Development of sustained-release antimicrobial dental varnishes effective against Streptococcus mutans in vitro

Two antimicrobial varnishes were developed to be applied to the teeth for the eradication of Streptococcus mutans infections. One of them contained chlorhexidine acetate as the antimicrobial agent and the other, erythromycin base. Both varnishes contained Sumatra benzoin. Each of the two antimicrobial agents was shown to be highly effective against S. mutans and to be compatible with the benzoin vehicle. When applied to extracted teeth, both varnishes dried to form a tough, adherent, and colorless transparent layer. Dried samples of the varnishes, when suspended in frequently-changed buffer, released their microbial agents at low but bactericidal levels for at least 12 days. After the first day, drug release from the chlorhexidine varnish showed approximately zero-order kinetics, while the erythromycin varnish showed a combination of zero-order and first-order kinetics.