Saliva, salivary micro-organisms, and oral health in the home-dwelling oldelderly - A five-year longitudinal study

High scores of chair-side salivary microbial tests have been found to be re lated to an increased prevalence and incidence of coronal and root caries. Many elderly face an increased risk of the growth of oral microbes, and pre vious studies have reported high salivary microbial counts in elderly popul ations. The aim of this follow-up study was to compare, at five-year interv als, stimulated salivary flow rates with the numbers of selected salivary m icro-organisms (mutans streptococci, lactobacilli, and yeasts) in a group o f home-dwelling elderly in Helsinki. A further aim was to study the influen ce of baseline microbial counts on five-year root caries increments and rat es of tooth loss. The baseline study population was comprised of 270 subjec ts who were all participants in the population-based Helsinki Aging Study. Salivary flow rates and microbial conditions were determined as part of the ir 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(R) for m utans streptococci, Dentocult LB(R) for lactobacilli, and Oricult N(R) for yeasts) were used for the enumeration of micro-organisms, after the collect ion of paraffin-wax-stimulated whole saliva. The stimulated whole saliva fl ow 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 (pai red 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 hi gh microbial counts than persons with natural dentitions. None of the saliv ary factors correlated with the root caries incidence or the number of teet h lost during the five-year follow-up.