Abstract
Cobalt-chromium-based (CoCr) alloys are more frequently used in dental field compared with the precious metal alloys because they are cheaper, resistant to corrosion and compatible with dental ceramic that is used as aesthetic component of prosthetics. The physical properties of CoCr based alloys available on the dental materials market are variable, depending on the concentrations of elements such as tungsten (W) and molybdenum (Mo). This study assessed the corrosion behavior and surface properties of five commercially available CoCr alloys with different contents of W and Mo. Firstly, the alloy casted samples were analyzed from the corrosion's point of view in artificial saliva (Ringer Solution). A current potential was applied to the surfaces for 120min, in an open circuit. Secondly, the specimens of dental casting alloys (CoCrMo, CoCrMoW and CoCrW alloys) were oxidized at high-temperature. All the samples were analyzed with a scanning electron microscope (SEM) and microscopic images of the oxide films on the alloys surface were captured. The high content W alloys showed a linear and stable anticorrosion tendency in an open circuit current potential applied to the surface, in artificial saliva compared with the alloy without W, whose passive layer broke and recreated at the same potential. The SEM analyses showed that the CoCr-based alloys with 15% wt. content of W had created a stable oxide layer, with a higher density than the alloy without W. In conclusion, the stability and resistance of oxide passive layer on CoCrW alloys surface had better anti-corrosion properties than the CoCrMo alloys. CoCr-based alloys with W content can be used as a single casted alloy for prosthetics dental structures, avoiding bimetallism and the corrosive effect in contact with saliva.
Highlights
Alloys have been used in medicine since 1900s in orthopedics, and in dental medicine for their mechanical and physical properties
The first test was performed for measuring the tendencies of the alloys to create a surface passive layer in electrolytic liquid, as anticorrosion response, in open circuit potential (OCP)
The open circuit potential was measured for 120 minutes; the curve aspects and the tendency of potential to achieve 0 mV value were evaluated
Summary
Alloys have been used in medicine since 1900s in orthopedics, and in dental medicine for their mechanical and physical properties. The main advantage of non-precious alloy is represented by the surface-passive oxide layers that provide the biocompatibility in the oral cavity and corrosion resistance [1]. The acid medium of the oral cavity and the changes in saliva composition influence the behavior of dental alloys surface in the oral cavity [2]. The problem concerning corrosion is represented by the products released in saliva when the materials are introduced in oral cavity as prosthodontics structures [3,4]. The commercial dental alloys that are used for casting the prosthetics parts have high biocompatibility properties [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
