Abstract

Background: The present study aimed to evaluate the antimicrobial capacity of experimental chitosan/propolis-based varnishes against the main microorganisms associated with the development of dental caries in the oral cavity, S. mutans and S. sobrinus. Materials and methods: Several types of varnishes were made, containing chitosan, nanochitosan, green propolis and red propolis, both in different concentrations. Initially, a 1.5% chitosan (QT) gel was made. Then, we prepared a nanoparticulate chitosan gel (QTNP), with or without propolis, at 5% and 10%, and added the nanoparticulate gel to the chitosan gel. The following varnishes have been made: V1 - (QT + nanoparticles) + 10% (QT-NP + green propolis); V2 - (QT + nanoparticles) + 10% (QT-NP + red propolis); V3 - (QT + nanoparticles) + 5% (QT-NP + green propolis); V4-(QT + nanoparticles) + 5% (QTNP + red propolis); V5-(QT + nanoparticles) + 10% QT-NP; V6-(QT + nanoparticles) + 5% QT-NP; V7- Control - Duraphat® and V8 - Chlorhexidine gel. Subsequently, the analysis was based on the qualitative method of inhibition halo, testing the antimicrobial activity of varnishes against oral microorganisms that cause caries disease. Therefore, the minimum inhibitory concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were established. Results: Microbial growth inhibition values were obtained for green propolis extract at concentrations up to 12.5% for S. mutans and 25% for S. sobrinus and for red propolis at concentrations up to 6.25% for both. Conclusion: It could be concluded that both propolis extracts (green and red) have significant antimicrobial capacity, bactericidal and bacteriostatic effects, highlighting the fact that the antimicrobial action of red propolis is more significant than the action of green propolis, given that at lower concentrations, red propolis has the same capacity to inhibit bacterial growth. 

Keywords

antimicrobial, chitosan, propolis, streptococcus, varnish