What actually happens during a root canal, step by step

Root canal treatment has a worse reputation than it deserves. Much of that reputation dates from a time before modern anaesthetic and rotary instruments. The rest survives because most people have no idea what the procedure actually involves, and imagination fills the gap badly.

So here is the whole thing, stage by stage, with nothing skipped.

What a root canal is for

Inside every tooth is a soft core called the pulp, containing the nerve and blood vessels. When decay, a crack or an injury lets bacteria reach it, the pulp becomes inflamed and then infected. That is what produces the severe, throbbing kind of toothache — and why it is so much worse at night.

A root canal removes that infected pulp, disinfects the space it occupied, and seals it. The tooth stays in your mouth and keeps working. Nothing is "pulled out" except the diseased tissue inside.

The alternative is extraction. Replacing a missing tooth with an implant or bridge is more involved and more expensive than saving the one you already have, and no replacement functions quite as well as a natural root.

Signs you might need one

• A throbbing ache that keeps you awake at night
• Lingering sensitivity to hot or cold — the ache continues well after the drink is gone
• Sharp pain when biting down, or when you release the bite
• Swelling or tenderness in the gum near one particular tooth
• A tooth that has darkened compared with its neighbours
• A small pimple-like bump on the gum that keeps returning

A tooth can also need a root canal without hurting at all, which is exactly why an X-ray matters more than how it feels.

Does a root canal hurt

This is the question almost everyone asks, and avoiding it helps nobody. So, plainly: the treatment itself should not hurt. The tooth is fully numbed first, and we check that it is numb before starting.

What people remember as "root canal pain" is nearly always the toothache that brought them in. The infection is the painful part. The root canal is what removes it. Most patients describe the appointment as long rather than painful — the main complaint is having to keep the mouth open.

One caveat worth being honest about: a tooth with an active abscess can be harder to numb, because inflamed tissue is more acidic and resists local anaesthetic. If that happens there are ways around it — additional techniques, or settling the infection first and treating a few days later. Nobody should be working on a tooth you can still feel.

Step one: X-ray and examination

Nothing starts before imaging. A digital X-ray shows how many canals the tooth has, what shape they are, how far the infection has travelled, and whether bone around the root tip has been lost.

This is not a formality. Front teeth usually have one canal; molars typically have three or four, sometimes an extra one hiding. Missing a canal is the single most common reason a root canal fails years later, so knowing the anatomy before starting matters. You are shown the image and told what it means.

Step two: numbing the tooth

Local anaesthetic is given and we wait for it to take full effect — not a token thirty seconds. This is the part patients worry about most, so to be explicit: if you can still feel the tooth, say so and more anaesthetic is given. Starting on a tooth that is not fully numb is not something any dentist wants to do either.

Step three: isolating the tooth

A rubber dam — a thin sheet that isolates the tooth being treated — is placed. Patients sometimes find this the strangest-sounding part, but it does two useful things: it keeps saliva and its bacteria out of a canal being disinfected, and it stops anything small reaching the back of your throat. It also means you can swallow normally during the appointment.

Step four: reaching and removing the pulp

A small opening is made in the top of the tooth. Through it, the inflamed pulp is removed. This is the moment the pressure inside the tooth is released, and it is what stops the toothache — many patients notice the relief there and then.

Step five: cleaning and shaping the canals

Each canal is cleaned along its full length with fine instruments and disinfecting solution, then shaped so it can be filled completely with no voids.

This stage takes the longest, and it is the stage that decides whether the treatment lasts. The working length is measured so the cleaning goes to the end of the root and no further. Rushing this is how root canals fail, which is a large part of why the appointment is not a quick one.

Step six: sealing

The cleaned canals are filled with a rubber-like material and sealed, so bacteria cannot re-enter. In a single sitting root canal this happens in the same appointment. In a multi-visit approach a medicated dressing sits inside the tooth for a week or two first.

Step seven: the crown

A tooth that has had its pulp removed becomes more brittle, and back teeth take heavy chewing forces. A crown fitted over the tooth protects it from splitting.

For molars this is not really optional if you want the treatment to last. A root-treated back tooth left without a crown is at genuine risk of fracturing — and a tooth that cracks below the gumline usually cannot be saved a second time. For a front tooth with minimal damage, a filling is sometimes enough.

Single sitting versus multiple visits

Conventionally a root canal is spread over three or four appointments across several weeks, with a temporary filling between each. A single sitting RCT completes the cleaning, shaping and sealing in one appointment.

The advantages are real: fewer injections, fewer trips to the clinic, and less time walking around with a temporarily sealed tooth that could leak or fracture between visits.

It is not right for every case, and any dentist telling you otherwise is overselling. A tooth with active swelling, pus discharge, or a severe infection may genuinely do better with a medicated dressing first. That should be explained after the X-ray, not discovered partway through.

How it feels afterwards

Expect the tooth to feel tender for a day or two, particularly when biting on it. The tissue around the root tip has been inflamed and takes a little while to settle. Ordinary painkillers are enough for most people.

• Chew on the other side until the permanent crown or filling is in place
• Avoid anything hard or sticky on that tooth
• Take painkillers before the anaesthetic wears off rather than waiting for pain to build
• Keep brushing the area normally — the gum needs to stay clean

How long does a root canal last

A well-done root canal with a proper crown on top can last decades — many last for life. Success depends mostly on three things: whether every canal was found and cleaned, whether the seal held, and whether the tooth was protected with a crown afterwards.

The treated tooth can still get decay at the margins, so it needs the same brushing and cleaning between teeth as any other. It no longer has a nerve, which means it will not warn you with sensitivity if decay starts — another reason for regular check-ups.

Root canal or extraction

Extraction is quicker and cheaper on the day. It is rarely cheaper over a lifetime.

A missing back tooth lets the neighbouring teeth drift and the opposing tooth over-erupt, which changes the bite. The jawbone where the root used to be gradually shrinks. Replacing the tooth properly with an implant or a bridge costs more than the root canal and crown would have.

Extraction is the right call when the tooth is cracked below the gumline, too broken down to restore, or has lost too much supporting bone. Those are real limits, and you should be told plainly which situation you are in.

What it costs

The cost depends on which tooth and what the X-ray shows. A front tooth with one canal is not the same job as a molar with four, and a retreatment of a previously failed root canal is more involved again. The crown afterwards is a separate cost.

You get the figure after the examination and before any treatment starts — never afterwards. Call the clinic on +91 90503 21319 for current charges.

Common myths worth clearing up

• "Root canals are agonising." The infection is what hurts. The treatment is what removes it, under full anaesthetic.
• "It is better to just pull the tooth." Almost never true where the tooth is restorable, for the reasons above.
• "Root canals cause illness elsewhere in the body." This traces to research from the 1920s that was discredited long ago and has never been reproduced.
• "If it stopped hurting, I do not need it any more." A pulp that dies stops signalling. The infection stays and usually returns with swelling.
• "A crown afterwards is the dentist upselling." On a molar it is what stops the tooth splitting.

If a tooth has been keeping you awake, an examination and an X-ray will tell you where you stand — including, sometimes, that you do not need a root canal at all. At DentoCare that assessment is done by Dr. Sakshi Garg, whose focus is endodontics, inside Kalawati Anand Hospital in Sonipat.