| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1992: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1991: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
In this study, we analyzed organic acids in carious dentin and dental plaque by HPLC. In carious dentin, lactate (mean: 30.7% of total acids) and acetate (mean: 36.7%) were the major acids as we reported previously. However, a high amount of formate (mean: 13.4%) and succinate (mean: 11.2%) were detected in the arrested type carious dentin, although only a little amount of formate and succinate were detected in the active type carious dentin. Formate and succinate in carious dentin were confirmed by Carboxylic Acid Analyzer and enzymatic assay. Existence of high amount of formate in carious dentin implies that bacteria having pyruvate formate-lyase are living in the arrested caries lesions and that the conditions in the lesions are strictly anaerobic. Detection of plenty of succinate in carious dentin indicates that succinate-producing bacteria, such as Actinomyces, Bacteroides, Propionibacterium, and Arachnia, are harboring in the arrested caries lesions. Furthermore, we compared organic acids among carious dentin, dental plaque covered on the caries lesion, and dental plaque on the sound teeth in the same mouth. Both active carious dentin and dental plaque on the caries lesion contained high amount of lactate over after being starved for long time, whereas dental plaque on the sound tooth surface had little lactate without sugar-intake. This difference implies that dentin caries establish a stable environment in which acids were produced are not easily washed away by saliva.
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