Xerostomia, or chronic dry mouth, occurs when salivary glands do not produce enough saliva to keep the mouth adequately moist. This dryness is more than just an inconvenience; it represents a serious threat to oral health. A lack of saliva significantly increases the risk of dental decay, meaning dry mouth definitively causes cavities. Saliva is a highly complex biological fluid integral to maintaining the delicate balance of the oral environment and protecting teeth.
How Saliva Protects Teeth from Decay
Saliva performs multiple functions that shield the teeth from the corrosive effects of bacteria and acid. One primary role is physical cleansing, washing away food debris and the sticky plaque where harmful bacteria thrive. This mechanical action helps to clear the oral cavity of fermentable carbohydrates that would otherwise be converted into damaging acids.
The fluid also possesses a sophisticated buffering capacity, neutralizing acids produced by oral bacteria after eating or drinking. Saliva uses a carbonic acid/bicarbonate buffer system to raise the pH level of the mouth back toward a neutral level of approximately 7.0. Without this buffering ability, the enamel remains exposed to prolonged acid attacks, leading to demineralization and the formation of cavities.
Saliva is crucial for the continuous process of remineralization, which is the natural repair mechanism for early enamel damage. It is supersaturated with inorganic components like calcium and phosphate, which are delivered directly to the tooth surface. When the enamel loses minerals due to acid erosion, these compounds are deposited back into the tooth structure, effectively rebuilding and strengthening it.
Finally, saliva contains various immunoproteins and antimicrobial agents, such as enzymes and antibodies, that help control the population of bacteria in the mouth. This antibacterial action limits the growth of cavity-causing microbes. When saliva flow is reduced, all these protective mechanisms are compromised, accelerating the rate of decay.
Factors That Reduce Saliva Flow
The most common cause of chronic xerostomia is the use of medications, with over 400 different types of drugs listing dry mouth as a potential side effect. Multiple classes of prescription and over-the-counter drugs have anticholinergic effects, meaning they interfere with the nerve signals that stimulate the salivary glands to produce fluid. These frequently include antidepressants, antipsychotics, and antihistamines used for allergies.
Medications for cardiovascular conditions, such as some diuretics and antihypertensive agents, are also common culprits. Diuretics increase fluid excretion from the body, leading to dehydration that can manifest as reduced salivary flow. Other drug classes that frequently contribute to dry mouth include opioids, muscle relaxers, and certain stimulants used for conditions like ADHD.
Systemic health issues can also significantly impair salivary gland function. Sjögren’s syndrome, an autoimmune disorder, specifically targets the body’s moisture-producing glands, leading to persistent and severe dry mouth. Diabetes can also be a factor, as uncontrolled blood sugar levels can affect the nerves responsible for salivary secretion. Patients who have undergone radiation therapy for head and neck cancers often experience irreversible damage to their salivary glands.
Strategies for Managing Dry Mouth and Protecting Teeth
Managing dry mouth starts with a consultation with a healthcare professional to review all medications and address any underlying health conditions. A doctor may be able to adjust the dosage or switch a patient to an alternative medication that has less of a drying effect. For instance, certain selective serotonin reuptake inhibitors (SSRIs) may cause less dry mouth compared to older tricyclic antidepressants.
Patients should focus on increasing moisture and stimulating natural saliva flow. Regularly sipping water throughout the day is highly recommended to stay hydrated and keep the mouth moist. Chewing sugar-free gum or sucking on sugar-free candies can stimulate the salivary glands, with products containing xylitol being particularly helpful because the sweetener inhibits the growth of cariogenic bacteria.
Using specialized over-the-counter products can provide symptomatic relief and direct protection. Saliva substitutes, often available as sprays or gels, can temporarily coat and moisten the oral tissues. Using a cool-mist humidifier at night can also reduce dryness, especially for individuals who breathe through their mouths while sleeping.
Aggressive oral hygiene adjustments are necessary to prevent accelerated decay. Individuals with xerostomia should use a fluoride toothpaste at least twice daily and may benefit from prescription-strength, high-fluoride options recommended by a dentist. Frequent professional dental checkups, often every three to four months instead of the typical six, allow for early detection and intervention of decay. It is also wise to avoid alcohol-based mouthwashes, as the alcohol can further dry and irritate oral tissues.