Ureolytic bacteria were detected in the plaque flora of six subjects, and included members of the genera Actinomyces, Bifidobacterium, Staphylococcus, and Streptococcus. Proportions of these organisms did not change after subjects mouthrinsed thrice daily for four days with a plaque-mineralizing solution which contained urea and monofluorophosphate. The effectiveness of this rinse depends on the rapid metabolism of urea to alkali by plaque organisms, causing fluoridated apatite to precipitate in the matrix. Analysis of our data suggests that a numerically minor component of the flora, with a high turnover rate, is responsible for most of the ureolysis and the subsequent mineral precipitation.
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