Relationship between halitosis and periodontal disease - associated oral bacteria in tongue coatings

Aim The objective of our study was to investigate the relationship between halitosis and oral bacteria in tongue coating (TC) and saliva samples from patients with halitosis, and to evaluate the effect of tongue cleaning on halitosis. Methods Ninety-four participants complaining of oral malodour were included in the study. Organoleptic (OR) values, volatile sulphur compound (VSC) concentrations determined by gas chromatography and TC scores were used as clinical parameters of halitosis. Quantitative real-time polymerase chain reactions were used to determine the numbers of periodontal disease-associated oral bacteria. Results There was a significant correlation between TC scores and OR values, methylmercaptan (CH3SH) concentrations and VSC concentrations (Spearman's rank-correlation coefficient test, P<0.01). There was also a positive correlation between the clinical parameters of halitosis and total bacterial numbers and Prevotella intermedia, Fusobacterium nucleatum and Campylobacter rectus concentrations in the TC samples. However, there was no similar correlation with respect to the saliva samples. The participants were sub-divided into two groups based on whether they had the habit of tongue cleaning or not. The participants with the habit of tongue cleaning had significantly lower OR scores, VSC concentrations and P.intermedia, F.nucleatum and C.rectus levels than the other participants (Mann-Whitney U-test, P<0.05). Conclusion These results suggested that periodontal disease-associated oral bacteria in TCs are closely related to halitosis and that tongue cleaning may be an effective method for improving halitosis.