A novel visual test for hydrogen sulfide on the tongue dorsum

Takashi Kanehira,Yoshihiro Fujii,Hiroshi Izumi,Hirohisa Hongo,Kazumi Osada,Junji Takehara,Kozo Asano,Wataru Sakamoto

doi:10.4236/ojst.2012.24054

Abstract

Objective: The purpose of this study was to develop a novel colorimetric system for direct detection of hydrogen sulfide on the tongue dorsum from subjects with complaints of halitosis. Method: An assay system comprised of a cotton swab impregnated with zinc sulfate, attached chromatography paper, stabilizing solution, and coloring reagents for the methylene blue technique was developed. Using this system we investigated on the visualization of the hydrogen sulfide on the solid phase and possibility for evaluating the origin of oral malodor on the tongue dorsum. Results: The assay system made possible visualization of a linear curve ranging from 5.3 ng to 85 ng of hydrogen sulfide, with low reagent consumption and miniaturization. However, the sensitivity was different for gaseous and fluid samples. The biofilm of the tongue dorsum from subjects with complaints of halitosis showed different shades of methylene blue depending on the concentration of hydrogen sulfide. A positive correlation was found between hydrogen sulfide on the tongue dorsum and the concentration of VSC hydrogen sulfide in mouth breath as measured using an Oral Chroma semiconductor gas sensor. Conclusion: The results of this study suggest that the novel assay system can be used as a visual warning sensor for halitosis by measuring hydrogen sulfide on the tongue dorsum.

Highlights

Oral malodor is a common problem that affects people in daily life
Several investigators reported that oral malodor was associated with hydrogen sulfide-producing bacteria among tongue biofilm microflora [7,8,9], VSC are produced from methionine and cysteine in mammalian tissue and by bacteria [10]
With the attachment of the paper column and addition of stabilizing solution the distinct blue color was clear on the swab, whereas the chaotic brown color moved into the paper column (Figure 3(d)). These results confirmed the utility of the novel assay system with a colorimetric sensor for direct detection of hydrogen sulfide on the cotton swab

Summary

Introduction

Most reports agree that the most frequent sources of oral malodor exist within the oral cavity and include bacterial reservoirs such as the tongue dorsum, saliva and periodontal pockets, where anaerobic bacteria degrade sulphur-containing amino acids to produce foul smelling VSC (hydrogen sulfide, dimethyl sulfide, and methyl mercaptan) [1,2]. Several investigators reported that oral malodor was associated with hydrogen sulfide-producing bacteria among tongue biofilm microflora [7,8,9], VSC are produced from methionine and cysteine in mammalian tissue and by bacteria [10]. Direct detection of hydrogen sulfide on the tongue dorsum remains difficult and the assessment of clinical oral malodour is usually done by measuring VSC levels in mouth breath using a gas chromatography-semiconductor gas sensor (Oral Chroma) and organoleptic scoring [5,11]. We tried to develop a method for visualization of the hydrogen sulfide on the tongue dorsum using methylene blue, which has been widely utilized for continuous, quantitative monitoring of hydrogen sulfide in biological samples

Methods

Results

Conclusion