Saliva has proven to be a discriminating element in forensic arenas, a
n effective indicator of acute diseases of salivary glands, and a prom
ising probe for drug monitoring. With the advent of sensitive immunoch
emical assays, the compositional profile of human salivary secretions
has been expanded considerably. Thus, the establishment of a range of
''normal values'' for a variety of ''intrinsic'' and ''extrinsic'' sal
ivary components represented the initial step to use saliva as a diagn
ostic tool of oral health status. Unfortunately, numerous cross-sectio
nal studies have shown a wide individual variation in the salivary com
position of healthy populations, thus precluding its use as a diagnost
ic chair-side test for the screening of the most common chronic oral d
iseases (e.g., caries and periodontal disease). A possible explanation
may arise from the wide functional versatility of salivary molecules.
For instance, it has been recognized recently that in addition to its
digestive properties, salivary amylase may modulate bacterial coloniz
ation, whereas histatins are not only antifungal but also bactericidal
. Thus, low levels of already known antimicrobial salivary molecules (
e.g., secretory IgA, lactoferrin, and lysozyme) could be compensated w
ith higher concentrations of other molecules with antimicrobial activi
ty, such as amylase and histatins. Consequently, for caries and period
ontal diseases, longitudinal sialochemical studies may yield more insi
ght than cross-sectional studies.