Could a chelant improve the effect of curcumin-mediated photodynamic antimicrobial chemotherapy against dental intact biofilms?

To our knowledge, there is still no evidence in relation to the combination of curcumin with chelants to improve the effects of antimicrobial photodynamic therapy (aPDT) on complex dental caries biofilms. Therefore, the aim of this study was to evaluate the antimicrobial effect of curcumin-ethylenediaminetetraacetic acid (EDTA)-mediated aPDT on the vitality of intact biofilms of dentin caries microcosms. Biofilms were grown on glass slabs in McBain medium plus 1% sucrose in microaerophily at 37 °C for 5 days. Then, biofilms were treated with associations of 600 μmol L curcumin combined or not with 1% EDTA and 37.5 or 75 J cm LED (455 nm). The vitality was determined by a confocal laser scanning microscopy (CLSM) after staining biofilms with a mixture of 2.5 g L fluorescein diacetate and 0.25 g L ethidium bromide. Statistical analysis was conducted by Kruskal-Wallis and post hoc Dunn's test (P < 0.05). Three treatments were able to reduce the vitality of overall biofilms: curcumin + 75 J cm LED, curcumin-EDTA + 37.5 J cm LED, and curcumin-EDTA + 75 J cm LED. Also, the vitality of inner layers of biofilms was significantly reduced only after the combination of aPDT with EDTA. Therefore, the association of curcumin and EDTA improved the antimicrobial effect of aPDT on dentin caries microcosms, considering the application of lower light densities and deeper layers of biofilms.