Background to xerostomia

Xerostomia is the subjective experience of mouth dryness. This is a common condition, with a prevalence of 20% in the general population, with a higher prevalence of up to 50% in the elderly.¹

A healthy individual produces up to 1.5 L of saliva daily. Saliva functions to moisten the oral mucosa and maintain oral health. In response to the sensory stimulation provided by food, saliva production is increased, allowing it to fulfill the additional functions of moistening food enabling it to be more easily masticated and swallowed; initiating digestion of starch and fats; improving the ability to taste food; washing away food residues from the teeth; and neutralising acids from food.¹ Saliva is also necessary for speech.²

A reduction of saliva production to 50% of normal (hyposalivation) will normally lead to a patient experiencing xerostomia.² Hyposalivation causes difficulties in eating, chewing and swallowing, with the ability to taste and speak also affected.² Within dentistry, hyposalivation is recognised as a cause of xerostomia-related caries.³

It should be noted that xerostomia refers to the sensation of dry mouth, and is distinct from hyposalivation, although the latter condition will often give rise to the complaint of 'dry mouth'. Xerostomia can be experienced in the absence of hyposalivation. There are many causes of xerostomia including medical conditions and medical treatments (over 400 medications can cause this condition).²

Causes of xerostomia^1,2

Temporary hypofunction

Short-term drug use (e.g. antihistamines) Viral infection (e.g. mumps) Dehydration Psychological conditions (e.g. anxiety, depression)

Chronic hypofunction

Chronically administered drugs antidepressants antihypertensives opiates bronchodilators proton pump inhibitors antipsychotics antihistamines diuretics antineoplastics Autoimmune disorders Sjögren's syndrome Primary biliary cirrhosis Endocrine disorders Diabetes mellitus Hypothyroidism Infections Human immunodeficiency virus Hepatitis C Neurological disorders Parkinson's disease Bell's palsy Genetic diseases Cystic fibrosis Downs syndrome Coeliac disease Nutritional deficiencies Head and neck radiation Graft versus host disease Bone marrow transplant

 

Lifestyle factors such as smoking, chewing tobacco and alcohol consumption have been linked to xerostomia.² Alcohol consumption has a diuretic effect on the body⁴ which can lead to dehydration, exacerbating xerostomia.² Abuse of alcohol is a recognised risk factor for hyposalivation.⁵

References

1. Furness S et al. Interventions for the management of dry mouth: topical therapies. Cochrane Database of Systematic Reviews 2011, Issue 12. Art. No.: CD008934.
2. Glore RJ et al. A patient with dry mouth. Clin Otolaryngol 2009; 34: 358–363.
3. Su N et al. Caries prevention for patients with dry mouth. J Can Dent Assoc 2011; 77: b85.
4. Eggleton MG. The diuretic action of alcohol in man. J Physiol 1942; 101: 172–191.
5. Friedlander AH et al. Alcohol abuse and dependence. Psychopathology, medical management and dental implications. JADA2003; 134(6): 731–740.