Corrosion resistance and biocompatibility of physical vapour deposition coatings for dental applications

Abstract

Abstract Titanium nitride coatings might conceivably improve the corrosion behaviour of dental alloys. To assess this possibility, rest potential and potentiodynamic polarization measurements were carried out on six non-precious and precious metal reduced dental alloys. TiN was deposited by 10 different coating methods on the alloys. It was found that the corrosion resistance depends on the base material, the structure of the deposited titanium nitride and the coating method. In many cases the coatings are permeable to the surrounding electrolyte. Therefore electrochemical reactions can occur with the base material and provoke microscopic and occasionally even macroscopic lesions of the deposits. Recording of the rest potential of the untreated material in comparison with the coated material yields values in the region of passivity of the base alloy. Thus the coatings do not aggrevate corrosion behaviour. Current density vs. potential measurements exhibit a markedly lower corrosion current as compared with the base metal even for coatings permeable to the electrolyte. Furthermore, the investigation revealed impermeable deposits. Thus the applied electrochemical examination could be used as an easy quality assurance for thin film coatings. Biological experiments were carried out on impermeable specimens to prove the biocompatibility of the coatings. No harmful effect was found on cell growth and cell life, so the TiN surface belongs to the class of cell-biological acceptance.