Dry mouth: before treating the symptom, look at the medication list

Xerostomia is a symptom the patient reports as a nuisance and which the dentist should read as a major risk factor. Saliva is not merely moisture: it is the principal protective system of the oral cavity.

Its functions are multiple and irreplaceable. It buffers the acids produced by bacteria, supplies calcium and phosphate for remineralisation, mechanically clears debris, and contains antibacterial enzymes and immunoglobulins.

When flow falls, all these functions fail together. The most visible clinical result is a marked rise in caries, with a characteristic distribution.

Xerostomia-related caries affects the necks and root surfaces, areas relatively protected in patients with normal flow. An adult suddenly developing multiple cervical lesions should be investigated for dryness.

The commonest cause is pharmacological, and this is the step that gets skipped. Hundreds of active substances list xerostomia among their side effects, and older patients often take several together.

The classes most involved are antidepressants, antihypertensives, antihistamines, diuretics, anxiolytics and drugs for incontinence. Combining them multiplies the effect.

Asking for the medication list before prescribing any product is therefore the first step. In some cases the physician can alter the therapy or the timing of doses, and that resolves more than any saliva substitute.

Other causes deserve consideration: head and neck radiotherapy, Sjögren's syndrome, uncontrolled diabetes, dehydration, habitual mouth breathing.

Products fall into two categories with different logics. Saliva substitutes are gels or sprays that moisten the mucosa: they address the symptom, give immediate relief and last a short time.

Stimulants act on the remaining glands. Sugar-free sweets or gum, preferably with xylitol, stimulate flow mechanically and gustatorily, and work as long as functioning glandular tissue remains.

Xylitol adds an effect of its own: it cannot be metabolised by Streptococcus mutans, and repeated use lowers the cariogenic load. That is a double benefit in a patient already at high risk.

Fluoride protection must be reinforced in these patients, and standard concentration is not enough. A 5000 ppm toothpaste has one of its soundest indications here, possibly alongside professional applications.

In summary: xerostomia is a risk factor for root caries before it is a nuisance, the cause is often pharmacological and should be sought in the medication list, substitutes relieve while stimulants address the cause, and high-concentration fluoride is indicated.