O5 
Clinical association of volatile sulfur compounds, Halimeter values, organoleptic score and tongue coating in oral malodor

Objective  Oral malodor is now generally accepted to be the main cause (about 90%) of bad breath. The objective of this study is to evaluate the potential power of volatile sulfur compounds (VSC), Halimeter values, organoleptic score (OLS) and tongue coating in assessing oral malodor.Methods  We investigated the mouth‐ and nose‐breath of 42 subjects with oral malodor, visiting our bad breath clinic. The methods used were gas chromatography, Halimeter measurements, organoleptic scoring (OLS) and tongue coating measurements.Results  The concentrations of hydrogen sulfide (H2S), methylmercaptan (MM, CH3SH) and dimethylsulfide (DMS, CH3SCH3) in the mouth‐breath of the 42 patients with oral malodor amounted to 0.74 ± 0.95 (s.d.), 0.42 ± 0.30, and 0.29 ± 0.19 nmol l−1, respectively. H2S and MM were absent in nose‐breath of all patients, indicating that the origin of these VSC is the mouth. DMS in nose‐breath (0.21 ± 0.12 nmol l−1) was similar to that in mouth breath, indicating that the origin of DMS lies outside the mouth. The recognition threshold value of MM is four to 30 times lower than that of H2S and about three times lower than that of DMS, indicating that MM is the major source of oral malodor. A significant correlation (r = 0.726, P < 0.001) was found between mouth‐H2S and mouth‐MM. No significant correlations were found between these two VSC and DMS. The correlations of H2S and MM with the Halimeter measurements, with OLS and with tongue coating are all highly significant.Conclusions  Oral malodor is mainly caused by MM. The Halimeter is most sensitive for H2S. Nevertheless, thanks to the good correlation between H2S and MM, the Halimeter remains a useful apparatus in predicting oral malodor. OLS and tongue‐coating assessments are also useful methods in detecting oral malodor.