Effect of antimicrobial photodynamic therapy on specific microorganisms from dentin caries microcosms

Abstract

This study will be performed in two steps. The first step aims to evaluate the effect of Antimicrobial Photodynamic Therapy (aPDT) on specific microbial groups from dentin caries microcosms. Dentin samples will be collected from cavitated lesions of ten 7-11 year-old children to grow biofilms on bovine dentin specimens for 72 h. Subsequently, biofilms will be treated by association between curcumin and a blue LED (420 nm) or methylene blue and a red LED (630 nm). The viability of specific microbial groups will be determined by counts of Colony Forming Units of total microorganisms (Tryptic Soy Blood Agar), total streptococci (Mitis Salivarius Agar), mutans streptococci (Mitis Salivarius Agar plus bacitracin 0.2%), and lactobacilli (Rogosa Agar plus glacial acetic acid 0.13%). The method of enzymatic spectrophotometry will be performed to evaluate the concentration of L-lactate in the culture media. The quantification of total microorganisms, total streptococci, total lactobacilli, Prevotella spp., Bifidobacterium spp., Streptococcus mutans, Streptococcus intermedius, Lactobacillus acidophilus, Veillonella spp., Propionibacterium spp. e Actinomyces naeslundii will be performed by Real Time-PCR. The second step will evaluate the effect of distinct protocols of aPDT on the viability of microorganisms from different biofilm depths. Intact biofilms, treated or not with aPDT, will be stained with a mixture of ethidium bromide and fluorescein diacetate and assessed by confocal laser scanning microscopy. Statistical analysis will be based on the normality and homogeneity of the data. P values <0.05 will be considered significant. (AU)