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Dryness of the Mouth

Essentials

  • The feeling of dry mouth is often due to reduced or lacking salivary flow.
  • It is most common in people aged over 65 and in postmenopausal women.
  • Possible causes
    • Local factors (such as smoking, radiotherapy of the head or neck region)
    • Systemic diseases, and Sjögren's syndrome, in particular Primary Sjögren's Syndrome
    • Medication
    • High consumption of coffee or tea with caffeine
    • High alcohol consumption
  • Oral inflammation, soreness and dental caries due to dry mouth should be prevented by providing appropriate guidance and treatment.

Aetiology

  • Local factors
    • Smoking
    • Mouth breathing
    • Sialolithiasis
    • Tumours in the mouth or pharynx
    • Radiotherapy of the head or neck region
  • Systemic diseases
    • Autoimmune diseases, and Sjögren's syndrome, in particular Primary Sjögren's Syndrome
    • Endocrine diseases (diabetes, hypo- or hyperthyroidism)
    • Loss of appetite, anorexia nervosa
    • Psychiatric and neurological diseases: depression, anxiety, Parkinson's disease
    • Infections (HIV, hepatitis)
    • Metabolic diseases: dehydration, chronic kidney disease
    • Genetic causes
  • Medication
    • Anticholinergic drugs (antipsychotic agents, tricyclic antidepressants, antihistamines, drugs for urinary incontinence)
    • Drugs for allergies and asthma
    • Antihypertensive medication (all groups)
    • Sympathomimetics
    • Osteoporosis medication (bisphosphonates)
    • Antirheumatic drugs (methotrexate, some biological agents: adalimumab, certolizumab pegol)
    • Antidiabetic drugs (GLP-1 analogues, SGLT2 inhibitors)
    • Psychotropic drugs (benzodiazepines, tricyclic antidepressants, SSRIs and other new antidepressants, lithium, antipsychotic agents)
    • Opioids
    • Cytostatic drugs
    • Many other drugs, such as gabapentin, pregabalin, antiepileptic drugs

Symptoms

  • Hyposalivation (reduced salivary flow rate) predisposes and often leads to symptoms such as
    • rapid decay of the teeth
    • mucosal problems (e.g. candidosis, mucosal ulcers)
    • foul-smelling breath
    • soreness of the tongue, burning mouth syndrome (burning sensation, smarting of the oral mucosa)
    • unusual taste sensations (e.g. metallic taste)
    • difficulty in wearing removable dentures
    • difficulties with speech, eating and swallowing.

History

  • When do symptoms occur?
    • During the day
    • At night when waking up
    • When speaking
    • When eating, swallowing
      • Is it difficult to swallow dry food?

Clinical examination

  • General condition
    • Are there signs of diabetes or other systemic disease (such as weight loss, increased diuresis, thirst)?
  • Mouth
    • Lips: dryness, cracking, angular cheilitis Cheilitis
    • Oral cavity: dryness, condition of the mucosa, gums, dentition
    • Tongue: dryness, atrophy, erythema, loss of papillae, candidiasis
    • Teeth: enamel damage, tooth decay, caries, condition of any dentures or bridges
  • Neck
    • Palpation
    • Salivary glands

Diagnosis

  • Diagnosis is usually based on symptoms of dry mouth and local findings.
  • Does the patient have an underlying disease or other predisposing factor?
  • In unclear cases, measurement of the salivary flow rate (by a dentist or an oral hygienist)
    • The easiest method for measuring the salivary flow rate is to quantify the amount of saliva produced during 5 minutes while chewing on a piece of paraffin wax. Normally this amount should exceed 7.5 ml. In hyposalivation, the stimulated salivary flow rate is less than 3.5 ml/5 min.
    • The resting salivary flow rate measured without chewing should be at least 4.5 ml in 15 minutes, the limit for hyposalivation being less than 1.5 ml.
  • Other possible examinations
    • Basic blood count with platelet count
    • fasting plasma glucose, HbA1c
    • Antinuclear antibodies
    • Sjögren antibodies (SSA and SSB antibodies)
    • Salivary gland biopsy (Sjögren's syndrome, tumours, inflammation)

Management Topical Therapies for Dry Mouth

Oral hygiene

  • Careful cleaning of the teeth and interdental spaces every day to remove plaque is essential. In addition to fluoride toothpaste the use of some other local fluoride supplement, such as fluoride-containing mouthwashes or fluoride lozenges, is recommended. Fluoride toothpaste (e.g. Duraphat 5 mg/g® )️ available in pharmacies can be used to prevent dental caries in patients with dry mouth, in particular.
  • Dietary sugar should be minimized.
  • Removable dentures and bridges should be cleaned especially well. They should not be kept in the mouth at night but instead in a dry and airy container, at least if there is inflammation or ulceration under the devices.
  • A patient who suffers from dryness of the mouth needs professional advice on how to clean his/her teeth and dentures and on daily preventive dental care. The patient should visit dental care services more frequently than usual, as often as every 3-6 months.

Chewing

  • Each of the 5-6 regular meals and snacks a day should also contain food that requires chewing. Ending a meal by eating vegetables, nuts or cheese or chewing xylitol chewing gum, which all increase salivation, is beneficial. Chewing cheese or xylitol after a meal also increases the salivary pH to normal levels more quickly.
  • Sugar-containing or acid snacks or drinks should be avoided between meals; this includes acidic fruit.

Xylitol-containing chewing gum, tablets and lozenges

  • Chewing gum sweetened with xylitol is a good way to enhance salivary flow between and after meals.
  • Xylitol-sweetened lozenges or lozenges containing xylitol and fluoride can be used instead of chewing gum.
  • If the mouth is very dry and lozenges do not dissolve, a moisturizing gel or cooking oil can be used to moisturize the mouth.

Oral moisturizing agents

  • It is most important that the patient drinks sufficient amounts of plain water or non-flavoured mineral water and frequently rinses the mouth with water.
  • Saliva substitutes and gels make the oral mucosa feel smoother, preserve humidity longer than water alone, and may be helpful especially during the night. Such products, available in pharmacies, can be used regularly if needed.
  • Dry oral mucosal membranes and lips may also be moisturized with cooking oil or with suitable skin oil or spray (e.g. Ceridal® ).
  • Using oil-containing nasal sprays or drops may help to reduce mouth breathing.

Medication

  • Review the patient's medication; can any medicines safely be changed to others that cause less drying of the mouth?
  • For patients who suffer from severe dryness of the mouth and fulfil certain criteria, pilocarpine tablets 5 mg 3-6 times daily can be used. However, pilocarpine has anticholinergic adverse effects and many interactions with other drugs. It is thus mainly suited for a carefully selected group of patients, and it is of no benefit if the functioning of the salivary glands has completely ceased.

    References

    • Tan ECK, Lexomboon D, Sandborgh-Englund G, et al. Medications That Cause Dry Mouth As an Adverse Effect in Older People: A Systematic Review and Metaanalysis. J Am Geriatr Soc 2018;66(1):76-84 [PubMed]
    • Wolff A, Joshi RK, Ekström J, et al. A Guide to Medications Inducing Salivary Gland Dysfunction, Xerostomia, and Subjective Sialorrhea: A Systematic Review Sponsored by the World Workshop on Oral Medicine VI. Drugs R D 2017;17(1):1-28 [PubMed]
    • Riley P, Glenny AM, Hua F, et al. Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy. Cochrane Database Syst Rev 2017;7(7):CD012744 [PubMed]
    • Furness S, Bryan G, McMillan R, et al. Interventions for the management of dry mouth: non-pharmacological interventions. Cochrane Database Syst Rev 2013;2013(9):CD009603 [PubMed]
    • Furness S, Worthington HV, Bryan G, et al. Interventions for the management of dry mouth: topical therapies. Cochrane Database Syst Rev 2011;(12):CD008934 [PubMed]