Combined effectiveness of beta-cyclodextrin nanoparticles in photodynamic antimicrobial chemotherapy on in vitro oral biofilms

Abstract

This study aimed to investigate if beta-cyclodextrin nanoparticles potentiate the photodynamic antimicrobial chemotherapy (PACT) effects in single and microcosm oral biofilms using methylene blue (MB) and a red laser. Background data: Studies of PACT have demonstrated promising effects; however, the association of nanoparticles with photosensitizers could enhance the antimicrobial result. Materials and methods: Biofilms were grown on enamel blocks either with Streptococcus mutans or in a microcosm model (salivary microorganisms) supplemented with sucrose. PACT using 50 mu M MB associated or not with 32 mu M encapsulated beta-cyclodextrin with MB for 5 min, followed by irradiation with red laser (lambda = 660 nm, 320 J/cm(2)), was conducted and the counts of viable microorganisms in proper selective media were determined. Data were analyzed by one-factor ANOVA, followed by Tukey's test, or Kruskal-Wallis test, followed by Dunn's post hoc test, all with a significance level of 5%. Results: In the single-species biofilm model, a significant reduction in S. mutans counts was found for all groups when light was present. In the microcosm biofilm model, no significant difference was found among the groups for total streptococci, but a significant reduction of S. mutans was observed for the PACT group of encapsulated beta-cyclodextrin+MB. However, no statistically significant difference was observed among the PACT groups. Conclusions: PACT with beta-cyclodextrin mediated with MB associated with a red laser reduced S. mutans in microcosm biofilms. However, the presence of beta-cyclodextrin nanoparticles did not potentiate the PACT effects in single or microcosm oral biofilms