Elsevier

Journal of Dentistry

Volume 32, Issue 7, September 2004, Pages 555-559
Journal of Dentistry

The assessment of methyl mercaptan, an important clinical marker for the diagnosis of oral malodor

https://doi.org/10.1016/j.jdent.2004.06.001Get rights and content

Summary

Objective. This study aimed to determine the clinical assessment of volatile sulfur compound (VSCs) for the evaluation of noticeable oral malodor using gas chromatography (GC).

Methods. The oral malodor of 127 adult patients was investigated using the organoleptic test and GC, and the relation between the organoleptic evaluation and VSCs were analyzed.

Results. The optimum cut-off values of CH3SH, H2S and total VSC (CH3SH+H2S) to discriminate between the patients with and without noticeable oral malodor were obtained from ROC curves, and determined to be 0.44, 1.10 and 2.20 ng/10 ml, respectively. The logistic regression was analyzed for estimation of the association between an organoleptic evaluation greater than a slight level and the groups with CH3SH, H2S or total VSC with concentrations above the optimum cut-off value. Only CH3SH showed an independent association with noticeable oral malodor.

Conclusions. It was evident that CH3SH was a more useful marker for the evaluation of oral malodor than H2S. Moreover, it appears CH3SH is the predominant causative factor of noticeable oral malodor.

Introduction

The organoleptic intensity of oral malodor correlates with the level of methyl mercaptan (CH3SH) and hydrogen sulfide (H2S), which are volatile sulfur compounds (VSCs), in mouth air.1., 2., 3. CH3SH and H2S are regarded as the main components of oral malodor.1., 4., 5.

Furthermore, there is an organoleptic difference in the malodor between CH3SH and H2S.6., 7. It is evident that organoleptic evaluations of standard concentrations of CH3SH and H2S show that the CH3SH has a lower threshold of objectionability than the H2S.6., 8., 9. Therefore, CH3SH is generally regarded as the stronger factor to influence oral malodor compared with H2S. However, according to increases in the concentrations of CH3SH and H2S, the organoleptic evaluation of the H2S tends to be similar to the CH3SH since the H2S has a greater odor-power than the CH3SH and the difference in organoleptic evaluation of each the VSCs depends on the odor-power as well as the threshold.9 When VSCs are detected from mouth air, a combination of the CH3SH and H2S is assumed in many cases. Consequently, it is not evident how the difference in each concentration of CH3SH and H2S reflects the organoleptic evaluation in vivo.

The measurement of VSCs by gas chromatography (GC) has been demonstrated to allow a consistent and quantitative determination of separate VSC components.10., 11. To use GC analysis data of the VSCs more successfully, it is necessary to establish more practical markers linking VSCs to the diagnosis of oral malodor. This study aimed to determine the role for quantitative assessment of the VSCs for the diagnosis of oral malodor.

Section snippets

Subjects

The subjects comprised 127 adult patients (30 males and 97 females) who visited the Preventive Dentistry and Breath Odor Clinics of Kyushu Dental College Hospital complaining of oral malodor. Their average age was 46.3±13.0 years (mean±SD). At the initial visit, the patients' chief complaints, along with brief systemic and dental history, were obtained, and preliminary oral examinations were conducted. Then, all the subjects were informed about the examination of oral malodor and instructed to

Results

The Spearman correlation coefficients between the organoleptic score and the log concentrations of the CH3SH, the H2S, and the total VSC was r=0.746 (p<0.001), r=0.590 (p<0.001) and r=0.744 (p<0.001), respectively. In addition, the correlation coefficient between CH3SH and H2S was r=0.750 (p<0.001), and the correlation coefficients between the total VSC and CH3SH, and H2S were r=0.923 (p<0.001) and r=0.898 (p<0.001), respectively.

In this study, the subjects were divided into groups of five

Discussion

In addition to VSCs, mouth air includes volatile compounds such as indole and skatole which may influence the organoleptic evaluation of oral malodor. Several studies suggest that oral malodor may increase when such compounds are released into the oral headspace when saliva dries out on the mucosal surfaces.14., 15. However, there is no evidence of a relation between the other volatile compounds except for VSCs and the organoleptic evaluation in mouth air. Thus, VSCs are presently used as the

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