A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Analytical Study Regarding the Behavior of Cr-Co and Ni-Cr in Saliva

Background and Objectives: The interaction between dental alloys and saliva affects both its own properties and those of metallic materials. Materials and Methods: Samples made of Cr-Co and Ni-Cr were studied. It was opted for corrosion under tension, scanning electron microscopy was used to characterize the surface morphology, and the chemical composition of the surface was assessed with the help of an Energy Dispersive Spectrometer. In vitro testing of the cytotoxic impact of the study eluates was carried out by flow cytometric analysis. Results: Pitting areas appear in the mass of the Ni-Cr alloy. Nickel, Manganese, and Cobalt dissolve and go into the solution. Corrosion is superficial in the case of the Cr-Co alloy, the corrosion points are shallow, and the amount of dissolved metal is relatively small. Mostly Nickel passes into the solution, unlike Chromium and Cobalt, which remain at this level. We noticed an increase in the viability of cell cultures in the case of Cr-Co alloy and a decrease in the number of living cells (87%) for Ni-Cr alloy. Conclusions: Common alloys (Ni-Cr and Cr-Co) are prone to corrosion, because they lack structural features that would shield the alloy from corrosion agents.

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

The oral cavity has specific and individualized characteristics, with pH, saliva flow, buffer capacity, temperature, and microorganisms content influencing oral health. Currently, the prevalence of gastroesophageal reflux disease (GERD) is constantly increasing. The objective of this study was to evaluate and compare the saliva quantity at 5 min, salivary pH, and salivary buffer capacity in patients with and without GERD, necessary for establishing the correct dental treatment plan. A Saliva-Check Buffer (GC) kit was used for the determination of salivary variables. The total number of 80 patients included in the study were divided into a study group and a control group, each containing 40 patients. Saliva quantity at 5 min was lower in patients suffering from GERD. The salivary pH of these patients turned to acid values compared to the salivary pH of controls, where the values were within the normal range. In patients with GERD, the determined salivary buffer capacity was low or very low. The use of the Saliva-Check Buffer (GC) kit is a simple, easy, non-invasive and patient-accepted method, which can also be used in the dentist’s office to assess the saliva buffer capacity and pH, variables that are important for establishing a correct dental treatment plan.

A Combined Strategy to Improve the Performance of Dental Alloys Using a New CoCrNbMoZr Alloy with Mn and Si Coated via an Anodic Oxidation Procedure

The aim of the paper is based on a combined approach to improve dental alloy performance using a new Ni-free Co–Cr composition with Mo, Nb and Zr and coated with an anodic oxidation film. The coated and uncoated samples were surface characterized by performing SEM (scanning electronic microscopy), XRD (X-rays diffraction) contact angle measurements and corrosion studies with open circuit potential, potentiodynamic polarization and EIS (impedance electrochemical spectroscopy) procedures. The SEM equipment with an EDX (Energy-dispersive X-ray spectroscopy) module indicated the sample morphology and the XRD investigations established the formation of the oxides. The electrochemical procedures were performed in Ericsson artificial saliva for coated samples in various conditions. Based on all the experiments, including the decrease in the hydrophobic character of the uncoated samples and the decrease in the hydrophilic values of the anodized alloys, the improved performance of the coated samples was established as a conclusion.