic absorption spectrometer (GBC model 904AA, Scientific Equipment Pty, Victoria, Australia)
Summary
Corrosion can be described as the deterioration of materials by aggressive action of the atmosphere and/or oral fluids. This term is used for metallic materials, and the mechanism of corrosion is mainly electrochemical when considering those environments [1]. The degradation of a material is said to be continuous in the mouth due to abrasion of foods, liquids and toothbrushes [2] originating metallic ions and/or debris These ions and/or debris released from dental alloys can induce adverse biological reactions such as gingival swelling and erythema, mucosal pain or lichenoid reactions. If these ions are not tolerated by the organism, the organism may be injured (toxicity and risk of sensitization) and if they are absorbed in sufficient quantity, clinical implant failure can happen due to osteolysis, cutaneous allergic reactions, or remote site accumulation [3]
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