Mesoporous Calcium-Silicate Nanoparticles Loaded with Low-Dose Triton-100+Ag+ to Achieve Both Enhanced Antibacterial Properties and Low Cytotoxicity for Dentin Disinfection of Human Teeth

Antimicrobial Effects of Formulations of Various Nanoparticles and Calcium Hydroxide as Intra-canal Medications Against Enterococcus faecalis: A Systematic Review

The combination of calcium hydroxide (Ca(OH)₂) and nanoparticles (NPs) offers a promising approach to improving the efficacy of intra-canal treatments. Their synergistic effects can enhance antimicrobial action, improve penetration, and promote better healing outcomes in endodontic therapy. This review article examines the antimicrobial efficacy of various nanoparticles combined with Ca(OH)₂ against Enterococcus faecalis (E. faecalis) compared to Ca(OH)₂ alone as an intra-canal medicament. The analysis is based on in vitro studies involving bacterial inoculation on human-extracted teeth. Publications from 2013 to 2024 were retrieved from databases such as PubMed, Scopus, the Cochrane Library, and EBSCOhost and were screened according to specific inclusion criteria. Ultimately, 11 studies met these criteria for inclusion in the systematic review. A meta-analysis was not conducted due to the heterogeneity of the studies regarding the duration of medicament application, analytical methods, and result interpretations. The results indicate that NPs combined with calcium hydroxide exhibit superior bactericidal effects compared to Ca(OH)₂ alone, suggesting their potential as effective intra-canal medicaments. Thus, a systematic review concluded that nanoparticle-based Ca(OH)₂ intra-canal medicaments exhibit superior antibacterial/antimicrobial capabilities against E. faecalis when compared to Ca(OH)₂individually.

Biomimetic Scaffolds of Calcium-Based Materials for Bone Regeneration

Calcium-based materials, such as calcium carbonate, calcium phosphate, and calcium silicate, have attracted significant attention in biomedical research, owing to their unique physicochemical properties and versatile applications. The distinctive characteristics of these materials, including their inherent biocompatibility and tunable structures, hold significant promise for applications in bone regeneration and tissue engineering. This review explores the biomedical applications of calcium-containing materials, particularly for bone regeneration. Their remarkable biocompatibility, tunable nanostructures, and multifaceted functionalities make them pivotal for advancing regenerative medicine, drug delivery system, and biomimetic scaffold applications. The evolving landscape of biomedical research continues to uncover new possibilities, positioning calcium-based materials as key contributors to the next generation of innovative biomaterial scaffolds.

Mechanisms of Triton X-100 reducing the Ag+-resistance of Enterococcus faecalis

To investigate the mechanism of Triton X-100 (TX-100) reducing the Ag+-resistance of Enterococcus faecalis (E. faecalis), and evaluate the antibacterial effect of TX-100 + Ag+ against the induced Ag+-resistant E. faecalis (AREf). The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of AgNO3 against E. faecalis with/without TX-100 were determined to verify the enhanced antibacterial activity. Transmission electron microscopy (TEM) was used to observe the morphological changes of E. faecalis after treatment. The intra- and extracellular concentration of Ag+ in treated E. faecalis was evaluated using inductively coupled plasma mass spectrometer (ICP-MS). The changes in cell membrane potential and integrity of treated E. faecalis were also observed using the flow cytometer. Moreover, AREf was induced through continuous exposure to sub-MIC of Ag+ and the antibacterial effect of TX-100 + Ag+ on AREf was further evaluated. The addition of 0.04% TX-100 showed maximal enhanced antibacterial effect of Ag+ against E. faecalis. The TEM and ICP-MS results demonstrated that TX-100 could facilitate Ag+ to enter E. faecalis through changing the membrane structure and integrity. Flow cytometry further showed the effect of TX-100 on membrane potential and permeability of E. faecalis. In addition, the enhanced antibacterial effect of TX-100 + Ag+ was also confirmed on induced AREf. TX-100 can facilitate Ag+ to enter E. faecalis through disrupting the membrane structure and changing the membrane potential and permeability, thus reducing the Ag+-resistance of E. faecalis and enhancing the antibacterial effect against either normal E. faecalis or induced AREf.

An Acid-Responsive Iron-Based Nanocomposite for OSCC Treatment

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer, characterized by invasiveness, local lymph node metastasis, and poor prognosis. Traditional treatment and medications have limitations, making the specific inhibition of OSCC growth, invasion, and metastasis a challenge. The tumor microenvironment exhibits mildly acidity and high concentrations of H2O2, and its exploitation for cancer treatment has been widely researched across various cancers, but research in the oral cancer field is relatively limited. In this study, by loading ultra-small Prussian blue nanoparticles (USPBNPs) into mesoporous calcium-silicate nanoparticles (MCSNs), we developed an acid-responsive iron-based nanocomposite, USPBNPs@MCSNs (UPM), for the OSCC treatment. UPM demonstrated excellent dual enzyme activities, generating toxic ·OH in a mildly acidic environment, effectively killing OSCC cells and producing O2 in a neutral environment to alleviate tissue hypoxia. The results showed that UPM could effectively inhibit the proliferation, migration, and invasion of OSCC cells, as well as the growth of mice solid tumors, without obvious systemic toxicity. The mechanisms may involve UPM inducing ferroptosis of OSCC cells by downregulating the xCT/GPX4/glutathione (GSH) axis, characterized by intracellular iron accumulation, reactive oxygen species accumulation, GSH depletion, lipid peroxidation, and abnormal changes in mitochondrial morphology. Therefore, this study provides empirical support for ferroptosis as an emerging therapeutic target for OSCC and offers a valuable insight for future OSCC treatment.

Silver Nanoparticles as an Intracanal Medicament: A Scoping Review

Silver nanoparticles (AgNPs) release Ag ions with potent bactericidal and anti-inflammatory effects. They have shown promising results as an intracanal medicament for removing Enterococcus faecalis (E. faecalis), a resistant bacterium associated with root canal failures. This review summarizes the role of AgNPs as an intracanal medicament. Original research articles on AgNPs as an intracanal medicament were searched in databases such as MEDLINE (PubMed), Scopus, and Embase, resulting in 24 studies. They showed that AgNPs effectively eliminated E. faecalis and reduced postoperative pain following root canal therapy. However, these effects should be further verified through clinical trials as most of the studies were in vitro.