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.
Causes of Xerostomia:
- Anticholinergic Agents
- Sedatives & Anxiolytic Agents
- Muscle Relaxant Agents
- 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
- 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.