Previously, we have shown that sublethal exposure of blue light caused increased cell membrane permeability in Fusobacterium nucleatum. The aim of the present study was to test the effect of this exposure on the activity of Lavender, Sage, Echinacea and Mastic gum extracts against volatile sulfide compound (VSC) production by Fusobacterium nucleatum. Bacterial suspensions were pre‐exposed to blue light (400–500 nm) bellow minimal inhibitory dosage (sub‐MID). Exposed and nonexposed samples were inoculated into test tubes containing growth medium, filtered saliva with or without herbal extracts. Following incubation, test tubes were tested for malodor production (odor judge scores), VSC levels (OralChroma), salivary protein degradation (SDS‐PAGE) and bacterial cell membrane damage (fluorescence microscopy). Results showed that sub‐MID blue light exposure significantly increased the ability of Lavender and Echinacea to reduce VSC production by Fusobacterium nucleatum by more than 30%. These results suggest that sublethal blue light exposure may be useful to increase the efficacy of antimalodor agents.

Oral malodour is thought to be caused mainly by the production of volatile sulfide compounds (VSCs) by anaerobic Gram-negative oral bacteria. Previous studies have shown that these bacteria are susceptible to blue light (400-500 nm wavelength). In the present study, we tested the effect of blue light in the presence of zinc, erythrosine B or both on malodour production in an experimental oral biofilm. Biofilms were exposed to a plasma-arc light source for 30, 60 and 120 s (equal to energy fluxes of 41, 82 and 164 J cm "2 , respectively) with or without the addition of zinc acetate, erythrosine B or both. After the light exposure, biofilm samples were examined for malodour production (by an odour judge) and VSC production (with a Halimeter), and VSCproducing bacteria were quantified using a microscopy-based sulfide assay (MSA) and in situ confocal laser scanning microscopy (CLSM). Results showed that exposing experimental oral biofilm to both blue light and zinc reduced malodour production, which coincided with a reduction in VSC-producing bacteria in the biofilm. These results suggest that zinc enhances the phototoxicity of blue light against malodour-producing bacteria.

Oral malodour is considered to be caused mainly by the production of volatile sulfide compounds (VSC) by anaerobic gram‐negative oral bacteria. Previous studies showed that these bacteria were susceptible to blue light phototoxicity mediated by the production of reactive oxygen species (ROS). In the present study, we tested the effect of blue light on the integrity Fusobacterium nucleatum's membrane, cellular proteins and DNA. Bacterial samples were exposed to high intensity blue light for 0, 70, 140 and 280 s (i.e. fluences of 0, 96, 192 and 384 J cm−2, respectively). Following light exposure, bacterial samples were examined for membrane damage using fluorescence microscopy, intra‐cellular protein analysis using electrophoresis (SDS‐PAGE) and DNA fragmentation using ultra–filtration. Results showed that the increasing exposure of bacterial samples to blue light caused increased membrane permeability concomitant with a reduction in intra‐cellular proteins and DNA fragments content. These results suggest that membrane damage is the main effect of high intensity blue light exposure on malodour producing bacteria.

Oral malodour is considered to be caused mainly by the production of volatile sulfide compounds (VSC) by anaerobic Gram-negative oral bacteria. Previous study showed that these bacteria were susceptible to blue light (wavelengths of 400-500 nm). In the present study, we tested the effect of blue light in the presence of red dyes on malodour production in an experimental oral biofilm. Biofilms were exposed to a plasma-arc light source for 30, 60, and 120 s (i.e. fluences of 41, 82, and 164 J cm, respectively) with the addition of erythrosine, natural red and rose bengal (0.01, 0.1 and 1% w/v). Following light exposure biofilm samples were examined for malodour production (Odour judge), VSC production (Halimeter), VSC producing bacteria quantification using microscopy sulfide assay (MSA) and reactive oxygen species (ROS) production. Results showed that the exposure of experimental oral biofilm to blue light in the presence of rose bengal caused an increased reduction in VSC and malodour production concomitant with an increase in ROS production. These results suggest that rose bengal might be effective as a blue light photosensitizer against VSC producing bacteria.

Streptococcus mutans is considered a major cariogenic bacterium. Most anti-cariogenic dentifrices are limited by a short exposure time. The aim of the present study was to test the hypothesis that adding a mucoadhesive agent to the formulation may increase its bioavailability and efficacy. We tested the effect of adding hydroxyethyl cellulose (HEC) to an herbal extract solution containing lavender, echinacea, sage, and mastic gum, which have been previously shown to be effective against Streptococcus mutans. Mucin-coated wells were treated with four test solutions: saline, herbal extracts, herbal extracts with HEC, and chlorhexidine. The wells were incubated with Streptococcus mutans and studied for biofilm formation (Crystal violet assay), acid production (lactate assay), acid tolerance (ATPase assay), and exopolysaccharide (EPS) production using fluorescent microscopy. The results showed that the addition of HEC to the herbal extract solution caused a significant reduction in Streptococcus mutans biofilm formation, lactic acid production, and EPS quantity (p < 0.001). These results suggest that HEC may be a beneficial added excipient to herbal extracts in an anti-cariogenic formulation.