Managing dry mouth

Xerostomia, also known as dry mouth, is a common symptom associated with a decrease in the amount or quality of saliva. Xerostomia is not a disease in itself but may be a symptom of a disease or a side effect of medical treatment. It is also a very common daily condition among the patient population over the age of 50 (Streebny LM, Valdini A, 1987; Astor FC, Hanft KL, Ciocon JO, 1999).

Although not life threatening, dry mouth can have a serious negative effect on the patient’s quality of life. These effects may include:
• Changes in dietary habits and subsequent nutritional status
• Difficulty with speech
• A decrease in taste
• Intolerance to removable dental prosthesis
• An increase in susceptibility to dental caries. 

Dry mouth can be part of the normal ageing process. As you get older, your salivary glands may secrete less saliva. Thirst and your perception of thirst may also change; thirst receptors in your brain become less responsive to your body’s need for fluids. However, most xerostomia is related to the medications taken by older adults rather than to the effects of ageing (McDonald E, Marino C, 1991).

Causes of xerostomia
There are over 600 medications (prescribed and OTC) that produce dry mouth as a side effect, causing the salivary glands to produce less saliva (Streebny LM, Schwartz SS, 1997). Among the more likely types to cause problems are:
• Some of the drugs used to treat depression and anxiety
• Antihistamines
• High blood pressure medications
• Anti-diarrhoeals
• Muscle relaxants
• Drugs for urinary incontinence
• Central-acting analgesics
• Antacids
• Parkinson’s disease medications.

The symptom may worsen when medications are combined.

Cancer therapy
Patients with head and next cancer tend suffer more often than others from pronounced xerostomia. Chemotherapy drugs can change the nature of saliva and the amount produced (Scully C, Sonis S, Diz PD, 2006). Radiation treatments to the head and neck can damage salivary glands, leading to the glandular tissue becoming fibrous and causing a marked decrease in saliva production. Radiation therapy is cumulative and the changes at the tissue level (i.e. decreased vascular innervation) is often permanent.

Nerve damage
Damage to the nerves that innervate the salivary glands can affect the amount or type of saliva produced, depending upon which gland is affected.

Damage can result from surgery, physical injury or compression from tumours located in the head or neck region. Nerve innervation changes are often irreversible due to severance of the proximal and distal portions of the nerve. Damage due to pressure may be reversed if the pressure can be decreased or eliminated surgically.

Salivary duct stones
Salivary duct stones result in blockages of the salivary glands ducts, decreasing the flow of saliva. When these become chronic issues pressure atrophy may result in the gland, leading to permanent changes in glandular output of saliva. Removal of the stone will remove any discomfort associated with the pressure in the gland and allow salivary flow to improve.

Inflammation of the salivary glands
Inflammation can result from infection in the oral cavity, for example stomatitis. Any inflammation of the glands will constrict the opening of the gland, decreasing the flow of saliva.

Tumours of the glands
Generally, a tumour will only affect one salivary gland; therefore the other glands will continue to secrete saliva. Treatment involves excision of the entire gland to prevent recurrence of the tumour and the subsequent result is diminished salivary volume.

Dehydration can result from any number of causes, ranging from blood loss to renal failure or modified dietary intake that does not allow sufficient hydration. Lack of fluid in the body results in decreased amounts and thick, ropey saliva being produced. It is important to make sure  sufficient fluids are being taken in each day. Most people need to consume eight pints of
fluid daily.

Medical conditions
Dry mouth can result from health conditions that include:
• The autoimmune disease Sjögren’s syndrome (Dyke S, 2000
• Endocrine disorders (e.g. diabetes) (Wollner D, 2003)
• Alzheimer’s disease (Chiappelli F et al, 2002)
• Parkinson’s disease (Proulx M et al, 2005)
• AIDS (Reznik DA, 2005)
• Stroke (Koh MS et al, 2002)
• Anxiety disorders and depression.

Miscellaneous factors
In addition, smoking or chewing tobacco can affect saliva production, aggravating dry mouth. Nicotine is a vasoconstrictor, which can lead to a decrease in salivary function via the minor salivary glands (Bouclin R, Landry RG, Noreau G, 1997).

Snoring and mouth breathing can also contribute to dry mouth. People who breathe through their mouth as opposed to their nose often experience dry mouth due to air drying out the mucosal lining of their mouth (Lavigne GJ et al, 1999).

Dry nasal membranes may lead to difficulty breathing through your nose. Keeping the membranes moist with saline nose spray will help in breathing through the nose and make the throat more comfortable.

Limited stimulation of the salivary glands may occur when chewing is decreased.  The glands are stimulated to produce saliva when chewing occurs. Limited chewing, for any reason, can result in decreased stimulation of the salivary glands and therefore decreased salivation. With disuse comes atrophy of the gland tissue. This can be an important factor in older patients, especially those in care facilities. These patients are often fed foods that require very minimal chewing, which leads to decreased salivary output; in turn, this leads to less desire to eat and chew.  This forms a vicious cycle, affecting the quality of life.

On a given day, the average healthy adult produces about three pints of saliva. Saliva is an essential body fluid for the protection and preservation of the oral cavity and oral functions. It is produced by the three pairs of major salivary glands and hundreds of minor salivary glands. Its value is seldom appreciated until there is not enough. Saliva is mostly water, but it also contains over 60 substances (for example, enzymes, proteins, mucous and minerals such as calcium).

The functions of saliva are to:
• Protect and cleanse the oral mucosa (moister tissue is more resistant to abrasion)
• Lubricate food, making it easier to swallow (especially with regard to drier or harder foods)
• Help with speech (speech is easier when the tissue is lubricated)
• Protect the teeth against decay (through washing debris from the teeth and immune reaction to the bacteria that break down foods to create acids)
• Protect the mouth, teeth and throat from infection by bacteria, yeasts and viruses
• Support and facilitate a sense of taste
• Initiate the digestive process through enzymatic action.

Reduced saliva production can result in a build-up of bacterial plaque, leading to dental caries and gum disease. Although individuals with reduced saliva production are more susceptible to these types of problems, a good oral hygiene routine that helps to prevent bacterial accumulation can limit the harm caused by reduced salivary flow.

Saliva helps neutralise acids in the mouth and pharynx. This is important for patients suffering from gastro-oesophageal reflux disease (GORD). As acid reflux rises up into the pharynx, and sometimes even into the mouth, saliva dilutes the acid, helping to protect the teeth and soft tissue.

Substances that can increase oral dryness and therefore should be limited or avoided include:
• Tobacco
• Alcohol
• Caffeine
• Carbonated beverages
• Foods with a high sugar content
• Spicy food
• Hot foods
• Acidic foods such as citric fruits and tomatoes.

Signs and symptoms of xerostomia
Patients with dry mouth may be asymptomatic or unaware of this complication. They may report a need to sip water continually, difficulty eating dry foods, waking up thirsty during the night, difficulty wearing a denture or a diminished ability to taste foods. Aside from the sensation of dryness in the mouth, xerostomia may result in:
• Saliva that seems thick and stringy
• Sores or split skin at the corners of the mouth
• Generalised irritated and inflamed mucosal tissue
• Bad breath
• Difficulty speaking
• Difficulty swallowing
• A burning or tingling sensation of the tongue
• An altered sense of taste
• Increased plaque and periodontal disease
• Presence of cervical decay, especially the mandibular teeth.

A good oral hygiene régime is essential for maintaining oral health. Saliva has a major role in this process.

Saliva substitutes
Saliva substitutes are useful when there is insufficient or no functioning glandular tissue or when other saliva promotion methods are inadequate. Saliva substitutes are necessary for chronic dry mouth, particularly for dry mouth caused by radiotherapy. Water, ice chips and atomised water sprays are good for temporary oral relief, however they do not contain any of the protective substances that normal saliva contains. A properly balanced saliva substitute product should be of neutral pH and contain electrolytes to make the composition similar to that of natural saliva, coating the mouth with a film and helping to protect the mucous membrane.

Specialised products are available that help to treat dry mouth and contain salivary enzymes to help the body’s natural defences reduce harmful bacteria.

Artificial saliva products are a good adjunct during the day, to improve comfort and make eating easier. These products are applied topically, typically in a spray bottle, and may be used as often as is needed during waking hours. Moisturising gels are better suited for nocturnal hours, because they remain in contact with the mucosal tissue for longer than the sprays. These can be applied at bedtime or may be considered for use during the day with nursing home patients who are unable to use the spray or drink fluids without assistance. The moisturising gels may also be placed in removable prosthetics to aid in retention due to lack of saliva.

Additional adjuncts
As these patients are at a higher risk of caries and periodontal disease, use of fluoride supplements in the form of rinses and topical gels can decrease the chance of dental disease. These rinses should be limited to rinsing and excess should be expectorated. 

Fluoride topical gels and use of a neutral sodium fluoride is recommended, so avoid the etching of enamel seen with acidified formulations.  The gels may be applied either at bedtime with a toothbrush after using toothpaste or, when the patient wears a partial denture, a drop may be placed into the prosthesis at the rests/clasps before insertion of the prosthesis.

Patients who have a higher decay rate may require a stent to be worn for a period of time each day. These can be fabricated from the same material and design as bleaching trays.

Strengthening and recalcification of the cervical hypocalcified areas is the goal to prevent these areas from becoming carious. This may be accomplished using fluoride-containing products but can also be augmented through the use of MI Paste (GC), a patient-applied calcium and phosphate paste (Reynolds EC et al, 1999; Reynolds EC, 2000). The calcium and phosphate help to replace molecular calcium on the enamel’s surface and will buffer the oral acid levels. This product contains casein phosphopeptide (CPP), which are naturally occurring molecules that are able to bind calcium and phosphate ions. This yields a stable complex of amorphous calcium phosphate (termed Recaldent) (Sakaguchi Y et al, 2005; Hicks J, Flaitz C, 2005). As this is derived from casein, a milk protein, this product is contraindicated for patients who are sensitive to milk protein. There appears to be no link with those who are lactose intolerant and use of this product. 

Patients who present with an acute episode of irritated and inflamed tissue may find it difficult to eat or communicate. These patients may receive temporary relief using a prescription mouth rinse.

Sodium lauryl sulfate is a common preservative found in toothpastes that has been found to be an irritant in some patients, especially those with dry mouth. Use of a toothpaste without this preservative can eliminate the tissue irritation seen in these patients when they try to brush their teeth. Natural toothpastes such as Tom’s of Maine or toothpastes formulated for patients with dry mouth may help patients maintain better oral hygiene. 

Because alcohol is a drying agent, it should be avoided in oral rinses. Numerous alcohol-free rinses are now available in shops. These are usually situated with the other rinses and oral care products.

Some have recommended use of lemon-flavoured boiled sweets to stimulate saliva production. If this is recommended, sugar-free sweets should be used so that caries potential is not influenced negatively.

Identification of salivary issues
An in-office single-visit salivary test called Saliva-Check is now available. This allows the practitioner to check the patient’s salivary quality, pH and buffering capacity (Knight G, 2004).
Once saliva problems are identified, the practitioner can recommend a course of preventive care that includes:
• Introducing supplements (salivary substitutes, fluoride, CPP-ACP)
• Lifestyle changes (increased water intake, decreased diuretic intake – caffeine, alcohol, etc)
• Increasing saliva stimulation (chewing gum and low acid foods)
• Altering the oral hygiene regimen (increased brushing and cleaning, improved cleaning and flossing methods).

Dry mouth can have life-altering consequences, affecting quality of life. As we age we are more likely to have health issues that require us to take multiple medications. Each medication alone can increase dry mouth and when combined these effects can be very difficult for the patient.  Unfortunately, there may not be alternative medications for their particular affliction that do not have the side effect of dry mouth. Treatment therefore needs to be directed to minimising the symptoms of dry mouth locally with moisturisers and improved oral hygiene.

Decreasing dry mouth and its symptoms can have a profound effect on quality of life, especially for those patients living in care facilities who are unable to care for themselves fully. With elimination of these symptoms, the patient may find eating easier and an improvement in their nutritional status can make a big difference.

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