Effect of Alkaline Peroxides on the Surface of Cobalt Chrome Alloy: An In Vitro Study

Effects of disinfectants on physical properties of denture base resins: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The disinfection of removable dental prostheses and orthodontic appliances is essential to preventing transmission of pathogens. However, whether different disinfection solutions and durations affect the physical properties of denture base resins is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to statistically analyze the influence of disinfectants on the physical properties of denture base resins.

MATERIAL AND METHODS

A systematic search in Medline, Embase, PubMed, and Cochrane Library databases was conducted to evaluate the effects of chemical disinfection on the physical properties of denture base resins such as surface morphology, roughness, hardness, and flexural strength. Of 1909 studies, 44 studies were included in the systematic review and 41 in the meta-analysis. Heterogeneity was analyzed by using I2 statistics. The influence of different disinfection solutions and durations on the physical properties was further analyzed, and the risk of bias evaluated. Statistical analyses were performed by using the RevMan 5.4 software program with the standardized mean differences (SMDs) and 95% confidence intervals (CIs).

RESULTS

Of the 44 included studies, 40 studies were assessed as having a low risk of bias, and 4 had an unclear risk of bias. Meta-analysis results showed that compared with the control, disinfection could not significantly affect surface roughness and hardness within 60 minutes of immersion in disinfectant solutions or flexural strength within 30 minutes (roughness: P=.79, I2=0%; flexural strength: P=.08, I2=0%; hardness: P=.05, I2=19%). In addition, the physical properties were not significantly affected when glutaraldehyde, chlorhexidine, and peracetic acid were repeatedly used for more than 30 minutes.

CONCLUSIONS

Most of the disinfectants did not reduce the physical properties of denture base resin within 30 minutes of immersion. Glutaraldehyde, chlorhexidine, and peracetic acid are recommended if longer immersion or repeated disinfection is required.

Strategies for Preventing and Treating Oral Mucosal Infections Associated with Removable Dentures: A Scoping Review

Oral infections occur due to contact between biofilm rich in Candida albicans formed on the inner surface of complete dentures and the mucosa. This study investigated historical advances in the prevention and treatment of oral mucosal infection and identified gaps in the literature. Bibliographic research was conducted, looking at PubMed, Embase, Web of Science, and Scopus, where 935 articles were found. After removing duplicates and excluding articles by reading the title and abstract, 131 articles were selected for full reading and 104 articles were included. Another 38 articles were added from the gray literature. This review followed the PRISMA-ScR guidelines. The historical period described ranges from 1969 to 2023, in which, during the 21st century, in vitro and in vivo studies became more common and, from 2010 to 2023, the number of randomized controlled trials increased. Among the various approaches tested are the incorporation of antimicrobial products into prosthetic materials, the improvement of oral and denture hygiene protocols, the development of synthetic and natural products for the chemical control of microorganisms, and intervention with local or systemic antimicrobial agents. Studies report good results with brushing combined with sodium hypochlorite, and new disinfectant solutions and products incorporated into prosthetic materials are promising.

Action of chitosan-based solutions against a model four-species biofilm formed on cobalt-chromium and acrylic resin surfaces

OBJECTIVE

To evaluate the anti-biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans.

BACKGROUND

Biofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation.

MATERIALS AND METHODS

The anti-biofilm action of the experimental chitosan-based solutions and Nitradine™ was evaluated on acrylic resin and cobalt-chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology.

RESULTS

Only chitosan reduced the viability of C. albicans on cobalt-chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan-based solutions neither promoted substantial alteration of the metabolic activity of the four-species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells.

CONCLUSION

Although chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four-species biofilm from the Co-Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Antimicrobial activity of cleansers on the cobalt-chromium surface of removable partial denture: a systematic review

This study aimed to review systematically the literature about the antimicrobial action of evaluated cleansers on the Co-Cr alloy of RPD. The search was conducted in MEDLINE/PubMed, Scopus, Lilacs, Embase and Science Direct May, 2022. The review was performed based on PRISMA guidelines and recorded in Open Science Framework. Independent reviewers performed the search, selection, extraction, and analysis of the data. The risk of bias of the in vitro and clinical trials studies was analyzed by the Joanna Briggs Institute tool. A total of 187 articles were found and 9 were included. The cleansers that showed antimicrobial action were 2% and 5.25% sodium hypochlorite, 0.12% chlorhexidine and NitrAdine effervescent tablet. Polident, Corega Tabs effervescent tablets and 5 mg/mL chitosan solution showed intermediate effects. Propolis and green tea toothpaste were not effective. Three articles presented a high risk of bias and 6, low risk. The cleansers that showed the highest antimicrobial efficacy on Co-Cr alloy were 0.12% chlorhexidine digluconate and NitrAdine and can be safely used on RPD framework.

Effects of disinfection with a vinegar-hydrogen peroxide mixture on the surface composition and topography of a cobalt-chromium alloy

STATEMENT OF PROBLEM

Choosing the best disinfection agent for removable partial dentures may be challenging since most commercially available disinfection solutions alter the properties of the metal framework.

PURPOSE

The purpose of this in vitro study was to analyze the changes in the surface topography and elemental composition of a cobalt-chromium (Co-Cr) alloy when immersed in a vinegar-hydrogen peroxide mixture.

MATERIAL AND METHODS

Disk-shaped specimens (N=50) were fabricated with Co-Cr alloy and randomly distributed into 5 groups (N=10) according to the immersion solutions: distilled water (control) (W); 0.5% sodium hypochlorite (H); 3% hydrogen peroxide and water in a 1:1 ratio (HP); vinegar and water in a 1:1 ratio (V); and vinegar and 3% hydrogen peroxide mixture in a 1:1 ratio (VHP). The immersions simulated 90 uses of 10 minutes each. The surface topography and the elemental composition were analyzed with scanning electron microscopy and energy-dispersive spectroscopy, before (T0) and after (T1) the immersions. The 2-way ANOVA for repeated measures was used for statistical comparisons (α=.05).

RESULTS

The tested mixture (VHP) did not change the metal surface topography or increase the oxygen proportion, indicating that no corrosion occurred. Similarly, groups W, HP, and V had no topographic changes and nonsignificant statistical differences at T1 for elemental composition (P>.05). However, the specimens immersed in sodium hypochlorite (H) showed staining, surface irregularity, composition change, with an appearance of 22.56% more oxygen, 41% less chromium, and 28.77% less cobalt at T1 (P<.05).

CONCLUSIONS

The immersion of Co-Cr alloy in a vinegar-hydrogen peroxide mixture did not change the surface structure of the metal.

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.

Denture cleanliness and hygiene: an overview

Dentures are an excellent treatment modality for partial and edentate patients; however, improper denture care and hygiene can result in both decreased longevity of the prosthesis and increased risk of developing dental caries, periodontal disease and oral candidosis. Previously, it has been shown that patients and dental professionals are unaware of the different materials and methods available for optimum denture care and hygiene. This article provides an overview of the key legislation and main commercially available methods for denture cleanliness and hygiene, and serves as a basis for providing tailored denture hygiene for denture wearers.

Patients typically demonstrate poor levels of denture hygiene which impacts oral health.

Denture hygiene instructions comprise mechanical and chemical methods; both should be tailored to the denture wearer.

Denture base and denture teeth materials had different compatibility with different denture cleaning methods.

Effect of a vinegar-hydrogen peroxide mixture on the surface properties of a cobalt-chromium alloy: A possible disinfectant for removable partial dentures

STATEMENT OF PROBLEM

A vinegar-hydrogen peroxide mixture has been reported to be effective in eliminating Candida albicans and Staphylococcus aureus from acrylic resin, and its action has been reported to be comparable with that of sodium hypochlorite or peracetic acid. However, the effects of this mixture on cobalt-chromium alloys remain unknown.

PURPOSE

The purpose of this in vitro study was to evaluate the surface roughness, Knoop microhardness, surface free energy, and wettability of a cobalt-chromium alloy when exposed to a vinegar-hydrogen peroxide mixture.

MATERIAL AND METHODS

Fifty specimens of cobalt-chromium alloy were fabricated and immersed for 900 minutes, simulating 3 months of a daily 10-minute immersion in the following chemical agents (n=10): distilled water (W); 0.5% sodium hypochlorite (H); 3% hydrogen peroxide and water dilution in 1:1 ratio (HP); white-wine vinegar and water dilution in 1:1 ratio (V); and vinegar and hydrogen peroxide mixture in 1:1 ratio (VHP). Surface roughness, Knoop microhardness, surface free energy, and wettability were measured with single blinding before and after immersions. Data were statistically analyzed by using 2-way repeated measures ANOVA (α=.05).

RESULTS

The vinegar-hydrogen peroxide mixture did not affect the surface roughness or Knoop microhardness. However, 0.5% sodium hypochlorite significantly increased the roughness and decreased microhardness. Surface free energy and wettability increased after immersions, regardless of the types of solution.

CONCLUSIONS

Immersion in a vinegar-hydrogen peroxide mixture did not affect the surface characteristics of a cobalt-chromium alloy.

Effect of Denture Cleansers on Cobalt-Chromium Alloy Surface: A Simulated Period of 5 Years' Use

PURPOSE

To compare the effect of solutions of effervescent tablets (ET), cetylpyridinium chloride (CPC), and experimental solutions of Ricinus communis on the surface of cobalt-chromium (Co-Cr) alloys.

MATERIALS AND METHODS

Fifty-five specimens of Co-Cr were prepared by the lost-wax casting method using circular patterns (∅12 × 3 mm). The specimens were randomly divided into 5 groups: deionized water (control); 2% R. communis; 10% R. communis; ET, and CPC. The surface roughness of specimens (n = 10) was evaluated before immersion (baseline), and at simulated times of ½, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, μm) and profilometer (Ra, μm). The surface topography and chemical composition (n = 1) was qualitatively analyzed with scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Data were subjected to Kruskal-Wallis followed by Dunn tests, and Friedman followed by Wilcoxon tests (α = 0.05).

RESULTS

For Sa, there was no difference for the solution factor. For the time factor a significant difference was found with 2% R. communis solution among baseline and ½, 2, 3, and 5 years (p < 0.001) and with 10% R. communis solution between 1 and 2 years (p = 0.007), with decreasing roughness over time. For Ra, cetylpyridinium chloride exhibited less roughness than 10% R. communis solution in ½ (p = 0.048) and 5 years (p = 0.013). In the SEM and EDS analysis the solutions did not present deleterious effects or changes in the chemical composition on the surfaces.

CONCLUSIONS

Although a significant difference was found for the roughness, the results, below 0.2 μm, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.