Evaluation of laser fluorescence in combination with photosensitizers for detection of demineralized lesions

Lesion activity assessment of early caries using dye-enhanced quantitative light-induced fluorescence

We aimed to determine whether dye-enhanced quantitative light-induced fluorescence (DEQLF), wherein porous structure of caries lesions is stained with a fluorescent dye, could quantitatively distinguish between active and inactive caries. A total of 126 bovine specimens were prepared to artificially simulate caries activity. Active caries were demineralized with 1% carbopol solution for 3 (A3), 5 (A5), and 10 days (A10). For inactive caries, half specimens in each group were remineralized with 2% NaF and reallocated into three groups (I3, I5, and I10, respectively). Wet specimens were dried with compressed air for 10 s and then dyed with 100-µM sodium fluorescein for 10 s. Fluorescence images of speicmens were captured with a QLF-digital 2 + Biluminator. Fluorescence intensity (ΔG) was measured in fluorescence images of dyed specimens. ΔG between active and inactive groups was compared using independent t-test, and ΔG among active groups (or inactive groups) were compared using ANOVA (α = 0.05). ΔG in the active groups was 33.7-59.0 higher than that in the inactive groups (P < 0.001). Except between I3 and I5, there was significant differences in ΔG according to the demineralization period (P < 0.001). DEQLF might be used to evaluate early caries activity, and longitudinally monitor changes in lesion activity.

Photosensitizers attenuate LPS-induced inflammation: implications in dentistry and general health

Antimicrobial photodynamic therapy (aPDT) is a complementary therapeutic modality for periodontal and endodontic diseases, in which Gram-negative bacteria are directly involved. Currently, there are few evidences regarding the effects of aPDT on bacterial components such as lipopolysaccharide (LPS) and it would represent a major step forward in the clinical use of this therapy. In this context, this study aimed to evaluate the efficacy of different photosensitizers (PSs) used in aPDT in LPS inhibition. Four PSs were used in this study: methylene blue (MB), toluidine blue (TBO), new methylene blue (NMB), and curcumin (CUR). Different approaches to evaluate LPS interaction with PSs were used, such as spectrophotometry, Limulus amebocyte lysate (LAL) test, functional assays using mouse macrophages, and an in vivo model of LPS injection. Spectrophotometry showed that LPS decreased the absorbance of all PSs used, indicating interactions between the two species. LAL assay revealed significant differences in LPS concentrations upon pre-incubation with the different PSs. Interestingly, the inflammatory potential of LPS decreased after previous treatment with the four PSs, resulting in decreased secretion of inflammatory cytokines by macrophages. In vivo, pre-incubating curcumin with LPS prevented animals from undergoing septic shock within the established time. Using relevant models to study the inflammatory activity of LPS, we found that all PSs used in this work decreased LPS-induced inflammation, with a more striking effect observed for NMB and curcumin. These data advance the understanding of the mechanisms of LPS inhibition by PSs.