What actually happens during a root canal
A step-by-step look at root canal treatment: why a tooth may need one, what happens at each stage, what it usually feels like, and how the tooth is protected.
Few words in dentistry make people as tense as “root canal.” Most of that reputation comes from the pain of an infected tooth, which is the problem a root canal treats. The treatment itself is done with the tooth numbed. Knowing what will happen, step by step, takes much of the worry out of it.
This lesson explains why a tooth might need a root canal, what happens during treatment, what it usually feels like, and what comes after.
What a root canal is
Every tooth has a soft center called the pulp, which holds its nerves and blood vessels. The pulp fills a small chamber inside the crown of the tooth and runs down each root through a thin channel. That channel is the root canal, and the treatment is named after it.
In root canal treatment, the dentist removes damaged or infected pulp, cleans and shapes the inside of each canal, and then fills and seals it. The tooth stays in your mouth. A fully grown tooth can keep working without its pulp, because the tissues around the root still hold it in place. To see the pulp and canals in a drawing, read The parts of a tooth, explained.
Why a tooth might need one
The pulp can be damaged when bacteria get deep inside the tooth, or when the tooth is hurt. Common causes include:
- a deep cavity that reaches the pulp
- a crack or chip in the tooth
- a blow to the mouth, even one that left no visible damage
- many repairs to the same tooth over the years
Once the pulp is infected, it can’t heal on its own. Without treatment, the infection can spread to the bone at the tip of the root and form an abscess, a pocket of pus.
Signs can include:
- pain that lingers after something hot or cold
- pain when you bite
- a tooth that has turned darker
- swelling in the gum, or a small bump on the gum that drains
Sometimes there are no signs at all, and the problem first shows up on an X-ray. None of these signs means you need a root canal for certain. Only an exam can tell.
Before treatment starts
First, your dentist examines the tooth and takes X-rays to see the roots and the bone around them. You may have simple tests, such as touching the tooth with something cold or tapping on it gently, to see how the pulp responds.
Then your dentist explains what they found and what your options are. Usually, the choice is between saving the tooth with a root canal and removing it. You’ll hear what each one involves before you decide.
If you have swelling or a fever, you may be given antibiotics first. Antibiotics can calm an infection that has spread, but they can’t reach inside the tooth, so they don’t take the place of treatment.
What happens, step by step
Treatment usually takes one or two visits. A front tooth usually has one canal, while a molar can have three or four, so the time depends on the tooth. Figure 1 shows the three stages.
- Decay
- Pulp
- Opening
- Canals
- Crown
- Filling
- Numbing. The dentist numbs the tooth and the gum around it with a local anesthetic, a medicine that blocks feeling in one area. Treatment doesn’t start until the tooth is numb.
- Keeping the tooth clean and dry. A thin sheet of rubber, called a dental dam, goes around the tooth. It keeps saliva out of the tooth and keeps the cleaning liquids out of your mouth.
- Making a small opening. The dentist makes a small opening in the top of the tooth to reach the pulp.
- Cleaning and shaping the canals. The pulp is removed with very thin instruments. The canals are then rinsed with a disinfecting liquid and shaped so they can be filled. Each canal is measured to its tip, often with an X-ray, so the cleaning reaches its whole length. This is the middle panel of figure 1.
- Filling and sealing. The clean canals are filled with a rubbery material called gutta-percha and sealed so bacteria can’t get back in.
- Closing the opening. A filling closes the top of the tooth. If treatment takes two visits, a temporary filling protects the tooth in between, sometimes with medicine inside.
What it feels like
With the tooth numb, most people say a root canal feels much like having a filling, only longer. You’ll feel pressure and some vibration, and you’ll hear the instruments. The goal is that you feel no sharp pain. If you do, raise your hand, and the dentist can stop and add more numbing.
For many people, the hardest part is keeping their mouth open for a long time. A small prop can rest your jaw, and you can ask for a break when you need one. If you’re anxious, say so before you start. Many people find it helps to hear each step explained as it happens, and you can also ask about sedation options.
The first few days afterward
Once the numbness wears off, the tooth may feel tender for a few days, especially when you bite. This is common, and an over-the-counter pain reliever usually helps, if it’s safe for you. Until the tooth has its final filling or crown, chew on the other side and avoid hard or sticky food.
Call your dentist if you have swelling, pain that gets worse instead of better, or a bite that feels uneven. Call, too, if a temporary filling comes out.
Why a crown often comes next
The third panel of figure 1 shows a crown on the treated tooth. A crown is a cap that covers the whole tooth. A tooth that needs a root canal has often lost a lot of its structure to decay, older fillings, and the opening made during treatment. Back teeth take the most chewing force, so without a crown they’re more likely to crack.
That’s why back teeth usually need a crown after a root canal, while a front tooth with plenty of healthy structure may need only a filling. Your dentist will tell you which your tooth needs, and how soon. Putting it off can let the tooth break or let bacteria leak back in. With a good crown or filling and regular care, a tooth that has had a root canal can often last for many years.
The other choice: removing the tooth
Removing the tooth is also an option, and sometimes it’s the only one. A tooth that’s cracked below the gumline, or that has too little healthy structure left, may not be possible to save.
A missing tooth leaves a gap, though, and nearby teeth can drift into it over time. Replacing it with an implant, a bridge, or a partial denture means more treatment later. Implant, bridge, or denture explains those choices. When a tooth can be saved, keeping it is often the simpler path in the long run.
Questions worth asking
- How likely is it that this tooth can be saved?
- How many canals does it have, and how many visits will it take?
- Will it need a crown afterward, and how soon?
- What could happen if I wait?
Finding out what your tooth needs
Many root canals are done by general dentists. Some, often on teeth with curved or hard-to-reach canals, are referred to an endodontist, a dentist with extra training in treating the pulp. Dr. Minici is a general dentist, and he’ll tell you whether he would treat your tooth or refer you.
To learn more, see root canal therapy and dental crowns, or read about tooth extractions. Every tooth is different, and an exam is how you find out whether a root canal is right for yours.
Questions about your own teeth?
An exam is how you find out what’s right for you. Tell us a little about what’s going on, and we’ll call you to find a time.