Dental caries and salivary and microbial conditions in 50-60-year-old persons.

In a group of 124 persons, 50-60 yr old, the prevalence at baseline of mutans streptococci (MS) and lactobacilli and the salivary secretion rate and buffer capacity were examined. The mean secretion rate was 1.58 mL/min with a flow rate below 1 mL/min found in 20% of the persons. A buffer capacity below end pH 5.5 was observed in 64% of the subjects. MS was not detected in 5% of the persons whereas 17% had 10(6) or more MS per ml saliva. Lactobacilli were not found in 10% of the persons while 21% had counts in excess of 10(5) CFU mL. A new examination 5 yr later in 1986 revealed no significant changes in secretion rate and buffer capacity or in the population of lactobacilli, whereas markedly elevated levels of salivary MS were found. S. sobrinus was detected in 35-37% of the persons at the two examinations. Persons with both S. mutans and S. sobrinus had more MS than persons with only S. mutans.