Teeth can become sensitive for a variety of reasons. One common cause is when the protective layers of your teeth are worn down or cracked. Enamel protects the outer layer of a tooth, and cementum protects the outer layer of a tooth's root. When enamel or cementum wears away or becomes damaged, it exposes the soft underlying layer called dentin. Dentin is affected by heat, cold, and pressure, which causes the nerves in the tooth to have sensitivity and pain. This can make drinking hot or cold beverages difficult. Also, applying pressure to the tooth may result in hypersensitivity. Teeth can become sensitive for several other reasons as well. For example, an infection or inflammation of the root can cause pain or sensitivity, especially when biting. If your gums are receding, exposing a tooth's root, or if an infection is below the gum's surface, you may experience sensitivity, and sometimes following oral surgery, temporary sensitivity may occur. It is important to let your doctor know that you are having sensitivity so they can determine the cause. The longer you go without intervention may require increasingly extensive and costly treatment to alleviate the pain. There are preventative and corrective treatment options available, but will vary based on the underlying cause and the extent of the tooth damage. If you have sensitive teeth, working closely with your doctor is critical.