A root canal is a straightforward procedure where your dentist removes infected tissue from inside your tooth, cleans the hollow space, and seals it to prevent future infection. The whole process typically takes one to two visits, each lasting 30 to 90 minutes depending on which tooth is involved. Here’s what actually happens at each stage.
How Your Dentist Knows You Need One
Before scheduling a root canal, your dentist runs a series of tests to confirm the nerve inside your tooth is damaged beyond repair. The key distinction is between reversible and irreversible damage. If a cold stimulus on your tooth causes pain that fades within a second or two, the nerve is likely still healthy enough to recover on its own. But if that pain lingers for 30 seconds or more after the cold is removed, or if you’re getting spontaneous throbbing that worsens when you lie down, the nerve is past the point of healing.
Your dentist will also tap on the tooth, press on the gums around it, and take X-rays to check for infection at the root tip. In some cases, a 3D scan (called CBCT imaging) provides a far more detailed view. These scans detect problems invisible on standard X-rays, including extra canals and tiny fractures, catching issues that would otherwise be missed roughly 30% of the time.
Numbing the Tooth
The procedure starts with local anesthesia, the same type of numbing injection used for a filling. Your dentist applies a topical gel to the gum first so you feel less of the needle. The most common anesthetic is lidocaine, sometimes combined with a small amount of epinephrine to keep the area numb longer. For lower back teeth, your dentist may use a nerve block that numbs the entire lower jaw on one side. If you’re especially anxious, sedation options ranging from oral medication to nitrous oxide can help you relax.
Once the area is fully numb, you’ll feel pressure and vibration during the procedure but not sharp pain. A rubber sheet called a dental dam is stretched over the tooth to isolate it, keeping saliva and bacteria out of the work area and giving your dentist a clean, dry field.
Opening the Tooth
Using a small drill, your dentist creates an opening through the top (crown) of the tooth to reach the pulp chamber inside. The pulp is the soft tissue that contains the tooth’s nerve, blood vessels, and connective tissue. In a healthy tooth, the pulp keeps the tooth alive during development, but an adult tooth can survive without it because surrounding tissues continue to nourish the root.
The opening is surprisingly small. For a front tooth, it’s made on the back surface. For a molar, it’s on the chewing surface. The goal is to remove just enough tooth structure to access every canal inside the root.
Removing the Infected Tissue
This is the core of the procedure. Your dentist uses a series of tiny, flexible files, some thinner than a sewing needle, to clean out the infected or dead pulp tissue from each canal. The files gradually increase in size, shaping the canal walls into a smooth, tapered funnel that can be thoroughly disinfected and sealed.
Throughout the filing process, an antimicrobial rinse is flushed repeatedly through each canal. This solution dissolves any remaining organic tissue and kills bacteria hiding in the microscopic side branches that files can’t physically reach. A second rinse is used to clear away the mineral layer that builds up on the canal walls, ensuring the final seal bonds tightly. Electronic sensors measure the exact length of each canal so the cleaning reaches all the way to the tip of the root without going past it.
Why Missed Canals Matter
One of the biggest challenges is finding every canal inside the tooth. Molars commonly have three or four canals, but some have extra ones that are easy to overlook. Studies show that about 12% of root canal treated teeth have at least one untreated canal, and when a canal is missed, infection develops around the root tip roughly 83% of the time. This is a major reason some root canals fail. Magnification tools like dental microscopes and 3D imaging have significantly improved detection, but canal anatomy varies widely from person to person.
Filling and Sealing the Canals
Once the canals are shaped, disinfected, and dried, your dentist fills them with a rubber-like material called gutta-percha. These small, cone-shaped points are fitted into each canal along with a sealer that bonds to the canal walls. Newer bioceramic sealers are designed to work well in the moist environment inside a tooth. They expand slightly as they set (less than 0.2% of their volume), which helps close any microscopic gaps. Over time, these sealers form a mineral layer where they contact living tissue, creating a tight biological seal at the root tip.
After the canals are filled, the access hole in the crown is closed with a temporary filling material. At this point, the tooth is structurally intact but weaker than it was before treatment.
Getting the Permanent Crown
A root canal removes the nerve and blood supply from inside the tooth, which makes it more brittle over time. Without a crown, the tooth is vulnerable to cracking under normal chewing forces. Dentists typically recommend placing a crown within one to two weeks of the root canal. Waiting several weeks or months increases the risk of fracture, shifting, or the need for retreatment or extraction.
The crown appointment is separate. Your dentist reshapes the outer tooth, takes impressions or digital scans, and fits a custom crown that restores the tooth’s original shape and strength. Until the permanent crown is placed, avoid chewing hard foods on that side.
What Recovery Feels Like
Most people feel some tenderness around the treated tooth for a few days after the procedure, particularly when biting down. This is normal inflammation at the root tip and typically peaks within the first 24 to 48 hours before gradually fading. Over-the-counter pain relievers like ibuprofen or acetaminophen are usually enough to manage it. Some people feel fine the same evening.
You can eat as soon as the numbness wears off, which takes two to four hours depending on the anesthetic used. Stick to softer foods for the first day or two, and chew on the opposite side while the temporary filling is in place. Brushing and flossing can continue normally, just be gentle near the treated tooth.
Success Rates and What Can Go Wrong
Root canals are one of the most reliable procedures in dentistry. Initial treatments succeed 75 to 85% of the time depending on how strictly success is measured, with most treated teeth lasting decades or a lifetime with proper care. The most common reasons for failure are missed canals, incomplete sealing, or reinfection through a cracked filling or crown.
If a previously treated tooth develops new infection, a retreatment can be performed. This involves reopening the tooth, removing the old filling material, re-cleaning the canals, and sealing them again. Retreatment success rates range from about 71 to 87% in the first few years, somewhat lower than initial treatment because the canals have already been altered and may be harder to clean thoroughly. In cases where retreatment isn’t feasible, a minor surgical procedure called an apicoectomy can remove the infected tip of the root directly.