Tooth sensitivity: Causes and remedies

For people with tooth sensitivity, eating or drinking certain substances or those at certain temperatures causes discomfort or pain in their teeth. At least 40 million adults suffer from sensitive teeth in the United States, according to the Academy of General Dentistry. 

The pain is often sharp and sudden, but it is temporary. Tooth pain occurs when stimuli, such as hot and cold, reach a tooth's exposed nerve endings, according to the Cleveland Clinic. Fortunately, sensitive teeth can be treated, and the condition can improve. 

Causes of tooth sensitivity

There are no at-risk groups for tooth sensitivity. It can happen to anyone, according to Dr. Margaret Culotta-Norton, a dentist in Washington, D.C. and former president of the D.C. Dental Society.

"The most common symptom … is a sudden, sharp flash of pain when teeth are exposed to air, cold, sweet, acidic or hot foods," Culotta-Norton told Live Science. Some people may also experience tooth sensitivity from brushing or flossing their teeth.

Tooth sensitivity generally results from a layer of the tooth called dentin being exposed. The outside of each tooth is normally covered by a hard outer layer, called enamel or cementum, which protects that dentin — the softer, inner layer of the tooth. Enamel protects the crown, the part of the tooth that's visible above the gum. Cementum covers the dentin surrounding the root, the pointy part of the tooth that extends into the jaw bone, according to the American Dental Association. The gum also protects the root. If the enamel or cementum gets worn down or if the gum line has receded, then the dentin becomes exposed. "Cavities, cracked teeth, gum recession, enamel and root erosion all cause dentin to be exposed," Culotta-Norton said. "Dentin is connected to the nerve that triggers pain in sensitive teeth."

Dentin contains thousands of microscopic tubules, or channels, leading to the tooth's pulp, according to the Academy of General Dentistry. When exposed, these dentinal tubules allow heat, cold or acidic substances to reach the nerves inside the tooth, causing pain, according to the Cleveland Clinic. Pain is the only type of response that the nerves inside teeth have, Live Science previously reported. 

According to the Cleveland Clinic, some factors that contribute to sensitive teeth may include:

• Brushing too hard or using a hard-bristled toothbrush. This can wear down enamel, causing dentin to become exposed, or encourage gum recession.
• Gum recession. This often happens in people suffering from gum disease, including gingivitis. Gum recession exposes the dentin.
• Cracked teeth. Cracks can become filled with bacteria from plaque and cause inflammation in the pulp of the tooth. In more severe cases, it may lead to abscess and infection.
• Teeth grinding or clenching. This can wear down enamel.
• Plaque buildup.
• Long-term use of mouthwash. Some over-the-counter mouthwashes contain acids. If dentin is exposed, the acids can worsen existing tooth sensitivity and further damage the dentin layer. There are neutral fluoride mouthwashes available that might be a better option.
• Acidic foods. These can encourage enamel reduction.
• Dental procedures. Teeth may be sensitive after professional cleaning, root planing, crown replacement and other procedures. Usually the pain will disappear in four to six weeks.

Tooth sensitivity after a filing

Some people may experience tooth sensitivity after having a cavity filled, according to the Cleveland Clinic. Fortunately, tooth sensitivity following a filling should improve on its own within a few weeks. 

Sometimes teeth become sensitive when biting down after a filling. This can happen because the filling is too high and prevents your bottom and top teeth from fitting together properly. In this case, the dentist may need to reshape the filling. If you get a metal filling and it touches another type of metal, such as a gold or silver crown, when you bite down, the contact between the two different metals may cause some pain initially, but it should subside.

If you have toothache-like pain after a filling and it doesn't go away, the interior of the tooth, called the pulp, may be severely inflamed. This inflammation is called pulpitis, according to the Merck Manual. If the inflammation is so severe that the pulp becomes necrotic, or starts to die, it may require a root canal, in which the damaged tissue is replaced with a filling of a rubber-like substance called gutta-percha or another material, according to the Academy of General Dentistry.   

Tooth sensitivity after whitening treatments

Teeth-whitening treatments — done either in a dentist's office or using an over-the-counter product — contain harsh chemicals (hydrogen peroxide or carbamide peroxide) that remove stains, but they can also cause tooth sensitivity. When peroxide penetrates the enamel, it can temporarily irritate the tooth. Overuse of whiteners can also damage the enamel and gums, according to the American Dental Association.   

Several studies have investigated ways to lessen pain after dentist-performed teeth-whitening treatments. A 2018 study in the journal Operative Dentistry found that patients taking acetaminophen/codeine before treatment did not reduce pain. A 2016 study in the journal Lasers in Medical Science found that irradiating teeth with low-level lasers after a whitening treatment reduced pain levels significantly compared with patients who did not receive any laser treatment. And a 2018 study published in The Journal of the American Dental Association found that applying a desensitizing gel before whitening significantly reduced tooth sensitivity after treatment.

Another potential solution is changing the formula of whitening products. A 2017 study published in the journal Clinical Oral Investigations found that reducing the acidity in bleaching gels resulted in significantly less pain with the same whitening results. 

Tooth sensitivity treatment

"Sensitive teeth never completely disappear," Culotta-Norton said. "Symptoms may be less or even seem to go away for a while, but unless the reasons why a person's teeth become sensitive are completely eliminated the sensitivity will come and go."

There are several types of treatment available, and each dentist has his or her favorites that they are most likely to recommend, according to Culotta-Norton. She stressed that there is no single treatment option that works for everyone. "Proper diagnosis of the reason for the sensitivity is essential in treating sensitivity. If the reason for the sensitivity is addressed, the treatment chosen will be more successful in decreasing pain. If the dentist just treats sensitivity without addressing the reason for it the problem will continue and get worse," she said. 

The following are some at-home treatments suggested by the Cleveland Clinic:

• Desensitizing toothpaste. There are several brands of toothpaste for sensitive teeth that are available. Your dentist may recommend one, or you may have to try different brands until you find the product that works for you. Be sure to use fluoridated toothpaste for sensitive teeth, not tartar-control toothpaste. Try spreading a thin layer of desensitizing toothpaste on the exposed tooth roots before bed.
• Use a soft-bristled toothbrush.
• Avoid highly acidic foods.
• Use a fluoridated mouthwash daily.
• Avoid teeth grinding. Consider getting a mouth guard.

The following are some dental procedures that may reduce tooth sensitivity, according to the American Dental Association:

• Bonding, crowns or inlays. These may fix a tooth flaw or decay that is causing sensitivity.
• Fluoride gel.
• Surgical gum graft. This will protect the root and reduce sensitivity if the gum tissue has eroded from the root.
• Root canal. This is a last-resort treatment for severe tooth sensitivity that has not been helped by other methods.

Fluoride treatment for sensitive teeth

A review article published in 2015 in the journal Caries Research suggests that fluoride alone can't prevent tooth erosion, which can lead to tooth sensitivity. The authors suggest that treatments combining fluoride with polyvalent metal ions and some polymers may offer more protection. The authors said that more studies were needed to determine the efficacy of these additives. 

In 2014, the FDA approved the use of silver diamine fluoride (SDF) to treat tooth sensitivity, according to the Association of State and Territorial Dental Directors (ASTDD), a national oral health nonprofit. The topical treatment has long been popular in Asia and Europe and used to prevent pain and caries. A short-term 2011 clinical trial in Peru published in the Journal of Dental Research found that participants with tooth sensitivity who underwent topical SDF applications experienced significantly reduced levels of pain. The application of SDF results in a harder tooth surface, helping to prevent further decay. It also protects exposed dentin from potentially painful stimuli by partially blocking the dentinal tubules, according to a University of California San Francisco protocol for using SDF to treat cavities, published in the Journal of the California Dental Association. 

Silver diamine fluoride treatments must be applied by a dental practitioner, according to the ASTDD. When applied over spots of demineralized (damaged) enamel or dentin, silver diamine fluoride results in a permanent black spot on the tooth. It does not stain healthy teeth, however. Silver diamine fluoride treatments arose out of the Japanese practice of tooth blackening, called ohaguro, in the 19th century, according to the journal Oral Science. People with silver allergies should not use this treatment. 

This article was updated on May 18, 2021 by Live Science contributor Ashley P. Taylor.