In vitro antimicrobial efficacy of an oral rinse

A commercially-available non-alcohol oral rinse (Crest Pro-Health Rinse, Procter&Gamble) has been marketed for use in reducing oral plaque and gingivitis. Objective: Compare the in-vitro effectiveness of two commercially-available oral rinses, one containing cetylpyridinium chloride (Crest Pro-Health Rinse) and the other containing cetylpyridinium chloride and alcohol (Cepacol, Combe), in reducing viability of common oral flora. Methods: Five species of oral flora (S.sanguinus, S.mutans, L.casei, A.odontolyticus, and C.albicans) were grown in culture, suspended in normal saline on 96-well plates, and exposed to each of three oral-antimicrobial rinses – Peridex (Zila), Cepacol, Crest Pro-Health Rinse - or a control group (no antimicrobial rinse) (n=24). Species were exposed to a fluorescent dye, alamar blue (Biocourse), which is reduced by bacteria causing fluorescence. Viability was demonstrated through fluorescence readings on a spectrophotometer (Synergy, BioTek) at 485/590nm. Species were cultured and cfu/mL were determined after each treatment in order to compare with fluorescence readings (n=3). Mean fluorescence, cfu/mL and st dev were determined and comparisons were made using 1-way ANOVA/Tukey HSD (alpha=0.05). Results: Different results were observed between fluorescence and cfu techniques for A.odontolyticus and C.albicans, however, exposure to all three oral rinses significantly reduced fluorescence readings for the remaining species vs. control (p<.001). No significant differences in cfu/mL or fluorescence were found between Cepacol and Crest Pro Health Rinse (p>.05). For three bacteria, Cepacol and Crest Pro Health Rinse performed significantly better (cfu/mL) than Peridex and control (p<.01). Conclusions: Alamar blue fluorescence may not be accurate test for determining viability of all oral species. All three rinses significantly reduced the number of bacteria (cfu/mL) vs. control. Removing alcohol from the oral rinse did not significantly affect its efficacy in-vitro. Tables: different letters denote significant differences by column.