This article is general information for our patients, not a diagnosis. If something in your mouth hurts, changes, or worries you, have it examined.
The symptoms below are clues, not verdicts. Whether a tooth needs a root canal comes from pulp testing and an X-ray read with your history and an exam: how the nerve answers cold, whether it hurts to tap, whether infection has reached the bone at the root tip. A tooth that’s gone quiet can still turn out to be dead.
What a root canal is, and what it’s for
Under a tooth’s hard outer layers sits a soft core of nerves and blood vessels (the pulp, or simply the nerve). It runs down narrow channels inside each root, the root canals, which give the treatment its name. A healthy nerve keeps the tooth alive and lets it sense hot and cold. Once badly damaged or infected, it can’t repair itself; left alone, it tends to bring pain and eventually tooth loss.
A root canal (your dentist may call it endodontic treatment; “endo” means “inside”) treats the inside of the tooth instead of taking the whole tooth out. We clear the unhealthy nerve, disinfect the canals and seal them, and the tooth stays.
Why a tooth may need one
A tooth tends to need a root canal when the nerve is inflamed beyond healing or has died. The usual causes are deep decay, a crack or an injury.
- An irritated nerve that can still recover (reversible pulpitis). A quick twinge from cold, hot or sweet that’s gone within seconds. A filling can often calm it, with no root canal needed.
- Inflammation past the point of return (irreversible pulpitis). When the irritation keeps up (deeper decay, a leaking filling, a crack), the pain tends to linger for minutes after the trigger, come on by itself, and feel worse lying down at night. This is the most common reason we recommend a root canal, though the tests and X-ray confirm it.
- A dead nerve, then an abscess (a pocket of infection). Left long enough the nerve dies, and the tooth may go quiet for a while. The bacteria travel out the root tip into the bone, where infection can build into an abscess with swelling, a bad taste, pain on biting, or a gum “pimple” that weeps. Facial swelling, a fever, or pain you can’t control is the point for our emergency dental care in Barrie; here’s what a dental abscess feels like and when it is an emergency.
Once a nerve is past healing or dead, the realistic choice is to treat the inside of the tooth or remove it; see deciding between saving a tooth and taking it out.
What actually happens during the treatment
We numb the tooth, isolate it behind a thin rubber sheet, clean and shape the canals, then fill and seal them, usually over one or two visits.
- Numbing. The same freezing you’d have for a filling. We don’t start until you’re comfortable.
- Isolating the tooth. A thin latex-free sheet (a rubber dam) goes over the tooth so only it pokes through, keeping saliva and its bacteria out of the canals and small instruments and rinses away from your throat.
- Opening the tooth. A small opening in the biting surface reaches the canals. Front teeth usually have one canal; back teeth often have two to four, which is why they take longer.
- Cleaning and shaping. Fine flexible files clean the dead or infected tissue from each canal. I measure each canal’s length, to the root tip and not beyond, with a small electronic gauge, often double-checked on an X-ray, and rinse throughout with a disinfecting solution (a dilute, dental-strength relative of household bleach) that reaches what the files can’t.
- Filling and sealing. I fill the clean, dry canals with a soft rubbery material (gutta-percha) and a sealer so bacteria can’t easily move back in.
- Rebuilding the tooth. I close the opening with a filling, on back teeth usually a temporary step until the crown.
Badly infected teeth are sometimes treated over two visits, with a medicated dressing sealed inside between them; single-visit treatment is common too.
Does a root canal hurt — during and after?
With the tooth properly frozen the treatment itself shouldn’t hurt; afterward it’s often tender for a few days and tends to settle on its own.
During: once numb, most people feel pressure and vibration rather than pain, much like a filling. A badly infected tooth can be harder to freeze fully, so now and then I add more freezing or change approach. If dread of the chair has kept you away, tell me — we go at your pace, explain before we treat, and take breaks whenever you need them.
After: the tooth and gum often feel tender or “bruised” for a few days, especially when biting, as the area heals. Most people manage with painkillers from the pharmacy; a pharmacist can advise which suit you if you take other medicines or have a health condition. A smaller number get a sharper flare-up early on.
| Normal after a root canal | A reason to call us |
|---|---|
| Tenderness or a “bruised” feeling for a few days, worse when you bite | Severe pain that keeps climbing instead of easing |
| Soreness that fades within a few days to a week | Swelling of the face or gum, or a gum “pimple” that weeps |
| A mild flare-up in the first day or two, eased by over-the-counter painkillers | A fever, or pain you can’t control |
How many visits does it take, and how long?
Most root canals take one or two visits of about 60 to 90 minutes, depending on how many canals the tooth has and how infected it is. The permanent crown on a back tooth is usually a separate, later visit. For especially tricky teeth, such as very curved or narrowed canals or a re-do of a previous root canal, I may refer you to an endodontist, a dentist with years of extra training on the inside of teeth.
Does the CDCP cover a root canal?
For eligible patients, the Canadian Dental Care Plan (CDCP) does include root canal (endodontic) treatment among the services it helps toward — it isn’t cosmetic, it’s saving a tooth. What the plan pays is a share of a set CDCP fee, and the share depends on your household income, so a portion may still be yours to cover; pre-authorization is sometimes needed for the more involved teeth. The simplest thing is to let us check your specific coverage before we start — our team handles the CDCP paperwork with you and gives you a written estimate of any remaining cost, so there are no surprises. Many private insurance plans cover root canals too. If cost is the reason you’ve been putting a sore tooth off, phone us on 705-721-9229 and we’ll sort out the coverage side first.
On fees generally: the amount depends on the tooth and how many canals it has, and you’ll always get that estimate in writing before anything begins.
Does the plan cover the crown afterwards?
Often, yes — a crown after a root canal is treatment the Canadian Dental Care Plan can help toward, but crowns carry their own criteria and usually need the plan’s approval before we start. That is the part worth knowing early, because the crown and the root canal are treated as two separate questions by the plan even though clinically they are one job: the treatment that saves the tooth, and the cover that stops it splitting afterwards. What decides it is the state of the tooth — how much solid structure is left and whether a simpler repair would hold. We submit the case and the x-rays, and you get the plan’s position in writing before we book the crown. Call us at 705-721-9229 or book online, and for who qualifies and how the plan works overall, see the Canadian Dental Care Plan explained.
How well do root canals work?
Re-examined a few years on, roughly 66% to 95% of root canals are judged successful; the range is wide mostly because studies define “success” differently. For how long the tooth stays in, one large US study of more than 70,000 treated teeth found half still working after about 11 years, and around a quarter (26%) past 20 years. The teeth lost early were very often the ones never properly rebuilt.
A root canal can fail, usually if bacteria survive in a hard-to-reach canal, get back in through a leaking filling, or the tooth later cracks. The options then are re-treatment, a minor procedure on the root tip, or removing the tooth.
Why do I need a crown afterward?
A back tooth tends to turn more brittle after a root canal, so a crown, a cap over the whole tooth, is usually needed to keep it from splitting under chewing forces. Skipping it is the most common way a good root canal is lost. Front teeth take gentler forces and often do well with a bonded filling instead.
A crowned back tooth stays in place in roughly 94% of cases at five years, against about 63% with a filling alone, a gap that comes down to teeth cracking.
| After a root canal | What the studies suggest for keeping the tooth |
|---|---|
| Back tooth with a crown over the whole biting surface | Around 94% still in place at five years |
| Back tooth left with a filling only | Around 63% — many more split and are lost |
| Front tooth (often no crown needed) | About the same either way |
Timing matters too: back teeth crowned within about four months are roughly three times less likely to be lost than those left longer, since waiting leaves the tooth open to a fracture or a leak that re-infects the work.
Are root canals bad for my health?
Root canals are not bad for your health: the idea that they cause disease elsewhere in the body traces to a 1920s “focal infection” theory that a treated tooth could seed infection into the heart, joints or other organs. Researchers were dismantling it by the 1930s, and the American Association of Endodontists is clear there’s no valid scientific evidence linking a properly done root canal to cancer or disease elsewhere. Leaving a dead, infected nerve in place is the real health concern. If something you’ve read worries you, ask me.
This guide is part of our Adult Patient Information library.
If anything here sounds like your tooth, book through our contact page and we’ll take a proper look.
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