A root canal is a procedure that removes infected or dying tissue from inside a tooth, then seals the interior space to save the tooth from extraction. It’s one of the most common dental procedures performed, with a long-term survival rate of about 85% after 10 years, and it’s far less painful than its reputation suggests.
Why a Root Canal Becomes Necessary
Every tooth has a soft core of living tissue called the pulp, which contains nerves and blood vessels. When bacteria reach the pulp through deep decay, a crack, or trauma, the tissue becomes inflamed. If the inflammation progresses far enough, the pulp can’t heal on its own, and the tooth will eventually die if left untreated.
There are a few distinct stages that lead to a root canal. In the earliest stage, the pulp is inflamed but still alive. You might feel sharp pain from hot or cold foods that lingers for 30 seconds or longer after the stimulus is gone, spontaneous pain that hits without any trigger, or pain that gets worse when you lie down or bend over. Over-the-counter pain relievers typically don’t help much. In some cases, the inflammation is advanced but produces no symptoms at all, often discovered only when a dentist finds deep decay on an X-ray.
If untreated, the pulp dies entirely. At that point the tooth may actually stop hurting for a while, since the nerve is no longer functioning. But the infection doesn’t disappear. It spreads to the bone around the root tip, causing pain when you bite down or press on the gum near the tooth. An abscess can form, bringing swelling, fever, and a bitter taste in your mouth. A root canal addresses all of these stages by removing the source of infection while preserving the outer structure of the tooth.
What Happens During the Procedure
The entire process typically takes one to two appointments, each lasting 60 to 90 minutes depending on the tooth. Front teeth with a single root canal are faster; molars with three or four canals take longer.
The first step is numbing the tooth. Your dentist or endodontist (a specialist in root canals) uses a local anesthetic injection near the tooth. For lower molars, which are notoriously harder to numb when inflamed, additional techniques are available. These include injections directly into the bone surrounding the tooth, which achieve success rates around 90%, or injections into the ligament around the root. Nitrous oxide (laughing gas) can also be added. The goal is complete numbness before any work begins, and your provider will test the tooth before proceeding.
Once the tooth is numb, a small rubber sheet called a dental dam is placed around the tooth to isolate it and keep saliva out. Then the dentist drills an opening through the top of the tooth to access the pulp chamber. This is called the access cavity.
From there, the core of the procedure is cleaning and shaping. Using a series of tiny, flexible files, the dentist works through each canal inside the root, removing the pulp tissue and widening the canal walls. Modern practices use motorized rotary files made of a nickel-titanium alloy that flex with the natural curves of the root. Throughout this process, the canals are repeatedly flushed with a disinfecting solution. The irrigating liquid is pumped in and out with a fine needle, agitated up and down to reach every surface. Between each file, the canal is flushed again. This constant cycle of filing and irrigating is what eliminates bacteria from the complex interior anatomy of the tooth.
To measure the exact length of each canal, dentists use electronic apex locators: small devices that clip to the file and detect when the tip reaches the end of the root. These tools are more precise than X-rays alone, accurate to within fractions of a millimeter in most cases. X-rays are still taken to confirm, but the electronic measurement guides the process in real time.
How the Tooth Is Sealed
Once the canals are cleaned, shaped, and dried, they need to be filled to prevent bacteria from re-entering. The standard filling material is gutta-percha, a rubber-like substance that comes in tapered cones matched to the shape of the prepared canal. A thin layer of sealer cement is applied to bond the gutta-percha to the canal walls and fill microscopic gaps.
Newer bioceramic sealers have improved this step significantly. These are calcium-based cements that actually absorb moisture to set, making them well suited for the wet environment inside a tooth. As they harden, they expand slightly (less than 0.2% of their volume), creating a tighter seal. They also form a mineral layer that bonds to the surrounding tooth structure and has natural antibacterial properties. The gutta-percha cone serves as a solid core that pushes the sealer into irregular spaces and, importantly, can be removed if the tooth ever needs retreatment.
Why You Need a Crown Afterward
A root canal removes the living tissue that once supplied moisture and nutrients to the tooth, leaving it more brittle over time. The access hole drilled through the top also removes a meaningful amount of tooth structure. For these reasons, most root-canal-treated teeth, especially premolars and molars that bear heavy chewing forces, need a crown to prevent fracture.
After the root canal, the access opening is sealed with a temporary or permanent filling material to create a moisture barrier over the gutta-percha. If the tooth has lost significant structure from decay, a buildup of composite material restores enough shape for a crown to grip onto. The crown is then placed over the entire tooth, distributing biting forces evenly and protecting the weakened structure underneath. Front teeth with minimal decay sometimes survive with just a filling, but your dentist will evaluate the remaining tooth structure before making that call.
Recovery and Pain Expectations
For most people, post-procedure soreness is mild and fades within two to three days. The tooth and surrounding gum may feel tender to pressure, which is normal. Standard over-the-counter pain relievers like ibuprofen or acetaminophen handle it well for most patients.
Signs that something needs attention include intense throbbing pain, significant swelling, fever, or a bitter taste in your mouth. If any of these persist beyond three days, or if pain gets worse instead of better, contact your dentist or endodontist for evaluation. These symptoms can indicate a persistent infection or a complication that needs follow-up treatment.
Cost by Tooth Type
The cost of a root canal depends largely on which tooth is involved, because molars have more canals and take longer to treat.
- Front teeth: approximately $500 to $1,100 for the root canal alone, or $800 to $1,500 including a crown.
- Molars: approximately $1,000 to $1,600 for the root canal, or $1,300 to $2,000 or more with a crown.
Dental insurance typically covers a portion of both the root canal and the crown, though coverage varies widely by plan. Some offices also offer payment plans. The total cost is generally less than extracting the tooth and replacing it with an implant, which can run $3,000 to $5,000 or more.
Long-Term Success
A 10-year retrospective study found that root-canal-treated teeth had an 85% survival rate, even when the procedures were performed by dental students rather than specialists. When performed by experienced endodontists with modern tools and materials, success rates are generally higher. The most common reason a root canal fails over time is reinfection, often caused by a crack in the tooth, a delayed crown placement, or an unusually complex canal anatomy that wasn’t fully cleaned during the original procedure. Retreatment is possible in many of these cases, preserving the tooth for additional years.