Re-Root Canal Treatment

Re-Root canal treatment involves removing the infected root filling, cleaning the canal and replacing the root filling.

Re-Root Canal Treatment

A tooth that has been root treated can last many years, particularly if it is appropriately restored following root canal treatment.  On occasion, teeth can fail to heal or become infected again.  This can happen months or years after the original treatment.  The tooth becomes painful and sometimes a gum boil can appear, sometimes there are no symptoms and the failure is only detected with an x-ray.  Carrying out re-treatment can give the tooth a second chance.

Failure of a root canal treatment can happen for several reasons:

Most common:

  • Bacteria (infection) remaining within the canals e.g missed or incompletely filled canals
  • New bacteria have entered the root canal e.g through a lost or broken restoration (filling/crown/bridge), decay or root fracture

Less common:

  • Infection has spread from within the root canal and into surrounding tissues
  • A reaction to the filling materials placed beyond the root canal into the tissues surrounding tooth
  • A cyst has developed at the end of the root (although often these will heal with root canal treatment)


Local anaesthetic is always used to numb the tooth, which is isolated from the rest of mouth with rubber dam.  This is extremely important for a number of reasons:-

  • It protects you from inhaling/swallowing instruments
  • It allows the use of strong disinfectants to clean out root canals
  • It also prevents bacteria from saliva getting into the tooth  

Access is made through the tooth into the root canal.  The previous root filling is removed to allow any infected parts of the canals to be accessed and cleaned.  Any other issues, such as missed and blocked canals or broken instruments, can be tackled at the same time.  Once the root canals have been located, small files are used to clean and shape them together with copiously rinsing with disinfectants to remove any bacteria.  If the cleaning and shaping of canals takes more than one visit, the tooth is dressed using an antibacterial paste within the canals and a temporary filling is placed.

Once the root canals are as clean as possible, they are filled and covered to protect them from bacteria re-entering.  In some cases, the tooth will need to be restored with a more permanent restroration, such as a crown, to again prevent bacteria getting back in and causing the root treatment to fail.

We plan for 2 x 90 minute appointments but some cases allow us to complete treatment within 1 visit.

Is it painful?

It will not be painful during the treatment, but you should expect mild discomfort for 2-3 days afterwards.  This is best managed with a simple painkiller such as Ibuprofen or paracetamol.

Alternatives to root canal treatment:

There are no alternatives if you wish to retain your tooth.  The only other option is to have the tooth extracted.  This will leave a gap you might be happy to accept, or you may want to look at options to fill gaps, which could include a denture, bridge or implant.

Factors which increase success:

  • Treatment completed by a specialist
  • Being able to find all the root canals and clean, shape and fill them to the end of the roots
  • Having a good quality permanent restoration placed as soon as possible after treatment.  In the case of heavily filled back teeth, a crown is the restoration of choice.  This increases the chance of tooth survival by 6 times.

Factors which decrease success:

  • If there is a radiolucency (dark shadow) on the x-ray associated with the tooth
  • If there is a sinus (gum boil) associated with the tooth
  • If a large, longstanding perforation (communication through the root into the surrounding gum or bone) is present
  • Where the root treated tooth is used to support a denture or bridge.