Dry Mouth

Introduction

Saliva is a dynamic fluid which maintains the oral cavity (both hard and soft tissue) in a healthy condition. As such, reduced salivary flow can have many bad consequences on oral health. Dry mouth also sometimes known as xerostomia is the subjective feeling of dryness in the mouth due to a reduction in salivary flow rates or changes in the quality of the saliva. Saliva is produced by the three pairs of major salivary glands and numerous minor salivary glands. The three major salivary glands are the:

  • Parotid glands
  • Submandibular glands
  • Sublingual glands

Saliva has many important roles in the oral cavity. It assists with eating, speaking, swallowing and keeping the mouth healthy. Thus having a dry mouth can adversely affect the individual’s quality of life. This condition is more commonly seen in the older population however, salivary gland dysfunction is not completely an age related condition, though there may be some changes in the salivary gland due to aging. The reason that a dry mouth is experienced more frequently by the older age group is possibly linked to the fact that a dry mouth is a known side effect of many medications that are usually prescribed for non-communicable diseases that are more prevalent amongst those aged 40 and above. It is also a common manifestation of many systemic diseases.

What causes a dry mouth?

The most common cause for a dry mouth in the majority of people would be an inadequate intake of water and fluids resulting in dehydration. Dehydration can also be due to the intake of substances that are diuretic, excessive physical activity and exposure to heat. Diuretics are substances that cause an increased output of urine. A commonly ingested diuretic would be caffeine. Dehydration is seen to cause a more prolonged and profound period of salivary dysfunction in older rather than younger individuals. An individual’s emotional and mental status can influence the salivary flow rate. Anxiety, fear and stress can all cause a decrease in salivary flow resulting in a dry mouth that is usually transient in nature.

An important cause for a dry mouth is medication. More than 100 prescribed drugs can cause dryness of the mouth as a side effect. The following are the usual offending drug groups:

  • antihistamines
  • antidepressants
  • anticholinergics
  • antihypertensives
  • antipsychotics
  • anti-Parkinson agents
  • diuretics and
  • sedatives

It should be remembered that many of these medications are for long-term use and cannot be stopped with consulting with your attending doctor.

Several medical conditions are also associated with a reduction in salivary flow rates such as:

  • Diabetes; oral dryness is worse in poorly controlled diabetics
  • Sjogren’s syndrome
  • Radiation therapy involving the salivary glands
  • Chemotherapy
  • Sarcoidosis
  • Amyloidosis
  • HIV-salivary gland disease
  • Rheumatoid arthritis
  • Systemic lupus erythematosus etc

In these conditions, the severity of dry mouth is usually dependent on the severity and control of the primary medical condition. And at times, the medication used for the management of these conditions can also predispose to a dry mouth. Dry mouth associated with cancer therapy for the head & neck region is usually due to radiation-induced changes to the salivary glands that may be in close proximity to the main tumour. These changes to the glands are dependent on the dosage of radiation and are usually permanent.

What are the symptoms associated with a dry mouth?

Patients with a dry mouth may complain of difficulty with performing normal oral functions such as eating, speaking and swallowing. This is more so with foods that are dry, and crumbly such as toast and crackers. There may also be increased discomfort with hot and spicy foods. In brief, without adequate saliva, almost any food may be difficult to chew and swallow. This in turn can cause loss of appetite and weight. The following are a list of other symptoms / problems that may be experienced by patients with a dry mouth:

  • Taste disturbance.
  • Cracked lips.
  • Bad breath.
  • Thick / frothy / ropey saliva
  • Burning sensation in the mouth.
  • Dry / rough tongue.
  • Difficulty / pain when using dentures.
  • Oral infections
  • Salivary gland stones
  • Salivary gland infections
  • Tooth decay
  • Gum disease
  • Ulcers

Oral dryness is also usually more severe at night as even in normally functioning salivary glands, the saliva flow is reduced greatly when asleep.

Complications

As mentioned above, a dry mouth increases the risk for oral infections, gum disease and tooth decay due to the loss of the protective effects of saliva. At times, a dry mouth may be an early symptom for other systemic diseases such as diabetes, Sjogren’s syndrome, scleroderma etc.

Management:

Management is dependent upon the cause of the dry mouth. To determine the underlying cause for the dry mouth, your doctor will have to obtain a comprehensive medical history and perform a thorough clinical examination. At times, several other tests such as blood tests, urine analysis, salivary flow rate tests, x-rays or scans and even a biopsy may be necessary to determine the cause of the dry mouth. Patients with a chronic dry mouth which is not due to dehydration may require a multi-disciplinary approach involving different specialists.

Oral dryness can be managed symptomatically with moisturizing agents and lubricants such as artificial saliva, which can be used throughout the day. Using sugar free chewing gums or candies can also stimulate the production of saliva. As a preventive measure against tooth decay, your dentist may recommend the use of neutral topical fluorides either in the form of gels or mouth rinse. Maintaining good oral hygiene and visiting your dentist on a regular basis can reduce the complications that arise from a dry mouth.

In very severe cases, your attending specialist may prescribe medications that can increase saliva production, however these medications have several other side-effects which will be explained in detail by your attending specialist.

Self-care measures:

Things to do:

  • Sip on water or sugar-free drinks throughout the day.
  • Use an atomizer/spray bottle (Figure 1) containing clean water or saliva substitutes to moisten mouth. Spray the mouth hourly / when necessary.
    Figure 1: Examples of spray bottles
  • Keep water at your bedside as well
  • Take small sips of water with each mouthful of food. This will make chewing and swallowing easier.
  • Eat soft and creamy foods (soups, casseroles) or foods with a high liquid content (water melon, grapes).
  • Moisten foods with gravy/sauce/olive oil etc (whenever appropriate)
  • Use saliva substitutes recommended by your specialist
  • Protect lips with lip balm.
  • Stimulate salivary flow with sugar-free chewing gums or sweets
  • Visit your dentist on a regular basis
  • Brush twice a day with fluoridated toothpaste and floss (follow instructions given by your dentist/specialist).
  • Maintain good denture hygiene and leave dentures out before going to sleep.
  • Consider using a humidifier for the bedroom

Things to avoid:

  • Tobacco products.
  • Alcoholic beverages
  • Spicy, acidic, sugary, hard and dry foods
  • Caffeinated beverages.
  • Alcohol containing mouthwash.

If you have a dry mouth, please consult your dentist/doctor.

References

  1. Porter SR, Scully C, Hegarty A: An update on the etiology and management of xerostomia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod (2004) 97: 28 -46
  2. Scully C. (2008). Oral and maxillofacial medicine- The basis of diagnosis and treatment. (2nd ed.) Elsevier.

 

Last Reviewed : 3 June 2014
Writer : Dr. Hans Prakash a/l Sathasivam
Accreditor : Dr. Lau Shin Hin

 

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