Dental caries is a highly prevalent chronic disease that leads to dental pulp inflammation. It is treated by removing the damaged tooth structure and applying a material that promotes resolution of pulpal inflammation. Tumor necrosis factor superfamily 14 (TNFSF14) is an immunomodulatory cytokine and a member of the TNF superfamily. This study aimed to evaluate the effect of TNFSF14 on the levels of inflammatory cytokines involved in pulpal inflammation using lipoteichoic acid (LTA)-induced human dental pulp stem cells (hDPSCs). hDPSCs were cultured and induced with LTA, followed by treatment with TNFSF14 at 25 and 50 ng/mL. Cellular viability was evaluated using the Alamar Blue assay. The levels of inflammatory cytokines IL-6, IL-8, IL-10, and TNF-α were quantified using reverse transcription–quantitative polymerase chain reaction (RT–qPCR) and enzyme-linked immunosorbent assay (ELISA). TNFSF14 at 25 and 50 ng/mL significantly reduced the mRNA and protein levels of pro-inflammatory cytokines TNF-α, IL-6, and IL-8, and increased the anti-inflammatory cytokine IL-10. In addition, TNFSF14-treated groups enhanced cell viability. Adding TNFSF14 to LTA-induced hDPSCs regulated the production of inflammatory cytokines by lowering the levels of IL-6, IL-8, and TNF-α and elevating IL-10 levels.

Herbal medicine combined with nanoparticles has caught much interest in clinical dental practice, yet the incorporation of chitosan with Salvadora persica (S. persica) extract as an oral care product has not been explored. The aim of this study was to evaluate the combined effectiveness of Salvadora persica(S. persica) and Chitosan nanoparticles (ChNPs) against oropharyngeal microorganisms. Agar well diffusion, minimum inhibitory concentration, and minimal lethal concentration assays were used to assess the antimicrobial activity of different concentrations of ethanolic extracts of S. persica and ChNPs against selected fungal strains, Gram-positive, and Gram-negative bacteria. A mixture of 10% S. persica and 0.5% ChNPs was prepared (SChNPs) and its synergistic effect against the tested microbes was evaluated. Furthermore, the strain that was considered most sensitive was subjected to a 24-h treatment with SChNPs mixture; and examined using SEM, FT-IR and GC–MS analysis. S. persica extract and ChNPs exhibited concentration-dependent antimicrobial activities against all tested strains. S. persica extract and ChNPs at 10% were most effective against S. pneumoni, K. pneumoni, and C. albicans. SEM images confirmed the synergistic effect of the SChNPs mixture, revealing S. pneumonia cells with increased irregularity and higher cell lysis compared to the individual solutions. GC–MS and FT-IR analysis of SChNPs showed many active antimicrobial phytocompounds and some additional peaks, respectively. The synergy of the mixture of SChNPs in the form of mouth-rinsing solutions can be a promising approach for the control of oropharyngeal microbes that are implicated in viral secondary bacterial infections.