Hot and cold foods commonly trigger tooth sensitivity, but if you have pain along with other symptoms – such as loose teeth, swollen gums or pain while chewing – you may have extremely sensitive teeth caused by another dental issue. Your dentist can determine the problem and appropriate treatment, but it's best to know what behaviour may be contributing to this oral issue.
The crowns, or the part of your teeth above the gumline, are covered with a layer of protective enamel. On the other hand, the roots below your gumline are protected with a material called cementum. Underneath the enamel and cementum lies dentin, which is less dense than the protective coverings. Dentin contains microscopic canals called dentin tubules, and when enamel or cementum wears away or becomes damaged, this exposes the dentin. When your gums recede and expose the dentin, the tubules allow fluid to flow into them and are affected by heat and cold causing the nerves in the tooth to have sensitivity and pain, according to the American Dental Association (ADA) Mouth Healthy website.
Why would the enamel or cementum wear away? You may be consuming too many acidic foods and beverages, brushing your teeth too aggressively, or overusing certain tooth-whitening products. However, with extremely sensitive teeth, or hypersensitivity, the more likely causes are those that expose more dentin: tooth cavities, worn fillings or fractured teeth.
As extremely sensitive teeth are frequently caused by a more complex dental problem, it's important to see a dentist and have the issue treated directly. This may involve installing a crown, inlay or bonding, depending on the problem. If you have gum problems that have progressed to a chronic or advanced stage, you'll need to treat this as well.
If you have lost gum tissue from the root, your dentist may recommend a surgical gum graft to cover and protect the roots. If you have persistent and severe sensitivity, an x-ray should be taken to determine if a root canal could be the issue, which, as the American Association of Endodontists (AAE) explains, removes the nerve so it's no longer there to cause you pain.
You may also find some relief from a desensitising toothpaste containing ingredients that help protect the tooth surface. Your dentist might also recommend a fluoride gel treatment, which strengthens your current tooth enamel, decreasing the sensations sent to the nerve.