LONGITUDINAL ANALYSIS OF THE ASSOCIATION OF HUMAN SALIVARY ANTIMICROBIAL AGENTS WITH CARIES INCREMENT AND CARIOGENIC MICROORGANISMS - A 2-YEAR COHORT STUDY

Previous studies of the possible associations of salivary antimicrobia l agents with dental caries have given controversial results, obviousl y mainly because almost all studies have been cross-sectional. Our aim was to find out, in a two-year longitudinal follow-up study, the asso ciations among selected salivary non-immune and immune antimicrobial v ariables, cariogenic bacteria, and caries increment. The study populat ion was comprised of 63 subjects, all of whom had their 13th birthday during the first study year. In addition to a comprehensive dental exa mination at baseline and after 2 yrs, paraffin-stimulated whole saliva samples were collected in a standardized way at six-month intervals. Saliva samples were analyzed for flow rate, buffer effect, lysozyme, l actoferrin, total peroxidase activity, hypothiocyanite, thiocyanate, a gglutination rate, and total and specific anti-S. mutans IgA and IgG, as well as for numbers of total and mutans streptococci, lactobacilli, and total anaerobic bacteria. Cluster analysis and Spearman-Rank corr elation coefficients were used to explore possible associations betwee n and among the studied variables. During the two-year period, a stati stically significant increase was observed in flow rate, thiocyanate, agglutination rate, anti-S. mutans IgA antibodies, lactobacilli, and t otal anaerobes, whereas lysozyme, lactoferrin, and total and anti-S.mu tans IgG antibodies declined significantly. Based on various analyses, it can be concluded that, at baseline, total IgG and hypothiocyanite had an inverse relationship with subsequent two-year caries increment, anti-S., mutans IgG antibodies increased with caries development, and mutans streptococci and lactobacilli correlated positively with both baseline caries and caries increment. Total anaerobic microflora was c onsistently more abundant among caries-free individuals. In spite of t he above associations, we conclude that none of the single antimicrobi al agents as such has sufficiently strong power to have diagnostic sig nificance in vivo with respect to future caries.