Helping patients with dry mouth


Xerostomia is defined as dry mouth resulting from reduced or absent saliva flow. Xerostomia is not a disease, but it may be a symptom of various medical conditions, a side effect of a radiation to the head and neck, or a side effect of a wide variety of medications. It may or may not be associated with decreased salivary gland function. Xerostomia is a common complaint found often among older adults, affecting approximately 20 percent of the elderly. However, xerotomia does not appear to be related to age itself as much as to the potential for elderly to be taking medications that cause xerostomia as a side effect.

Normal salivary function is mediated by the muscarinic M3 receptor. Stimulation of this receptor results in increased watery flow of salivary secretions. When the oral mucosal surface is stimulated, afferent nerve signals travel to the salivatory nuclei in the medulla. The medullary signal may also be affected by cortical inputs resulting from stimuli such as taste, smell, anxiety or depression. Efferent nerve signals, mediated by acetylcholine, also stimulate salivary glandular epithelial cells and increase salivary secretions.

Saliva components

Saliva is the viscous, clear, watery fluid secreted from the parotid, submaxillary, sublingual and smaller mucous glands of the mouth. Saliva contains two major types of protein secretions, a serous secretion containing the digestive enzyme ptyalin and a mucous secretion containing the lubricating aid mucin. The pH of saliva falls between 6 and 7.4. Saliva also contains large amounts of potassium and bicarbonate ions, and to a lesser extent sodium and chloride ions. In addition, saliva contains several antimicrobial constituents, including thiocyanate, lysozyme, immunoglobulins, lactoferrin and transferrin.

Functions of saliva

Saliva possesses many important functions including antimicrobial activity, mechanical cleansing action, control of pH, removal of food debris from the oral cavity, lubrication of the oral cavity, remineralization and maintaining the integrity of the oral mucosa.

Complications associated with xerostomia

Xerostomia is often a contributing factor for both minor and serious health problems. It can affect nutrition and dental, as well as psychological, health. Some common problems associated with xerostomia include a constant sore throat, burning sensation, difficulty speaking and swallowing, hoarseness and/or dry nasal passages.1 Xerostomia is an original hidden cause of gum disease and tooth loss in three out of every 10 adults.11 If left untreated, xerostomia decreases the oral pH and significantly increases the development of plaque and dental caries.Oral candidiasis is one of the most common oral infections seen in association with xerostomia.

Signs and symptoms of xerostomia

Individuals with xerostomia often complain of problems with eating, speaking, swallowing and wearing dentures. Dry, crumbly foods, such as cereals and crackers, may be particularly difficult to chew and swallow. Denture wearers may have problems with denture retention, denture sores and the tongue sticking to the palate. Patients with xerostomia often complain of taste disorders (dysgeusia), a painful tongue (glossodynia) and an increased need to drink water, especially at night. Xerostomia can lead to markedly increased dental caries, parotid gland enlargement, inflammation and fissuring of the lips (cheilitis), inflammation or ulcers of the tongue and buccal mucosa, oral candidiasis, salivary gland infection (sialadenitis), halitosis and cracking and fissuring of the oral mucosa.

Diagnosis and evaluation of xerostomia

Diagnosis of xerostomia may be based on evidence obtained from the patient’s history, an examination of the oral cavity and/or sialometry, a simple office procedure that measures the flow rate of saliva. Xerostomia should be considered if the patient complains of dry mouth, particularly at night, or of difficulty eating dry foods such as crackers. When the mouth is examined, a tongue depressor may stick to the buccal mucosa. In women, the “lipstick sign,” where lipstick adheres to the front teeth, may be a useful indicator of xerostomia.

The oral mucosa may be dry and sticky, or it may appear erythematous due to an overgrowth of Candida albicans. The red patches often affect the hard or soft palate and dorsal surface of the tongue. Occasionally, pseudomembranous candidiasis will be present, appearing as removable white plaques on any mucosal surface. There may be little or no pooled saliva in the floor of the mouth, and the tongue may appear dry with decreased numbers of papillae. The saliva may appear stringy, ropy or foamy. Dental caries may be found at the cervical margin or neck of the teeth, the incisal margins or the tips of the teeth.

Several office tests and techniques can be utilized to ascertain the function of salivary glands. In sialometry, or salivary flow measurement, collection devices are placed over the parotid gland or the submandibular/

sublingual gland duct orifices, and saliva is stimulated with citric acid. The normal salivary flow rate for unstimulated saliva from the parotid gland is 0.4 to 1.5 mL/min/gland. The normal flow rate for unstimulated, “resting” whole saliva is 0.3 to 0.5 mL/min; for stimulated saliva, 1 to 2 mL/min. Values less than 0.1 mL/min are typically considered xerostomic, although reduced flow may not always be associated with complaints of dryness.

Sialography is an imaging technique that may be useful in identifying salivary gland stones and masses. It involves the injection of radio-opaque media into the salivary glands. Salivary scintigraphy can be useful in assessing salivary gland function. Technetium-99m sodium pertechnate is intravenously injected to ascertain the rate and density of uptake and the time of excretion in the mouth. Minor salivary gland biopsy is often used in the diagnosis of Sjögren’s syndrome (SS), human immunodeficiency virus-salivary gland disease, sarcoidosis, amyloidosis and