Root Canal FAQs
Medically reviewed by Dr. Kayla Lebeau, DDS
Root canal treatment, answered honestly
No procedure in dentistry has a worse reputation, and almost none of it is deserved any more. The pain people associate with root canals is the pain of the infection that makes one necessary, the treatment is what relieves it.
For the procedure itself, see root canal treatment.
- PurposeTo save the tooth
- Usually takes1 to 2 visits
- ComfortComparable to a large filling
- Success rateAbove 90% for first-time treatment
Does it hurt, and do I really need one?
Is it as painful as people say?
No. With modern anesthetic and instruments, most people describe it as similar to having a large filling. Long rather than painful. The reputation comes from an era before that was true, and it keeps people in genuine pain far longer than necessary.
Why does my tooth hurt so much beforehand?
Because the pulp is inflamed inside a rigid chamber with nowhere to swell. That pressure on the nerve is what causes the throbbing, and why it is worse lying down. Releasing it is what the treatment does.
My pain stopped. Do I still need treatment?
Almost certainly yes, and this is important. Pain stopping usually means the nerve has died completely. The infection has not gone. It is moving into the bone around the root, where it forms an abscess. This is the most dangerous moment to assume you are better.
Can antibiotics fix it instead?
No. There is no blood supply inside a dead pulp for antibiotics to reach. They can settle facial swelling and buy time, but the infection returns unless the inside of the tooth is cleaned out.
Why not just take the tooth out?
Extraction is quicker and often cheaper on the day. Then you need an implant or a bridge, which costs considerably more and works less well than the tooth you already have. Keeping your own root is nearly always the better decision.
Can I just leave it?
The infection spreads into the bone. It does not resolve on its own, and the tooth becomes progressively harder to save.
The appointment itself
How many visits will it take?
Often one, sometimes two. Front teeth with a single canal are quicker; molars with three or four canals take longer. Where there is significant infection we sometimes place a medicated dressing and complete it at a second visit.
How long is each appointment?
Typically 60 to 90 minutes. Bring headphones if that helps, the length is the demanding part, not the sensation.
Why do you use a rubber dam?
It keeps the tooth completely dry and isolated. Saliva reintroduces the bacteria we are spending the appointment removing, and the dam also stops small instruments and irrigating fluid reaching your throat. It is not optional in careful endodontics.
What if I cannot get numb?
Infected tissue is more acidic and harder to anesthetize, so it does happen. There are additional techniques. Different injection sites, and anesthetic placed directly into the tooth. That reliably solve it. Tell us rather than enduring it.
Can I be sedated?
Yes. Sedation ranges from mild relaxation to remembering nothing at all, and it suits people who find the length of the appointment difficult.
Can I go back to work afterwards?
After local anesthetic, yes. The tooth is often tender to bite on for a few days. After sedation, no. Take the day.
Why the pulp has to come out
Inside every tooth is a chamber of soft tissue. Nerve, blood vessels and connective tissue. It does its important work while the tooth is developing. In an adult tooth it contributes very little, which is why a tooth survives perfectly well without it.
The problem is that this chamber is sealed inside a rigid box. When bacteria reach it, the tissue swells with nowhere to expand. That pressure on the nerve is the specific reason a dying tooth hurts so much more than a cavity does.
Once infected, pulp cannot recover. It is not a question of waiting to see. The bacteria travel down the canal and out of the root tip into the bone, which is how a toothache becomes a facial swelling.
Afterwards, and the long term
Why do I need a crown afterwards?
A back tooth that has had root canal treatment has lost internal structure and is more brittle. A crown holds it together. Skipping it is one of the most common reasons a successfully treated tooth is eventually lost to a vertical split, and a split root cannot be repaired.
How long will the tooth last?
A well-treated and properly crowned tooth can last the rest of your life. This is not a temporary measure or a way of postponing an extraction.
Will the tooth go dark?
A treated front tooth can discolor over time. Internal whitening usually corrects it, and a veneer or crown is the alternative if it does not.
What if it still hurts weeks later?
Some tenderness to biting for a week or two is normal. Persistent or increasing pain is not, and it needs re-examining, sometimes a canal was missed, sometimes the bite needs adjusting, and sometimes it is a crack.
Can root canal treatment fail?
Yes, in a minority of cases. The most common cause is a canal that was never found. Molars frequently have an extra one that does not appear on a flat X-ray. That is precisely what 3D imaging is for.
Can a failed root canal be redone?
Usually, yes. Retreatment reopens the tooth, removes the old filling material and cleans the canals again, and it succeeds in most cases. Where it cannot, minor surgery at the root tip is often possible. Extraction is the last resort, not the second option.
Is it true root canals cause illness?
No. This claim traces back to research from the 1920s that was long ago discredited and could not be reproduced. It circulates online and it has no support in current evidence, while untreated dental infection is a genuine and documented risk to health.
Am I safe to have it done while pregnant?
Yes, and treating an active infection is safer than leaving it. Tell us you are pregnant so we can adjust imaging and choice of medication.
Get out of pain and keep the tooth
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What it costs, and what insurance usually does
Cost depends mostly on which tooth. A front tooth has one canal; a molar often has three or four, sometimes more, and takes considerably longer to treat properly. That difference is the main driver, not the practice.
Two things worth planning for. First, the root canal is usually not the whole bill, a back tooth almost always needs a crown afterwards to stop it splitting, and that is a separate cost. We give you both figures at the start, not one and then the other.
Second, root canal treatment is restorative rather than cosmetic, so dental plans commonly cover a meaningful share. We check your specific plan and tell you the expected out-of-pocket figure in writing. If it is awkward, financing exists and staging the crown a little later is usually safe.
Does it hurt? The honest answer
The reputation is real but out of date. It comes from an era before modern local anesthetic and rotary instruments, and from the fact that people arrive for root canals already in severe pain, then remember the pain as belonging to the treatment.
What it actually feels like: pressure and vibration, much like having a deep filling, for somewhere between forty minutes and ninety depending on the tooth. Most patients tell us afterwards that the appointment was easier than the night before it.
One honest caveat. A hot, actively infected nerve can be harder to numb fully, because inflamed tissue resists anesthetic. We know this, we plan for it, and there are additional techniques for exactly that situation. Tell us if you start to feel anything. We stop and add more rather than asking you to push through. If dental anxiety is the real barrier, sedation is available and nobody will think less of you for asking.