<prompt> Cutting edges of the orthodontic instruments are made up ofAustenitic carbon steelMartensitic carbon steelFerritic carbon steelCementite carbon steel  <response>: Because of their high yield strength and hardness, martensitic stainless steels are used for surgical and cutting instruments. The austenitic stainless steels are the most corrosion-resistant of the three major types and are the stainless steels used for orthodontic wires, endodontic instruments, and crowns in pediatric dentistry.Ferritic Stainless Steels: These alloys provide good corrosion resistance at a low cost, when high strength is not required. They cannot be hardened by heat treatment or readily work-hardened. Consequently, they have little application in dentistry.Ref: Phillips 12th edition page 406 