Antimicrobial factors in saliva: ontogeny and relation to oral health

Antimicrobial agents (antibody and non-antibody) present in human saliva protect oral tissues by a variety of mechanisms, such as prevention of bacterial adhesion, agglutination of micro-organisms, and inhibition of multiplication and metabolism. However, studies in which the concentrations of various salivary antimicrobial agents have been correlated to the presence and severity of oral diseases--of dental caries, in particular--have produced controversial data, and it seems evident, also on the basis of the present study, that no single salivary antimicrobial factor (except flow rate) affects oral health to a significant degree. In the present study, we report the levels of some selected salivary antimicrobial agents in predentate and dentate human infants, with a comparison to the levels found in young adults' saliva. Salivary lysozyme, peroxidase, and hypothiocyanite concentrations were already at the adult level at the time when the primary teeth erupt, whereas immunoglobulin (IgA, IgG, and IgM), lactoferrin, myeloperoxidase, and thiocyanate concentrations were significantly lower in children than in adults. Dentate children had more IgG, thiocyanate, and protein in whole saliva than did predentate children.