What is root canal treatment and why is it necessary?
Root canal treatment (endodontics) is a dental procedure used to treat infection at the
centre of (root canal system) or at the end of a tooth root. The infection is caused by bacteria that
live in the mouth and invade the tooth. This can happen after:
•teeth cracking due to grinding/biting • tooth decay
• leaky fillings
• damage to teeth as a result of trauma, such as a fall
To treat the infection in the root canal, the bacteria need to be removed. This can be done
• reducing the bacteria from the root canal system (root canal treatment)
• removing the tooth completely (extraction)
The tooth needs to be assessed comprehensively if it is heavily broken down or has cracks present. If the tooth is structurally compromised resulting in a high chance of poor sealing or further breakdown, the tooth may not be the best candidate for root canal treatment as the longevity will be uncertain.
However, removing the tooth isn’t usually recommended as it’s better to keep as many of
your natural teeth as possible. After the bacteria have been removed, the root canal will be filled and the tooth sealed with a filling or crown. In most cases the inflamed tissue near the tooth will heal naturally.
Before having root canal treatment, your dentist may take a series of X-rays of the affected
tooth. This allows them to build up a clear picture of the root canal and assess the extent of
Root canal treatment is usually carried out under local anaesthetic, a painkilling medication
that numbs a specific area of the body. In some cases where the tooth has died and is no
longer sensitive, it may not be necessary to use a local anaesthetic. Occasionally, teeth may
be difficult to anaesthetise. On these occasions, your dentist can use special local
anaesthetic techniques to ensure your treatment isn’t painful.
Your dentist may place a rubber sheet (dam) around the tooth to ensure it is dry during
treatment. The dam also prevents you swallowing or breathing in any chemicals the dentist
Your dentist will open your tooth through the flat part at the top, or through the back of the
tooth if an incisor – to access the soft tissue at the centre of the tooth (pulp). They’ll then
remove any infected pulp that remains. If you have a dental abscess, which is a pus-filled
swelling, your dentist will be able to drain it at the same time.
Cleaning and filling the root canal
After the pulp has been removed, your dentist will clean and enlarge the root canal so it can
be easily filled. The root canal is usually very narrow, which makes it difficult to fill. Your
dentist will use a series of small files to enlarge the canals and make them a regular shape so
they can be filled. This part of the treatment may take several hours to complete, and
may need to be carried out over a number of visits.
Your front incisor and canine teeth (biting teeth) usually have a single root containing one
root canal. The premolars have one or two root canals, and back molar teeth (chewing
teeth) have two or three roots, each containing either one or two root canals. The more
roots a tooth has, or the more complicated and delicate the root, the longer the treatment will take to complete.
If the treatment needs to be carried out over several sessions, your dentist may put a small
amount of medication in the cleaned canal in between visits to kill any remaining bacteria.
The tooth will then be sealed using a temporary filling.
Following this stage you may experience a little tenderness which can be eased with normal
painkillers. If you experience more severe pain or swelling you must contact the practice for
an emergency appointment. If you have symptoms from the infection, such as a raised
temperature or large swelling, you may be given antibiotics to help manage and prevent
Sealing and fixing the tooth
At your next visit, the temporary filling and medication within the tooth is removed and the
root canal filling will be inserted. This, along with a filling, seals the tooth and prevents
reinfection. Again, you may experience a little tenderness following the treatment which
should resolve within a day or two. If the symptoms persist or worsen, you will need to
arrange another appointment.
Root-filled teeth are more likely to break than healthy unrestored teeth, so your dentist may
suggest placing a crown on the tooth to protect it.
In some cases a root-filled tooth may darken, particularly if it has died as a result of injury
like a knock to the tooth. There are several ways your dentist can treat discolouration, such
as whitening the tooth using chemicals.
A root canal procedure is performed using a strong local anaesthetic. Once this has taken effect, the patient should experience no more discomfort than any other invasive procedure.
There are two stages to treating an infected root canal; removal of the infected material and restoration of the tooth. An X-ray will always be taken first to ensure that no abscesses are present and if there are, they will be treated before the procedure commences.
Removing the infected material and tissues.
In order to access the root canals of the patient’s tooth, the top of the tooth is first of all removed. This allows the dentist to remove the infected pulp from the root canals and clean the hollow canals to eliminate any traces of infection that may be left behind (B & C).
Once the dentist is satisfied that the tooth is infection free, the restoration can take place.
Restoring the tooth
In order to restore the tooth to a functional state, the canals are first of all filled with a special filling known as ‘gutta percha’. This is a rubber like material that is used to fill and seal the canals (D).
The final part of the restoration is to complete the tooth. In nearly all cases, this is most effectively done using a dental crown. This will not only give it greater aesthetic appeal but also offers the strongest method available. In some cases, a simple filling may suffice, although this is likely to offer less strength than a crown. The restoration method used will depend on the extent of the treatment needed to clear the infection from the centre of your tooth (E & F).
Root canal treatment is usually successful at saving the tooth and clearing the infection.
One review of a number of studies found 90% of root-treated teeth survived for 8-10 years.
The study also found having a crown fitted to the tooth after root canal treatment was the
most important factor for improving tooth survival rates.
If you practise good oral hygiene, your treated tooth should survive for a long time.
The survival of your tooth depends on a number of factors, including:
• how much of the natural tooth remains
•Protecting what remains of the tooth
• how well you keep your teeth clean
• the biting forces on the tooth
If an infection does return, however, the treatment can be repeated.
Alternatively, if treatment has already been carried out to a high standard and the infection
remains, a small operation to remove the root tip (an apicectomy) may be carried out to
treat the infection.
Risks and complications
As with any medical or dental treatment, it is impossible to guarantee 100% success. Even
with an x-ray, the dentist can’t know the exact configuration of the root canals before
There are several factors which can affect the success of root canal treatment:
• the root canal configuration (position and shape) may make it difficult for the dentist
to access right to the tip of the root canal(s) which means that all the nerve tissue
may not be able to be removed
• some root canals can become “sclerosed”, meaning that they have become too
narrow or completely blocked, again preventing the dentist from accessing right to
the root tip
• if too much tooth structure has been lost due to decay it may be difficult or
impossible to provide an effective seal following root canal treatment – in this
instance the tooth may need to be extracted
• once the tooth has been accessed the dentist may find that there is a hairline crack
through the base of the tooth, often invisible to the eye or on an x-ray. In this
instance the tooth could not be saved
• some infections are very persistent and do not clear up following root canal
treatment, even with a course of antibiotics
If your dentist feels unable to provide the best outcome for your tooth themselves – for
example if the configuration is complex, or the root canals sclerosed – or if they have already
provided root canal treatment but it has not been successful then there are other options to consider for the tooth.
Following root canal treatment teeth become much more brittle and prone to fracture. This
can happen at any stage during or following the treatment. Your dentist may advise a crown
as the best long-term solution to protect the tooth. A period of several months to ensure the
tooth has completely settled is normally necessary before going ahead with the crown