Salivary glands produce saliva, which moistens food to make it easy to swallow and contains enzymes (proteins) to help break down food so it is easier to digest.
Salivary glands can malfunction, become infected, or blocked by stones that form in their ducts.
Malfunctioning salivary glands produce less saliva, which causes dry mouth and tooth decay.
Infected or blocked salivary glands cause pain.
Saliva flow can be measured, or doctors may biopsy salivary gland tissue.
Sometimes blockages in the ducts that lead from the salivary glands can be removed, but some people need to use saliva substitutes.
(See also Dry Mouth.)
There are three major pairs of salivary glands in the mouth:
In addition to these major glands, many tiny salivary glands are distributed throughout the mouth. All of the glands produce saliva, which aids in breaking down food as part of the digestive process.
Several types of disorders affect the salivary glands:
Salivary gland malfunction is more common among adults and usually involves too little saliva production. When the flow of saliva is insufficient or almost nonexistent, the mouth feels dry. This condition is called xerostomia (dry mouth).
Certain conditions can decrease saliva production:
Infections, such as human immunodeficiency virus (HIV) infection
Drugs, such as certain antidepressants, antihistamines, antipsychotics, anti-Parkinson drugs, sedatives, methyldopa, diuretics, and illegal methamphetamine
Chemotherapy or head and neck radiation for the treatment of cancer, or radioactive iodine for the treatment of thyroid cancer
Dry mouth due to radiation is usually permanent, especially if the radiation dose is high. Dry mouth due to chemotherapy is usually temporary.
However, not all cases of dry mouth are caused by salivary gland malfunction. For example, dry mouth may be caused by
The mouth may also dry somewhat as a person ages, although in such cases, drying is probably due to the greater likelihood of taking a drug that causes dry mouth rather than to the aging process itself.
Because saliva offers considerable natural protection against tooth decay, an inadequate amount of saliva leads to more cavities—especially in the roots of teeth. Dry mouth, if severe, can also lead to difficulty speaking and swallowing.
In rare cases, the salivary glands produce too much saliva. Increased saliva production is usually very brief and occurs in response to eating certain foods, such as sour foods. Sometimes even thinking about eating these foods can increase saliva production.
A stone can form from salts contained in the saliva. Stones are particularly likely to form when people are dehydrated or take drugs that decrease saliva production. People with gout are also more likely to form stones. Salivary gland stones are most common among adults. About 25% of people with stones have more than one.
Salivary stones create problems when they block the tube (duct) that carries saliva from the gland to the mouth. Blockage makes saliva back up inside the duct, causing the salivary gland to swell painfully. A blocked duct and gland filled with stagnant saliva may become infected with bacteria.
A typical symptom of a blocked salivary duct is swelling and pain over the gland that is affected. The pain and swelling worsen after eating, particularly when people eat something that stimulates saliva flow (such as a pickle or lemon juice) because when the duct is blocked, the saliva has no place to go and the gland swells. The swelling may go down after a few hours, and the duct may release a gush of saliva. Some stones do not cause any symptoms.
Salivary gland infection is also called sialadenitis. Most salivary gland infections occur in people who have something that blocks the flow of saliva (such as a stone) or who have very low flow of saliva. Infection is most common in the parotid gland and typically occurs in people who
Are in their 50s and 60s
Have a chronic illness and dry mouth
Have Sjögren syndrome
Have had radiation therapy to the mouth area or radioactive iodine therapy for thyroid cancer
Adolescents and young adults with anorexia are also prone to this infection. The usual infecting organism is the bacteria Staphylococcus aureus.
People with a bacterial infection of a salivary gland have fever, chills, and pain and swelling on the side of the face with the infected gland. The skin over the infected gland becomes red and swollen. Sometimes a collection of pus (abscess) forms in the gland, and a small amount of pus comes out of the duct of the gland.
Childhood mumps, certain bacterial infections (for example, of the tonsils or teeth), and other diseases that are typically more common among adults (such as AIDS, Sjögren syndrome, diabetes mellitus, sarcoidosis, and bulimia) often cause swelling of the major salivary glands.
Swelling also can result from cancerous (malignant) or noncancerous (benign) tumors in the salivary glands. Swelling resulting from a tumor is usually firmer than that caused by an infection. If the tumor is cancerous, the gland may feel stone-hard and may be fixed firmly to surrounding tissues (see Mouth and Throat Cancer). Most noncancerous tumors are moveable.
An injury to the lower lip—for instance, from accidental biting—may harm any of the minor salivary glands found there and block the flow of saliva. As a result, an affected gland may swell and form a small, soft lump (mucocele) that appears bluish. The lump usually disappears by itself within a few weeks to months.
There are no good tests to measure saliva production. However, the salivary glands can be squeezed (milked), and the ducts can be observed for saliva flow.
Swelling due to blockage of a salivary duct is diagnosed because of the relationship of pain to eating or drinking something that stimulates saliva flow. To diagnose other causes of swelling, a dentist or doctor may do a biopsy to obtain a sample of salivary gland tissue and examine it under a microscope. Other causes of blockage may be identified by newer techniques that use very small viewing tubes (endoscopes) that can be inserted into the salivary gland ducts.
If doctors are not able to make the diagnosis during the physical examination, they may do certain imaging studies, such as computed tomography (CT), ultrasonography, and sialography. Sialography is a type of x-ray that is taken after a dye that is visible on x-rays has been injected into the salivary glands and ducts.
If infection is suspected, doctors look for inflammation on imaging tests, such as a computed tomography (CT) scan, ultrasonography, or magnetic resonance imaging (MRI). If the doctor can squeeze pus from the duct of the affected gland, it is cultured (sent to the laboratory to try to grow bacteria).
For dry mouth, people should
Avoid drugs that decrease saliva production
Sip fluids throughout the day
Brush and floss regularly
Use fluoride rinses
Visit their dentist for examination and cleaning every 3 to 4 months
Sometimes a saliva substitute containing carboxymethylcellulose as a mouthwash
Sometimes chew sugarless gum or suck on xylitol lozenges
Some dentists have people wear plastic tooth covers filled with fluoride gel at night to prevent tooth decay due to dry mouth. Sometimes, drugs that increase saliva production, such as cevimeline or pilocarpine, help relieve symptoms. Such drugs may not help when the salivary glands have been damaged by radiation.
For salivary gland stones, people can take pain relievers (analgesics), drink extra fluids, massage the glands, apply warm compresses, and trigger saliva flow with lemon juice or wedges, sour candy, or a combination. If the stone does not pass on its own, a dentist can sometimes push the stone out by pressing on both sides of the duct. If that fails, a fine-wire‒like instrument can be used to pull out the stone. As a last resort, the stone can be removed surgically or through an endoscope.
For salivary gland infection, doctors give antibiotics and have people massage the glands and apply warm compresses. A salivary abscess needs to be cut open and drained. Staying hydrated, triggering saliva with lemon juice and hard candies, and having good oral hygiene are also important.
Salivary gland swelling treatment varies with the cause. A mucocele that does not disappear on its own can be removed surgically if it becomes bothersome. Similarly, both noncancerous and cancerous salivary gland tumors can usually be removed surgically.