How many roots and root canals do teeth have? -

Number of roots and expected number of root canals, by tooth type. / Tables and charts.

Many of the videos we feature on our website mention that some factors associated with the process of having root canal treatment hinge on how many individual roots and root canals the tooth has.

These include: treatment cost, the amount of procedure time needed and overall case complexity.

Table: Expected number of roots and root canals, by tooth type.

If you happen to know which of your teeth will receive treatment, the table below can give you an idea of how many roots and root canals it probably has.

A table showing how many roots and root canals different types of teeth have.

Actual numbers tends to vary.

As you can see in the chart above, teeth always have at least one root. And each tooth root always has at least one root canal. But beyond that basic format, a lot of variability can exist.

Variability in the number of roots.
Chart showing the number of roots per tooth type.

Chart showing the number of roots per tooth type.

a) Anterior (front) teeth.
  • Upper and lower central incisors, lateral incisors and cuspids (canines, eyeteeth) - Each has just 1 root.
b) Posterior (back) teeth.
  • Upper 1st premolars - 2 roots.
  • Upper 2nd premolars - Both 1 or 2 roots is possible.
  • Lower 1st and 2nd premolars (bicuspids) - Just have 1 root.
  • Upper 1st, 2nd and 3rd molars - 3 roots.
  • Lower 1st, 2nd and 3rd molars - 2 roots.
Variability in the number of root canals.

Each of a tooth's roots will have at least 1 root canal. But some characteristically have, or at least often have, more. Here are some examples of the common variations dentists know to look for.

  • Lower molars - It's expected that the front (mesial) root of a lower molar (especially a 1st molar) will have 2 canals. It's not uncommon that the back (distal) root will have 2 too.
  • Upper 2nd premolars - In the case that this tooth just has a single root, it's very common for it to have 2 canals.
  • Upper molars - It's common for the front (mesial) root of an upper molar (especially a 1st molar) to have 2 canals.
  • Lower central and lateral incisors - The single root of a lower incisor sometimes has 2 canals.
Other variations.

Beyond the general rules of thumb given above, other disparities can exist and are even fairly commonplace in the real world.

Dental journals are chocked full of case reports where a tooth receiving endodontic treatment was found to have a larger number of canals, or even roots, than expected.

Videos showing how many roots and root canals teeth have.

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 Watch Video Root canal treatment / Maxillary first premolar.

Run time of segment chosen: 1 minutes 3 seconds.   /   Type: Clinical video

Details about this video.

This clinical footage shows an upper first premolar receiving root canal treatment, and how this type of tooth while just having one root may still have two root canals.

More about this video ...
  • As mentioned in our text and charts above, an upper first premolar may have one or two roots. In this case, the tooth shown in the video seems to have just one (as evidenced by the x-rays of the tooth that are shown).
  • This one root, however, has two separate canals.

    (When viewing the segment of the video we've selected, you can see a "figure 8" shape inside the tooth. The two loop portions of the "8" are the openings where each root canal joins up with the tooth's pulp chamber.

Originally these two openings would have been substantially smaller in diameter. What you see in the portion of the video we've chosen is their shape after each root canal has been "worked." (Meaning instruments have been used inside each canal to clean it out and shape it, in preparation for the sealing process to follow.)

 Watch Video 4 root canals in mandibular right first molar.

Run time of segment chosen: 44 seconds.   /   Type: Clinical video

Details about this video.

This clinical footage shows a lower first molar undergoing root canal treatment, and how this type of tooth with its two roots may have four root canals.

More about this video ...
  • As mentioned in our text, a mandibular (lower) first molar always has two roots.
  • It's expected that the mesial (front) root will have two canals.
  • The distal (rear-most) root typically just has one canal, but it may have two (which is the case with the tooth shown in this video).
  • That makes for a total of four root canals present in this lower first molar.

When viewing this video, look for the two separate pairs of openings. These are literally the holes in the floor of this tooth's pulp chamber that lead down into its roots' canals.

Other things to know.

It seems that most of the work that the dentist is performing in the portion of the video we've selected involves opening up and flaring the upper 1/2 or so of each of the individual canals. Doing so will aid in both the remainder of the process used to clean them, and then their sealing procedure to follow.

This video segment also shows the dental microscope that the dentist is using during this procedure. It's important that all of a tooth's root canals are located and treated. The extra magnification that the use of a microscope can provide aids with these tasks.

The number of root canals generally correlates with treatment complexity.

In general, the greater the number of root canals that a tooth has, the greater the degree of difficulty associated with treating it.

That's not to say that teeth with two canals are twice as difficult to treat as those that have just one. But a dentist can generally anticipate that the canals they find in the former will likely be narrower, probably harder to locate, and potentially more challenging to work (clean and shape with their instruments) than teeth that have just a single canal.

Treatment complexity: Incisors vs. molars.

As an example, without question a dentist is likely to experience far fewer difficulties and frustrations when treating an upper incisor (a tooth known for typically having a single large canal), as opposed to an upper molar (which is likely to have at least 4 canals, 3 of which are usually relatively small in diameter).

Procedure cost and appointment time vary according to treatment complexity.

You'll find that the cost of root canal treatment, as well as the amount of time and/or number of visits it takes to complete it, generally correlates with the complexity of the tooth's anatomy (its combined number of roots and root canals).

a) Treatment costs.

If you'll explore this link (root canal treatment cost estimates - website: Animated-Teeth.com), you'll see how dentists categorize their fees for endodontic therapy according to tooth type (in this case a general proxy for expected number of tooth roots and root canals).

For example, you'll find that treating an upper molar (a tooth that has at minimum 3 canals) can be expected to cost roughly 30 to 40% more than an upper incisor (a tooth that just has a single canal).

b) Treatment / appointment time.

In corresponding fashion, appointments scheduled for treating a molar might be expected to run over an hour (and possibly more than one appointment may be needed).

In comparison, teeth having a single canal can often be treated in just a single appointment, lasting possibly on the order of 45 minutes or less.

 
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