Effect of mouth-rinse formulations on oral malodour processes in tongue-derived perfusion biofilm model

Abstract

An in vitro matrix biofilm perfusion model of tongue-derived microcosms for studying volatile sulfur compound (VSC) biogenesis has been previously described. The model was modified in order to monitor H(2)S in situ by use of a specialized electrode assembly based on microbial fuel cell technology. This system was designed to give real-time measurements expressed as electrode power output, which were proportional to H(2)S levels, measured by other means. In addition to the model modifications, the aim of this study was to demonstrate the biofilm responses following single or multiple exposure to biocidal, biostatic or VSC-inhibiting active compounds used in products. Tongue-derived biofilms (n = 6 per experiment) were perfused with one-fifth strength BHI at 20 ml h(-1) pH 7.2 and pulsed with putative treatment agent, placebo and controls including Zn(2+) ions and chlorhexidine (CHX). Compared with their pre-treatment conditions, all biofilms responded to the treatments in terms of reductions in hydrogen sulfide generation (as detected by the biofilm-electrode response) and other microbial volatile organic compounds (VOCs) as detected using a selected ion flow tube mass spectrometry analyser. The microbiological analysis of the treated and control biofilms show that test products (formulations with active agents) all gave reduced cell populations compared to the control biofilm. An order of effects (magnitude and duration) suggests that both the test agent and CHX produced the strongest reductions, distinct from the responses obtained for the placebo and water controls, which were largely similar. It is concluded that the in vitro perfusion model may be used to replicate many of the activities and reactions believed to be occurring by the tongue biofilm microflora within a real mouth, including H(2)S and VOC biogenesis and their inhibition by exposure to active agents.

Review:In vitrobiofilm models for studying oral malodour

“…The in vitro perfusion model has also been employed (using tongue‐scrape microflora) to study the effects of repeated exposure to CHX on VSC production measured using both a carbon veil electrode within the biofilm (liquid phase) and a halimeter (gas phase) . The microflora of the perfusate and the biofilm were assessed by microbiological techniques and polymerase chain reaction (PCR) to estimate diversity.…”

“…In vitro biofilm models for oral malodour (gas phase). [47] The microflora of the perfusate and the biofilm were assessed by microbiological techniques and polymerase chain reaction (PCR) to estimate diversity. Biofilms treated with a 1 ml pulse of 0.1% CHX twice a day for 3 days gave: (1) a large reduction in viable count (>90% kill), (2) a (slow) reduction in the VSC production rate, consistent with the reduction in microbes rather than direct inhibitory effects on the biotransformation steps, and (3) a preferential reduction of strict anaerobes.…”

Effect of photodynamic therapy for the treatment of halitosis in adolescents – a controlled, microbiological, clinical trial

“…Conventional halitosis treatment consists of the chemical reduction of microorganisms with mouthwashes, such as a 0.2% chlorhexidine solution, essential oils, triclosan and oxygenated water, the mechanical removal of intraoral nutrients with a tongue scarper or brush, odor masking with gum, mints or sprays and the transformation of VSCs using zinc combined with chlorhexidine [10][11][12][13][14][15][16]. However, the reduction in the bacterial load is hampered by the irregular characteristics of the dorsal surface of the tongue, which is lined with numerous papillae [12,13,17].…”

Photodynamic therapy as a novel treatment for halitosis in adolescents: study protocol for a randomized controlled trial

“…The conventional treatment of halitosis related to oral conditions consists of the chemical reduction of microorganisms with a mouthwash, such as 0.2% chlorhexidine, essential oils, triclosan and hydrogen peroxide, the mechanical removal of nutrients with a tongue scraper or brush, the masking of odor with chewing gum, mints and breath spray, and the transformation of VSCs using zinc plus chlorhexidine [ 2 , 5 , 10 , 12 , 35 – 37 ]. However, the irregular characteristics of the surface of the dorsum of the tongue make the adequate reduction in bacterial a particular challenge [ 2 , 36 , 38 ].…”