Xerostomia

Description

Xerostomia, also known as dry mouth, is marked by a significant reduction in the secretion of saliva. Signs and symptoms of xerostomia include:

• dryness of the mouth
• cracked lips, cuts, or cracks at the corners of the mouth
• taste changes
• a burning sensation of the tongue
• changes in the surface of the tongue
• difficulty wearing dental appliances (like dentures)
• difficulty swallowing fluids accompanied by an increase in thirst

Xerostomia makes the mouth less able to neutralize acid, clean the teeth and gums, and protect itself from infection. This can lead to the development of gum disease and cavities.

Saliva is necessary for carrying out the normal functions of the oral cavity, such as taste, speech, and swallowing. Saliva provides calcium and phosphate, minerals that protect the teeth against softening. It also contains substances inhibiting the production of bacteria that cause tooth decay. In addition, saliva buffers the acids produced when leftover food particles are broken down by bacteria.

Xerostomia causes the following mouth changes that can contribute to discomfort for the patient, and an increased risk for oral lesions:

• Saliva becomes thick and is less able to lubricate the mouth.
• Acids in the mouth cannot be neutralized, leading to mineral loss from the teeth.
• There is an increased risk for cavities because the mouth is less able to control bacteria.
• Plaque becomes thicker and heavier because of the patient's difficulty in maintaining good oral hygiene.
• The acid produced after eating or drinking sugary foods leads to further mineral loss from the teeth, causing even more tooth decay.

Causes

Xerostomia in cancer patients is primarily caused by the effects of radiation therapy on the salivary glands, usually the result of radiation to the head and neck area. These changes may occur rapidly and cannot normally be reversed, especially if the salivary glands themselves are irradiated. Within one week of starting radiation treatment, the production of saliva drops and continues to decrease as treatment continues. The severity of xerostomia is dependent upon the radiation dose and how many salivary glands are irradiated. Typically, the salivary glands inside the upper back cheeks (the parotid glands) are more affected than others. Salivary glands that are not irradiated may become more active as a way of compensating for the loss of saliva from the destroyed glands.

A number of medications can cause xerostomia, including many drugs used in the management of cancer or cancer treatment side effects. Some of these are: atropine, amitriptyline, carbamazepine, diphenhydra-mine, gabapentin, haloperidol, loperamide, lorazepam, meperidine, and scopolamine, among several others.