Bacteriostatic effects of nanometer silver disinfectant on the biofilms in dental unit water lines

Preparation and Characterization of Oxide Nanotubes on Titanium Surface for Use in Controlled Drug Release Systems

Preventing or treating infections at implantation sites where the risk of bacterial contamination is high requires the development of intelligent drug delivery systems. The objective of this work was to develop a production method and characterization of fourth-generation oxide nanotubes on titanium grade 4 surface as a potential drug carrier. This study focused on the anodizing process; physico-chemical characterization using FE-SEM, EDS, and FTIR; in vitro corrosion resistance in an artificial saliva solution; and determining the drug release kinetics of gentamicin sulfate using UV-VIS. The anodizing process was optimized to produce fourth-generation oxide nanotubes in a fluoride-free electrolyte, ensuring rapid growth and lack of order. Results showed that the length of the oxide nanotubes was inversely proportional to the anodizing voltage, with longer nanotubes formed at lower voltages. The nanotubes were shown to have a honeycomb structure with silver particles co-deposited on the surface for antibacterial properties and were capable of carrying and releasing the antibiotic gentamicin sulfate in a controlled manner, following Fick's first law of diffusion. The corrosion resistance study demonstrates that the oxide nanotubes enhance the corrosion resistance of the titanium surface. The oxide nanotubes show promise in enhancing osseointegration and reducing post-implantation complications.

Study on the disinfection effect of chlorine dioxide disinfectant (ClO2) on dental unit waterlines and its in vitro safety evaluation

BACKGROUND

Ensuring the safety of dental unit waterlines (DUWLs) has become a pivotal issue in dental care practices, focusing on the health implications for both patients and healthcare providers. The inherent structure and usage conditions of DUWLs contribute to the risk of biofilm formation and bacterial growth, highlighting the need for effective disinfection solutions.The quest for a disinfection method that is both safe for clinical use and effective against pathogens such as Staphylococcus aureus and Escherichia coli in DUWLs underscores the urgency of this research.

MATERIALS

Chlorine dioxide disinfectants at concentrations of 5, 20, and 80 mg/L were used to treat biofilms of S. aureus and E. coli cultured in DUWLs. The disinfection effectiveness was assessed through bacterial counts and culturing. Simultaneously, human skin fibroblast cells were treated with the disinfectant to observe changes in cell morphology and cytotoxicity. Additionally, the study included corrosion tests on various metals (carbon steel, brass, stainless steel, aluminum, etc.).

RESULTS

Experimental results showed that chlorine dioxide disinfectants at concentrations of 20 mg/L and 80 mg/L significantly reduced the bacterial count of S. aureus and E. coli, indicating effective disinfection. In terms of cytotoxicity, higher concentrations were more harmful to cellular safety, but even at 80 mg/L, the cytotoxicity of chlorine dioxide remained within controllable limits. Corrosion tests revealed that chlorine dioxide disinfectants had a certain corrosive effect on carbon steel and brass, and the degree of corrosion increased with the concentration of the disinfectant.

CONCLUSION

After thorough research, we recommend using chlorine dioxide disinfectant at a concentration of 20 mg/L for significantly reducing bacterial biofilms in dental unit waterlines (DUWLs). This concentration also ensures satisfactory cell safety and metal corrosion resistance.

Comparative evaluation of effect of sodium hypochlorite and chlorhexidine in dental unit waterline on aerosolized bacteria generated during dental treatment

BACKGROUND

In dentistry, nosocomial infection poses a great challenge to clinicians. The microbial contamination of water in dental unit waterlines (DUWLs) is ubiquitous. Such infected DUWLs can transmit oral microbes in the form of aerosols. Previous studies have suggested treating DUWLs with various disinfectants to reduce cross-contamination. The literature lacks a comparative evaluation of the effect of the use of 0.2% chlorhexidine (CHX) and 0.1% sodium hypochlorite (NaOCl) in DUWLs on aerosolized bacteria generated during dental procedures.

OBJECTIVE

To compare the effect of NaOCl and CHX in DUWLs on aerosolized bacteria generated during restorative and endodontic procedures.

MATERIALS AND METHODS

A total of 132 patients were equally divided into three groups (n = 44 in each group) according to the content of DUWL as follows. Group I-0.1% NaOCl Group II-0.2% CHX Group III-distilled water (Positive control) One-way ANOVA was performed and the Kruskal-Wallis test was used for intergroup comparison.

RESULTS

For the restorative procedure, inter-group comparison of mean colony-forming units (CFU) scores showed a statistically significant difference between the groups (p - .001) with the score of group 3 higher than group 2 followed by group 1. For the endodontics, an inter-group comparison of CFU scores showed a statistically significant difference between the groups (p - .003) with the mean score in group 1 being the lowest and group 3 being the highest.

CONCLUSION

The addition of NaOCl or CHX in DUWLs shows an effective reduction in aerosolized bacteria compared to distilled water.

The Application of Silver to Decontaminate Dental Unit Waterlines-a Systematic Review

The contamination of dental unit waterlines (DUWLs) is a major health concern since it can pose cross-infection risks among dental professionals and their patients. Silver is one of the widely used metals in medical fields due to its superior antimicrobial properties. Silver-based agents have been commercially available for the decontamination of dental unit water currently. This systematic review aims to examine the evidence supporting efficacy and safety of application of silver to decontaminate DUWLs. We performed a search of the peer-review literature of studies in six electronic databases using corresponding search terms. Eligibility was restricted to English-language studies exploring the application of silver to decontaminate dental unit water, e.g., silver-based disinfectants and silver-coated dental waterlines tubing. The search identified 148 articles, and 9 articles that met the criteria were synthesized with qualitative narrative analyses. We observed good evidence of antimicrobial efficacy of silver with hydrogen peroxide on diverse microorganism present in DUWLs. Furthermore, there is insufficient evidence on the application of silver nanoparticles (AgNPs) as an efficient material to control the biofilms in DUWLs. Post-treatment data of either the bactericidal and bacteriostatic effects of silver or AgNPs, especially the actual clinical efficacy of long-term application, are scarce. More high-quality research is needed to resolve the gap on the optimal dosage and treatment options required to control bacterial and biofilm in DUWLs with silver-containing materials.

Disinfection methods of dental unit waterlines contamination: a systematic review

Background. Severe contamination of dental unit waterlines was found in healthcare settings. The benefits of decontamination methods are controversial. The aim of this review was to systematically evaluate disinfection methods in contamination control of dental unit waterlines.Methods. The terms 'dental unit waterline(s) or DUWL(s) or dental unit water line(s)' were searched through PubMed, Cochrane Library, Embase, Web of Science and Scopusup to 31 May 2021. The DUWLs' output water was incubated on R2A agar at 20-28 °C for 5-7 days to evaluate heterotrophic mesophilic bacteria. The risk of bias was evaluated by a modified Newcastle-Ottawa quality assessment scale.Results. Eighteen papers from the literature were included. One study indicated that water supply played a crucial role in disinfecting DUWLs. Three studies indicated that flushing decreased bacteria counts but did not meet the American CDC standard (500 c.f.u. ml^-1). All chlorine- and peroxide-containing disinfectants except sodium hypochlorite in one of 15 studies as well as three mouthrinses and citrus botanical extract achieved the standard (≤500 c.f.u. ml^-1). The included studies were of low (1/18), moderate (6/18) and high (11/18) quality.Conclusion. Independent water reservoirs are recommended for disinfecting DUWLs using distilled water. Flushing DUWLs should be combined with disinfections. Nearly all the chlorine-, chlorhexidine- and peroxide-containing disinfectants, mouthrinses and citrus botanical extract meet the standard for disinfecting DUWLs. Alkaline peroxide would lead to tube blockage in the DUWLs. Regularly changing disinfectants can reduce the risk of occurrence of disinfectant-resistant strains of microbes.

Optimizing Safe Dental Practice During the COVID-19 Pandemic: Recommendations Based on a Guide Developed for Dental Practices in China

The current global coronavirus disease 2019 (COVID-19) outbreak is still exerting severe global implications, and its development in various regions is complex and variable. The high risk of cross-infection poses a great challenge to the dental practice environment; it is therefore urgent to develop a set of pandemic prevention measures to ensure dental practice safety during the COVID-19 outbreak. Therefore, we combined the epidemiological characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), public emergency measures for COVID-19, characteristics of dental practice, and relevant literature reports to develop a set of dynamic practice measures for dental practices in high-, medium-, and low-risk areas affected by COVID-19. This will help dental practices to achieve standard prevention and ensure their safe and smooth operation during the pandemic. It is hoped that these measures will provide a reference basis for dental hospitals and dental clinics in their care and pandemic prevention work.