The most common signs you need a root canal are tooth pain that lingers after hot or cold, throbbing or spontaneous toothache, pain when biting, a darkening tooth, and swelling or a pimple on the gum near a tooth. However, some teeth that need root canal treatment cause no symptoms at all, and only an examination with X-rays can confirm what is going on.
Root canal treatment has a reputation it does not really deserve. With modern local anaesthetic, most people find it feels similar to having a filling. Here is how to recognise the warning signs and what the treatment involves.
What is a root canal, and why is it needed?
Inside every tooth is a space containing the dental pulp: nerves, blood vessels and connective tissue. This space runs from the centre of the crown down through narrow canals in each root.
When the pulp becomes inflamed or infected, usually because of deep decay, a crack, a large or leaking filling, or an injury, it cannot heal on its own once the damage is severe. Bacteria can then spread through the canals to the bone around the root tip, causing an abscess. Root canal treatment removes the damaged pulp, cleans and disinfects the canals, and seals them to save the tooth.
Common signs you need a root canal
1. Lingering sensitivity to hot or cold
A quick twinge that disappears within seconds is common and often harmless. Sensitivity that lingers for 30 seconds or more after the hot or cold is removed can mean the pulp is inflamed and may not recover.
2. Spontaneous or throbbing toothache
Pain that starts without a trigger, throbs, or wakes you at night is a classic sign of irreversible pulp inflammation. Sometimes the pain is hard to pinpoint and may seem to come from the jaw, ear or another tooth.
3. Pain when biting or touching the tooth
If a tooth hurts when you chew or tap on it, the inflammation or infection may have spread to the tissues around the root tip. Pain on biting can also be a sign of a cracked tooth, which your dentist will check for.
4. Swelling, a gum boil or a bad taste
Swelling of the gum or face, a small pimple on the gum that may ooze (called a sinus tract), or a persistent bad taste can indicate an abscess. Facial swelling needs prompt attention, and swelling that spreads, or comes with fever or difficulty swallowing or breathing, needs urgent medical care.
5. A darkening tooth
A tooth that turns grey or darker, particularly after a knock, may have a pulp that has died. This can happen months or even years after an injury.
6. Pain that suddenly stops
If a severe toothache suddenly disappears, it can mean the nerve has died rather than recovered. The infection can remain and spread silently, so it is still worth having the tooth checked.
7. No symptoms at all
Some infected teeth cause no pain and are discovered on a routine X-ray, which shows a dark area of bone loss around the root tip. This is one reason regular check-ups matter.
How your dentist confirms the diagnosis
Symptoms alone are not enough to decide whether a tooth needs root canal treatment. Your dentist will usually:
- Ask about your symptoms: what triggers the pain, how long it lasts and whether it wakes you
- Examine the tooth and gums, and gently tap and press on teeth
- Test how the tooth responds to cold
- Take X-rays to look for deep decay, previous treatment and changes in the bone around the root
Where the anatomy is complex or the diagnosis is unclear, a 3D CBCT scan may help. We have CBCT imaging on site at our Macquarie Park practice, so it can be taken in the same building if needed.
What root canal treatment involves
Root canal treatment is often completed over two or more appointments, although some teeth can be treated in one.
- Local anaesthetic is given to numb the tooth and surrounding area.
- The tooth is isolated with a thin rubber sheet (rubber dam) to keep it clean and dry.
- An opening is made in the biting surface or back of the tooth, and the damaged pulp is removed.
- The canals are cleaned and shaped with fine instruments and disinfecting solutions. A medicated dressing and temporary filling may be placed between visits.
- The canals are filled and sealed once they are clean.
- The tooth is restored. Back teeth that have had root canal treatment are more prone to fracture, so a crown is often recommended to protect them.
You can find more detail on our root canal therapy page. Because the fee depends on which tooth is involved, how many canals it has, how many visits are needed and how the tooth is restored afterwards, a written estimate is given after assessment.
Risks, limitations and alternatives
Root canal treatment saves many teeth that would otherwise be lost, and treated teeth can last for many years. It is not certain to succeed, though. Possible issues include tenderness for a few days afterwards, a flare-up of infection, a canal that is very narrow, curved or blocked, an instrument separating inside the canal, or a crack that was not visible beforehand. Some teeth later need retreatment or minor surgery at the root tip, and some cannot be saved. Complex cases may be referred to a specialist endodontist.
The main alternative is to remove the tooth. Extraction is quicker, but a gap can lead to neighbouring teeth tilting and opposing teeth over-erupting, and replacing the tooth with an implant, bridge or denture adds cost and time. Your dentist will discuss the pros and cons of each option for your tooth.
Do antibiotics fix a tooth infection?
Antibiotics may be prescribed if an infection is spreading or you are unwell, but they do not remove the source of the infection inside the tooth. Without treatment of the tooth itself, the infection usually returns.
When to see a dentist
Book a dental appointment soon if you have lingering sensitivity, toothache, pain when biting or a darkening tooth. Do not wait for pain to become severe; earlier treatment is usually simpler.
Seek same-day care if you have significant pain or swelling. Our emergency appointments are offered same day where available, and calling before 10am gives you the strongest chance of being seen that day. If facial swelling is spreading, or you have a fever or difficulty swallowing or breathing, go to a hospital emergency department.
Frequently asked questions
Can a tooth that needs a root canal heal on its own?
Once the pulp is irreversibly inflamed or infected, it does not heal on its own. The pain may come and go or stop, but the infection can persist and spread without treatment.
Does root canal treatment hurt?
With local anaesthetic, most people find it feels similar to having a filling. The tooth may be tender for a few days afterwards, which is usually managed with over-the-counter pain relief as advised by your dentist.
How many visits does a root canal take?
Often two or more, depending on the tooth, the number of canals and whether there is infection. Some straightforward cases can be completed in one visit.
Do I need a crown after a root canal?
Back teeth are often crowned afterwards because they are more prone to fracture. Front teeth may only need a filling. Your dentist will advise based on how much tooth structure remains.
Is it better to pull the tooth instead?
Keeping your natural tooth is usually preferred where it can be saved, but extraction is sometimes the right choice. Your dentist will explain the options, costs and risks of each.
If you have any of these signs, an examination is the only way to know for sure. Call North Ryde Dentistry on (02) 8090 1102 or book an appointment.
This article is general information only and is not a substitute for advice from your own dentist. Any treatment carries risks; your dentist will discuss whether it is suitable for you.