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Corrosion behavior of dental alloys processed by laser-based additive manufacturing procedures

Interactions between oral environment and dental alloys can impair metal framework of dental restorations, due to corrosion compounds. The aim of the study was to determine corrosion resistance of dental Co-Cr alloys obtained by modern technologies, as selective laser sintering (SLS) and selective laser melting (SLM), depending on microstructure, pH and surface preparation. Materials and method: A commercial Co-Cr powder was used to prepare metallic plates both SLS and SLM technologies. Relief-firing under argon was conducted, and also oxide-firing. All specimens were polished. Half of them were air-blasted with 75 μm Al2O3 particles for ceramic veneering. Both polished and air-blasted samples, were divided into three groups, and exposed to different pH solutions: 2, 7 and 11. The degree of corrosion inhibition was determined for all specimens. Results: Lowest corrosion rate was observed in electrolyte with pH of 11, and the highest in pH of 2. Surface roughness pay an essential role, proved by the higher corrosion rate of the surfaces prepared for ceramic veneering. This is why corrosion behavior at metal-ceramic interfaces shows some particularities. Conclusions: Loss of adhesion at metal-ceramic interface is accentuated by oral environment through the intervention of corrosion on metal surfaces prepared for veneering.