Background Information on Xerostomia

Xerostomia is defined as “the subjective symptom of oral dryness whilst salivary gland hypofunction is an objective situation characterized by reduced salivary flow (Thomson, W. Murrray et al., 1999).” Xerostomia is frequently, but not always associated with salivary gland hypofunction.

Functions of Saliva

Important role in mastication, swallowing and formation of a nutritional bolus which aids in digestion.
Protects against thermal, mechanical and chemical irritants.
Guards oral tissues against physical and microbial insults.
Salivary proteins and mucins lubricate and coat oral tissues.
Maintains a neutral pH by acting as a buffer.
Demineralisation and remineralisation balance at the biofilm/enamel interface is affected by the ion concentration in saliva.

Etiology

Causes of Xerostomia:

1. Medications

Anticholinergic Agents
Diuretics
Sedatives & Anxiolytic Agents
Muscle Relaxant Agents
Steroids
Antihistamines
Antiemetics
Psychotropic Agents
Antihypertensive Agents

2. Systemic Diseases

Endocrine Disease – Diabetes Type 1 or 2, Thyroid Disease
Viral infections – HIV, Hepatitis C, Epstein-Barr, CMV, Human T - lymphotropic virus Type 1
Bacterial infections – Actinomycosis, Tuberculosis
Autoimmune diseases – Rheumatoid Arthritis, Systemic Lupus Erythematosus, Primary Biliary Cirrhosis, Scleroderma
Primary & Secondary Sjorgen’s Syndrome
End stage renal disease – Renal dialysis
Hematopoietic stem cell transplantation and chronic graft-versus-host disease
Parkinson’s disease
Cerebral Palsy
Anxiety or Depression
Post-traumatic stress disorder
Anorexia and Bulimia
Dehydration
Trauma to salivary glands

3. Radiation therapy

Xerostomia is a common side effect of radiation therapy when used as the primary or adjunctive treatment for primary or recurrent tumours of the head and neck (Porter S. et al., 2004). The most radiosensitive gland is the parotid gland followed by the submandibular, sublingual and minor salivary gland. Radiation doses as low as 20Gy can result in permanent salivary flow cessation if given as a single dose.