Evaluation of the antimicrobial potential of fluoride-free mouthwashes against Scardovia wiggsiae.

Abstract

Purpose: This study aimed to evaluate the antimicrobial efficacy of fluoride-free mouthwashes against Scardovia wiggsiae, a key bacterium associated with fluoride-resistant dental caries. The investigation focused on bacterial growth inhibition, planktonic cell viability, and biofilm formation.

Methods: Twelve commercially available fluoride-free mouthwashes with various active ingredients, including hydrogen peroxide, cetylpyridinium chloride (CPC), essential oils, and organic extracts, were tested. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were conducted to determine bacterial growth inhibition and killing potential. Planktonic cell viability and biofilm formation assays were performed at three dilutions (1:3, 1:6, and 1:12) using a 16-h culture of S. wiggsiae. Optical density (OD) values were measured at 595 nm for planktonic cells and 490 nm for biofilms.

Results: Significant variability was observed in bacterial inhibition among mouthwashes. Hydrogen peroxide- and CPC-based formulations demonstrated the strongest antimicrobial activity, significantly reducing bacterial growth, planktonic viability, and biofilm formation. Essential oil-based formulations exhibited moderate antimicrobial effects, with reduced efficacy at higher dilutions. Organic-based mouthwashes showed limited inhibition, while formulations containing zinc chloride and stabilised chlorine dioxide demonstrated the weakest effects.

Conclusion: Hydrogen peroxide- and CPC-containing mouthwashes exhibited the highest antimicrobial potential against S. wiggsiae and may serve as effective fluoride-free alternatives for high-risk populations. Essential oil-based formulations provided moderate benefits, whereas zinc chloride and chlorine dioxide showed minimal efficacy. These findings underscore the importance of selecting appropriate antimicrobial agents for biofilm control and caries prevention. Further in vivo studies are necessary to validate long-term effectiveness in clinical settings.