Tooth Sensitivity

Man eating ice cream and holding jaw in painDental patients often complain of tooth sensitivity. They usually describe it as a sharp pain, lasting several seconds, that is set off by eating or drinking something cold or sweet. They may also state that brushing in certain areas elicits a sharply painful response.

It is a legitimate complaint because it can be the source of great patient distress and anxiety. For dentists, it can be stressful as well, because tooth sensitivity is a complex condition that can be challenging to manage. It has several possible causes and can have serious implications, so careful evaluation is essential.

Why Do Teeth Become Sensitive?

The nerve of the tooth is unique, in that the only sensation it can transmit is pain. Any stimulus to the tooth—whether it is heat, cold, chemical, tension, or pressure—elicits this one response.

Most patient complaints of tooth sensitivity arise from a phenomenon that is more properly called dentin hypersensitivity. It is caused when the dentin, the layer of the tooth under the enamel, becomes exposed. The dentin contains thousands of microscopic nerve endings arising from the underlying dental pulp, or nerve, so it is exquisitely sensitive when touched or exposed to:

  • Cold air
  • Hot or cold substances
  • Sugar
  • Acidic substances

Although patients who are suffering from dentin hypersensitivity feel as though the actual nerve is exposed, it is really the dentin that is causing the pain. There are several causes for the dentin to become sensitive.

Gingival Recession

Tooth sensitivity most commonly occurs on the tooth near the gum line, where recession of the gum, or gingival recession, has occurred. Here, the enamel covering of the tooth becomes very thin before ending on the surface of the tooth root.

Tooth sensitivity can have several possible causes and can have serious implications, so careful evaluation is essential.

Patients who have recession resulting from gum disease often experience dentin sensitivity. This recession can be caused by the natural location of the tooth, vigorous brushing, the use of smokeless tobacco, or other types of trauma. Brushing too hard and vigorously with overly abrasive toothpaste and a brush with stiff bristles can further wear a shallow groove into the side of the tooth. Toothbrush abrasion exposes the ultra-sensitive dentin and causes the tooth to become sensitive.

Exposure to Acids

Teeth can also become temporarily sensitive in patients who expose their teeth to materials that are extremely acidic. Foods, such as a sour apple, can cause the teeth to become sensitive. This becomes more of a problem if taken to an extreme—for example, patients who suck on a lemon every day. This can cause the enamel to dissolve and expose the underlying dentin. When this happens, the sensitivity becomes more permanent and the tooth may need to be restored. This situation can also occur in patients who, for various reasons, vomit frequently. The acidic stomach contents can eventually dissolve the enamel from the teeth.

Poor Oral Hygiene

Patients should also be aware that simply failing to brush their teeth can contribute to tooth sensitivity. When patients allow dental plaque—the gummy, clear, bacteria-laden film that forms on teeth that are not brushed—to accumulate, the acidic nature of the plaque can cause the teeth to become sensitive. This is nature's way of reminding patients that it is time to pick up their brush and floss and start using them again.

Dental Procedures

Dental procedures are also a common cause of tooth sensitivity. Some tooth-whitening bleaches, which can be either acidic or alkaline, often cause tooth sensitivity for a day or two afterward. Also, the scaling and polishing that is performed during a routine teeth cleaning can cause temporary tooth sensitivity. A new filling, dental crown, or other restoration is typically sensitive for several days or weeks afterward. This side effect generally subsides after the dental pulp produces additional dentin internally. This healing process acts to distance the restorative material from the dental pulp.

Chipped and Cracked Teeth

Another common source of tooth sensitivity is a chipped or cracked tooth, which can expose the underlying dentin. The sensitivity may eventually clear on its own, although the tooth may need to be restored. If the crack extends deep into the tooth, the sensitivity may worsen and become what is termed irreversible pulpitis. If this happens, a root canal, meaning the complete removal of the dental pulp, may be required.

Close up of teethExcessive Biting Forces

Patients who grind their teeth are also likely candidates for tooth sensitivity. This unconscious habit can wear down the enamel and expose the dentin, but heavy biting forces can also cause sensitivity by a mechanism known as abfraction. Heavy chewing forces can torque or bend the tooth slightly, causing grooves to form in the tooth near the gum line. Abfraction lesions are virtually impossible to distinguish from those caused by toothbrush abrasion, and both are usually in play at the same time. The symptoms and treatment of the two concerns are identical.

How to Eliminate Tooth Sensitivity

As is usually the case, the treatment depends on the cause. Many forms of tooth sensitivity resolve in a matter of time, without any professional intervention. For example, sensitivity from restorative procedures or cosmetic treatment usually subsides within days, or weeks at the most. If not, root canal therapy may be required.

People who grind their teeth and are wearing off enamel might benefit from a bite guard to lessen the effects of their grinding habit. Those suffering from loss of enamel due to acid exposure may need the affected teeth restored using bonded composite resin or perhaps even crowns.

Desensitizing Toothpaste

Patients with persistently sensitive teeth should look in their local drugstore for one of the many desensitizing toothpastes currently on the market. These contain an active ingredient that works to desensitize the tooth either by numbing the exposed nerve endings or occluding the dentinal tubules which house them. Though it will not make a difference overnight, the active ingredient in this specialized paste will cause the sensitivity to eventually subside. If it does, the patient should continue to use this toothpaste at least part-time, indefinitely. If it is ineffective, they should try another brand with a different active ingredient.

Professional Help

If the sensitivity persists, it is time to consult a dentist. There are a variety of materials and techniques dental professionals have at their disposal that can help control the sensitivity. As a last resort, the patient may require the placement of a varnish or a bonded composite resin in the groove of the tooth where the sensitivity originates.

Preventing Dentin Hypersensitivity

Prevention of dentin hypersensitivity is literally in patients' own hands. They should first review the proper techniques for cleaning their teeth with their dental hygienist. These might include using a soft-bristled toothbrush and one of the more nonabrasive gel toothpastes.

The brushing technique is also important. Patients should never use a back-and-forth sawing motion, but rather a circular, up-and-down, jiggling movement. Effective oral hygiene for complete plaque removal is vitally important, but this does not mean scrubbing the teeth until the gums bleed.

Patients should also be aware of their diet and avoid food and drinks that are acidic. If they do expose their teeth to acids, they should brush their teeth or at least rinse with water soon afterward. Sucking on sour fruits for long periods at a time and sipping all day on highly acidic and sugar-laden juices, sodas, and other soft drinks will dissolve the tooth enamel and encourage tooth decay.

Contact a Dentist to Learn More

Tooth sensitivity is not pleasant, but neither is it a reason to panic. Patients should first try to control it themselves, but if this does not work, they should not hesitate to ask their dentist for help. Schedule an appointment to learn more about how you can find relief. 

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