Ex-vivo antimicrobial effects of commercial dentifrices on human oral bacteria

Objectives: This investigation determined the antimicrobial effects of dentifrices on oral samples from adults. Test dentifrice formulations with triclosan/copolymer/NaF (T), stannous fluoride/zinc lactate/hexametaphosphate (SZ) and NaF (F) were examined. The rationale for this ex-vivo study included: (a) determination of antimicrobial effects on the diverse bacteria of the human mouth; (b) tests on oral samples from a number of subjects to incorporate natural variations in bacterial diversity between subjects. The effects of treatment durations were examined. Methods: Ten healthy adults underwent a 1-week washout phase with a commercial fluoride dentifrice prior to studies. Oral samples collected from subjects were aliquoted for tests with each dentifrice. Equal amounts of a 1:2 slurry of test dentifrices were incubated with oral samples for 30, 60 and 120 seconds prior to microbial viability determinations on enriched bacteriological media following anaerobic incubation. Viable bacteria from all subjects following treatment with each test dentifrice were determined. Results: Viable bacteria in oral samples for tests ranged from 11-33 x 10⁷ CFU/ml. Ex-vivo dentifrice treatments resulted in significant reductions of oral bacteria versus untreated samples (p<0.05). Statistical analyses indicate that among dentifrices, treatment with T demonstrated statistically significant reductions of anaerobic bacteria at 30 seconds post-treatment versus dentifrices SZ and F (p<0.05). Similarly, treatment with dentifrice T resulted in statistically significant reductions of anaerobic bacteria versus dentifrices SZ and F after both 60 and 120 seconds of treatment (p<0.05). Treatment with dentifrice T resulted in up to a 98% decrease of oral bacteria. Conclusions: Treatment with triclosan/copolymer/NaF (T) resulted in statistically significant reductions of oral anaerobic bacteria as compared to treatments with the stannous fluoride/zinc lactate/hexametaphosphate (SZ) and the control NaF dentifrices (F) (p<0.05).