Evaluation of metal ion release and corrosion resistance of ZrO2 thin coatings on the dental Co–Cr alloys

Objectives. The aim of this study was to determine if electrolytic ZrO2 thin coatings increased the corrosion resistance and decreased the metal ion release of dental cobalt–chromium alloys. Methods. Dental Co–Cr alloys were electrolytically deposited with ZrO2 ceramic coatings using a 0.0625 M ZrO(NO3)2 solution, at various potentials, for 500 s. The electrolytic ZrO2 gel-coated specimens were annealed at 723 K for 1 h in air. Scanning electron microscopy (SEM) was used to observe the morphology of the ZrO2 ceramic coatings on Co–Cr alloys. A dynamic polarization test was used to compare the corrosion resistance of the ZrO2 coated and uncoated Co–Cr alloys in artificial saliva. Metal ion concentrations were determined with graphite furnace atomic absorption spectroscopy (AAS). Results. The SEM micrographs showed that the Co–Cr alloy can be coated with zirconia oxide at −0.7 V more homogeneously and more completely than at −1.5 V. The polarization curves indicated that the ZrO2 coating on Co–Cr alloys annealed at 723 K for 1 h in air exhibited better corrosion resistance in artificial saliva. The results of the AASs showed that the ZrO2-coated Co–Cr alloys decreased chromium ion release levels, as compared with the uncoated Co–Cr alloys. The scratch test indicated a good bond strength between the ZrO2 and Co–Cr alloy. Significance. The electrolytically deposited ZrO2 coatings on Co–Cr alloys may improve the corrosion resistance and decrease the release of metal ions. It is suggested that the electrolytic ZrO2 coating method could have a widespread application in dentistry in the future.