LONGITUDINAL-STUDY OF RELATIONS BETWEEN HUMAN SALIVARY ANTIMICROBIAL PROTEINS AND MEASURES OF DENTAL PLAQUE ACCUMULATION AND COMPOSITION

Many studies have attempted to relate levels of antimicrobial proteins in saliva to oral health; results have been inconsistent, and one rea son might be inconsistency of measures of plaque and saliva within sub jects. This study investigated associations between plaque and salivar y variables in longitudinal data. Whole saliva, and 8-h plaque pooled from buccal first permanent molars, was obtained from 32 dental studen ts on Tuesdays from 3:00-6:00 p.m. over 4 weeks. Salivary flow rate wa s determined, and samples were assayed for lysozyme, lactoferrin, tota l peroxidase, myeloperoxidase, OSCN-, sIgA and total protein. Colonies on mitis-salivarius agar were assigned to Streptococcus sanguis, Stre p. mutans or Strep. salivarius on the basis of morphology, supplemente d by the API Rapid Strep identification system. Consistency of values within subjects across weeks was evaluated by repeat-measures analysis of variance and intraclass correlation; data were transformed to redu ce skewness. Pearson's r was used to determine associations between pl aque and salivary variables. Significant intraclass correlations (alph a = 0.05) were found for all salivary variables except myeloperoxidase , and for total flora, total streptococci, Strep. sanguis and Strep. s anguis as a proportion of total streptococci. Significant Pearson corr elations with Strep. sanguis as a proportion of total streptocci were found for total protein (r = -0.24), sIgA (r = -0.22), lactoferrin (r = 0.19) and OSCN- (r = 0.20) when data from all weeks were pooled (n = 128). Strep. sanguis proportions tended to bc low in subjects with hi gh values for salivary proteins; the range of proportions was wider in subjects with low salivary values. These findings suggest some consis tency of weekly values for many plaque and salivary variables. They al so support previous cross-sectional data which suggested that salivary antimicrobial proteins may have some effect on plaque composition. Th is study was made before recent revisions in streptococcal taxonomy, a nd further research is needed to clarify interactions of salivary prot eins with currently defined species.