Definition of Xerostomia
Xerostomia is the subjective sensation or complaint of dry mouth, which may or may not be associated with objectively reduced salivary flow (salivary gland hypofunction). 1, 2
Key Distinguishing Features
Xerostomia represents the patient's symptom, while salivary gland hypofunction is the objective measurement of reduced salivary flow. 3 These two conditions often occur together but are not synonymous—patients can experience xerostomia with normal salivary gland function, or conversely, have reduced salivary flow without subjective complaints of dryness. 2, 4
Objective Measurement Criteria
When salivary gland hypofunction is present, it is characterized by a reduced salivary flow rate (SFR) of less than 0.1 mL/min. 1 This objective measurement helps distinguish true salivary dysfunction from the subjective sensation alone.
Clinical Presentation
Patients with xerostomia typically report:
- Oral dryness and discomfort that interferes with normal oral activities 5
- Difficulty with eating, speaking, swallowing, and wearing dentures 6
- Changes in taste perception 6
- Increased need for supplemental oral comfort agents or frequent water intake 7
Common Etiologies
Medication-Induced Causes
Medications represent the most common cause of xerostomia, particularly affecting elderly patients who are typically more heavily medicated. 2 Drugs with anticholinergic effects are primary culprits, including:
- Antihistamines, antidepressants (particularly tricyclics), anxiolytics, and antimuscarinics 1, 8
- Diuretics, calcium channel blockers, and lithium 1, 8
- Cardiac antiarrhythmic drugs and beta-adrenergic antagonists 8
- NSAIDs and chemotherapy agents 8
Disease-Related Causes
- Autoimmune diseases, particularly Sjögren's syndrome presenting with the classic "sicca complex" of dry eyes and dry mouth 1, 8
- Endocrine disorders including diabetes mellitus and thyroid dysfunction 1, 8
- Chronic kidney disease 1, 8
- Neurological conditions including Parkinson's disease 8
- High-dose radiation therapy to the head and neck region 1, 6
Other Contributing Factors
- Obstructive sleep apnea and other sleep disorders 1, 8
- Dehydration and fluid intake restrictions 1
- Mouth breathing and advanced age 1
- Salivary gland parenchymal fibrosis and atrophy 1
Clinical Significance
Chronic xerostomia significantly increases the risk of dental caries, tooth demineralization, tooth sensitivity, oral candidiasis, and other oral diseases that negatively affect quality of life. 3 The condition causes poor diet, malnutrition, and decreased social interaction due to difficulties with basic oral functions. 2
The complaint of xerostomia necessitates a complete evaluation of the patient's general health, salivary gland function, and potential underlying systemic conditions. 4 Dentists are commonly the first healthcare professionals to hear this complaint and play a critical role in directing appropriate evaluation and interdisciplinary care. 4