Dental plaque mass and acid production activity of the microbiota on teeth

With the purpose of elucidating the effect of dental plaque thickness on the acid production activity in dental plaque, we studied the prevalence of acid anions in dental plaque of children harbouring different amount of plaque on their teeth. On two occasions, the occurrence of plaque on the dentition was scored (Silness-Löe's index), and plaque on available smooth surfaces was collected and the wet weight determined. On the first occasion, the amount of acid anions in resting plaque, and on the second occasion, the acid anions of sucrose-exposed plaque were analysed with isotachophoresis. Mean value of plaque wet weights per individual dentition was 11.7 +/- 9.0 mg (first occasion) and 11.1 +/- 8.9 mg (second occasion). Dominating anions in resting plaque were acetate < propionate < lactate and in sucrose-exposed plaque lactate < acetate < propionate. The microbial acid production activity (acid anion per mg wet plaque weight) decreased with increasing weights of the plaque mass. The findings illustrate the cellular glycolytic metabolism of plaque microorganisms in thin and thick plaque, being a consequence of the diverse environmental condition existing in these ecosystems.