Antibacterial Efficacy of Novel Mouthrinse Formulations Containing Cetylpyridinium Chloride

Mouthrinses containing cetylpyridinium chloride (CPC) augment oral hygiene by inactivating oral bacteria. This investigation evaluated the antimicrobial effects of a mouthrinse with 0.075% CPC on planktonic cultures of oral bacteria and biofilms derived from human oral samples. Antimicrobial effects were evaluated with an alamarBlue® viability indicator, by culture for viable organisms and with confocal microscopy for biofilm viability. 

Methods:

An alamarBlue-based viability assay determined the immediate antimicrobial effects of a CPC mouthrinse (TR) or a control formulation without CPC (CR) on Actinomyces viscosus.  Cultures of Streptococcus mutans or Fusobacterium nucleatum were exposed to each formulation for 30 seconds and viable organisms determined after each exposure.  Plaques were cultivated on hydroxyapatite discs in medium inoculated with human saliva before short exposures to TR or CR.  Viability profiling by confocal microscopy using a LIVE/DEAD fluorescent viability stain evaluated three-dimensional effects within biofilms. Treatment-free controls were used throughout.

Results:

In the alamarBlue-based assay, TR reduced the viability of A. viscosus significantly more than CR (p<0.05).  Following exposure to TR, the viability of S. mutans and F. nucleatum was significantly and markedly reduced, compared to CR (6.2 and 4.4 log reductions, respectively, p<0.01).  Viability profiling of complex plaques indicated markedly greater bacterial inactivation following TR treatment, particularly within the plaque depths.

Conclusion:

A CPC mouthwash significantly inactivated oral bacteria, including Gram-positive, Gram-negative, aerobic and anaerobic species as well as within the depths of plaques derived from human samples.