Xerostomia involves a subjective dry mouth sensation, and therefore some patients may report dry mouth, in the presence of normal saliva flow, while other patients may have a reduced saliva flow (hyposalivation or hyposialia) that is not associated with the feeling of oral dryness. 

Xerostomia can frequently be underestimated, and therefore, it is good to start with a proper, in-depth medical history, recording any diseases or drugs that patients are taking that may possibly cause oral dryness (making it essential for dentists to be aware of any systemic diseases or drug treatments their patients are experiencing or undergoing). 

For many years, xerostomia has been considered to mainly affect the older adult population. However, daily in-office observation is revealing that this condition may affect any age, and is increasingly affecting young people, more women than men. 

Causes of xerostomia 

The most significant aetiological factors related to xerostomia are the following: head and neck radiation therapy, certain systemic conditions (primary and secondary Sjögren's syndrome, diabetes) and treatment with certain drugs. Over 500 drugs (42 drug groups) can cause xerostomia as a side effect. And there are psychogenic factors that have been linked to xerostomia, such as stress, anxiety or depressive symptoms. Antidepressants are the drugs that have been most typically associated with the occurrence of xerostomia (mainly tricyclic antidepressants), selective serotonin reuptake inhibitors (particularly when associated with benzodiazepines), antihypertensives, diuretics and angiotensin converting enzyme inhibitors (ACE inhibitors), oral hypoglycaemic agents, acetylsalicylic acid and inhaled corticosteroids. 

It is surprising that the drugs that are most xerostomising are also the most commonly prescribed (essentially for the treatment of cardiovascular diseases and mental disorders), which explains the current high prevalence of this condition. 

Xerostomia treatment 

Xerostomia patient needs are clear: to improve quality of life, and improve daily function. Patients need to have more saliva, to be able to eat and swallow without difficulty, to feel more moisture in their mouths and throats, since sometimes they can experience difficulty breathing, and to taste food better. Solutions must be on an individual basis. The aim is to find the treatment that is most beneficial and well-accepted by patients, for which proper diagnosis is necessary. 

A variety of therapeutic options is currently available, with the objective of providing topical and/or systemic salivary gland stimulation, alleviating symptoms and preventing and treating the associated complications. Saliva substitutes exist for palliative treatment: water, milk, tea, saline, sodium bicarbonate, and multi-component artificial saliva exists, sometimes containing saliva enzymes, and possibly including buffer systems or fluoride. The other mainstay of xerostomia treatment involves saliva stimulants, known as sialogogues (systemic or topical), which stimulate saliva production and whose action depends on the degree of involvement of the salivary glands. Among the most commonly used sialogogues (especially in cases of severe xerostomia) we find pilocarpine and cevimeline. These achieve the greatest stimulation, although they have side effects which must be considered. 

Topical sialogogues (indicated for less severe xerostomia), stimulate saliva production with taste and/or mechanical stimuli (in the form of tablets, sugar-free gums, mouthwashes or sprays). Weak acids have recently been added as topical sialogogues, including 1% malic acid, combined with xylitol and fluorides, (as acid is the ideal stimulant for saliva production), proving to improve symptoms in cases of drug-induced xerostomia by antidepressants and antihypertensives, without side effects and without damaging tooth enamel. 

Establishing a preventive plan, reinforcing oral hygiene techniques, regular check-ups and patient motivation are all essential. Although, in many cases, dentists are faced with the fact that dry mouth in many cases is very difficult to successfully treat. We must not forget that xerostomia can be reversible or irreversible, depending on its aetiology, which will indefinitely determine the action plan. 

Therefore, if salivary glands have been irreversibly affected, treatment will be more complex, making the problem more difficult to solve. If xerostomia is caused by drug intake, it can be reversed if the drug is discontinued, although in most cases, these are prescribed for chronic diseases, such as high blood pressure, and so patients will always have xerostomia.