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

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.