A Scoping Review on the Accuracy of Fit of Removable Partial Dentures in a Developing Digital Context

Purpose: The aim of this paper is to evaluate studies on the quality of fit of alloy removable-partial-dentures (RPDs) produced by computer-aided design/computer-aided manufacturing (CAD/CAM) and rapid prototyping (RP) technology. This paper offers a comprehensive scoping review of various methods of assessing the quality of fit of RPDs in the context of a developing digital approach to manufacturing and assessment. Methodology/Approach: A search was made using MEDLINE/PubMed, Scopus, and Science Direct to identify the studies of the accuracy of fit of RPDs. Findings: Optical and physical examination of dentures “in situ” on the model or in the patient’s oral cavity were the most commonly used methods for the assessment of fit of RPDs. Eighteen of the included studies assessed the internal fit between RPDs and oral tissues or models using either polyvinyl silicone materials as filler, calipers, photographs, and microscopes or a combination of these. Two studies used visual assessment. Most studies reported that the fit of RPDs ranged from satisfactory to excellent. However, many of these assessments seemed somewhat subjective and flawed with regard to assessing indentations of the framework into a model or distortion. Two papers used a new method of computer-based superimposition which included a color map of discrepancies to assess the fit of the machine-produced RPDs offering possibilities to quantify the assessment of fit, perhaps leading to a more objective assessment. Despite the limited number of clinical trials, the available evidence was thought to reinforce the claim that the fit of RPDs fabricated digitally was acceptable. Conclusion: The recent introduction of color maps to compare the differences between the fitting surface and the model is promising. However, a new method for displaying discrepancies shown by color maps is introduced, which could lead to a more quantitative assessment

Corrosion inhibition of the EtOH extract of Zygophyllum Fabago for carbon steel in 1M HCl

Natural extracts have found wide application in preserving metallic materials against corrosion. They are readily available, non-toxic, environmentally friendly, naturally degradable, highly effective and renewable. In this study, we used the EtOH extract of Zygophyllum Fabago (ZF) as a corrosion inhibitor for carbon steel in a molar hydrochloric acid solution. GC-MS analysis of the Zygophyllum Fabago oil extract revealed the presence of 18 compounds, of which vanillin (VN) was the main component at 27.78% by weight. The influence of ZF on corrosion inhibition was examined using electrochemical techniques such as open circuit potential (OCP), polarization curves (PC) and impedance spectroscopy (EIS), as well as scanning electron microscopy coupled to elemental analysis (SEM/EDX). The results show that ZF extract acts effectively as a mixed corrosion inhibitor, with cathodic activity predominating. Inhibition efficiency increased in proportion to inhibitor concentration and immersion time, reaching a rate of 87%. This protective effect can be explained by the formation of a protective layer on the steel surface. The adsorption of ZF on the steel surface follows the Langmuir isotherm, which is characterized by the formation of a protective layer on the steel surface. The adsorption of ZF on the steel surface follows the Langmuir isotherm, characterized by a physisorption mechanism. To confirm the experimental results, we carried out a theoretical study using Density Functional Theory (DFT) and Molecular Electrostatic Surface Potential (MESP), In order to have a clear understanding of the inhibition and adsorption mechanisms of various constituents of ZF on steel