High scores of chair-side salivary microbial tests have been found to be
related to an increased prevalence and incidence of coronal and root
caries. Many elderly face an increased risk of the growth of oral
microbes, and previous studies have reported high salivary microbial
counts in elderly populations. The aim of this follow-up study was to
compare, at five-year intervals, stimulated salivary flow rates with the
numbers of selected salivary micro-organisms (mutans streptococci,
lactobacilli, and yeasts) in a group of home-dwelling elderly in
Helsinki. A further aim was to study the influence of baseline microbial
counts on five-year root caries increments and rates of tooth loss. The
baseline study population was comprised of 270 subjects who were all
participants in the population-based Helsinki Aging Study. Salivary flow
rates and microbial conditions were determined as part of their dental
examination at the Institute of Dentistry, University of Helsinki, in
1990-1991. Of these subjects, 110 underwent a follow-up examination in
1995-1996. Commercially available kits (Dentocult SM strip mutans for
mutans streptococci, Dentocult LB for lactobacilli, and Oricult N for
yeasts) were used for the enumeration of micro-organisms, after the
collection of paraffin-wax-stimulated whole saliva. The stimulated whole
saliva flow rates of the subjects were significantly lower at the
follow-up than at baseline (paired t test, difference -0.16 mL/min; p
< 0.05), whereas buffer capacity was higher (paired t test,
difference 0.19 on a three-unit scale; p < 0.05). Apart from lower
salivary lactobacilli counts at follow-up (paired t test, difference
-0.44 CFUs/mL of saliva; p < 0.001), no changes were found in
salivary microbial levels. Salivary microbial counts were clearly
associated with the subjects' dentition types: More denture-wearers had
high microbial counts than persons with natural dentitions. None of the
salivary factors correlated with the root caries incidence or the number
of teeth lost during the five-year follow-up