Healthy teeth are usually not sensitive to temperature or the pressure of chewing. Teeth are considered sensitive if pain is experienced due to temperature, pressure, acidic foods or in the absence of chewing. Occasional aches or sensitivity is normal, after all teeth are connected to the central nervous system and some aches and pains are experienced throughout the body. Ongoing pain or sensitivity means something is wrong.
How it works
Sensitivity can be felt as an ‘all over’ sensation (generalized) or it can be felt in one specific area (localized). Since the covering of the tooth is enamel and enamel has no nerve connection, sensitivity or pain comes from the layer beneath the enamel known as dentin. Dentin is made up of tiny tubes that travel from under the enamel to the nerve chamber (see Parts of the Tooth). Whether it is hot, cold, acid, or pressure, the soft tissue moves toward the nerve, causing irritation, a signal is sent to the brain and the outcome is sensitivity/pain. Tooth decay allows acid, toxins and bacteria to travel through the dentinal tubules to the nerve. Sensitivity or pain is often caused by some type of break or opening in the enamel, exposing the dentin tubules and communicating with nerve chamber.
Causes of dentin exposure
Dentin exposure comes from any one of a number of problems:
- Gum shrinkage exposing the neck of the tooth, where the root and crown of the tooth come together. In some people, this area is not completely fused, exposing the underlying dentin and creating sensitivity.
- Cracks in the tooth exposing dentin. These cracks come from habits of chewing on ice, pens, pencils, or jaw breakers; the chronic grinding your teeth; trauma to the mouth; and/or the weakening of your tooth due to overly large fillings (see Cracked Tooth Syndrome).
- Enamel wear from acid erosion or clenching and grinding, exposing dentin.
- Notches at the neck of the tooth are called abfraction lesions. Abfraction lesions are caused by excessive force to your tooth. Teeth normally flex when loaded with pressure; forces that flex the tooth more than normal (clenching and grinding) cause the enamel to chip away at the gumline where enamel is thinner creating notches, leading to sensitivity.
- Excessive brushing (toothbrush abrasion) with a medium or hard toothbrush causing gum tissue and the softer root structure (see Parts of the Tooth: Cementum) to be eroded away.
- Excessive stress due to a filling or a crown that sits too high
- A blow to your tooth causing a fracture in the enamel (see Cracked Tooth Syndrome).
- A broken, fractured, or cracked filling
- A tooth that is dying from deep decay or a past history of deep decay (see Root Canal Treatment (Endodontics)
- Excessive amounts of bacterial plaque accumulated at the gum line in an area where the crown and root are not completely fused.
- Tooth decay, especially as the decay becomes larger
- Tooth whitening, especially long-term use of a whitening product
- Sensitivity following a dental procedure, which is usually temporary
- Excessive clenching and grinding, which pushes the tooth hard into the boney socket and irritates the bone, ligament, nerve, artery and vein (see Parts of the Tooth). This generally causes ‘all over’ sensitivity, especially to cold.
What can be done for tooth sensitivity?
Depending on the cause, tooth sensitivity can become a distressing, aggravating ailment. There are several possible remedies:
- There are toothpastes that reduce sensitivity due to gum shrinkage and enamel wear. These toothpastes require repeated use to reduce and/or eliminate sensitivity.
- Grinding of selected biting surfaces to remove high spots on teeth, crowns and fillings to improve the contact of or alignment between opposing teeth
- Wear a night guard while sleeping
- Use a soft toothbrush, never a medium or a hard brush. Thoroughly brush and floss your teeth daily to remove bacterial plaque; never “scrub” your teeth
- Placing a crown covering the cracked tooth enamel
- Professional desensitizers placed at the gum line and professional-strength fluoride treatments that help block the openings to the exposed dentin
- Limiting the use of whitening products and/or using a desensitizer in the whitening tray between whitening sessions
- Keeping regular Dental Exam appointments to ensure there is no active decay