The antimicrobial potential of 14 natural herbal dentifrices: results of an in vitro diffusion method study

Increasing numbers of Americans are using natural herbal products for general and oral health care. Few of these products, however, have undergone rigorous testing, as evidenced by the limited amount of information on their safety and efficacy in the literature. The authors conducted an in vitro study to evaluate the antimicrobial potential of 14 natural herbal dentifrices.

The authors used a diffusion method to evaluate the antimicrobial effectiveness of 14 natural herbal dentifrices against four microorganisms: Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and Candida albicans. Colgate Total (Colgate-Palmolive, New York City) and sterile pyrogen-free water served as the positive and negative controls, respectively. The authors tested the natural herbal dentifrices at full strength and at 1:1 dilution. They measured the zones of inhibition at 24 and 48 hours to evaluate the antimicrobial potential of the dentifrices.

Six herbal dentifrices were effective in inhibiting the growth of all four microorganisms. The positive control produced significantly sized inhibition zones with all four microorganisms, while the negative control produced no observable zones. Six herbal dentifrices produced larger inhibition zones with A. viscosus than did the positive control. Six herbal dentifrices were inhibitory against C. albicans at full strength, but at 1:1 dilution, only three had such inhibitory effect. One herbal dentifrice produced microbial growth around and over the samples, indicating possible microbial contamination of the toothpaste. Only one herbal dentifrice showed consistent antimicrobial activity against all four microorganisms.

The variation in antimicrobial inhibition among the herbal dentifrices indicates that more research is needed to validate their effectiveness claims.

This study provides practitioners with insight into the claims of natural herbal dentifrices' antimicrobial effects.