Saliva tests may some day be possible for the cataloging of the "complete" salivary proteome -- a set of proteins in human ductal saliva, said James E. Melvin, director of the Center for Oral Biology at the University of Rochester Medical Center, and an author on the paper.

Defining exact protein pathways on a comprehensive scale enables the development of early diagnostic testing and precise drug design.

The study, published in the Journal of Proteome Research, said that salivary proteins may represent new tools for tracking disease throughout the body -- tools that are potentially easier to monitor in saliva than in blood.

The researchers said the definition of saliva is evolving. Saliva once referred to everything in oral fluid, but among researchers today, saliva is increasingly reserved for just the salivary gland secretions -- ductal saliva.