Experimental Study Regarding the Behavior at Different pH of Two Types of Co-Cr Alloys Used for Prosthetic Restorations

Abstract

Cobalt-chromium (Co-Cr) alloys are widely utilized in dentistry. The salivary pH is a significant factor, which affects the characteristics and the behavior of dental alloys through corrosion. This study aimed to evaluate the corrosion behavior in artificial saliva with different pH values (3, 5.7, and 7.6) of two commercial Co-Cr dental alloys manufactured by casting and by milling. Corrosion resistance was determined by the polarization resistance technique, and the tests were carried out at 37 ± 1 °C, in Carter Brugirard artificial saliva. After the electrochemical parameters, it can be stated that the cast Co-Cr alloy has the lowest corrosion current density, the highest polarization resistance, and the lowest speed of corrosion in artificial saliva with pH = 7.6. In the case of milled Co-Cr alloy, the same behavior was observed, but in artificial saliva with pH = 5.7, it recorded the most electropositive values of open circuit potential and corrosion potential. Although both cast and milled Co-Cr alloys presented a poorer corrosion resistance in artificial saliva with a more acidic pH value, the milled Co-Cr alloy had better corrosion behavior, making this alloy a better option for the prosthetic treatment of patients suffering from GERD.

Evaluation of the Behavior of Two CAD/CAM Fiber-Reinforced Composite Dental Materials by Immersion Tests

“…Additionally, metals have great strength, are harder than natural teeth, have a very good thermal conductivity, and inferior thermic insulation in comparison to the natural teeth [ 10 ]. Furthermore, free ions released in the oral cavity because of metal corrosion can cause problems regarding the function of the prosthetic restoration and can influence the biological response to the dental alloy [ 11 ]. For these reasons (the disputable aesthetics of dental metals and alloys, as well as their physical and chemical properties), the research for other types of dental materials, preferably metal-free, are sustained [ 12 , 13 ].…”

Materials and manufacturing techniques trends in prosthetic dentistry.

“…In terms of biocompatibility and feasibility of the dental prosthetic restorations fabricated from metallic dental alloys, it can be stated that the corrosion resistance of these biomaterials in the oral cavity, which is known to be a harsh environment that is characterized by pH and temperature variation, but also by the bacterial load [3,4], is of significant importance and should be addressed accordingly. Thus, F. Bechir et al [5] analyzed the corrosion behavior in Carter Brugirard artificial saliva with different pH values, of 3, 5.7, and 7.6, respectively, at human body temperature (37 ±1 °C) of two Co-Cr dental alloys commercially available, in order to establish the influence of gastroesophageal reflux disease (GERD) on the investigated alloys. The investigated samples of Co-Cr dental alloy were manufactured by casting and milling (CAM).…”

“…The investigated samples of Co-Cr dental alloy were manufactured by casting and milling (CAM). GERD pathology is characterized by the pH variation of the oral fluid toward more acidic values, which can dramatically influence the characteristics, properties, and behavior of dental materials, including that of metallic dental alloys [5]. The corrosion tests highlighted that both Co-Cr dental alloys, which were cast and milled, have a better corrosion behavior at higher pH values of artificial saliva.…”

Comparative Study of Salivary pH, Buffer Capacity, and Flow in Patients with and without Gastroesophageal Reflux Disease

“…Salivary buffers are able to invert the low pH of dental plaque, and permit oral clearance, therefore obviating the enamel demineralization [ 17 ]. Through its buffering capacity, saliva also plays a major role in maintaining the teeth integrity (by controlling the demineralization, by the continuous promotion of enamel remineralization, and by providing the main protection against tooth erosion) [ 23 ], and of prosthetic restorations (by preventing the apparition of dental alloys corrosion) [ 24 ]. The concentration of buffering systems (mainly bicarbonate) grows with the rate of saliva secretion, and the buffering capacity can be ineffective in the case of low flow of unstimulated saliva [ 11 , 17 ].…”

“…In GERD, the reduced pH of the oral fluids influences the characteristics, properties, and behavior of dental materials, leading to a decreased life of prosthetic restorations used in the dental treatment of patients suffering from the disease [ 24 , 25 ].…”