One of the natural defenses of your body is saliva. Saliva is our body’s natural defense against plaque because it rinses out the bacteria in our mouth, which causes cavities as well as other harmful particles. The medical term for dry mouth is “xerostomia”, and is a condition commonly caused by decreased levels of saliva. People who have diabetes or eating disorders often times also have dry mouth. There are other factors that can diminish the production of saliva such as eating garlic, taking medications, smoking/chewing tobacco, and cancer therapy and treatment. Also, the elderly, and people with arthritis, and compromised immunities also frequently suffer from dry mouth.
Some mild symptoms include bad breath. If left untreated, dry mouth can lead to more serious complications such as burning tongue syndrome. This painful condition causes lack of moisture on the tongue.
Other less apparent symptoms are chronic thirst, overly-sensitive tongue, and difficulty speaking.
For people who have dry mouth and it is not caused by a medical condition, I recommend that you sip water regularly, avoid smoking, and chew gum. I would like to emphasize that there is no substitute for daily oral hygiene and visiting your dentist for regular checkups.
 http://www.youngdentistryforchildren.com/library/33/DryMouth.html, accessed December 27, 2011