Signs your root canal may need attention
- Pain coming back in a treated tooth
- Swelling or a small boil on the gum
- Tenderness when you bite down
- A tooth that keeps getting infected
- A crown or filling that broke or leaked
Home › Dental care guides › Failed root canal
Patient guide · Root canal retreatment
Failed root canal? What retreatment involves
A tooth that already had root canal treatment can sometimes start to hurt or swell again, months or even years later. That does not always mean the tooth has to come out. This guide explains the warning signs, how retreatment under a dental microscope works, and how to choose between saving the tooth and an implant. At Gentle Touch Dental Clinic, complex and failed root canals are treated by Dr. S. Barath Kumar (MDS Endodontics).
Signs an old root canal may have failed
- Pain coming back in a tooth that was treated before
- Tenderness when you bite or press on the tooth
- Swelling, or a small boil or pimple on the gum near the tooth
- A bad taste or pus near the tooth
- A tooth that keeps getting infected
- A crown or filling that broke, came loose or started to leak
- A dark area at the root tip on an X-ray, sometimes found at a routine check-up even without pain
Why root canals can fail
- An extra or hidden canal that was hard to find
- Cleaning that could not be fully completed, for example in curved or narrow canals
- A crown that was delayed, or a filling that started to leak and let bacteria back in
- New decay around the tooth
- A crack in the tooth or root
Teeth are complex, and these things can happen even with careful treatment.
How microscope-guided retreatment works
Retreatment means cleaning and sealing the root canals again. Every tooth is different; this is a general outline. It usually needs multiple sittings.
Examination, X-ray and second opinion
Dr Barath examines the tooth, reviews your symptoms and any earlier X-rays, and takes a new X-ray. A 3D scan (CBCT) may be advised to look for missed canals, cracks or infection. You will hear honestly whether the tooth can be saved, and what the options and fees are, before anything begins.
Numbing
The area is numbed with local anaesthetic so the treatment is comfortable.
Reaching the canals
The old crown, post or filling is removed, or an opening is made through it, to reach the root canals.
Removing the old root filling
The old filling material inside the canals is carefully removed under magnification.
Finding and cleaning every canal
The dental operating microscope gives magnification and bright light to find extra or hidden canals and check for cracks. The canals are cleaned, disinfected and shaped.
Medicine between visits
Medicine is often placed inside the canals and the tooth is closed with a temporary filling, giving the infection time to settle.
Sealing the canals
Once the canals are clean, they are filled and sealed again, and an X-ray checks the result.
Core build-up and new crown
The tooth is rebuilt from inside and usually covered with a new crown, so it is protected for everyday chewing. Getting the crown done on time matters.
When retreatment through the tooth is not possible, for example because of a post that cannot be removed safely, a small procedure at the root tip (root-end surgery or apicoectomy) may be discussed as another way to keep the tooth.
Save the tooth or get an implant?
Both are good options in the right situation. Here is a simple, honest comparison.
Root canal retreatment
- Keeps your own tooth, root and natural bite feel
- Usually preferred when the tooth is restorable
- No surgery to replace the tooth
- Usually needs a well-fitting crown afterwards
- Retreatment: ₹15,000 (multiple sittings); core build-up and crown extra
Extraction and dental implant
- A good option when a tooth cannot be saved
- Useful for deep root cracks or too little tooth left
- Involves removing the tooth and a minor surgery
- Usually takes a few months to complete
- Implant: from ₹35,000 (implant only); abutment and crown extra
What helps decide: how much healthy tooth is left, whether there is a crack in the root, the health of the gum and bone around the tooth, your general health, and your own preferences about time and cost. Dr Barath will advise you honestly after an examination and X-ray, including when an implant is the better choice.
Before your visit
- Bring any earlier X-rays, scans or treatment notes for the tooth, if you have them.
- Tell us when the root canal was done and whether a crown was placed.
- List your medicines and health conditions, such as diabetes or blood thinners.
- You can send your X-ray on WhatsApp first for an initial look.
When to seek care urgently
- Swelling of the face, jaw or gum that is getting worse
- Fever along with tooth pain
- Severe pain that does not settle with the advice given
- Difficulty opening your mouth, swallowing or breathing (go to a hospital emergency department immediately)
Aftercare tips
- Some tenderness for a few days is common. Follow the pain relief advice you are given.
- Avoid chewing hard food on the tooth until the crown is fitted.
- If the temporary filling feels high or comes out, contact the clinic.
- Keep your review visits so healing can be checked on X-ray.
- Get the core build-up and crown done on time, as advised.
- Brush twice a day and clean between your teeth.
New to root canal treatment? Read root canal treatment: what to expect, or our guide to root canal treatment.
FAQ
Common questions
Why did my root canal fail?
Common reasons include an extra or hidden canal that was not found, cleaning that could not be fully completed, a crown or filling that was delayed or started to leak, new decay, or a crack in the tooth or root. Teeth are complex, and these things can happen even with careful treatment.
Can every failed root canal be retreated?
Not always. Many teeth can be retreated, but a tooth with a deep crack in the root, very little healthy structure left or weak gum and bone support may not be restorable. An examination and X-ray, and sometimes a 3D scan, show what is possible for your tooth.
Is retreatment uncomfortable?
The tooth is numbed first, so most people find retreatment comfortable. It can take longer than a first root canal because the old filling material has to be removed. Some tenderness for a few days afterwards is common.
How many visits does retreatment take?
Retreatment usually needs multiple sittings. Medicine is often placed inside the canals between visits to help the infection settle before the canals are sealed. The dentist will tell you what to expect for your tooth.
Will I need a new crown?
Often, yes. The old crown may need to be removed to reach the canals, or it may be leaking. After retreatment, the tooth is rebuilt (core build-up) and usually covered with a new crown to protect it.
Should I get an implant instead?
Keeping your natural tooth is usually preferred when it can be restored. An implant is a good option when a tooth cannot be saved, for example because of a root crack. Dr Barath will explain both options honestly after examining the tooth, so you can decide.
Can I get a second opinion without a referral?
Yes. Second opinions are welcome and no referral is needed. You can send your X-ray and a short note about your symptoms on WhatsApp, and bring any earlier X-rays or treatment records to your visit.
How much does root canal retreatment cost?
A complex root canal or re-treatment (multiple sittings) is ₹15,000. X-rays taken during the treatment are included; the core build-up and crown are charged separately. The exact fee is confirmed after consultation. See re-treatment fees.
Root canal giving trouble again?
Send your X-ray and a short note to Dr. S. Barath Kumar on WhatsApp, or call the clinic. Second opinions are welcome, and no referral is needed.
Gentle Touch Dental Clinic · U 74, New No 58, 5th Main Road, Anna Nagar, Chennai 600040 (near Tower Park) · 098840 15026. Monday–Saturday: 9:30 AM – 1:30 PM and 4:30 PM – 8:30 PM. Sunday: closed; emergency appointments on call. Get directions.
This page is general information and not a diagnosis. Please see a dentist for advice about your own teeth.
At a glance
Root canal failed elsewhere? It can often still be saved.
If a tooth that already had a root canal is troubling you again, it does not always mean losing it. Dr. S. Barath Kumar (MDS Endodontics) treats complex and previously failed root canal cases under the dental microscope. Second opinions are welcome, and no referral is needed.
Second opinions welcomeNo referral needed
Why root canals fail
- An extra or hidden canal that was hard to find
- Cleaning that could not be fully completed
- A crown that was delayed or started to leak
- New decay around the tooth
- A crack in the tooth or root
Teeth are complex, and these things can happen even with careful treatment.
How microscope-guided retreatment helps
- Magnification and bright light to find hidden canals
- Careful removal of the old filling material
- Thorough cleaning, then a proper seal
- Keeping as much natural tooth as possible
Save the tooth or get an implant?
Both are good options in the right situation. Here is a simple, honest comparison.
Keep your natural tooth
Root canal retreatment
- Keeps your own tooth, root and natural bite feel
- Usually preferred when the tooth is restorable
- No surgery to replace the tooth
- Usually needs a well-fitting crown afterwards
Replace the tooth
Extraction and implant
- A good option when a tooth cannot be saved
- Useful for deep cracks or too little tooth left
- Involves removing the tooth and a minor surgery
- Usually takes a few months to complete
Keeping your natural tooth is usually preferred when it can be restored. Dr Barath will advise you honestly after an examination and X-ray, including when an implant is the better choice.
Get a second opinion on your tooth
Send us your X-ray on WhatsApp and a short note about your symptoms. We will get back to you with the next steps.
More dental care guides
Root canal treatment
Root canal treatment, microscopic RCT and retreatment of failed root canals.
Read the guide →Root canal: what to expect
Each step of root canal treatment, number of visits, crown and aftercare.
Read the guide →Toothache: what to do
Home care steps, warning signs and when to see a dentist.
Read the guide →Dental implants
Who implants suit, the options, the step-by-step journey and approximate fees.
Read the guide →Crowns, bridges & dentures
Crowns, bridges, dentures and implants for broken or missing teeth.
Read the guide →Tooth sensitivity
Why teeth feel sensitive to cold or sweet, home care and when to see a dentist.
Read the guide →Oral surgery
An overview of minor oral surgery, with clear aftercare tips.
Read the guide →Treatment costs
Approximate prices for consultation, cleaning, root canal, crowns, implants and braces.
See the costs →