Xerostomia

Xerostomia is the medical term for the subjective complaint of dry mouth due to a lack of saliva. Xerostomia is sometimes colloquially called pasties, cottonmouth, drooth, or doughmouth. Several diseases, treatments, and medications can cause xerostomia. It can also be exacerbated by smoking or drinking alcohol.

Xerostomia can cause difficulty in speech and eating. It also leads to halitosis and a dramatic rise in the number of cavities, as the protective effect of saliva's remineralizing the enamel is no longer present, and can make the mucosa and periodontal tissue of the mouth more vulnerable to infection. Heavy methamphetamine use can cause xerostomia, usually called "meth mouth" in this case; it can be worsened by methamphetamine at recreational doses causing tight clenching of the jaw, bruxism (compulsive grinding of the teeth), or a repetitive 'chewing' movement as if the user were chewing, but without food in the mouth.

Causes
Basically, xerostomia can be caused by excessive clearance (such as by excessive breathing through the mouth), or it may be caused by insufficient production of saliva (called hyposalivation).

Hyposalivation, in turn, may be a sign of an underlying disease, such as Sjögren's syndrome, poorly controlled diabetes, or Lambert-Eaton syndrome, but this is not always the case.

Other causes of insufficient saliva production include anxiety, drinking alcoholic beverages, physical trauma to the salivary glands or their ducts or nerves, dehydration caused by lack of sufficient fluids (extended exercise on a hot day can cause the salivary glands to become dry as bodily fluids are concentrated elsewhere), chemotherapy, and radiation therapy. Xerostomia is a common side-effect of various medications including some antidepressants, amphetamines and antihistamines, and of controlled substances such as cannabis and heroin. The vast majority of elderly people will suffer xerostomia to some degree; the most common cause is the use of medications. Output from the major salivary glands does not undergo clinically significant decrements in healthy older people; complaints of a dry mouth and findings of salivary hypofunction in an older person are not due to age as such. The results of one study suggested that, in general, objective and subjective measurements of major salivary gland flow rates are independent of age, sex, and race; signs and symptoms of dry mouth in the elderly are not a normal sequela of aging.

Treatment
Treatment involves finding any correctable causes and removing them if possible. In many cases it is not possible to correct the xerostomia itself, and treatment focuses on relieving the symptoms and preventing cavities. Patients with xerostomia should avoid the use of decongestants and antihistamines, and pay careful attention to oral hygiene. Sipping non-carbonated sugarless fluids frequently, chewing xylitol-containing gum, and using a carboxymethyl cellulose saliva substitute may help. Pilocarpine may be prescribed to treat xerostomia. Cevimeline (Evoxac) has been released for treatment of dry mouth associated with Sjogren's syndrome. Like pilocarpine, it is a cholinergic agonist.

Non-systemic relief can be found using an oxidized glycerol triesters treatment used to coat the mouth. Drinking water when there is another cause of the xerostomia besides dehydration may bring little to no relief and can even make the dry mouth more uncomfortable. The use by patients of an enzymatic product such as Biotene or other topical preparation produced "no effect on oral colonization by Candida species and cariogenic oral microflora", although "the palliative effects of Oral Balance gel and Biotene toothpaste were superior to the effects of a placebo" and did not "significantly lower salivary counts of ... Streptococcus mutans and Lactobacilli". Tests on candida yeasts in vitro rather than in patients found that "a lactoferrin-containing mouthwash has fungistatic properties".