When a tooth develops persistent, severe pain, it often signals an issue with the dental pulp, the soft tissue at its center. This pulp contains the nerves, blood vessels, and connective tissue that provide sensation. The need to “kill a nerve” means removing this infected or inflamed pulp tissue. This procedure is required when bacteria penetrate the hard outer layers of the tooth, usually through a deep cavity, crack, or trauma. If the tissue is not removed, the infection can spread through the root tip and form a painful abscess in the jawbone, so the procedure eliminates the source of inflammation while preserving the surrounding tooth structure.
Preparing for Nerve Removal
The process begins with a precise diagnosis, often involving a clinical examination, sensitivity tests, and X-rays to visualize the extent of the infection and the complex anatomy of the root system. Once treatment is confirmed, a local anesthetic is administered to the area surrounding the affected tooth, ensuring the patient feels no pain throughout the procedure. This medication works by temporarily blocking the sodium channels in the nerve cells, which prevents pain signals from being transmitted to the brain.
After the area is numb, the dentist places a thin sheet of material called a rubber dam over the tooth. This step isolates the tooth from the rest of the mouth, creating a sterile operating field free from saliva and oral bacteria. The rubber dam also serves as a safety barrier, preventing the patient from accidentally swallowing or inhaling any instruments or disinfecting solutions. This isolation is necessary for achieving a successful, bacteria-free environment within the tooth.
Accessing and Removing the Infected Pulp
The procedure continues with the creation of a small access opening through the biting surface of back teeth or the tongue-side surface of front teeth. Using a high-speed drill and specialized burs, the dentist removes decay and penetrates the enamel and dentin layers to reach the pulp chamber. This opening is shaped to provide a straight-line path into the root canals, which is necessary for effective cleaning and shaping of the narrow passages.
Once the pulp chamber is accessed, the inflamed or necrotic pulp tissue is physically removed from the chamber and the root canals, a process called pulpectomy. This is accomplished using a series of specialized, fine instruments known as endodontic files and reamers. These instruments progressively clean, scrape, and shape the internal walls of the canals. Modern dentistry often employs flexible nickel-titanium (NiTi) rotary files, which are engine-driven and follow the natural curvature of the root canal more efficiently than traditional stainless-steel hand files.
The dentist often uses a dental operating microscope, which can magnify the view inside the tooth up to 25 times. This high level of magnification and illumination is helpful for locating tiny, sometimes hidden, accessory canals within the tooth. Thorough removal of all infected tissue is the primary goal, as any remaining organic debris can lead to treatment failure and a recurrence of the infection. By removing the nerve tissue and its associated blood supply, the source of the patient’s pain is eliminated, and the risk of the infection spreading is contained.
Cleaning and Sealing the Root Canal
After mechanical tissue removal and shaping, the internal system undergoes chemical disinfection, which is equally important for success. This involves flushing the canals repeatedly with powerful irrigating solutions, primarily sodium hypochlorite (NaOCl). NaOCl is a potent antimicrobial agent that also possesses the ability to dissolve any remaining organic tissue and pulp remnants that the instruments cannot reach.
The irrigant is delivered deep into the canals using a syringe, ensuring the solution reaches the microscopic recesses and lateral branches of the root system. Another solution, often containing ethylenediaminetetraacetic acid (EDTA), may be used to help remove the smear layer—a film of debris produced during instrumentation. Once the canals are thoroughly disinfected and dried, the space must be permanently sealed to prevent future bacterial re-entry.
The final sealing process is called obturation, which involves filling the entire prepared root canal system. The standard material used is gutta-percha, a biocompatible, rubber-like material derived from natural tree sap. Gutta-percha cones are placed into the canal along with a specialized adhesive root canal sealer. The sealer fills the minute gaps and irregularities between the gutta-percha and the canal walls, creating a fluid-tight, three-dimensional seal from the crown to the root tip.
Restoring the Tooth Structure
With the internal infection resolved and the canal system sealed, the tooth’s outer structure must be restored and protected. A tooth requiring this procedure has already experienced significant structural compromise from the original decay or trauma. Further tooth material is removed to create the access opening, which structurally weakens the remaining shell.
Although dentin does not become significantly more brittle after pulp removal, the extensive loss of structure increases the tooth’s susceptibility to fracturing under chewing forces. Therefore, the final step usually involves placing a dental crown, which acts as a protective cap. The crown completely encases the entire visible portion of the tooth, distributing biting forces evenly and preventing cracks or fractures that could lead to tooth loss.
For molars and premolars, which bear the brunt of chewing pressure, a full-coverage crown is almost always recommended to ensure the tooth’s long-term survival. A front tooth with minimal structural loss might only require a strong, bonded filling. The permanent restoration is necessary to seal the access opening from the oral environment and provide the structural reinforcement needed for the tooth to function reliably for many years.