Why Root Canals Are Needed
A root canal becomes necessary when the pulp inside your tooth is infected or irreversibly inflamed. The pulp is the soft tissue at the center of each tooth that contains nerves, blood vessels, and connective tissue. It extends from the crown of the tooth down through narrow channels (root canals) to the tip of each root.
Common causes of pulp damage include deep decay that reaches the pulp chamber, a crack or fracture in the tooth, repeated dental procedures on the same tooth, and trauma (such as a blow to the face). Once the pulp is infected or dying, it does not heal on its own. Without treatment, the infection can spread to the bone around the root tip, forming an abscess.
Before the Procedure Starts
Understanding what happens before the actual root canal begins can help you feel more prepared on the day of your appointment.
Diagnosis and Imaging
Your dentist or endodontist will take X-rays of the tooth, and in many cases a cone-beam computed tomography (CBCT) scan, to see the root structure in three dimensions. This reveals the number and shape of root canals, the extent of infection, and any unusual anatomy. The endodontist may also perform cold tests or electric pulp testing on the tooth to confirm which tooth is the source of your symptoms.
Anesthesia
Before any work begins, the area around the tooth is numbed with local anesthesia. The injection itself may cause a brief pinch, but within a few minutes the tooth and surrounding tissue will be fully numb. If the tooth is severely infected, it can sometimes be harder to numb completely. In those cases, the endodontist has additional techniques to ensure you are comfortable, including supplemental injections directly into the ligament around the tooth.
You will be awake during the entire procedure. Sedation options such as nitrous oxide (laughing gas) or oral sedation may be available if you have significant dental anxiety. Discuss this with your endodontist before the appointment.
The Root Canal Procedure Step by Step
Once you are numb, the procedure follows a consistent sequence. Each step is designed to remove the infection, clean the canal system thoroughly, and seal it to prevent bacteria from re-entering.
Step 1: Rubber Dam Placement
A small sheet of rubber (called a rubber dam or dental dam) is placed over the tooth, isolating it from the rest of your mouth. The dam serves two purposes: it keeps saliva and bacteria from contaminating the tooth during the procedure, and it prevents the small instruments and irrigation solutions from reaching the back of your throat. The dam may feel slightly unusual, but it is not painful.
Step 2: Access Opening
The endodontist uses a small drill to create an opening in the top (crown) of the tooth. For a back tooth, this opening is on the biting surface. For a front tooth, it is on the back side. This access hole provides a pathway to the pulp chamber and root canals inside. You will hear the drill and feel vibration and pressure, but the anesthesia prevents pain.
Step 3: Removing the Infected Pulp
Using very small, flexible instruments called files, the endodontist removes the infected or dead pulp tissue from the pulp chamber and each root canal. The endodontist works under a surgical microscope that magnifies the inside of the tooth, allowing precise identification of every canal. Some teeth have canals that are extremely narrow, curved, or hidden, and the microscope makes them visible.
Step 4: Cleaning and Shaping the Canals
After the pulp is removed, the canals are cleaned and shaped using a combination of hand files and rotary (motorized) instruments. The endodontist flushes the canals repeatedly with an antimicrobial irrigating solution, typically sodium hypochlorite, to dissolve remaining tissue and kill bacteria. This step is critical because bacteria in the canal walls can cause reinfection if not thoroughly eliminated.
Shaping the canals creates a smooth, tapered channel that allows the filling material to seal tightly. An electronic apex locator measures the length of each canal to ensure the instruments reach the tip of the root without going beyond it.
Step 5: Filling and Sealing the Canals
Once the canals are clean and shaped, they are dried and filled with a rubber-like material called gutta-percha. The gutta-percha is heated and compressed into the canals, along with a sealer cement, to create a tight seal from the tip of the root to the access opening. This seal prevents bacteria from re-entering the canal system.
The access opening in the crown of the tooth is then sealed with a temporary or permanent filling material.
What You Feel During a Root Canal
The most common concern patients have is whether the procedure will hurt. With modern anesthesia techniques, most patients feel pressure but not pain during a root canal. The pressure comes from the instruments working inside the tooth and from the endodontist holding the tooth steady.
You will hear sounds from the drill, the suction, and the instruments, which can be unsettling if you are not expecting them. Some patients find it helpful to bring headphones and listen to music or a podcast during the procedure.
If you do feel sharp pain at any point, tell your endodontist immediately. Additional anesthesia can be administered. No ethical practitioner will continue working on a tooth that is not adequately numb.
How Long Does a Root Canal Take?
The length of the procedure depends on which tooth is being treated and the complexity of the case.
Duration by Tooth Type
Front teeth (incisors and canines) have a single root canal and are the fastest to treat, typically taking 30 to 45 minutes. Premolars usually have 1 to 2 canals and take 45 to 60 minutes. Molars are the most complex, with 3 to 4 canals (and sometimes more), and typically take 60 to 90 minutes.
One Visit vs. Two Visits
Most root canals are completed in a single visit. However, your endodontist may recommend splitting the treatment into two visits in certain situations: if the infection is severe and the canals need to be medicated between visits, if the tooth has complex anatomy that requires additional time, or if you are experiencing difficulty getting numb.
When treatment is split across two visits, a medicated paste is placed inside the canals and a temporary filling seals the tooth between appointments. The second visit, typically scheduled 1 to 3 weeks later, involves completing the cleaning and placing the permanent gutta-percha filling.
After the Root Canal
Once the root canal is finished, you can expect mild to moderate soreness around the tooth for a few days. This is normal and results from the manipulation of tissues at the tip of the root during the cleaning process. Over-the-counter anti-inflammatory medication such as ibuprofen is usually sufficient to manage any discomfort.
You can eat after the numbness wears off, but avoid chewing on the treated tooth until a permanent crown is placed. A root canal removes the blood supply to the tooth, which makes it more brittle over time. A crown protects the tooth from fracture. Your endodontist will refer you back to your general dentist or a prosthodontist for the crown, which is usually placed within 2 to 4 weeks.
Contact your dentist or endodontist if you experience severe pain that does not respond to medication, swelling that increases after the first 48 hours, or your bite feels significantly uneven.
Endodontist vs. General Dentist for Root Canals
General dentists perform root canals on a regular basis, and for straightforward cases they are often a good choice. An endodontist is a dentist who has completed 2 to 3 years of additional residency training focused entirely on root canal treatment and related procedures. Endodontists perform an average of 25 root canals per week compared to roughly 2 per week for a general dentist.
Consider seeing an endodontist if the tooth is a molar with complex canal anatomy, if this is a retreatment of a previously failed root canal, if you have been told the tooth may not be savable, if you have persistent pain that is difficult to diagnose, or if you have significant dental anxiety and want a provider who does this procedure all day every day. Learn more about endodontists on our [endodontics specialty page](/specialties/endodontics).
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