Salivary lactobacillus counts in the prediction of caries activity.

The aim of the study was to investigate the reliability and clinical value for prediction of caries activity of determining the number of lactobacilli in saliva, the salivary secretion rate and the presence of yeasts in the saliva. For this purpose one entire age group of pupils (115 14-year-olds) attending one of the compulsory 9-year comprehensive schools in Orebro was selected for longitudinal examination. Over a period of 64 weeks three clinical recordings were made and seven salivary samples were collected. The correlations between caries activity, caries frequency (DFS), lactobacillus counts, yeasts in saliva, salivary secretion rate and gingivitis were examined. The results showed that in spite of a well-organized dental health service, including adequate preventive measures, a pronounced variation in caries activity remained and thus a means of predicting the onset of caries would be a valuable asset. Statistically significant correlations were found between caries activity on the one hand and caries frequency and lactobacillus counts on the other. The lactobacillus count was found to be a suitable measure in predicting caries activity. It was concluded that the lactobacillus count should be used for caries prediction in healthy, properly treated patients. It is important that there are no areas of microbial retention on the teeth such as open carious lesions, poorly executed restorations, dentures or orthodontic bands. In such situations, the lactobacillus count seems to reflect the frequency of ingested fermentable carbohydrates and thus, indirectly, the risk of initiating carious lesions.