Chronic dry mouth (xerostomia) is a serious problem affecting millions of people throughout the world. Xerostomia can effect persons of any age, but it is much more prevalent in the elderly. It causes a wide range of problems including difficulty in swallowing (dysphasia), loss of the ability to taste (dysgeusia), difficulty in speaking, an increased rate of tooth decay, an inability to wear or retain dentures, and an increase in oral infections, especially yeast (thrush, caused by candida albicans). It is estimated that approximately 30% of persons over the age of 65 suffer from xerostomia.
There are three pairs of major saliva glands (each tinted yellow in the above diagram). The Parotid glands are on the sides of the jaw just below and in front of the ears. They are the “pickle glands” that create that funny feeling on the sides of your face when you first taste something really sour. The reason you feel it is that the parotids produce a sudden burst of saliva and express it into the mouth quite suddenly. The parotid glands empty through ducts called Stenson’s Duct (also tinted yellow in the diagram). They terminate in the mouth via tiny holes in what feels like little flaps of skin on the inside of the cheeks. You can feel these little flaps with the tip of your tongue. They are located on the cheeks on either side of your mouth beside the upper back teeth. The parotid gland secretes thin, watery saliva called “serous” fluid.
The sublingual and submaxillary (also called the submandibular) glands empty into the mouth through ducts under the tongue. The sublingual gland secretes mostly mucous. The submaxillary gland secretes a mixture of serous and mucous fluids.
All three glands are composed of little grape-like lobes composed of smaller clusters of cells called parenchymal acini all of which are connected by a branching “stem” which is composed of ducts which carry the saliva to the mouth.
On any given day, the average adult produces about three pints of saliva. Xerostomia is caused by decreased output of saliva by these three pairs of glands.
The image (below) on the top left is a cross section of the sublingual salivary gland, which secretes predominantly mucous. The one on the top right is a cross section of the parotid salivary gland which secretes mostly watery serous saliva. The red structures in these two images are cross sections through ducts, which have a branching structure throughout both glands. Smaller ducts join to form larger ones which in turn join to form still larger ducts etc. The parenchymal aceni are the small clusters of cells that make up the bulk of the glandular tissue. The mucous secreting parenchymal aceni seen in the image of the sublingual gland on the left look clear, while the serous secreting parenchymal aceni in the image of the parotid gland on the right stain purple. The stark blue material surrounding the larger ducts is connective tissue. The tiny purple dots are the cell nuclei in each parenchymal cell. The nuclei in the duct cells are red.
The lower image is a section through the submaxillary gland. This is a higher resolution image (more of a “close up”) than the other two images, and a different staining technique has been used in its preparation. The base stain is red instead of purple. However, the mucous secreting aceni are again clear and are shown to be in close approximation to the serous secreting aceni which stain red. The submandibular gland secretes a mixture of both types of saliva.
What causes xerostomia?
Xerostomia happens when the three sets of saliva glands described above are forced to decrease the output of saliva. There are two basic reasons why the saliva glands might cease to function at full capacity:
1. Certain drugs which may be taken for various reasons and for various medical conditions may cause the saliva glands to reduce their output. The following is a partial list of broad drug categories that may do this. If you think you may be taking a drug that is causing dry mouth, then check with your physician:
- antihistamines (the older types like Benedryl)
- Pseudoephedrine (also called Sudafed® but found in many other brands)–the only generic decongestant now available over the counter.
- antidepressants (old style types like Elavil, Flexaryl etc)
- anticholinergics (often used as decongestants as well as surgical drying agents like atropine and scopolamine.)
- anorexiants (diet pills)
- antihypertensives (blood pressure meds)
- antipsychotics (psychiatric drugs)
- anti-Parkinson agents, diuretics (“water pills”)
- sedatives (sleeping pills)
- Certain illegal recreational drugs
2. Some medical conditions or treatment modalities may destroy the parenchymal aciniwhich actually produce the saliva . These include:
- Radical radiotherapy (therapeutic x-ray treatments) for the treatment of head and neck cancer. Radiation to the head and neck area causes damage to the blood vessels and also kills off cells that are actively dividing, including saliva producing cells in the salivary glands.
- Chemotherapy for cancer. The dry mouth caused by chemotherapy is generally temporary, but can become a more chronic problem if the chemo is prolonged.
- Uncontrolled diabetes
- Systemic Lupus Erythematosis
- Sjörgren’s syndrome (an autoimmune disease which attacks all fluid producing glands in the body, including saliva and tear producing glands.
- Rheumatoid arthritis and systemic lupus erythematosis
- Up to 50% of individuals with rheumatoid arthritis also suffer from dry mouth. The term secondary Sjögren’s syndrome is used to refer to individuals with a connective tissue disease such as rheumatoid arthritis or systemic lupus erythematosus who also experience dry eyes and dry mouth.
Persons suffering xerostomia often also suffer from bad breath. Halitosis is a separate problem which has its own diagnostic and treatment protocols. Persons wishing to understand their bad breath, and how to treat it may consult my dedicated page on Halitosis
How can xerostomia be treated?
Unfortunately, xerostomia is a condition that currently has no definitive means for treatment. However, palliative treatments (treatments designed to improve symptoms without actually treating the underlying disease) and inductive treatments (treatments designed to induce the remaining salivary tissue to produce more saliva) are available.
Palliative treatment methods are useful in all cases of xerostomia, including those in which there is little remaining salivary tissue. These treatments involve non-prescription methods to stimulate remaining parenchymal tissues to produce more saliva, and some will supply missing naturally occurring enzymes and saliva-like moisture to the mouth.
Drink lots of sugarless fluids. When you drink water, it is always absorbed into the bloodstream. In an effort to restore normal osmotic body chemistry, the body will excrete the excess water in any way possible. Most of the excess water is absorbed through the kidneys and ends up as urine, but all excretory functions are increased, including saliva production. Sugar should be avoided because people with dry mouth are more prone to tooth decay and sugar is the prime villain when it comes to decayed teeth.
Chew gums and suck on mints or candy sweetened with xylitol. Chewing or sucking on a candy that does not promote decay stimulates saliva production. Any sugarless candy or gum is good for this purpose, but xylitol is an artificial sweetener that has been shown to inhibit bacterial growth in the oral cavity. You can buy less expensive mints and candies sweetened with xylitol over the internet (Google search). One new xylitol lozenge made specifically for people with dry mouth syndrome is called Xylimelts®. These are formulated to be “stuck” to the moist mucosa inside the cheeks and remain there releasing xylitol for many hours. Below is a list of some other gums and candies containing zylitol that you may find in supermarkets or drug stores:
- Biotene Dry Mouth Gum
(Laclede Research Labs)
- Biotene Dry Mouth Gum
(Laclede Research Labs)
- Ricochet Gum (Emerald Forest)
- Therabreath ZOX Mints (TheraBreath)
- TheraGum (Omnii)
- Xylitol Peppermint Mints (BioGenesis)
- Xponent Xylitol Gum
(Global Sweet Polyois)
- Xylitol Gum Power Bite
(Rocky Mountain Herbals)
- Carefree Koolerz (Hershey)
- Biotene Dry Mouth Gum
- Mints / lozenges / candies (manufacturer)
- XyliMelts (Oracoat) (Recommended)
- Ricochet Fruit Sours & Mints (Emerald Forest)
- Spry Mints (Xlear)
- Thayers Sugar-Free Citrus Dry Mouth Lozenges (Thayers)
- TheraMints (Omnii)
- Xylichew Mints (Xylichew)
- Xylitol Mints (Nature’s Sweet Life)
- Xylitol Mints (Xponent)
- Mini Mints, various flavors (Solaray)
NOTE: Xylitol is poisonous for your dog!
In dogs, xylitol causes a rapid and severe increase in blood insulin with resulting hypoglycemia (low blood sugar). This condition generally lasts between 6-24 hrs but can last up to several days. Clinical signs include vomiting, diarrhea, weakness, ataxia, tremors and possibly seizures. Deaths rarely occur in young and healthy animals, but of course, older animals are more likely to suffer more severe reactions.
Saliva substitutes such as Rosane, Salavart or Optimoist, when used over at least a two week period not only helps to restore moisture, but also tends to stimulate remaining parenchymal tissues to produce more saliva on their own.
Neutral Sodium Fluoride toothpaste (Prevident 5000) Prevident is a high fluoride toothpaste, often prescribed by dentists for patients suffering from generalized tooth sensitivity or rampant decay. It has the added benefit of stimulating saliva production if used several times a day regularly. It is applied to the teeth after brushing and flossing (with regular toothpaste and floss). Apply a small amount to the brush and brush teeth without water. Spit out, but do not rinse. Do not swallow. This is an especially recommended type of treatment since persons suffering xerostomia are also prone to rampant tooth decay, and the high fluoride content of this toothpaste inhibits the plaque organisms that cause decay, and helps to remineralize areas of tooth decay.
Biotene dry mouth products are highly recommended by dentists for patients with dry mouth. Biotene® toothpaste and Oralbalance® gel are available over-the-counter from Laclede, Inc. These are anti xerostomia dentifrices that contain three salivary enzymes, lactoperoxidase, glucose oxidase and lysozyme, specifically formulated to stimulate saliva and activate intra-oral bacterial systems. In my experience, these products work quite well.
XyliMelts (Oracoat) are are an especially easy to use lozenge which is coated on one side with a water activated adhesive which keeps it in place on the buccal mucosa (inside of the cheek). If placed very high in the back of the cheek mucosa before going to sleep, it releases xylitol most of the night and can markedly reduce the incidence of tooth decay due to dry mouth.
Inductive treatment options involve prescription drugs which, when taken as directed, will help to induce remaining parenchymal salivary tissues to produce the maximum amount of saliva possible. The patient needs to be under the care of a dentist or physician to get a prescription for these drugs.
Salagen (pilocarpine 5 mg tablets) The dentist prescribes 45 tablets. The patient takes a half tablet three times a day (every 8 hours) for the first month and then increases the dose slowly to the maximum 5 mg dose three times per day as tolerated. This drug works quite well, but there are some side effects which effect a minority of patients. These side effects include excessive sweating, gastrointestinal disturbance, increased lung secretions, blurred vision, and rarely slow or fast heart rate. Excessive sweating is reported as the most common side effect, the others being reported rarely. This drug should not be taken by persons suffering narrow angle glaucoma.
Evoxac (cevimeline HCl, 30 mg tablets) Evoxac is taken three times a day, just like Salagen. It is reported to have fewer side effects than Salagen because it exerts its primary effect on receptors found on salivary parenchymal cells. This drug should not be taken by persons suffering narrow angle glaucoma.
Non traditional treatment modalities:
Acupuncture relies on stimulating trigger points in the head and neck region with the goal of parasympathetic stimulation of functioning salivary tissues. This is accomplished by using a series of small needles of varying size inserted just under the skin in the area of the trigger points. Studies have shown that the effects of acupuncture provided relief for individuals with Sjorgrens syndrome for up to six months after treatment.
Acupuncture is like TENS therapy. TENS stands for Transcutaneous Electric Nerve Stimulation. This is quite similar to Acupuncture, but relies on low voltage electrical stimulation of the acupuncture trigger points instead of using needles. One study showed that patients who had suffered xerostomia after radiation therapy for head or neck cancer showed significant improvement when treated using TENS therapy twice per week for six weeks.
Future treatment modalities
Gene Transfer recombinant DNA technology is a new, cutting edge technology which shows promise in curing chronic xerostomia. Gene transfer technology uses a “cold” virus (an adenovirus) which has been modified to contain a gene encoding for a specific functional protein. The patient is infected with this virus and the virus transfers the gene to duct cells in the non-functioning salivary glands causing them to begin secreting again. This treatment modality is still in the animal-testing stage.
Guided tissue regeneration (GTR) is also a new, cutting edge technology which uses tissue cells cultured and grown outside of the human body, and then implanted in a patient using a polyglycolic acid polymer scaffold which is seeded with the cultured cells to recreate a functioning human organ. This technology is still in the experimental stage.
Persons with dry mouth syndrome are prone to a much more virulent form of tooth decay characterized by “rampant ectopic caries“. Rampant means that it tends to occur all over the mouth. “Ectopic” means that the tooth decay occurs on parts of the teeth that are not usually involved with decay.
In the case of dry mouth, The bacterial floral pattern shifts toward organisms which produce a great deal of acid when exposed to sugar, and persons with dry mouth are more prone to sucking on hard candies in order to produce more saliva in their mouth. This combination produces very fast and serious decay in areas of the teeth that are not protected by enamel, namely the exposed root surfaces.
Excessive exposures of the teeth to sugar causes decay in normally hydrated mouths too, but the decay generally happens in areas of the teeth protected by enamel, mostly in on the top surfaces (occlusal surfaces) of the back teeth, and in between the teeth where the teeth make contact with each other (interproximal surfaces). It happens at the point of contact between adjacent teeth because the teeth rub together at that point, and the buildup of plaque in the triangular space below the point of contact creates a constant supply of acid which works quickly on the enamel which is under assault from the constant rubbing. This type of caries is clearly seen on the x-ray image below:
In the case of dry mouth, however, the concentration of acid is much greater, and it begins dissolving the root surfaces which, though not under abrasive attack, are much softer than the enamel-protected contact areas:
In the image above, the root caries are indicated by the red arrow, and the blue arrow indicates the position in which normal interproximal caries is more prone to happen.
Good oral hygiene, including proper brushing and floss (or Stimudents) along with avoidance of sugar will reduce or eliminate the likelihood of the rampant decay associated with xerostomia. The use of xylitol candy or mints not only stimulates saliva production, but also reduces the bacteria count in the mouth helping to further prevent tooth decay.