The effect of disinfecting solutions on bending properties and weight changes of Co-Cr and Ti-6Al-7Nb alloys for dentures

Effect of sanitizing solutions on cobalt-chromium alloys for dental prostheses: A systematic review of in vitro studies

STATEMENT OF PROBLEM

Given the wide use of cobalt-chromium (Co-Cr) alloys, especially for removable partial dentures, and the importance of chemical solutions to complement the cleaning of dental prostheses, safe disinfection products should be identified for the regular decontamination of Co-Cr dental prostheses.

PURPOSE

The purpose of this systematic review of in vitro studies was to determine the effects on the properties of Co-Cr dental alloys of the various chemical agents used to clean dental prostheses.

MATERIAL AND METHODS

In vitro studies were included based on a literature search conducted in March 2022 in the Medline/PubMed, SCOPUS, Web of Science, Virtual Health Library, and Embase databases. Independent reviewers performed the search, selection, extraction, and analysis of the data. The review was performed based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The quality of the included articles was evaluated by using parameters adapted from the Consolidated Standards of Reporting Trials (CONSORT) guidelines, and the risk of bias analysis was performed based on previous studies.

RESULTS

Among the 15 included studies, the chemical agents evaluated were alkaline peroxides and hypochlorites, mouthwashes containing cetylpyridinium chloride and chlorhexidine, diluted acids, and enzymes. Some peroxides produced increased ion release, surface roughness, and mass loss of the alloys. The hypochlorites were responsible for the greatest surface corrosion, yielding dark stains, rough regions, and depressions. Acetic and peracetic acids and mouthwashes containing chlorhexidine and cetylpyridinium did not produce significant changes in Co-Cr alloys. Most studies presented moderate risk of bias.

CONCLUSIONS

According to the included studies, mouth rinses containing cetylpyridinium chloride or chlorhexidine and solutions with acetic and peracetic acid could be safely used to chemically sanitize Co-Cr prostheses. Alkaline peroxides should be used with caution, and alkaline hypochlorite solutions should be avoided.

Influence of various class cleaning agents for prosthesis on Co–Cr alloy surface

Introduction

Denture cleaners should not be harmful to dental prostheses elements, but immersions in cleaner solutions during a long time of using prosthesis may cause changes on Co–Cr alloy surfaces. There are five classes of denture cleaners: alkaline hypochlorites, alkaline peroxides, disinfectants, diluted acids, and enzymes. The aim of this work was to evaluate the influence of denture cleaners solutions on the surface properties of Co–Cr alloy.

Materials and method

Specimens cast from cobalt–chromium alloy were divided into eight groups: 1 – dry; 2 – ultrapure water; 3 – 20% wt/wt sodium; 4 – 20% chlorhexidine digluconate; 5 – Correga Tabs BioFormula; 6 – 20% wt/wt citric acid; 7 – 0.5% NaOCl; and 8 – 5.0% NaOCl. After immersion in 200 mL of cleaning agent solution at 45°C in 3 years, simulation of use, surface roughness, contact angle, surface free energy (SFE), and microscopic observation was performed.

Results

For citric acid and NaOCl, roughness (R a) raised clearly. These cleaning agents also caused R q, R v, R p, and R Sm to increase the most. The observed water contact angle after using denture cleaners, especially citric acid, and NaOCl decreases, and the values of SFE increase. Under a digital microscope, the harmful effect of citric acid and solutions of NaOCl was visible.

Conclusions

Diluted acids and alkaline hypochlorites in presented concentrations influence Co–Cr surface parameters like roughness and wettability. Other classes of denture cleaning agents do not affect surface roughness parameters which make them safer for the metallic components of removable partial dentures.

Antifungal effect of tea extracts on Candida albicans

Determining whether tea extracts are effective in removing Candida albicans (C. albicans) from dentures is of interest. This study aimed to investigate the antifungal effect of tea extracts on C. albicans. One green tea (Anji white tea, AGW) and 2 oolong teas (Tie Guan Yin, TGY; Da Hong Pao, DHP) of different concentrations were tested. C. albicans suspensions were inoculated on the plates and the numbers of colony-forming units (CFU) in the culture medium were used to screen for the optimum tea extracts. Polymethyl methacrylate (PMMA) specimens that contained C. albicans biofilms were then treated with the tea extracts and the numbers of CFU were counted. The antifungal activities of the tea extracts were not significantly correlated with their catechin concentrations. Although AGW at 10.0 mg/mL and DHP at 2.5 mg/mL significantly inhibited C. albicans in the culture medium, the extracts failed to exert inhibitory effects against C. albicans biofilms on the PMMA surfaces.