Xerostomia Management
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Direct answer
How much saliva the mouth holds decides comfort, speech, taste and whether teeth survive — and xerostomia, the subjective feeling of a dry mouth, is managed by first separating it from hyposalivation, the measured reduction in flow. Unstimulated whole saliva below about 0.1-0.2 mL/min defines hyposalivation. Management climbs a ladder: correct the cause where possible (drug review, glycaemic control), stimulate residual function with sugar-free gum and, if needed, sialagogues such as pilocarpine 5-7.5 mg three times daily, substitute moisture with gels and sprays, and protect the dentition aggressively with high-fluoride regimes, because the dry mouth caries fast. Salivary candidosis and denture intolerance are treated alongside.
What you must remember
- Symptom versus sign: xerostomia is the complaint, hyposalivation the measurement — a patient can feel dry with normal flow (anxiety, mouth breathing, many drugs) or have severe loss without complaining; sialometry settles it.
- Flow numbers: normal unstimulated whole saliva about 0.3-0.4 mL/min or more, stimulated 1.5-2.0 mL/min; hyposalivation is commonly defined as unstimulated below 0.1-0.2 mL/min.
- Drugs head the cause list: anticholinergics, tricyclic antidepressants, antihistamines, antipsychotics, some antihypertensives, diuretics and opioids — polypharmacy in the elderly stacks them additively.
- The two structural causes: Sjögren's syndrome (sicca plus anti-Ro/La antibodies, focal lymphocytic sialadenitis on lip biopsy) and head-and-neck radiotherapy, with major-gland damage beyond about 30 Gy being largely irreversible per conventionally quoted thresholds.
- Sialagogue doses: pilocarpine 5-7.5 mg three times daily (cholinergic — sweating, flushing, urinary frequency; avoid in uncontrolled asthma and angle-closure glaucoma); cevimeline 30 mg three times daily as the better-tolerated alternative.
- Substitutes: frequent water sips, carboxymethylcellulose- or mucin-based gels and sprays; acidic substitutes are avoided when teeth remain, since they erode.
- Preventive dentistry is non-negotiable: 1.1 per cent (5000 ppm) sodium fluoride paste daily, 5 per cent fluoride varnish (22,600 ppm) three-monthly, chlorhexidine rinses and short recall intervals — radiation caries can destroy a dentition in months.
- Expect candidosis: dry mucosa and denture bases colonise readily; treat with topical antifungals and leave dentures out at night.
A stepwise plan around one patient
A 60-year-old woman, six months after 60 Gy of radiotherapy for a tongue cancer, arrives with a sandpaper mouth, trouble swallowing tablets and new cervical caries. Step one, quantify: unstimulated flow measures 0.05 mL/min — true hyposalivation, and radiation makes recovery unlikely, so the plan is palliative and protective rather than curative. Step two, substitute: water bottle habit, a carboxymethylcellulose gel at night when the mucosa sticks to the pillow, and a saliva substitute spray for daytime. Step three, stimulate what remains: sugar-free xylitol gum after meals, then a pilocarpine trial starting 5 mg three times daily, warning her about sweating and checking for asthma; benefit appears within weeks or the drug stops. Step four, protect the teeth: 5000 ppm fluoride paste twice daily, fluoride varnish every three months, chlorhexidine gel for plaque control, diet counselling away from sticky sugars. Step five, treat the complications — fluconazole for her erythematous candidosis and a soft reline for the denture that no longer seats. Reviewed three-monthly, she illustrates the whole ladder in one chair.
Where students slip
The objective-subjective distinction is the first casualty: candidates answer "drink more water" to every dry mouth, when the examiner wants sialometry, a drug history and a Sjögren's screen before labelling. The second slip is pharmacology detail — pilocarpine's muscarinic side effects and its avoidance in asthma and narrow-angle glaucoma are precisely what the prescription question tests, and cevimeline's name should follow it. The third is the erosion trap: citric-acid sialagogues and acidic substitutes stimulate flow but demineralise teeth, so in a dentate irradiated patient they are wrong — the safer answer is xylitol gum plus fluoride. Finally, forgetting candidosis in the dry mouth loses an easy mark, because the two travel together in almost every examination vignette.
Frequently asked questions
What flow rate defines hyposalivation?
Unstimulated whole saliva below about 0.1-0.2 mL/min on sialometry, with stimulated flow below about 0.7 mL/min; symptoms alone cannot make the diagnosis.
What is the dose of pilocarpine for dry mouth, and its caveats?
5-7.5 mg orally three times daily; a muscarinic agonist causing sweating and flushing, avoided in uncontrolled asthma, acute iritis and angle-closure glaucoma.
Which cause of xerostomia is largely irreversible?
Radiotherapy above roughly 30 Gy to the major salivary glands, hence the aggressive preventive plan in irradiated patients.
How is radiation caries prevented?
High-concentration fluoride (5000 ppm paste daily, 22,600 ppm varnish three-monthly), chlorhexidine, diet control and frequent recall — beginning before radiotherapy, not after lesions appear.
How do substitutes and sialagogues differ?
Substitutes (carboxymethylcellulose or mucin gels, sprays, water) replace moisture passively; sialagogues (pilocarpine, cevimeline, chewing) drive the patient's own residual secretion.