Cobalt-Chromium Alloys

Cobalt-chromium (Co-Cr) alloys are widely used base metal alloys in dentistry, valued for their high strength, rigidity, corrosion resistance, and cost-effectiveness. The typical composition includes 60-65% cobalt, 25-30% chromium, and smaller amounts of molybdenum, tungsten, and carbon. The chromium content forms a passive oxide layer that provides excellent corrosion resistance. Traditional applications include removable partial denture frameworks, where Co-Cr's high modulus of elasticity allows thinner, lighter frameworks compared to gold alloys. The material is also used for PFM crown and bridge substructures, implant bars, and full-arch implant frameworks. Its strength and rigidity make it particularly suitable for long-span bridges. Modern manufacturing of Co-Cr dental restorations increasingly uses CAD/CAM milling and selective laser melting (SLM) 3D printing, which produce restorations with improved accuracy and reduced porosity compared to traditional casting. Co-Cr alloys are generally well-tolerated, though rare allergic reactions to cobalt or chromium have been reported. They offer an economical alternative to precious metal alloys without significant compromise in clinical performance.