Effect of mucoadhesive agent HEC on herbal extracts retention and VSC producing bacteria reduction in an experimental oral biofilm.

Mucoadhesive tablets containing herbal formulation have been previously shown to reduce oral malodour. The aim of the present in vitro study was to test the effect of the mucoadhesive agent hydroxyethylcellulose (HEC) added to a liquid phase herbal extract formulation on the mucoadhesive retention of the active ingredients and their effect against malodour production. Experimental oral biofilms were grown on mucin coated glass slides treated with liquid phase solutions of herbal extract with or without HEC as well as saline and 0.2% chlorhexidine as controls. Biofilms were quantified for volatile sulfide compounds (VSC) producing bacteria using CLSM and sampled for a salivary incubation assay to test for malodour production (odour judge), VSC production (Halimeter) and salivary protein degradation (SDS-PAGE). Results showed that the addition of HEC to the herbal extracts solution has significantly increased its mucin retained activity against malodour producing bacteria and their resulting malodour and VSC production and proteolytic activities. Taken together, results of the present study suggest that the addition of HEC to a liquid phase herbal extract solution may increase its bioavailability time and efficacy. However, due to the limitations of this in vitro study additional clinical investigations are needed.

Effect of red dyes on blue light phototoxicity against VSC producing bacteria in an experimental oral biofilm.

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-2, 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.