Not all crowns require a root canal, as these two dental procedures serve fundamentally different purposes. A dental crown is a custom-made cap placed over the visible portion of a tooth, restoring its structure, shape, and function. A root canal, technically known as endodontic therapy, involves removing the infected or inflamed soft tissue, called the pulp, from the tooth’s interior. The need for a root canal is determined by the health of the internal nerve, while a crown addresses external structural damage.
The Primary Function of a Dental Crown
A dental crown’s main purpose is to restore and protect a tooth that has been structurally compromised but maintains a healthy internal nerve. The tooth’s pulp, which contains the nerves and blood vessels, remains viable and does not require treatment. Crowns are often used for teeth with large, failing fillings where the remaining natural tooth structure is insufficient to support a new restoration.
The protective cap prevents the tooth from fracturing under chewing forces. Teeth that are severely worn down from grinding or have non-pulp-exposing fractures also benefit from a crown. This restoration shields the weakened outer structure, allowing the healthy pulp tissue inside to remain undisturbed.
Crowns may also be placed for purely aesthetic reasons, such as covering a discolored or misshapen tooth. In these cases, the crown acts as a protective and cosmetic shield. The goal is to provide a durable, full-coverage restoration that extends the life of the tooth.
When a Root Canal Is Necessary for Treatment
A root canal is required when the pulp tissue is irreversibly inflamed or infected, known as irreversible pulpitis or pulpal necrosis. This internal damage occurs when deep decay penetrates the enamel and dentin layers into the pulp chamber. Once bacteria reach the pulp, they cause infection and inflammation that cannot heal.
Severe dental trauma, such as a deep fracture or forceful blow, can also cause nerve death or expose the pulp, necessitating a root canal. If the infected pulp is not removed, the infection can spread into the jawbone, forming a painful dental abscess. The endodontic procedure cleans, disinfects, and seals the internal root canal system to eliminate the infection and save the tooth.
Following a root canal, the tooth often becomes more brittle because it loses the internal blood supply that keeps it hydrated. Consequently, a crown is typically placed over the treated tooth, especially molars or premolars, to protect the weakened structure from fracturing. The root canal treats the internal disease, and the crown provides external structural reinforcement.
Addressing Pulp Irritation After Crown Preparation
Even if the pulp is healthy initially, preparing a tooth for a crown can cause irritation. Crown preparation involves using high-speed drills to remove a significant amount of structure, shaping the tooth to accommodate the cap. The vibrations and heat generated by this drilling can traumatize the pulp tissue.
This trauma can cause temporary inflammation called reversible pulpitis, which usually causes short-term sensitivity to temperature that resolves within a few days or weeks. If the preparation is aggressive or the tooth had deep, pre-existing decay, the pulp may suffer irreversible damage. This condition, irreversible pulpitis, will not resolve on its own.
Signs that a crowned tooth requires endodontic treatment include lingering pain after exposure to hot or cold temperatures, spontaneous or throbbing pain, or tenderness when biting down. These symptoms indicate the pulp has died or is dying, allowing bacteria to colonize the root canal system. In these delayed cases, the crown is accessed through a small opening to perform the root canal, saving the tooth without removing the existing restoration.