Development of new method for the treatment of halitosis using molecular biological technique

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Oral malodor is mainly associated with the condition of the oral cavity and is originates from a variety of products produced by the bacterial metabolism of amino acids in materials such as food debris, desquamated cells from oral mucosa and leukocytes that accumulate in the mouth. These metabolites include volatile sulfur compounds (VSC), indole, skatole, amines and ammonia. Of these compounds, VSC are the main cause of oral malodor.In this study, the characteristics of patients complaining of halitosis were examined and the diagnostic accuracy of methods of measuring halitosis was evaluated. The organoleptic test revealed that 55% of the subjects had no or slight odor. There was a significant correlation between the organoleptic score and the total VSC level determined by other methods. The amount of tongue coating was significantly greater in the halitosis-positive group than in the halitosis-negative group, whereas there was no difference in the salivary flow rate between the two groups.The ability of periodontopathic Porphyromonas gingivalis to produce methyl mercaptan was examined. The invasive strain W83 and W50 produced large amounts of methyl mercaptan. We cloned and sequenced the gene encoding L-methionine-α-deamino-γ-mercaptomethane-lyase (METase) from P.gingivalis W83. We also constructed a METase-deficient mutant of P.gingivalis W83. The mutant showed a marked decrease in the formation of methyl mercaptan from L-methionine and decreased virulence compared with the wild-type strain W83. Inactivation of METase may be effective for the inhibition of oral malodor.