Aging and saliva: a review of the literature.

It is often assumed that salivary secretion reduces with age. About 25% of the elderly suffer from oral dryness and related complaints. Nevertheless, data on stimulated salivary flow rate in healthy elderly revealed no significant age-related decrease other than a slight decrease of the secretion from the (sero)mucous glands under conditions of minimal or extended stimulation. With regard to salivary gland morphology and composition of saliva, age-related changes have been reported in healthy individuals, too. With increasing age, the number of acini reduces and the amount of fatty and fibrous tissue increases. Moreover, animal studies revealed that the synthesis of proteins is reduced by 60% in advanced years. These data indicate that changes might occur in concentration and/or activity of the organic components of saliva. In human studies, the concentration of sIgA in labial saliva and the concentrations of high-molecular and low-molecular mucins in mucous saliva appeared to be reduced with age. Since sIgA and mucins are important in the immunologic and non-immunologic defense of the oral cavity, both defense systems are reduced in healthy elderly. Analysis of these data suggests that the oral soft tissues may become somewhat more susceptible to environmental factors due to a reduction of the immunological and non-immunological defense systems.