A root canal treatment, or endodontic therapy, saves a tooth by removing infected or inflamed pulp tissue from the inside. A dental crown is a protective cap placed over a damaged tooth to restore its shape, size, strength, and appearance. When a crowned tooth develops a new infection, a root canal may be necessary. In most cases, a root canal can be successfully performed directly through the existing crown, allowing the dentist to treat the tooth’s internal structure without removing the external restoration. This preserves the integrity of the crown while resolving the internal issue.
Why Dentists Opt to Keep the Crown
The decision to perform the procedure through the existing crown is primarily driven by preserving the existing restoration. Removing a cemented crown is a complex process that frequently results in irreparable damage, necessitating a costly and time-consuming replacement. Maintaining the original crown saves the patient the expense of a new restoration and avoids the need for a temporary crown period.
Keeping the crown also preserves the tooth’s established margin seal, the boundary where the crown meets the natural tooth structure. If this seal is intact, disturbing it by removing the crown introduces a risk of leakage and potential secondary decay. When the crown is structurally sound and well-fitting, accessing the tooth through it is the most conservative approach.
The Process of Accessing the Tooth
The procedure begins with the dentist or specialist using X-rays to precisely map the internal tooth anatomy, including the location of the pulp chamber and the root canals. This mapping is important because the crown obscures the natural tooth surface. A local anesthetic is administered, and a small access opening is created by drilling directly through the crown material. Specialized high-speed burs are used to cut through materials like porcelain, ceramic, or metal without causing structural damage to the surrounding restoration.
The opening is carefully positioned to allow straight-line access to the pulp chamber floor, the gateway to the root canals. Once located, the infected pulp tissue is removed using fine instruments, and the canals are meticulously cleaned, shaped, and disinfected. This cleaning requires precision, relying on pre-operative imaging and tactile feel to navigate the hidden canals. After cleaning, the canals are filled with gutta-percha, an inert, rubber-like material that seals the root system.
When the Crown Must Be Removed
Despite the advantages of working through the crown, removal is mandatory in specific situations. The most common reason is the presence of decay or bacterial infiltration underneath the crown, often visible on X-rays. If the crown has poor margins, bacteria can leak in and cause decay on the underlying tooth structure, which must be fully cleaned and sealed.
A damaged or fractured crown also necessitates removal, as a compromised restoration cannot provide long-term protection for the treated tooth. If the tooth’s internal anatomy is highly complex or calcified, the endodontist may require a direct, unobstructed view of the pulp chamber floor to locate all the fine canals. In these instances, achieving a complete and successful root canal outweighs the effort of replacing the crown.
Sealing and Restoring the Access Point
Once the root canal is completed and the root system is sealed, the final step involves permanently restoring the access opening. The dentist carefully cleans the internal cavity to remove any debris that could interfere with the bonding process, ensuring a strong and durable final restoration.
A permanent filling material, often a tooth-colored composite resin, is placed into the access hole and cured. The restorative material must create a tight, impermeable seal to prevent future bacterial contamination from reaching the treated root canal system. The composite resin color is matched closely to the existing crown, ensuring the repaired area is aesthetically discreet.