Characteristics of extra-oral halitosis induced by functional constipation: a prospective cohort study

Characteristics of extra-oral halitosis induced by functional constipation (FC) have never been revealed. To address this, this prospective cohort was conducted with 100 FC patients, who were divided into a halitosis group and a negative group. Organoleptic score (OLS) ⩾ 2 in nose breath was diagnosed as extra-oral halitosis. Concentration of overall volatile sulfur compounds (VSCs) measured by Halimeter, concentration of hydrogen sulfide (HS), methanethiol (MT), dimethyl sulfide (DMS) and their total amount measured by OralChroma in nose breath was recorded asC-VSC,C-HS,C-MT,C-DMS andC-sum respectively. We found that 82% (82/100) of the FC patients had extra-oral halitosis. However, only 12.5% (3/82) and 1.22% (1/82) of halitosis group were correctly diagnosed with the current diagnostic threshold ofC-VSC ⩾ 110 parts per billion (ppb) and ⩾150 ppb.C-VSC,C-DMS andC-sum were significantly higher in the halitosis group compared to the negative group (allP< 0.001), with ratios of about 2.2 times, 3.1 times and 2.1 times respectively.C-HS andC-MT were low and not significantly different between the groups. Positive correlations were observed among OLS,C-VSC,C-DMS andC-sum. The area under curve of receiver operating characteristics ofC-VSC, C-DMS andC-sum for predicting FC-induced halitosis was 0.909, 0.9073 and 0.962 respectively, with the threshold values of ⩾36 ppb, ⩾52 ppb and ⩾75 ppb respectively. Therefore, we conclude that: (1) DMS is the primary contributor to FC-induced extra-oral halitosis. (2) OLS, Halimeter and OralChroma are consistent in detecting FC-induced extra-oral halitosis. (3) The diagnostic threshold for Halimeter should be adjusted toC-VSC ⩾ 36 ppb and the diagnostic threshold for OralChroma should be set asC-DMS ⩾ 52 ppb for diagnosing FC-induced extra-oral halitosis.