Clinician’s Corner: Overcoming the Sensation of Dryness of the Mouth (Xerostomia)

Dr. Mabi Singh DMD, MS
Professor, Oral Medicine Service,
Department of Diagnostic Sciences,
Tufts University School of Dental
Medicine, Boston MA

The subjective sensation of dryness in the mouth, known as xerostomia, typically results from hypofunction (decreased function) or reduced production of saliva by the salivary glands. Salivary characteristics can range from watery to thick, foamy, viscous, ropey, stringy, to complete absence of saliva, depending on the functioning of the remaining salivary glands to produce water and salivary proteins. At times, changes in physical characteristics may give the perception of having too much saliva (subjective sialorrhea), even though the volume is lessened. Hypofunctioning of the salivary glands leads to the reduced production of saliva and the subjective perception of dryness in the mouth. Treatment and relief from the sensation of dryness hinge upon the ability of the salivary glands to produce saliva, and the same treatment may have different outcomes individually. Additionally, the mouth is a highly dynamic organ involved in the clearance of contents, requiring multiple approaches for effective management and relief of dryness. 

Some suggestions and explanations for relief from subjective sensation of dryness of mouth:

• Perception of dryness increases with an increase in friction in the mouth, as one of the principal functions of saliva is to lubricate. When this function is reduced or lost, normal and simple activities like eating, speaking, and swallowing become challenging. Application of viscous lipids (fats) or thick gels or oral health products directed for the relief of oral dryness on the mucosal surfaces, including the inner lips, can help reduce friction and trap moisture under the fatty film layer. To create the slippery layer, breaking Vitamin E caplets, pulling oil such as olive, sesame, coconut, or using products designed for such purpose in mouth may be helpful. Nipple creams, lipstick, or chap sticks containing petrolatum or lanolin products may also be helpful for dried and chapped lips.
• Due to the repeated attempt to wet the lips by sticking the tongue out, habits can be developed, and these repetitive movements may cause tongue irritation and translate into burning sensation. 
• Gustatory (sense of taste) or mechanical stimulation with chewing gum, lozenges, candies, mucosal adhesive tablets with mint flavors, and Xylitol can enhance saliva stimulation depending on the availability of the working salivary glands. However, care should be taken when introducing strong flavors such as mint, as there may not be enough saliva to dilute the taste, which could potentially lead to irritation or discomfort, even a burning sensation. Since the oral cavity is a dynamic organ and the contents are cleared quickly these have to be introduced repeatedly depending on how dry the mouth is. 
• Introducing products containing “arginine” or L-arginine, such as toothpaste or candies or soft chews, into the mouth not only stimulates salivary flow but also can lower acidity by raising pH levels through neutralizing acidity. This may slow down the growth of cavity-causing bacteria and Candida (yeast). It is advisable to dissolve candies slowly rather than chewing them, as the teeth of Sjögren's patients are typically brittle or heavily restored. 
• Salivary proteins, such as mucins, are effective wetting and lubricating agents and are abundant in unstimulated saliva. Thus, even if hydration levels are optimal, the loss of salivary proteins may induce a sensation of dryness in the mouth. Frequent sipping of water may wash away mucins from the mouth, and the hydration caused by the introduction of water to oral tissue may be temporary or even result in a feeling of increased dryness afterwards. It may be more beneficial to drink a glass of water, as hydration is essential for our bodies, and introduce something (such as chewing gum or lozenges or tablets that stick to gum or cheek) into the mouth rather than taking big and frequent sips. Alternatively, taking very small sips of water solely to wet the oral tissue without swallowing may help hydrate and retain, instead of wash away, the salivary proteins in the mouth.  
  
  The amount of water needed for an individual depends on factors such as body size, physical activities, and environmental conditions. Ingesting excessive amounts of water beyond the body’s requirements may lead to dilution of sodium levels and result in frequent urination.
• The natural rate of saliva production is influenced by the body’s circadian rhythm, with  production typically being lowest at certain times of the day such as at night. Additionally, environmental factors such as low humidity due to forced hot air heating systems, geographical location, mouth-breathing, and sleep disorders can contribute to increased dryness of the mouth. Methods to reduce moisture evaporation from the mouth may include using a chin strap, taping the mouth, or placing a mucoadhesive tablet on the gums or on the inside of cheek. However, it’s  advisable to consult with a specialist to prevent potential adverse events and increase effectiveness of such measures. Taking a sialogogue, (many call as saliva pill) (described below) during bedtime can help.
• The average unstimulated salivary flow is approximately 0.3 ml/min, and when it falls below the level of 0.1 ml/min, it is classified as salivary hypofunction. Although oral dryness can be perceived even with normal flow, it is generally accepted that dryness of the mouth becomes noticeable below the level of 0.1 ml/min. One effective method of increasing salivary flow is through the use of prescription sialagogues such as pilocarpine HCl and cevimeline HCl. 
  
  To enhance the tolerability of these pharmaceutical agents, it is advised to gradually increase the dose, a process known as titration. For example, patients should start by taking one tablet (5 mg in the case of pilocarpine HCl) or one 30 mg capsule of cevimeline HCl with food to slow down absorption and reduce side effects such as sweating, increased acid production, chills, or increased heart rate. While these side effects do not affect everyone, they may occur in a small percentage of individuals. Titration helps in overcoming and building tolerance to these medications. Pilocarpine HCl can be taken up to 30 mg a day in divided dosages, and cevimeline HCl up to 3-4 capsules a day. If intolerance develops, lowering to tolerable dosage is suggested. 
  
  The effectiveness of these medications depends on dosage and the availability of functioning salivary glands to increase saliva production. If there are no salivary glands to produce saliva due to advanced conditions of the disease and irreversible damage, there may be minimal relief from dryness even with medication. Individuals with working salivary glands typically respond well to treatment. However, in some cases, the drug may take longer to have an effect in certain individuals, potentially requiring an extended trial period before determining its efficacy. Therefore, it is advisable to persevere with the medication rather than abandoning it immediately. 
• Another method to improve salivary flow is applying warm moist heat compresses to the salivary glands and gently massaging them. Professional suctioning or “boogieing” of the parotid and submandibular glands can also help, reducing the formation of mucus plugs or salivary gland stones in the salivary ducts. Additionally, this technique can provide relief from compression on the facial nerves caused by creating pressure on the salivary glands. 
• The use of ultrasonic toothbrushes for tongue brushing, electrical stimulation of nerves, mechanical vibration of the salivary glands, and other similar techniques have shown mixed results in increasing saliva production and reducing the subjective sensation of dryness in certain patient populations. Sjögren's patients have reported varied success with acupuncture as well. 

In summary, addressing the subjective sensation of dryness can significantly impact the quality of life for sufferers, and it should be tackled through multiple approaches, as not all individuals may respond well to a single method. Relief from dryness largely relies on the remaining functionality of the salivary glands, and there is no single “dry mouth” product that can replace natural saliva. It is important to experiment with different products to find what works best for each individual, and maintaining compliance with the chosen approach is crucial. 

This article was first published in the March/April 2024 issue of Conquering Sjögren’s.