Medically reviewed by Dr. Timur Mozner, DDS - General Dentistry | 20+ Years Experience | Last Updated: October 2026
It depends on why the first root canal failed. If the original treatment missed or under-filled a canal and the infection around the root is small, a retreatment by a skilled clinician is often worth trying, and you keep your own tooth. If the tooth is cracked, has little healthy structure left, or sits in a large, long-standing infection, taking it out and placing an implant usually gives you the more predictable result.
Dr. Timur Mozner of Creative Dental of Syosset sums up the money side in one line:
"Retreatment often has a lower upfront cost but an uncertain long-term prognosis, while an implant usually has a higher initial cost but typically offers a more predictable, longer lifespan over a ten-year period."
Why does a root canal fail years after it was done?
When a root canal fails, bacteria have found their way back into the tooth, or were never fully cleared. The usual reasons:
- A canal was missed or filled short. Molars often have a small extra canal that is easy to miss, and a filling that stops short of the root tip leaves space for infection.
- The seal leaked. New decay under an old crown, or a temporary filling left too long, lets saliva and bacteria into the treated canals.
- The tooth cracked. A crack running down the root is the failure that retreatment cannot fix.
An X-ray or a 3D CT scan usually shows which of these you are dealing with, how big the infection at the root tip has become, and how much bone is left.
When is root canal retreatment worth it?
Retreatment means reopening the tooth, removing the old filling material, cleaning the canals again (including any that were missed) and resealing them. It works best when the first treatment was the problem and the tooth itself is still sound. Dr. Mozner puts the conditions this way:
"Retreatment can only be successful to a good degree over the long term if the original root canal treatment reflected inadequately treated root canals (short fill) and there was No huge infection, big abscess and granulomatous inflammation associated with it."
He adds a second condition: the result is contingent on the specialist doing the retreatment having very good clinical skills. Retreatment is detailed work, commonly done by an endodontist (a root canal specialist) using a microscope, and he is frank that it carries no 100% guarantee of long-term success compared with extraction and an implant.
When is a failed root canal tooth better extracted than retreated?
These findings tip the decision toward extraction, because the tooth is unlikely to hold up even after a perfect retreatment:
- a vertical crack in the root
- too little tooth left above the gum to hold a new crown securely
- a large abscess or long-standing inflammation that has eaten away the surrounding bone
- a tooth that is already loose because of bone or gum loss
- a tooth that has already been retreated once and failed again
Between retreatment and extraction sits an apicoectomy, a minor surgery where a specialist removes and seals the infected root tip through the gum. It is usually considered when going back in through the crown is impractical, such as under a post that would be risky to remove.
Root canal retreatment vs dental implant: cost and lifespan over ten years
Price the whole path for each option, then compare.
A retreatment often also means a new crown, because the old one may have to come off to reach the canals. The upfront bill is lower and you keep your natural root. The risk is the part Dr. Mozner calls uncertain: if the infection returns, you may pay for the extraction and implant later anyway, on top of the retreatment.
An implant path includes the extraction, often a bone graft, the implant, the connector piece (abutment) and the crown, usually spread over a few months. The upfront bill is higher. In return, an implant can't get a cavity or need another root canal, though the gum around it still needs regular care. Read more about how long dental implants actually last, including what shortens their life.
Over ten years, the real cost depends on whether the first fix holds, which is why the cause of the failure matters more than the day-one price.
Can a dental implant go in the same day as the extraction?
Sometimes. In Dr. Mozner's words:
"Yes, in some instances an implant can be placed the same day as an extraction, provided there is enough healthy bone to achieve stability and no acute, severe infection present."
A failed root canal often comes with infection at the root tip, so many of these cases follow a staged plan: the tooth comes out, the socket is cleaned and grafted, and the implant goes in once the site heals. Our article on same-day extraction and implant covers who qualifies.
Questions to ask before you choose retreatment or an implant
- What does the scan show as the reason the root canal failed?
- Is there a crack, and is enough tooth left for a new crown?
- Who would do the retreatment, and do they use a microscope?
- If the retreatment fails, what is the plan and the added cost?
- If we extract, can the implant go in the same day, or will the site need a graft first?
Getting a second opinion on a failed root canal in Syosset
At Creative Dental of Syosset, Dr. Timur Mozner can look at the tooth on a 3D CT scan taken in the office before you choose a path. He has placed about 3,000 dental implants, and he refers complex molar root canal treatment to an endodontist when a case calls for a specialist's microscope. If your root canal tooth is acting up again, book a consultation to see what the scan shows. You can also read about dental implants at Creative Dental of Syosset.
Disclaimer: This information is provided for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Reading this article does not establish a doctor-patient relationship. Please schedule a consultation with our team to discuss your individual needs.