An Oxygen-Releasing Mouthwash Reduces Porphyromonas gingivalis Biofilm and Suppresses fimA and hagA Expression
Introduction and Aims
Porphyromonas gingivalis is a key periodontal pathogen whose biofilm and virulence limit the effectiveness of mouthwashes such as chlorhexidine (CHX). This study evaluated the antibacterial, antibiofilm and virulence effects of an oxygen-releasing mouthwash against P. gingivalis, complemented by in silico docking and cytotoxicity testing on human oral fibroblasts.
Methods
P. gingivalis ATCC 33277 was grown anaerobically. Minimum inhibitory (MIC), bactericidal (MBC) and biofilm inhibitory concentrations (MBIC) were determined by resazurin-based microdilution and crystal violet biofilm assays, with 0.12% CHX as control. Biofilm structure and viability were analysed by confocal microscopy. Quantitative PCR measured expression of 6 virulence- and biofilm-associated genes. Molecular docking of sodium perborate to protein targets used AutoDock GNINA. Fibroblast cytotoxicity (ISO 10993-5 threshold ≥70% viability) was evaluated over 30 min to 24 h.
Results
Bluem mouthwash showed concentration-dependent inhibition of P. gingivalis with minimum inhibitory (MIC), bactericidal (MBC) and biofilm inhibitory concentrations (MBIC) values of 0.78%, 1.56% and 3.12%, respectively. At 0.78%, biofilm biomass decreased to around 45% and at concentrations of ≥3.12% was reduced to ≤20%, with greater reduction than 0.12% CHX. Confocal imaging showed reduced biomass and thickness with a predominance of nonviable cells at higher concentrations. Bluem mouthwash was associated with downregulation of virulence-related genes, with fimA and hagA expression reduced at concentrations ≥0.78%, whereas 0.12% CHX increased fimA expression. Molecular docking predicted moderate binding affinities of sodium perborate with key virulence proteins, including kgp and mfa1. Bluem concentrations ≤0.78% maintained noncytotoxic fibroblast viability, while ≥1.56% and 0.12% CHX were cytotoxic across all tested periods.
Conclusion
The oxygen-releasing mouthwash inhibited P. gingivalis biofilm formation, modulated virulence-associated gene expression and showed a wider noncytotoxic range on oral periodontal fibroblasts than chlorhexidine.
Clinical Relevance
These findings on an oxygen-releasing mouthwash may help guide concentration selection and inform its potential adjunctive use in periodontal protocols, but clinical outcome studies are still needed before routine use can be recommended.
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