A root canal removes infected or dead tissue from inside a tooth, then seals the space to save the tooth from extraction. The entire process typically takes one or two appointments, each lasting 30 to 90 minutes depending on the tooth. Here’s what happens at each stage, from diagnosis through recovery.
How Your Dentist Determines You Need One
Before recommending a root canal, your dentist runs a series of tests to figure out what’s happening inside the tooth. The most common is a cold test: a cold stimulus is applied to the tooth, and the response tells the story. A healthy tooth reacts briefly, with any sensation disappearing within one to two seconds after the stimulus is removed. A tooth with irreversible damage produces sharp pain that lingers for 30 seconds or longer. If the nerve tissue has already died, the tooth won’t respond to temperature at all.
Your dentist will also tap on the tooth and have you bite down on a small instrument to check whether infection has spread to the bone and tissues around the root tip. X-rays reveal bone loss, abscesses, or other changes around the root. In every case, adjacent and opposite teeth are tested first so both you and the dentist have a normal baseline for comparison.
Numbing the Tooth
The procedure begins with local anesthesia, the same type of injection used for a filling. Your dentist injects a numbing agent near the nerve that supplies the tooth. For lower back teeth, this is typically a nerve block that numbs one side of the jaw. Upper teeth usually require injections closer to the tooth itself. If you’re anxious about needles, nitrous oxide (laughing gas) can be administered alongside the injection to increase comfort and effectiveness.
Teeth with active infections can sometimes be harder to numb fully. If the initial injection isn’t enough, your dentist has several supplemental options, including injections directly into the ligament around the tooth or into the bone near the root tip. The goal is always the same: you should feel pressure but not pain throughout the procedure.
Isolating and Opening the Tooth
Once you’re numb, a rubber dam (a thin sheet of rubber or silicone) is placed over the tooth. This keeps the treatment area dry, prevents bacteria from saliva entering the tooth, and stops any small instruments or rinse solutions from reaching your throat. Only the tooth being treated pokes through the sheet.
Your dentist then drills a small access hole through the chewing surface (for back teeth) or the back side (for front teeth). This opening is just large enough to reach the pulp chamber, the hollow space inside the tooth where the nerve and blood vessels live.
Removing the Infected Tissue
Through that access hole, your dentist uses a series of very thin, flexible files to remove the pulp tissue from the chamber and from each root canal. A molar can have three or four canals, sometimes more. Some of these canals are extraordinarily narrow, and specialists often use a dental operating microscope that magnifies the field up to 25 times. At that magnification, subtle differences in the color and texture of the inner tooth wall become visible, helping the dentist locate every canal opening and avoid removing healthy tooth structure.
The files work in a specific pattern, starting wider at the top of the canal and progressing to the tip of the root. As the files move through each canal, they shape the space into a smooth, tapered funnel. This shape is critical because it allows cleaning solutions to reach the full length of the canal and ensures the filling material can seal tightly later.
Disinfecting the Canals
Mechanical cleaning alone can’t eliminate all the bacteria inside a tooth. Throughout the shaping process, your dentist flushes the canals repeatedly with a sodium hypochlorite solution, essentially a medical-grade bleach. This solution dissolves any remaining tissue fragments and kills bacteria hiding in the microscopic side branches that files can’t physically reach. After the canals are fully shaped, a final rinse is left in place for several minutes before being flushed out with saline.
This irrigation step is one of the most important parts of the entire procedure. The thoroughness of disinfection directly influences whether the treatment succeeds long-term.
Filling and Sealing
Once the canals are clean, dry, and shaped, they need to be sealed to prevent reinfection. The standard filling material is gutta-percha, a natural rubber-like material that’s biocompatible and can be compacted tightly into the canal space. Your dentist places gutta-percha cones into each canal along with a thin layer of sealer, a cement-like paste that bonds to the canal walls and fills any microscopic gaps.
Newer bioceramic sealers have properties that make them particularly well-suited for this job. They’re hydrophilic, meaning they work well in the moist environment inside a tooth. They expand very slightly as they set (less than 0.2% of their volume), which helps create a tighter seal. And they form a mineral layer where they contact tissue fluid, which promotes healing at the root tip.
After the canals are filled, the access hole in the crown of the tooth is closed with a temporary filling.
Getting a Permanent Crown
The root canal itself saves the tooth from infection, but the tooth still needs structural protection. A tooth that has had its nerve removed becomes more brittle over time, and the access hole weakens the remaining structure. Most back teeth need a full crown (cap) placed over them to prevent fracture during chewing.
Dentists generally recommend placing the crown within one to two weeks of the root canal. Waiting a month or longer increases the risk of the tooth cracking under normal chewing pressure, shifting position, or needing retreatment. Front teeth, which bear less biting force, may sometimes be restored with a filling alone, but your dentist will assess this on a case-by-case basis.
What Recovery Feels Like
On the day of the procedure, you’ll feel mild tenderness and pressure once the numbness wears off. Sensitivity when biting is common. Over days two and three, a dull ache may persist, but it should be noticeably less intense than day one. By days four through seven, most soreness fades and daily activities feel comfortable again. By the second week, the tooth should feel essentially normal, especially once the permanent crown is in place.
Until the numbness fully wears off, avoid eating so you don’t accidentally bite your cheek or tongue. Once you can eat, stick to soft foods and avoid anything sticky (like gum or taffy) that could pull out a temporary filling, anything hard (like ice or hard candy) that could crack the weakened tooth, and anything extremely hot or cold that might trigger sensitivity.
Long-Term Success Rates
Root canals have a strong track record. Four-year tooth survival rates sit around 95% for both first-time and repeat treatments, according to prospective research published in the International Endodontic Journal. Over longer follow-up periods of two to ten years, pooled survival rates range from 86% to 93%. The most important factors in long-term success are thorough disinfection during the procedure and timely placement of a permanent crown afterward.