Salivary conditions and cariogenic microorganisms in 55, 65, and 75-year-old Swedish individuals.

Secretion rate, buffer capacity, and cariogenic microorganisms of resting and stimulated whole saliva were examined in 208 55-, 65-, and 75-yr-old Swedes. The secretion rate for both resting and stimulated saliva decreased with age. When the use of drugs was taken into account the difference in terms of age group was significant for resting saliva alone (P less than 0.01). In 22% the resting saliva was less than 0.1 ml/min, and in 5% the stimulated saliva was less than 0.7 ml/min. Persons with subjective dryness in the mouth had a lower salivary flow. Men had higher secretion rates than women irrespective of medication (P less than 0.05). The buffer capacity was strongly correlated to the secretion rate of both resting and stimulated saliva (r = 0.39 and r = 0.44, respectively). The number of mutans streptococci and lactobacilli increased with age, although significant in terms of age group for lactobacilli alone (P less than 0.05). The number of these microorganisms was lower in resting saliva than in stimulated saliva (P less than 0.0001). Individuals harboring both Streptococcus mutans and Streptococcus sobrinus had higher values of mutans streptococci in resting and stimulated saliva than those harboring only S. mutans (P less than 0.001). Actinomyces viscosus and Actinomyces naeslundii comprised greater than or equal to 1% of the total CFU in 89% of the plaque samples. The corresponding figures for lactobacilli and mutans streptococci were 6% and 38%, respectively.