P30 Relationship of oral malodor with tongue microbiota analyzed with real‐time PCR

Abstract

Oral malodor is thought to mainly originate from the bacterial population present on the surfaces of tongue. However, the relationship between oral malodor and tongue microbiota has been little studied. In the present study, we analyzed tongue microbiota with real‐time PCR and examined an association of oral malodor with tongue microbiota. The subject population consisted of 37 patients who complained of oral malodor. Oral malodor was assessed by an organoleptic test (OLT) and volatile sulfur compound (VSC) levels by gas chromatography. Real‐time PCR was carried out in tongue biofilm samples using a LightCyclerTM system as previously described (Kuboniwa et al. 2002) and the bacterial proportion in clinical sample was used as a quantitative parameter. The correlation coefficient between the proportion of total five Gram‐negative anaerobes (P. gingivalis, T. forsythensis, P. intermedia, P. nigrescens,and T. denticola) and total VSC level (r = 0.84) was higher than that between the bacterial proportion and OLT score (r = 0.24). In these five Gram‐negative anaerobes, the proportions of P. intermedia, P. nigrescens and T. denticola were correlated with the concentration of hydrogen sulfide (r = 0.79, 0.73 and 0.50, respectively). The proportions of P. gingivalis, P. intermedia and P. nigrescens were also correlated with the concentration of methyl mercaptan (r = 0.91, 0.40 and 0.71, respectively). When a linear regression analysis was conducted using the proportion of each of five Gram‐negative anaerobes as independent variable, the explanatory power of these independent variables showed 77% for total VSC level and 10% for OLT score. These results suggest that Gram‐negative anaerobes in tongue microbiota may contribute VSC production and may be also related to oral malodor.