A root canal treatment is needed when the pulp inside the tooth becomes infected due to bacteria entering through cracks, decay, or failing restorations. This causes inflammation and can lead to an abscess, pain, and swelling. Eventually the tooth may die. When a tooth dies, the root canal system is infected. To remove the infection, the tooth can either be extracted or undergo a root canal treatment. During a root canal treatment, the infected pulp is removed and the inside of the tooth is cleaned and sealed to prevent reinfection and allow the tooth to be saved and function normally.

1. Why is a root canal treatment needed?
Julie K Kilgariff
Specialist in Endodontics
www.julie4endo.com

2. Here is an extracted lower premolar tooth

3. In the centre of the root is the space that the
tooth nerve (pulp) resides in. This is the root
canal.
Front teeth often just have 1 canal whereas back
teeth can have several.
This makes back teeth more challenging to treat
endodontically

4. This extracted
tooth has been
x-rayed.
The x-ray image makes it
possible to see the hard tissue
layers which make up the tooth.
Enamel (surface layer seen in mouth.
Lightest grey colour on x-ray)
Dentine (the porous, sensitive part of the
tooth)
Root canal system containing
the pulp (dark grey ‘line’ in middle of root)

5. The nerve (pulp) in the tooth is alive and
generally gives no painful feelings when it is
healthy.
If bacteria (from the mouth/saliva) gain
access to the pulp, inflammation results
and this often, although not always, causes
pain.
Bacteria enter the tooth via cracks, tooth
fractures/chipped teeth, decay and around
failing/leaking restorations

6. Depending on how healthy the pulp was prior to the bacterial
invasion, it may recover and go on to function in a pain-free way
again.
This would normally happen as a result of treatment.
For example: If the tooth was fractured, a filling (restoration)
is placed to repair the fracture and prevent further bacterial
access to dentine and pulp. The inflammation and pain subsides.

7. In some teeth, the bacterial attack can
be overwhelming and the tooth goes on to
die. This is when an abscess results.
Abscesses can be acutely painful. Some
patients report sleep disturbance due to
the severity of the pain; swelling of the
tissues inside and sometimes outside the
mouth can often be seen.
Some teeth die quietly, with little
symptoms noticed and they are identified
at a later stage when a routine x-ray is
taken and highlights problem.
The problem seen on x-ray when teeth die is a dark shadow
(radiolucency) around the root of the tooth caused by the
bacterial infection of the root canal system.
Example: This lower
right molar tooth has 2
extensive fillings. The
pulp has died
2 Fillings
(restorations)
Root canal
system
Radiolucencies
in jaw bone
(caused by
infection in
root canal)

8. When a tooth dies, the root canal system is infected.
There are 2 options to remove the infection:
1. Extract the tooth (removing the infection within it) and either
accept the space or plan for a tooth replacement, if possible
2. Root canal treat the tooth (removing the infection by disinfecting
the root canal and filling it up to prevent re-infection)
A root canal treatment allows the tooth to function as
normal, stay relatively unchanged in appearance (in your
mouth), but on x-ray, the root canal treatment can be seen.

9. The success of the root canal treatment depends on
circumstances and can be very high.
At your assessment appointment you will be advised of the likely success in your particular case.
After root canal
treatment.
The root filling is seen
on x-ray
JKK
Before treatment
JKK

10. To learn more about root canal treatments, please
see:
‘What does Root Canal Treatment
Involve?’