Hagan Dentistry
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What causes tooth sensitivity?

December 6, 2017
Posted By: Dr. Andrew Hagan
Diagram of Tooth Anatomy

What causes tooth sensitivity?

Most of us experience tooth sensitivity at some point in our lives. Fortunately, for many of us, the sensitivity resolves all on its own. However, others experience prolonged, continuous tooth sensitivity.

Before I discuss common causes of sensitivity, here is a quick and basic tooth anatomy lesson. The white part of the tooth that is above the gum line is covered with a substance called enamel. Enamel acts as an insulator to the inside of the tooth. Meanwhile, the inner layer of the tooth is called dentin. There are cells in the dentin that connect directly to the nerve on the inside of the tooth. These cells are what contributes to tooth sensitivity.


Most people are aware that cavities can cause tooth sensitivity. Cavities occur when acid produced by sugar-consuming bacteria softens and makes holes in the teeth. Small cavities that are still entirely in the enamel are not typically sensitive. However, once the cavity enters the dentin layer of the tooth, they tend to provoke sensitivity. The cavity breaks down the barrier that the enamel provides and allows foods and drinks to come in contact with the cells inside the dentin. This, in turn, causes a painful sensation inside the nerve of the tooth. If the cavity gets large enough to enter or come close to the nerve space (pulp) of the tooth, it will usually move beyond sensitivity to a pain sensation and often an infected tooth.

Sensitivity caused by sweets is a common indicator of a possible cavity. However, sensitivity to hot or cold foods and beverages can also indicate a cavity. Tooth sensitivity tends to be localized to one or a few teeth. However, in people with multiple cavities, the sensitivity can be more widespread. Typically, sensitivity caused by cavities will not get better unless the cavity is treated by a dentist.

Gum Recession

The other most common cause of sensitivity that we see is sensitivity caused by gum recession. Gum recession essentially means that part of the root of the tooth is no longer covered by the gums and is exposed to the rest of the mouth. Gum recession can be caused by many factors, including gum disease, overaggressive brushing, and teeth out of alignment.

The root part of the tooth is covered by a very thin, soft layer called cementum. After the gums recede, the cementum is often eroded by brushing or by foods in the diet. This then leaves the underlying dentin layer exposed to the rest of the mouth. Again, the dentin layer has cells that are connected to the nerve of the tooth so it is easy for food and drinks to cause painful sensations.

Sensitivity caused by gum recession tends to be more generalized over multiple teeth. It is frequently associated with a sensitivity to cold foods and drinks. Often people with gum recession-associated sensitivity will feel the sensitivity along the gum line on the outside/ cheek side of the teeth.

Sensitivity caused by gum recession can frequently be lessened by using toothpastes such as Sensodyne that contain potassium nitrate. Potassium nitrate basically helps seal the pores in the dentin so that food can’t reach the cells inside the dentin as easily. It often takes a couple of weeks of using potassium nitrate to notice improvement in sensitivity. Unfortunately, the sensitivity will often return after discontinuing use of the toothpaste. Prescription strength fluoride toothpastes also work well, and we have several materials in our office that can be helpful as well.

Other Causes

There are several other things that can cause tooth sensitivity. Among them are clenching and/or grinding your teeth, sinus infections, overzealous tooth whitening, and injury/trauma to the teeth. It is always a good idea to ask a dentist if you are having sensitivity that lasts longer than a couple of weeks or sensitivity that seems to be getting worse.

We welcome you to call Hagan Dentistry if you would like to discuss your sensitive teeth and the options we have to help them feel better. Find our information here

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