Saliva is the product of the salivary glands, it consists in fluid and proteins whose function is, formally, maintaining the health of the oral cavity and, since this cavity is one of the main portals to the external environment, of the whole organism (1). Among the several important functions of the saliva, we can not fail to mention all those connected with the teeth, such as the initialisation of the enamel and mucosal film that contributes to the adhesion and colonisation of microorganisms and, thus, to the formation of the resident oral microbiota (2). In normal conditions, while maintaining a neutral pH, saliva lubricates and cleanses teeth and the oral mucosa, contributes to taste, bolus formation, mastication and swallowing, initiates the digestion of starch, prevents tooth demineralization, rejects unwanted microbial attacks and, last but not least, facilitates the articulation of speech (3), as all of us have experienced when trying to talk in case of “zeroed salivation”.
The conditions in the oral cavity are continuously changing due to the exposure to the external environment, but, if we leave out the “qualitative” issues about saliva, the condition that is characterised by an effective or perceived reduction in the flow of saliva is called xerostomia, from the greek words ξηρός (xeros) and στόμα (stoma) whose meaning is "dry mouth”. This objective condition is quite common during anxiety and among older patients subjected to radiation treatment for head and neck cancers or affected by autoimmune exocrinopathy, known as Sjögren's syndrome. This hypo-function of the salivary glands could lead to an increased frequency of caries, candida infection, dysarthria and dysphagia.
In this issue of Italian Journal of Dental Medicine a detailed overview on xerostomia is published stating that ageing and medications play a critical role in objective hypo-salivation, while female gender and psychological factors are much more involved with subjective oral dryness (4). Indeed, as we know, dry mouth and eye symptoms are reported in about 30% of persons ageing over 65 years, particularly in women. But why medication side effects should be considered the most common contributing factor? Simply because elderly patients, often, suffer from several chronic diseases and, consequently, do use more drugs than any other age group. With ageing a diminished physiological reserve is reported and this reserve can be further reduced by acute/chronic diseases and by the effects of drugs. In most developed countries, about 75% of the population over 65 years take prescription and OTC drugs. At any time, any average elderly person uses from four to five prescription drugs and two OTC drugs (5). Thus, since drugs that can cause xerostomia, such as Antihistamines, Antihypertensives Antidepressants, Benzodiazepines, Phenothiazines, Proton-pump inhibitors, are very common, we can say that (even) xerostomia is largely a iatrogenic matter.
1. Pedersen AML, Sørensen CE, Proctor GB, Carpenter GH, Ekström J. Salivary secretion in health and disease. J Oral Rehabil. 2018 Jun 7. [Epub ahead of print] Review.
2. Costalonga M, Herzberg MC. The oral microbiome and the immunobiology of periodontal disease and caries. Immunol Lett 2014 Dec;162(2 Pt A):22-38. Epub 2014 Nov 8. Review.
3. Tyldesley, Anne Field, Lesley Longman in collaboration with William R. Tyldesley's Oral medicine (5th ed.). Oxford: Oxford University Press; 2003. pp. 19, 90–93.
4. Teresa J, Giju Baby G, Mathews B, Eby A, Sheeba P, Jacob K, Pearly P. Xerostomia – An overview. Italian Journal of Dental Medicine 2018; 3(2).
5- Jansen PA, Brouwers JR. Clinical pharmacology in old persons. Scientifica (Cairo). 2012;2012:723678. Epub 2012 Jul 28. Review.