Antibacterial Mechanism and Dental Applications of Silver NanoparticlesIf you are interested in products related to the research phase in this field, please contact for further inquiries.
Silver nanoparticles (AgNPs) have emerged as a transformative force in the field of dentistry, offering unparalleled antibacterial properties that enhance both the efficacy and safety of dental treatments. These nanoparticles, with diameters typically less than 100 nm, possess a high surface area-to-volume ratio, which endows them with potent antimicrobial capabilities even at low concentrations. This article explores the multifaceted role of silver nanoparticles in dentistry, detailing their antibacterial mechanisms, clinical applications, and safety considerations.
Fig 1. The antibacterial actions of silver nanoparticles (AgNPs). (Yin I. X., et al., 2020) Silver nanoparticles exert their antibacterial effects through multiple mechanisms. The primary mechanism involves the continuous release of silver ions (Ag+), which adhere to bacterial cell walls and cytoplasmic membranes, increasing permeability and disrupting the bacterial envelope. Once inside the cell, silver ions deactivate respiratory enzymes, generate reactive oxygen species (ROS), and interrupt adenosine triphosphate (ATP) production, leading to cell death. Additionally, silver nanoparticles can directly penetrate bacterial cell walls, causing membrane denaturation and perforation, which results in cell lysis. The antibacterial efficacy of silver nanoparticles is influenced by their size, shape, and surface modifications, as well as the surrounding media's composition. Smaller, spherical nanoparticles tend to release more silver ions due to their larger surface area, making them more effective in bacterial eradication.
In prosthetic dentistry, acrylic resin is commonly used to fabricate removable dentures. However, these materials can harbor opportunistic oral pathogens, leading to infections such as denture stomatitis. The incorporation of silver nanoparticles into acrylic resin inhibits the growth of bacteria like Streptococcus mutans, Escherichia coli, and Staphylococcus aureus, as well as the adhesion of Candida albicans, a key opportunistic pathogen. Moreover, silver nanoparticles enhance the mechanical properties of acrylic resin, increasing its flexural strength, elastic modulus, thermal conductivity, and compressive strength. This dual benefit of antimicrobial activity and improved mechanical properties makes silver nanoparticles an ideal additive for denture fabrication.
Residual bacteria in prepared tooth cavities and microleakages along tooth–restoration interfaces can lead to secondary caries. Adding silver nanoparticles to adhesive systems and composite resins provides significant antimicrobial properties, preventing biofilm formation and inhibiting cariogenic bacteria. Composite resins containing silver nanoparticles have no significant adverse effects on fibroblasts, as the daily release of silver ions is very low. Additionally, silver nanoparticles can be immobilized in biocompatible polymer films to maximize their lethal effect on microbial cells without harming human cells.
Silver nanoparticles offer a promising alternative to sodium hypochlorite in intracanal irrigation for endodontic treatment. Gutta-percha coated with silver nanoparticles serves as an effective antimicrobial obturator for root canal obturation. Mineral trioxide aggregate (MTA), widely used in pulp-capping, apexification, and sealing perforations, can be enhanced with silver nanoparticles to improve its antibacterial properties against anaerobic endodontic pathogens and Candida albicans. Studies have shown that silver nanoparticle-based irrigation solutions are as potent as sodium hypochlorite in eliminating bacteria while being more biocompatible and less damaging to dentine and periapical tissues.
Enamel caries, or white spot lesions, are common complications in orthodontic patients. Silver nanoparticles can be added to adhesive materials like resin-modified glass ionomers and composite adhesives to inhibit biofilm growth. Orthodontic elastomeric modules, such as ligatures, can also be allied with silver nanoparticles to prevent enamel caries by inhibiting bacterial adhesion and releasing silver ions over an extended period. These materials are biocompatible, with no significant cytotoxic or mutagenic effects, and maintain their mechanical properties, such as shear bond strength.
Peri-implant infections pose a significant threat to dental implant success. Modifying implant surfaces with silver nanoparticles using various coating methods has shown long-term antibacterial effects by steadily controlling silver ion release. Larger-sized silver nanoparticles embedded in titanium implants exhibit better antibacterial properties due to increased proton consumption. These nanoparticles can kill bacteria like Staphylococcus aureus and Pseudomonas aeruginosa at low concentrations without cytotoxic effects on osteoblastic cells. Additionally, titanium implants embedded with silver nanoparticles enhance bone mineral density, bone formation, and trabecular pattern without harming adjacent tissues.
Periodontitis, a chronic inflammatory disease caused by various microorganisms, requires effective infection control to disrupt biofilms and suppress inflammation. Silver nanoparticles, unlike traditional antibiotics, do not induce bacterial resistance and can significantly enhance the bactericidal properties of antibiotics, even restoring the efficacy of inactive antibiotics against multi-resistant strains. Smaller-sized silver nanoparticles show higher antibacterial properties against oral anaerobic pathogens. Guided tissue regeneration membranes with silver nanoparticles reduce bacterial adherence and penetration, improving clinical outcomes for intrabony defects. Periodontal dressings coated with silver nanoparticles accelerate wound healing, promoting new collagen synthesis and neovascularization.
Despite the numerous benefits of silver nanoparticles, concerns regarding their toxicity and environmental impact persist. Laboratory studies have reported that silver nanoparticles can induce oxidative stress and impair mitochondrial function in human cells. Silver accumulation in organs like the liver and spleen has been observed following massive doses, raising concerns about potential long-term effects. However, clinical studies have shown that silver nanoparticles can express anti-inflammatory properties and are biocompatible with fibroblasts and keratinocytes. Silver accumulation in organs can mostly be cleared after 8 weeks, and no significant adverse effects have been reported in animal or clinical studies.
The potential hazard of silver nanoparticles to marine life if released into the environment is another area of concern. However, the toxicity of silver nanoparticles can be influenced by their interactions with other materials and organic compounds, which can either increase or decrease their toxicity. Therefore, a nanomaterial-specific evaluation is essential to ensure their safe use for humans and the environment. Ongoing research continues to uncover new insights into the safety and efficacy of silver nanoparticles, paving the way for their broader application in dentistry.
The incorporation of silver nanoparticles into dental materials holds great promise for enhancing both the mechanical properties and antibacterial efficacy of these materials. Although the exact antibacterial mechanisms are not yet fully understood, ongoing research continues to uncover new insights. As the clinical significance of potential toxicity remains unknown, further studies are crucial to fully harness the potential of silver nanoparticles in dentistry while ensuring their safety for human use and environmental protection. The future of dentistry is bright with the advent of silver nanoparticles, offering a safer and more effective treatment option for patients worldwide.
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This article is for research use only and cannot be used for any clinical purposes.
