Why does a cracked tooth hurt?
To understand why a cracked tooth hurts, it helps to know something about the anatomy of the tooth. Inside the tooth, under the white enamel and a hard layer called the dentin, is the 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. Eventually, the pulp will become damaged to the point that it can no longer heal itself. The tooth will not only hurt when chewing but may also become sensitive to temperature extremes. In time, a cracked tooth may begin to hurt all by itself. Extensive cracks can lead to infection of the pulp tissue, which can spread to the bone and gum tissue surrounding the tooth.
What are the different types of cracks?
There are many different types of cracked teeth. The treatment and outcome for your tooth depend on the type, location, and severity of the crack.
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 appearance.
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 relieved. A fractured cusp rarely damages the pulp, so root canal treatment is seldom needed. The tooth will usually be restored by your dentist with a full crown.
This crack extends from the chewing surface of the tooth vertically towards the root. Sometimes the crack may extend below the gum line, and in severe instances, into the root. A cracked tooth is not completely separated into two distinct segments. Because of the position of the crack, damage to the pulp is common. Root canal treatment is frequently needed to treat the injured pulp. Your dentist will then restore your tooth with a full crown to bind and protect the cracked tooth.
Early diagnosis is important. Even with high magnification and special lighting, it is sometimes difficult to determine the extent of a crack. A cracked tooth that is not treated will progressively worsen, eventually resulting in the loss of the tooth. Early diagnosis and treatment are essential in saving these teeth.
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. In rare instances, endodontic treatment and a crown or other restoration by your dentist may be used to save a portion of the tooth.
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 gum become infected. Treatment usually involves extraction of the tooth. However, endodontic surgery is sometimes appropriate, as a portion of the tooth can be saved by removal of the fractured root.