What’s the Risk? Dry Mouth and Saliva

Saliva is one of the most important protective mechanisms of the teeth. It contains proline-rich proteins and glycoproteins, mucins, calcium, phosphate, and bicarbonate, along with a host of other antibacterial, antiviral, and antifungal constituents. Saliva performs many functions, including assisting in food digestion, protecting the body from microbes, balancing the pH in the mouth, and supporting the remineralization of teeth.¹ The body maintains the hypermineralized structures (teeth) by continually bathing them with a supersaturated solution of tooth mineral.² Without saliva, teeth would simply dissolve.

Due to saliva’s protective functions, a lack of saliva, often referred to as dry mouth or, more technically, xerostomia, is a major risk factor for dental disease.^3,4 Consequently, it is a risk factor question when a dental practitioner discusses a patient’s dental caries risk.

Studies have shown that dry mouth affects 20%-46% of the total population.

Everyone, at some point in his or her life, suffers from dry mouth.¹ But a significant feature of dry mouth is that it occurs in women more often than in men; it is also more prevalent among older adults than in young or middle-aged individuals, is usually more severe during sleep when salivary glands naturally produce less saliva, and can occur due to many factors. While only a small percentage of patients self-report symptoms of dry mouth, studies have shown that dry mouth affects 20%–46% of the total population.¹

Some of the causes of dry mouth are stress, poor diet, age, heredity, disease, and commonly used medications that cause dry mouth as a side effect.

There are a few ways to identify if a patient does not have enough saliva and has “dry mouth” as a risk factor. First, if any in the following list of common dry mouth questions occurs occasionally or more often during the day, a healthy dry mouth relief therapy should be investigated:

1. My mouth feels dry.
2. I notice a lack of saliva in my mouth.
3. I get up at night to drink.
4. My mouth feels dry when eating a meal.
5. I have difficulties swallowing certain foods.
6. I sip liquids to aid in swallowing foods.
7. I suck on sweets or cough drops to relieve dry mouth.
8. My throat feels dry.
9. My mouth becomes dry when speaking.
10. I regularly use ______ to keep my mouth moist.

Some of the causes of dry mouth are stress, poor diet, age, heredity, disease, and commonly used medications that cause dry mouth as a side effect.

Another method of identifying dry mouth is the resting or stimulated saliva flow test.

For the resting saliva test, the dental practitioner may ask a patient to spit into a measuring cup without any oral stimulation for one minute and then assess the amount of saliva. If the resting saliva flow is less than 0.1ml/min, it is very low, 0.1–0.25ml/min is low, and 0.25–0.35ml/min is normal.

For the stimulated saliva test, the dental practitioner may ask a patient to spit into a measuring cup while chewing on a piece of sterile wax for five minutes. If the stimulated saliva flow is less than 0.7ml/min, it is very low or high risk, 0.7–1.0ml/min is low, and 1–3ml/min is normal.

Many dental practitioners can also identify upon oral inspection if there is a saliva/dry mouth issue present. Another simple test is resting saliva flow, which averages about 0.3 ml/min. The practitioner can retract the lower lip and observe saliva droplets forming on the mucosa of the lip from the minor salivary glands found there. Within a minute, there should be numerous droplets of saliva. Another quick indication for saliva flow is to just look at the floor of the mouth. The body produces about 1 liter of saliva every day, and a healthy patient will have saliva pooling at the floor of the mouth. Not all dental practices, however, perform saliva testing.

1. Leo M. Sreebny and Arjan Vissink, Dry Mouth, the Malevolent Symptom (Hoboken, NJ: Wiley-Blackwell, 2010), 12, fig. 1.2.2.
2. O. Fejerskov and E. Kidd, Dental Caries: The Disease and Its Clinical Management (Oxford, UK: Blackwell Munksgaard, 2003).
3. Sophie Domejean, Joel M White, and John D. B. Featherstone, “Validation of the CDA CAMBRA Caries Risk Assessment —A Six-Year Retrospective Study,” J Calif Dent Assoc 39, no. 10 (2011): 709–15.
4.  http://www.ada.org/sections/newsAndEvents/pdfs/ltr_dry_mouth_110427.pdf