The mouth’s soft tissue is called oral mucosa. It is similar to skin in its form and function.
Oral mucosa is situated at the entrance of the digestive and respiratory tracts.
If saliva flow is compromised or inactive (due to cancer therapy, medication side effects, autoimmune diseases among other reasons) The oral mucosa will be dry, placing the mouth at severe risk (oral mucosa is also subjected to numerous natural and man-made xenobiotics)
A xenobiotic (Greek, xenos "foreign"; bios "life") is a compound that is foreign to a living organism.
Principal xenobiotics include: drugs, carcinogens, pesticides, cosmetics, flavourings, fragrances, food additives, industrial chemicals and environmental pollutants various compounds that have been introduced into the environment by artificial means