Updated: Oct 14
On average a root canal can take anywhere from 45-90 minutes per appointment but it can vary depending on a couple of factors. The type of tooth, the size of the infection, and tooth abnormalities can all influence the amount of time it can take and the number of appointments.
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How long root canals take for each type of tooth
There is a direct correlation between the type of tooth that needs a root canal and the amount of time it requires to complete the procedure. The primary reason for the time correlation has to do with the number of nerves each type of tooth has. A larger tooth will have more nerves while a smaller tooth will typically have less nerves. It makes sense if you think about it because the more nerves you need to remove from the tooth, the more time it would take.
Incisors and Canines
The incisors and canines can have a root canal done in the shortest amount of time, clocking in at around 45 minutes total. The sole reason is because they tend to only have 1 nerve within the tooth so it does not require additional time unlike the other teeth. More nerves requires more work and more time. You'll be in and out of the dental office at the speed of light if you need the procedure done on one of these.
The premolars can take 45-60 minutes to complete a root canal because they often have 1-2 nerves within the tooth. If they have only one nerve then it'll just take 45 minutes but if they have 2 then it'll probably take about 60 minutes.
Whether they have 1 or 2 nerves is out of your control because that has more to do with genetics and what you've inherited from your parents. The premolar with the highest chance of having 2 nerves would be the upper first premolar.
Upper first premolar: 1 nerve =19.5%; 2 nerves = 79.5%; 3 nerves = 1%
Upper second premolar: 1 nerve = 56%; 2 nerves = 42%; 3 nerves = 2%
Lower first premolar: 1 nerve = 92%; 2 nerves = 8%
Lower second premolar: 1 nerve = 92%; 2 nerves = 8%
The teeth that take the longest to do a root canal would be the molars because it takes on average 60-90 minutes to complete. The reason is because they are the largest type of teeth and consequently have the most nerves. The molars often have a minimum of 3 nerves but they can have more than that.
Upper first molars: 3 nerves = 47%; 4 nerves = 53%
Upper second molars: 3 nerves = 59%; 4 nerves = 46%
Lower first molars: 1 nerve = 0.5%; 2 nerves = 18%; 3 nerves = 79.5%; 4 nerves = 2%
Lower 2nd molars: 1 nerve = 0.5%; 2 nerves = 18%; 3 nerves = 79.5%; 4 nerves = 2%
It all depends on your tooth and how many nerves it has, it may take close to the full 90 minutes if you happen to have a molar that has 4 nerves!
You shouldn't be doing root canals on wisdom teeth because they're difficult to access and they have the greatest variation in tooth anatomy.
Difficult to access - they are literally the last tooth in the mouth. Most people don't even have enough space for them and they're only partially erupted because they're impacted. That makes it next to impossible to even do a root canal on them.
Unpredictable tooth anatomy - the wisdom teeth are known to come in the greatest variation of shapes and number of nerves. This makes them incredibly unpredictable so the success rate for them are very low. We're not sure if you should even bother trying to spend money on it.
Due to the difficulty and cost involved, we would recommend against doing a root canal on any wisdom teeth. For those reasons, we are unable to give an estimated time for how long a root canal would take on them. Only superhero dentists in your dreams can complete that procedure on these teeth!
Factors that make your root canal take longer
Aside from the more nerves in a tooth, the longer a root canal takes, there are other factors that can add to treatment time. The two most prominent factors would be the size of the infection and also if the tooth has any structural abnormalities. These not only increase the amount of time needed but may also require additional appointments in order to remove the tooth and have it properly cleaned out.
The presence and size of the infection will often dictate how long a root canal takes because the larger the infection the more time it would require. In fact, if there is a visible abscess associated with the tooth, the root canal treatment would often require two separate visits to complete the procedure.
This means that for a front tooth that should've only taken 1 visit and 45 minutes to do a root canal, it will instead take 2 visits and probably a total of 60-90 minutes. The reason for the extra visit is that your dentist will have to place an antibiotic medication within the tooth for about 1-3 weeks before having you return to complete the procedure.
For a tooth without an abscess, they can remove the nerve and fill it back in the same day. However for the ones with an abscess, the extra step of placing a medication is required in order to ensure that the infection is completely eliminated.
Here is an x-ray of what a tooth abscess looks like:
What it looks like on an x-ray is a big dark circle around the tip of the root. You won't see the abscess disappear on the x-ray until many months after the root canal is completed. That is how long it takes for the bone that has been destroyed by the infection to fill back in.
Certain tooth anomalies can increase the time to do a root canal because they can make the treatment more complicated. Some of these abnormalities include curved roots, calcified canals, and pulp stones.
Most tooth roots have an ever so slight curvature but in some extreme scenarios, they can have some pretty exaggerated bends. The root curving increases the complexity of the case because your dentist has to proceed more slowly, otherwise they run the risk of breaking their root canal files inside the canal. The files are least likely to break in a straight canal. The greater the degree of curvature the greater the chance for them to break during treatment.
Sometimes due to trauma, the canals where the nerves are can start to calcify and close off. This makes it difficult to find and access the nerves because the opening is so small. In a healthy tooth, the canals are large and wide open which makes it very easy to find the nerve.
Here is are x-rays comparing a calcified canal vs a non-calcified one:
The tooth on the left has a non-calcified canal. You can tell by the large black line running through it to the tip of the root. That black line is the nerve.
The tooth on the right has a calcified canal. You can tell by an almost non-existent black line running through the root. It is still there but it is very thin and faint. You can barely see it when you compare it to the tooth on the left.
When the tooth is calcified, your dentist will be spending a lot of trying drilling around just to locate where the opening of the nerve is. That certainly adds time to the root canal procedure.
The kidney can get stones and your teeth can too, they are called pulp stones. They are basically calcifications or small rock like structures that are stuck in the pulp of the tooth. Since they are hard and blocking the way to get to the nerve, your dentist will need to drill through it. This additional step can add time to the root canal procedure.
Root canal procedures will take on average about 45-90 minutes but there are certain factors which may add time to the treatment. Therefore don't be surprised if it takes longer than the expected time and also if it takes more than one visit as well.
It is good to know how long a root canal takes but what is even better is if you catch all of these dental problems early so that they don't end up as one! That is why it is important to get your dental check up every 6 months.
Author: Written by Dr David Chen DDS, a long island city dentist.