Dental caries, mutans streptococci, lactobacilli, and saliva secretion rate in adults.

In 718 Swedish patients, equally divided into four age groups (19-25, 26-45, 46-60, greater than 60 yr), salivary levels of mutans streptococci and lactobacilli, saliva secretion rate, and DMFS were registered. No significant differences were found between the various age groups either in salivary factors or in caries (D). Number of missing (M) and filled (F) surfaces increased with age. Prevalence of root caries, which increased with age, was significantly correlated to number of exposed root surfaces independent of age. Of the total study group, 50% had greater than or equal to 10(6) mutans streptococci and 40% had greater than or equal to 10(5) lactobacilli per mL saliva. Three percent had a saliva secretion rate of less than or equal to 0.5 mL/min. Correlation analyses showed that both mutans streptococci and lactobacilli significantly correlated to the caries prevalence but the r-value never exceeded 0.34.