Antibacterial activity of silver nanoparticles activated by photodynamic therapy in infected root canals

Silver Nanoparticles in Dental Applications: A Descriptive Review

Silver nanoparticles have been a recent focus of many researchers in dentistry, and their potential uses and benefits have drawn attention in dentistry and medicine. The fabrication and utilization of nanoscale substances and structures are at the core of the rapidly developing areas of nanotechnology. They are often used in the dental industry because they prevent bacteria from making nanoparticles, oxides, and biofilms. They also stop the metabolism of bacteria. Silver nanoparticles (AgNPs) are a type of zero-dimensional material with different shapes. Dentistry has to keep up with changing patient needs and new technology. Silver nanoparticles (AgNPs) can be used in dentistry for disinfection and preventing infections in the oral cavity. One of the most interesting metallic nanoparticles used in biomedical applications is silver nanoparticles (AgNPs). The dental field has found promising uses for silver nanoparticles (AgNPs) in the elimination of plaque and tartar, as well as the elimination of bacterial and fungal infections in the mouth. The incorporation of AgNPs into dental materials has been shown to significantly enhance patients' oral health, leading to their widespread use. This review focuses on AgNP synthesis, chemical properties, biocompatibility, uses in various dental fields, and biomaterials used in dentistry. With an emphasis on aspects related to the inclusion of silver nanoparticles, this descriptive review paper also intends to address the recent developments of AgNPs in dentistry.

Silver Nanoparticles and Their Therapeutic Applications in Endodontics: A Narrative Review

The efficient elimination of microorganisms and their byproducts from infected root canals is compromised by the limitations in conventional root canal disinfection strategies and antimicrobials. Silver nanoparticles (AgNPs) are advantageous for root canal disinfection, mainly due to their wide-spectrum anti-microbial activity. Compared to other commonly used nanoparticulate antibacterials, AgNPs have acceptable antibacterial properties and relatively low cytotoxicity. Owing to their nano-scale, AgNPs penetrate deeper into the complexities of the root canal systems and dentinal tubules, as well as enhancing the antibacterial properties of endodontic irrigants and sealers. AgNPs gradually increase the dentin hardness in endodontically treated teeth and promote antibacterial properties when used as a carrier for intracanal medication. The unique properties of AgNPs make them an ideal additive for different endodontic biomaterials. However, the possible side effects of AgNPs, such as cytotoxicity and tooth discoloration potential, merits further research.

Influence of antimicrobial photodynamic therapy on the bond strength of endodontic sealers to intraradicular dentin: A systematic review and meta-analysis

BACKGROUND

The objective of this systematic review and meta-analysis (SRMA) was to investigate the influence of antimicrobial photodynamic therapy (aPDT) on the bond strength of endodontic sealers to intraradicular dentin.

METHODS

This SRMA followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered in the International Prospective Registry of Systematic Reviews (PROSPERO) (CRD42022319856). A population, intervention, control, and outcome (PICO) question was formulated: "Does antimicrobial photodynamic therapy decrease the bond strength of root canal sealers?". A literature search was performed in PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ProQuest databases until July 2022. Joanna Briggs Institute Critical Assessment Guidelines for Quasi-Experimental Studies were used for quality assessment. The meta-analysis was based on the inverse variance (IV) method (p<0.05).

RESULTS

Out of an initial 345 articles, 8 in vitro studies were included, published between 2013 and 2022. The studies were qualitatively analyzed; two studies showed a positive effect, two studies a negative effect, and the other studies showed no effect on bond strength of endodontic sealers to intraradicular dentin. Seven of the studies were included in the SRMA, which indicated that there was no significant difference in bond strength when using aPDT (P = 0.90; MD: -0.03; 95% CI: -0.46 to -0.41). There was a high level of evidence for each meta-analysis outcome.

CONCLUSION

It can be concluded that the use of aPDT as a method of root canal disinfection does not negatively influence the bond strength of endodontic sealers in the root canal.

The application of selenium nanoparticles for enhancing the efficacy of photodynamic inactivation of planktonic communities and the biofilm of Streptococcus mutans

Objective

Streptococcus mutans is one of the principal causative agents of dental caries (tooth decay) found in the oral cavity. Therefore, this study investigates whether selenium nanoparticles (SeNPs) enhance the efficacy of photodynamic therapy (PDT) against both planktonic communities and the one-day-old biofilm of S. mutans. In this study, the planktonic and 24-h biofilm of S. mutans have been prepared in 96-cell microplates. These forms were treated by methylene blue (MB) and SeNPs and then were exposed to light-emitting diode (LED) lighting. Finally, the results have been reported as CFU/ml.

Results

The outcomes demonstrated that MB-induced PDT and SeNPs significantly reduced the number of planktonic bacteria (P-value < 0.001). The comparison between the treated and untreated groups showed that combining therapy with SeNPs and PDT remarkably decreased colony-forming units of one-day-old S. mutans biofilm (P-value < 0.05). The findings revealed that PDT modified by SeNPs had a high potential to destroy S. mutans biofilm. This combination therapy showed promising results to overcome oral infection in dental science.

Functionalized Nanoparticles Activated by Photodynamic Therapy as an Antimicrobial Strategy in Endodontics: A Scoping Review

The eradication of endodontic pathogens continues to be the focus of the search for new root canal system (RCS) disinfection strategies. This scoping review provides a comprehensive synthesis of antimicrobial photodynamic therapy (aPDT) using nanoparticles (NPs) as an alternative to optimize RCS disinfection. A systematic search up to March 2021 was carried out using the MEDLINE, EMBASE, Scopus, Lilacs, Central Cochrane Library, and BBO databases. We included studies focused on evaluating the activation of NPs by aPDT in inoculated root canals of human or animal teeth or bacterial cultures in the laboratory. The selection process and data extraction were carried out by two researchers independently. A qualitative synthesis of the results was performed. A total of seventeen studies were included, of which twelve showed a substantial antibacterial efficacy, two assessed the substantivity of the disinfection effect, and three showed low cytotoxicity. No adverse effects were reported. The use of functionalized NPs with photosensitizer molecules in aPDT has been shown to be effective in reducing the bacteria count, making it a promising alternative in endodontic disinfection. Further studies are needed to assess the development of this therapy in in vivo conditions, with detailed information about the laser parameters used to allow the development of safe and standardized protocols.