If you have been told you need a root canal, it is natural to feel a little anxious. The reassuring news is that modern root canal treatment is carried out under local anaesthesia, and many patients find it feels similar to having a filling, only longer. Its purpose is to remove inflamed or infected tissue from inside the tooth, clean the space thoroughly and seal it, so that you can keep your natural tooth instead of losing it. Below we explain the signs that may point to a problem, what actually happens inside the tooth, how the treatment works step by step and what to expect afterwards.
Signs you might need a root canal
Problems with the nerve of a tooth do not always cause obvious symptoms, and some infections are only discovered on an X-ray during a routine check. When there are signs, they can include:
- Lingering pain: a toothache that throbs, wakes you at night or carries on for a long time, rather than coming and going quickly.
- Sensitivity that stays: pain with hot or cold food and drinks that lasts well after the hot or cold has gone.
- Pain when biting: tenderness when you chew or press on a particular tooth.
- Swelling: swelling of the gum or face near a tooth, or a small pimple-like bump on the gum that may release fluid.
- A darkening tooth: a tooth that turns grey or darker, sometimes long after a knock or injury.
- Deep decay or a crack: damage that has reached close to the nerve of the tooth.
These symptoms can also have other causes, such as gum problems, sinus congestion or a cracked filling, and pain sometimes eases even though an infection remains. Only a dentist, with a clinical examination and X-rays, can tell whether root canal treatment is needed. If you have facial swelling that is spreading, difficulty swallowing or breathing, or a fever, seek urgent medical care.
What happens inside the tooth
Beneath the hard outer layers of enamel and dentine, every tooth has a soft core called the pulp. It contains nerves, blood vessels and connective tissue, and it runs from the crown of the tooth down through narrow channels inside the roots: the root canals. Front teeth often have a single canal, while back teeth usually have several, sometimes with curved or complex shapes.
When bacteria reach the pulp, for example through deep decay, a crack, a leaking filling or after an injury, the pulp can become inflamed. Because it is enclosed by hard walls, the swelling has nowhere to go, which is one reason the pain can be so intense. If the problem is not treated, the pulp may die, and bacteria can spread through the tip of the root into the surrounding bone, where an abscess can form.
Once a tooth is fully developed, it does not need its pulp to stay in the mouth, because it is supported and nourished by the tissues around the root. That is why removing the pulp, disinfecting the canals and sealing them can allow the tooth to keep working for chewing and smiling.
The procedure step by step
The details vary with the tooth and the situation, but root canal treatment generally follows these stages.
- 1
Step 1
Local anaesthesia
The area is numbed with a local anaesthetic, just as for a filling, so you shouldn't feel pain during the procedure. A very inflamed tooth can sometimes take longer to numb. Let your dentist know if you feel anything, as additional anaesthetic can usually be given.
- 2
Step 2
Isolation with a rubber dam
A thin protective sheet called a rubber dam is placed around the tooth. It keeps the tooth dry and free of saliva, which contains bacteria, and it stops small instruments and rinsing solutions from going into your mouth. You can still breathe and swallow normally while it is in place.
- 3
Step 3
Opening the tooth and locating the canals
The dentist makes a small opening in the top of the tooth to reach the pulp chamber and find the entrances to the canals. Dentists may use magnification to see the fine details inside the tooth, and X-rays or an electronic measuring device can help determine the length of each canal.
- 4
Step 4
Cleaning and shaping
Using very fine instruments, the dentist removes the inflamed or infected pulp and shapes the canals so that they can be cleaned and filled properly. Throughout this stage the canals are rinsed with disinfecting solutions to wash away bacteria and debris. This is the most important part of the treatment and can take time, especially in back teeth with narrow or curved canals.
- 5
Step 5
Filling the canals
When the canals are clean and dry, they are filled and sealed, usually with a rubber-like material called gutta-percha together with a sealing paste. This closes the space so that bacteria cannot easily get back in. If more than one appointment is planned, a medicated dressing may be placed in the canals between visits instead, and the tooth is closed with a temporary filling.
- 6
Step 6
Temporary or final filling
The opening in the top of the tooth is then closed. Sometimes a temporary filling is placed first and replaced with a permanent restoration at a later visit; in other cases the final filling is placed straight away. A tight seal at the top of the tooth is important, because leakage can let bacteria back into the canals.
- 7
Step 7
Often a crown afterwards
Teeth that need root canal treatment have often already lost a lot of structure to decay or old fillings, and back teeth in particular can become more brittle afterwards. For this reason, your dentist may recommend a crown or an onlay to protect the tooth from breaking. Front teeth with less damage may only need a filling. Your dentist will explain which option is suitable for your tooth.
One visit or more?
Many root canal treatments can be completed in a single appointment, while others are spread over two or more visits. This depends on factors such as the number and shape of the canals, how severe the infection is, whether there is swelling or drainage, and how much time is needed to clean the tooth thoroughly. A complex molar, or a tooth that has had root canal treatment before and needs retreatment, may require more time.
Your dentist will tell you what to expect once the tooth has been assessed. If you are travelling for treatment, it is worth discussing the possible schedule in advance, including when the final filling or crown can be placed, so that you can plan your stay with some flexibility.
After treatment
Once the anaesthetic wears off, it is common for the tooth and the area around it to feel tender for a few days, especially when biting. This usually improves steadily. Your dentist can advise you on suitable pain relief if you need it.
- Avoid eating until the numbness has worn off, so that you do not accidentally bite your cheek or tongue.
- Be gentle with the tooth until it has received its final filling or crown, as it can be more likely to break in the meantime.
- Keep brushing and cleaning between your teeth as usual, including around the treated tooth.
- Attend any follow-up appointments, including the visit for a crown if one has been recommended.
Contact your dentist if swelling appears or increases, if pain gets worse rather than better after a few days, if your bite feels high, or if a temporary filling comes out. Seek urgent care if you develop spreading swelling, a fever, or difficulty swallowing or breathing.
What affects the long-term outcome
Root canal treatment often allows you to keep the tooth for many years, but no dentist can promise a particular result, because success depends on several factors:
- How much healthy tooth structure remains, and how well the tooth is restored afterwards.
- How complex the canals are, and whether all of them can be cleaned and sealed.
- Whether there was a long-standing infection in the bone around the root.
- The quality of the seal at the top of the tooth, which helps prevent new leakage.
- Your gum health, your oral hygiene and habits such as grinding.
Healing of the bone around the root can take months and is usually checked on later X-rays. Occasionally a treated tooth develops problems again. In that case, options may include retreating the canals, a minor surgical procedure at the tip of the root, or extraction. Your dentist can explain how these factors apply to your own tooth.
Alternatives: extraction and replacement
The main alternative to root canal treatment is removing the tooth. Extraction can be quicker in the short term and is sometimes the better choice, for example when a tooth is cracked deep below the gum, too broken down to restore, or has a poor outlook because of advanced gum disease.
Losing a tooth does have consequences, though. A gap can allow neighbouring teeth to drift and tilt, can affect your bite and chewing, and over time the bone in that area can shrink. Replacing the missing tooth with a dental implant, a bridge or a removable denture usually involves further treatment and time, and each option has its own benefits and limitations.
Leaving an infected tooth untreated is generally not advisable, because infection can persist or spread even when the pain settles down. A good dentist will discuss the realistic options for your situation, including the pros and cons of keeping or removing the tooth, so that you can make an informed decision.
Next steps
If you have a painful tooth, or have been told that you need root canal treatment, you are welcome to send us your recent X-rays together with a short description of your symptoms. Our team can review them and explain what an examination would need to assess. A definite diagnosis and treatment plan can only be made after seeing you in person, but getting advice early can help you understand your options and avoid waiting until a problem becomes urgent.
