top of page

Root Canal: Things To Know

Updated: Feb 6

A root canal is an endodontic dental procedure that removes the nerve from an infected, abscessed, or severely decayed tooth. Your dentist will drill through the enamel and dentin until it reaches the pulp chamber. Then the nerves can be removed from the canals with a combination of hand files and rotary files.

Completed root canal on molar
Completed root canal on molar

Afterwards, the canals and the entire interior of the tooth will be disinfected. Once it is all clean, the canals will be obturated (filled) with a root canal filling material called gutta percha. A temporary filling will then be placed in the tooth and you may return to your restorative dentist for a core build up and a crown.

Since only the nerve gets extirpated and not the entire tooth, the tooth can remain in the mouth after completion of the procedure. This is in stark contrast to an extraction which removes the entire tooth from mouth. For this reason alone, root canals are often referred to as "saving teeth".

Table of contents:


When is a root canal needed?

The most obvious reason for needing a root canal is when the tooth nerve gets infected which results in unbearable tooth nerve pain. However there are times where asymptomatic teeth without a toothache can need it too.

When root canals are needed:

  • Pulp decay. Untreated enamel decay will progress through the stages of tooth decay and end up at the tooth nerve. Once the nerve gets affected it will need a root canal.

  • Tooth nerve pain. Spontaneous tooth pain that comes and goes is a sign of nerve pain.

  • Pulpitis. The pulp can become inflamed and result in reversible or irreversible pulpitis.

  • Abscess. Infections that are left untreated will swell up into an abscess.

  • Dead tooth. Teeth that have died will become discolored and look grey.

  • Pimple on the gums. Gum boils next to teeth are signs of an abscessed tooth.

  • Fracture. Mild tooth fractures can sometimes still be saved with a root canal. The more severe breaks will require an extraction instead.

  • Trauma. Sports injuries or accidents to teeth may sometimes result in root canals.

  • Crowned teeth. Sometimes teeth with crowns on them can get infected but fortunately a root canal can be done through it.

Teeth that need root canals will look different on x-rays. It's radiographic appearance can be used as a diagnostic tool to determine if a root canal is needed.

How common is it?

According to statistics, over 41,000 root canal treatments are performed on a daily basis. That means over 15 million teeth undergo the treatment every single year. Therefore it is not unusual if you happen to need one since it is fairly common.

Who does the procedure?

If you need a root canal, most general dentist offices should be able to help you. Although if you can find an endodontist (root canal specialist) it would be even better! On average, the specialist can handle more complex cases than the general dentist.

Our recommendation would be if you need a root canal treatment on a molar you should definitely seek out the endodontist. The reason being that the molars tend to have multiple nerves in one tooth. The specialists all have a big microscope that can magnify the tooth 10-40x for better visualization.

Of course that is not to say that your primary dentist can't do it, it all depends on their particular skill set. Some of them like doing the procedure and do a lot of it while others refer out all of the cases.


Root canal procedure - What to expect

Unlike a tooth extraction, root canal treatment (RCT) do not require much preparation at all. To be quite honest, you don't need to treat it any different than a dental filling in terms of preparation beforehand.

Just make sure you have a nutritious meal before the appointment because you won't be able to eat for 2-3 hours afterwards. The no eating rule is due to the numbness from the local anesthesia (lidocaine). Once it wears off you will be immediately fully functional.

Steps of the procedure

root canal steps diagram
  1. Sign consent forms. Read all of the risks and benefits. Last chance to ask questions.

  2. Administer local anesthesia. Topical anesthesia (benzocaine) is applied first, followed by the injection with lidocaine or articaine.

  3. Place rubber dam. A rubber dam is placed over the tooth that needs the root canal. This contraption isolates the tooth from the rest of the mouth. It serves two purposes.

  • Prevent saliva contamination. The procedure demands that the tooth be as sterile as possible. Saliva contains a lot of bacteria so it is paramount to keep saliva away.

  • Patient safety. The rubber dam prevents you from swallowing endodontic files as well as sodium hypochlorite (bleach). Accidents do happen and this contraption minimizes its occurrence.

  1. Occlusal reduction. This step will flatten the cusps of the teeth or reduce the overall occlusion of the tooth by about .5-1 mm. This incredibly important step accomplishes two things.

  • Provide a consistent measuring point for the lengths of the canals.

  • Reduces post-operative pain. If your dentist forgets to do this step you'll often feel pain when you bite down!

  1. Tooth access opening. This is the part when your dentist drills through the enamel and dentin in order to reach the pulp. The pulp chamber is where the tooth nerve is located.

  2. Cavity removal. All tooth decay needs to be excavated prior to going into the canals. Otherwise bacteria can re-infect the root canal.

  3. Cleaning the canals. The actual process of extirpating the tooth nerve. This is done with endodontic files, EDTA, and also sodium hypochlorite.

  4. Shaping the canals. The canals need to be flared out and shaped to fit the root canal filling material. The shaping of it will also remove additional tooth structure to ensure cleanliness and disinfection.

  5. Disinfection. After the root canal has been cleaned and shaped, a final round of disinfection is required prior to filling it. Different dentists will have different preferences as to the combination of disinfectants (sodium hypochlorite, chlorhexidine, EDTA) to use.

  6. Obturation. The canals are obturated with gutta percha, which is the filling material.

  7. Temporary filling. The pulp chamber is then filled in with a temporary material called Cavit G. It is soft and malleable but will harden once it comes into contact with water. This material is preferred over a permanent filling due to its ease of removal.

  8. Return to a restorative dentist. The root canal is now completed but treatment for the tooth does not end there. The temporary will need to be replaced with a core build up and a porcelain crown.

temporary filling material for root canals
temporary filling material

Most commonly, a core build up is done prior to the crown placement. Although your dentist may opt for a prefabricated post and core or even a cast post and core. That would depend on how much tooth structure you're missing.

How long do root canals take?

On average, a root canal will take about an hour per appointment. Depending on the complexity of the case and also which tooth is involved, it may take 1-3 appointments total.

Examples of tooth conditions and required time/visits:

  • Vital front teeth can be completed in an hour with one appointment.

  • Non-vital teeth will require two hours and two appointments.

  • Abscessed teeth will most likely require three hours and three appointments.

Do root canals hurt?

Hearing the word "root canal" will make most people tremble in fear with their knees giving out because of the anticipation of pain.

However that couldn't be further from the truth because the procedure is not supposed to hurt. You will be thoroughly numb after you receive adequate local anesthesia so you shouldn't feel a thing. In fact, sedation is not common for root canals at all and are mostly used during wisdom teeth extractions.

Nonetheless there is an exception and that is if you have a "hot tooth." This condition is when the tooth is so inflamed or infected that it has difficulty in getting numb. What you'll find is that your dentist will give you multiple doses of lidocaine but it just won't get anesthetized.

Whenever we have this happen, we usually stop the procedure and prescribe the patient antibiotics and pain medication. After about 2 days of taking the medication, they can return to try again. The second time will usually only require a single dose of lidocaine. Round two will be painless, we promise.


Risks, benefits, and alternatives


As with all procedures, root canals are not all benefits with no risks. These are potential adverse effects or outcomes which may occur during or after the procedure.

  • Tooth discoloration. Teeth that have been treated with root canals will slowly start to discolor over time because the tooth is now dead. They'll look a little bit more yellow or grey after each year. This is why you need a crown over it to come up the color.

  • Separated file. It is not uncommon for a rotary endo file to separate inside of the canal. In other words, the nickel titanium file can break inside of your tooth and be stuck there permanently. However most times, the endodontist can work around the separated file.

  • Sodium hypochlorite accident. A rubber dam is used during the procedure to prevent these accidents but sometimes it can still happen. A tell tale sign is when your face swells up like a balloon after the root canal.

  • Bruising. Contusions can occur from the penetration of the dental anesthetic injection.

  • Curved canals. Depending on the severity of the root curvature, it may increase the chances of files separating. It may also make it impossible to clean out the canals fully.

  • Potential re-infections. It is not a one time done deal because the teeth can get re-infected. A sign of this is if the abscess is still there even after the RCT. If that occurs you may need to do a root canal retreatment.

Molar with curved canals x-ray
Credit: Dr Zegar Zegar

The x-ray above shows a completed root canal where you can see some of the extreme curvatures of the canals. When a file has to navigate through these, we're honestly quite amazed at how more files don't break... The flexibility of nickel titanium files is impressive.

Here is a video demonstrating the rotary files navigating through curvatures on a fake canal:


As scary as it may seem to you, the benefits are quite bountiful. It is typically more beneficial to get it than to choose its alternative, a tooth extraction.

  • Saving teeth. The only other alternative for teeth that need root canals would be an extraction. By getting the procedure you can save your tooth instead of pulling it out.

  • Instant pain relief. Painkillers aren't very effective for tooth nerve pain but this procedure can alleviate your pain immediately. It will no longer feel cold sensitivity after.

  • Treats infections and abscesses. Cavity fillings can't get rid of abscesses but root canals can. It is one of the few ways to effectively treat infections.

  • Safe. Since it is not a surgical procedure, the risks involved are significantly lower than an extraction. The after effects are similar to getting a dental filling done if you don't have any facial swelling.

However you should be aware that after the root canal the tooth will be dead. That is a good thing because it will no longer experience any pain.


There is only ONE ALTERNATIVE to a root canal and that is to get a tooth extraction. There is no other dental procedure known to man that can treat tooth nerve pain. The decision for what to do with the tooth comes down to if you want to save it or take it out.

Although if you do opt for the alternative you still need to decide how to replace the missing tooth afterwards. Will you get a bridge or an implant?


Recovery and Outlook

Root canal recovery time

The recovery time will differ depending on if you had facial swelling prior to starting the treatment. If you did then it would take more time and if you didn't, there shouldn't be much discomfort at all.

Recovery timeline:

  • Root canals with no facial swelling should only take a day to recover. You may feel a little sore and tender but you shouldn't have much pain. After all, there are no more nerves in the tooth so it can't feel any pain even if it wanted to.

  • Root canals with facial swelling will take about 2-3 days to recover. If your face was swollen going into the procedure you will be prescribed antibiotics. The recovery time isn't so much due to the procedure itself but rather waiting for the antibiotics to kill the infection and reduce the swelling. About 2-3 days is how long you can expect for the swelling to completely dissipate.

What can I eat and drink after?

You should wait about 2-3 hours after the root canal before you even attempt to eat anything. This is because the numbness from the anesthesia takes about that long for it to wear off. You don't want to end up chewing your lip or your tongue while you're still numb.

You can eat whatever you like but try to avoid hard crunchy foods (seeds, popcorn, nutes, etc) on the affected side. You want to be more gentle on that side for the next 2-3 days while the tooth is recovering. Please try to chew more on the opposite side in the meantime.

Beverage wise you can drink whatever you like. Do try to minimize the sugary drinks because too much of it can result in cavities. You don't want to have to go through another root canal do you?

Do I need a chaperone for the appointment?

Unless you are getting sedated, you won't need a chaperone for the appointment. You should be able to get to and from the appointment just fine on your own. However if you want someone there for moral support then feel free to bring a friend!

Root canal aftercare

After the root canal is completed, you will leave with a temporary filling in the tooth. You can brush it and floss like any other tooth in the mouth. No special care is required.

Exception: If the decay started from in between the teeth, you may be advised to avoid flossing the area. This is because you may floss out the temporary filling by accident if you do. If the temporary is on the chewing or occlusal surface then you can floss as much as you want.

How long do root canals last?

Nothing lasts forever except diamonds but root canals can last for a very long time. The recommendation is to leave them alone if they are not causing problems nor have signs of re-infection.

You only need to retreat them if something happens to them. Otherwise you should let sleeping dogs lie. We've seen many root canals successfully last for decades! If you need an example, Dr Chen has a tooth with a root canal that is nearly 20 years old. There are no problems and it's going strong.

When to call your dentist

Most root canals are uneventful and typically do not require a follow up with the treating dentist. However complications may arise as with all things... Here are some signs on when you should contact your dentist.

  • Swelling that does not improve. Infections should slowly start clearing up after the treatment. If you notice that the facial swelling is not going down, that is a cause for concern. Perhaps the antibiotics is not working or you need the tooth cleaned out again.

  • Increasing pain. Pain in between root canal appointments are referred to as "flare ups" which basically means that you need the canals cleaned out some more. There is probably still bacteria that is left inside of the tooth.

  • Missing temporary filling. You can accidentally floss out the temporary filling.

  • Pimple on the gums. If a gum boil develops after the root canal, you will need to go back to your dentist. They will need to place an antibiotic inside of the canal in order to get rid of the pimple on the gums.

  • Cracked tooth. If you wait too long after the treatment to get a crown on the tooth, you can fracture it. This usually happens if you bite down on something very hard the wrong way. The purpose of the porcelain crown is to protect the tooth after this treatment.

When you don't need to call a dentist

A lot of patients panic when they feel the temporary filling with their tongue and notice that it is shrinking. They think that their temporary has fallen out whenever they feel this.

However the temporary material is meant to slowly dissolve over time, hence why it is temporary and not permanent. A little bit of dissolution is fine and is not a cause for concern. It was designed to last a few weeks so as long as you make it back to your dentist within 1-3 weeks you should be fine.



David Chen 200 x 200.jpg

About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

Association Memberships:

Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

bottom of page