When cold water touches your teeth, a sudden, sharp sensation can occur. This common discomfort, known as dentin hypersensitivity, affects many individuals, with some reports indicating it impacts about one in eight Americans. It often arises from specific triggers like temperature changes or certain foods and drinks. Understanding its causes can help manage it.
How Teeth Sense Cold
A tooth has several layers. The outermost layer of the tooth crown, visible above the gum line, is enamel, the hardest substance in the human body. Beneath this protective enamel lies dentin, a softer and more porous layer. The innermost part of the tooth is the pulp, which contains nerves and blood vessels.
Dentin is permeated by millions of microscopic channels called dentinal tubules. These tiny tubules contain fluid and connect directly to the nerve endings located within the pulp. When the protective layers of enamel or gum tissue are compromised, these tubules become exposed to the oral environment.
The hydrodynamic theory explains how cold stimuli cause pain. When cold water or other cold stimuli contact exposed dentin, it causes the fluid inside these dentinal tubules to rapidly move or shift away from the pulp. This sudden movement of fluid stimulates the nerve endings, leading to the sharp pain of tooth sensitivity. Research indicates that sensitive dentin often has a greater number of open and wider tubules, contributing to increased fluid flow and nerve stimulation.
Underlying Reasons for Sensitivity
Tooth sensitivity often develops when the protective enamel or gum tissue no longer fully covers the dentin, exposing the microscopic tubules within. One common cause is enamel erosion, which can result from regularly consuming acidic foods and drinks like citrus fruits, sodas, coffee, or wine. Aggressive tooth brushing or abrasive toothpastes can also wear down enamel over time, especially along the gumline where it is thinnest. Conditions such as acid reflux can also contribute to enamel loss by repeatedly exposing teeth to stomach acid.
Gum recession is another frequent reason for sensitivity, occurring when the gum tissue pulls away from the teeth, exposing the root surfaces. The roots are naturally covered by a softer material called cementum, which wears away more easily than enamel, leaving the underlying dentin exposed.
Other factors can also lead to dentin exposure and sensitivity. Tooth decay (cavities) directly erodes enamel and dentin, creating openings that allow stimuli to reach the pulp. Cracked or chipped teeth can also expose inner tooth layers, leading to sudden, sharp pain. Old or worn fillings may develop cracks or gaps, allowing irritants to seep in.
Teeth grinding (bruxism) places excessive pressure on teeth, which can wear down enamel and cause small fractures, contributing to sensitivity. Some dental procedures, such as professional teeth whitening, dental cleanings, or the placement of new fillings, can temporarily increase tooth sensitivity. This is often due to temporary irritation of the pulp or increased exposure of dentin during the process.
Managing Tooth Sensitivity
Managing tooth sensitivity often involves adjustments to daily oral hygiene practices. Using a desensitizing toothpaste can be effective, as these products contain compounds like potassium nitrate or stannous fluoride that help block the tiny tubules in dentin, reducing the transmission of pain signals to the nerves. Consistent use, typically twice daily for at least a few weeks, is often needed for noticeable improvement.
Proper brushing technique is important to prevent further enamel wear and gum recession. Use a soft-bristled toothbrush and gentle, circular motions rather than aggressive scrubbing, holding the brush at about a 45-degree angle to the gums. Avoiding highly acidic foods and drinks, or limiting their consumption, can help protect enamel from erosion. If you consume acidic items, rinsing your mouth with water afterward can help neutralize acids and reduce their impact.
For those who grind their teeth, a custom-fitted nightguard can help protect teeth from the forces of bruxism, preventing further enamel wear and sensitivity. A fluoride rinse can also strengthen enamel and provide an additional protective barrier. A simple warm saltwater rinse can help reduce inflammation and soothe irritated gums, which may contribute to sensitivity.
When to See a Dentist
While home care can help manage mild tooth sensitivity, professional dental evaluation is beneficial in some situations. If the sensitivity is severe, persistent, or does not improve after a few weeks of consistent at-home measures, consulting a dentist is a good step. Pain that affects only one tooth, rather than a general sensitivity, can also signal a more localized issue.
A dental visit is also advisable if sensitivity is accompanied by other symptoms, such as visible tooth decay, a cracked or chipped tooth, or gum complications like swelling or significant recession. Pain experienced specifically when biting down can indicate a cracked tooth or a problem with a filling. A dentist can identify the underlying cause and recommend appropriate treatments.
Professional treatments for tooth sensitivity can include in-office fluoride applications, which strengthen enamel and reduce sensitivity. Dental bonding or sealants can be applied to cover exposed root surfaces or areas of worn enamel, creating a protective layer. In cases of significant gum recession, a gum graft might be recommended to cover exposed roots. If sensitivity stems from deep decay or pulp inflammation, root canal therapy may be necessary to remove the affected nerve and alleviate pain.