In a recent study, Dr. Martinus J. Verkaik, et al evaluated the antimicrobial efficacies of 2 toothpaste formulations containing natural antimicrobials (herbal extracts and chitosan) against oral biofilms of different composition and maturational status. Bacteria from a buffer suspension or fresh saliva were adhered to a salivary conditioning film for 2 hours, after which they were grown for 16 hours. Dual-species biofilms were prepared from Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, and multispecies biofilms were grown from freshly collected human saliva. The biofilms were exposed to 25 weight percent toothpaste supernatants. A mouthrinse containing chlorhexidine and a buffer were used as positive- and negative-controls, respectively. Antibacterial efficacy was concluded from acute killing, bacterial removal, prevention of bacterial redeposition, and continued killing during redeposition. The study found that the herbal- and chitosan-based supernatants showed immediate killing of oral biofilm bacteria, comparable with chlorhexidine. Exposure of a biofilm to these supernatants or chlorhexidine yielded ongoing killing of biofilm bacteria after exposure during redeposition of bacteria to a matured 16-hour biofilm, but not to a much thinner initial biofilm formed only by 2 hour's adhesion. This suggests that thicker, more matured biofilms can absorb and release oral antimicrobials.
The study concludes that supernatants based on herbal- and chitosan-based toothpastes have comparable immediate and ongoing antibacterial efficacies as chlorhexidine. Natural antimicrobials and chlorhexidine absorb in oral biofilms, which contributes to their substantive action.
The entire article, entitled "Efficacy of Natural Antimicrobials in Toothpaste Formulations Against Oral Biofilms in Vitro" is available in the March issue of the Journal of Dentistry as well as online at the Web site jodjournal.com.
(Source: Journal of Dentistry, March 2011, Volume 39, Issue 3, Pages 218 to 224)