Abstract

Background: Environmental concerns are increasing rapidly, and the industry

and public are more concerned about natural resources and recycling. Today, it is equally important to take into account cost, ecological factors in production and recycling of materials used in various fields.

Purpose: The aim of this study was to evaluate corrosion rate, compositional changes and ion release of recasted Ni-Cr dental casting alloy

Materials and Methods: Commercially available Ni -Cr alloy (Bellabond) was used in the study. The recasting was done without any addition of new alloys and recasted up to six times. Corrosion rate was determined by Tafel extrapolation method in artificial saliva in pH 2.3, 6.7 and in 0.9% saline solution at pH 7.3. The compositional changes were studied by Inductively coupled Plasma – Atomic emission Spectroscopy (ICP-AES) method. Ion release during storage in artificial saliva and saline solution for one week and four weeks was detected by using
atomic absorption spectroscopy (AAS).
Results: The corrosion rate was found slightly increased with recasting numbers up to six times. The quantities of ions released increased as the recasting number increases. These changes were not clinically significant. During recasting procedure, there was a change in their alloy compositions, which increases the corrosion rate in recasted alloys.
Conclusion: The recasting technique can be accepted in dental practices. This
study showed the possibilities of safe usage of recasted alloys up to certain generations in dentistry and in later stages if it is not suitable for dentistry it can be directed to other fields of industries, where the biocompatibility is not a major requirement. This lowers the environmental burden, health hazards and protects imbalance of natural resources

Key words: Waste dental casting alloys, corrosion, Ni-Cr, Ion release, Artificial saliva, Saline solution