Why does a cracked tooth hurt?

Inside the tooth, under the white enamel and a hard layer called the dentin, is the inner soft tissue called the pulp. The pulp contains blood, vessels, nerves, and connective tissue.

When the outer hard tissues of the tooth are cracked, chewing can cause movement of the pieces, and the pulp can become irritated. When biting pressure is released, the crack can close quickly, resulting in a momentary, sharp pain. Irritation of the dental pulp can be repeated many times by chewing. The tooth will not only hurt when chewing but may also become sensitive to temperature extremes.

Extensive cracks can lead to infection of the pulp tissue, which can spread to the bone and gum tissue surrounding the tooth.

Types of Cracks

There are many different types of cracked teeth. The treatment and outcome for your tooth depends on the type, location, and severity of the crack.

Craze Lines
Craze lines are tiny cracks that affect only the outer enamel. These cracks are extremely common in adult teeth. Craze lines are very shallow, cause no pain, and are of no concern beyond appearances.

Fractured Cusp
When a cusp (the pointed part of the chewing surface) becomes weakened, a fracture sometimes results. The weakened cusp may break off by itself or may have to be removed by the dentist. When this happens, the pain will usually be relieves. A fractured cusp rarely damages the pulp, so root canal treatment is seldom needed.

Split Tooth
A split tooth is often the result of the long term progression of a cracked tooth. The split tooth is identified by a crack with distinct segments that can be separated. A split tooth can never be saved intact. The position and extent of the crack, however, will determine whether any portion of the tooth can be saved.

Vertical Root Fracture
Vertical root fractures are cracks that begin in the root of the tooth and extend toward the chewing surface. They often show minimal signs and symptoms and may therefore go unnoticed for some time. Vertical root fractures are often discovered when the surrounding bone and bone become infected.