What is root canal treatment (endodontic therapy)?

- What is its purpose? What does it accomplish? Why is having it important and a cure?

What does
root canal
accomplish?

Link to 'What does root canal accomplish?' section.

What does root canal therapy do?

You may find yourself in the situation where you've been told that your tooth needs root canal treatment. And you understand that it offers a way of saving your tooth.

But what you don't get is how it accomplishes this. You don't understand the underlying purpose of having endodontic therapy, and what it changes about your tooth.

These issues are the subject of this page. Below we outline the goals and objectives of this procedure, and explain what's different about your tooth afterward that makes it so it can be retained.

Our website also explains ...

After you've read this page, scroll back to the list below. It contains links to our other pages that provide additional information about having root canal.


Root canal therapy treats the nerve space inside a tooth.

This slide series explains what treatment accomplishes.

1) What is root canal treatment?

Root canal (endodontic) therapy refers to the process where a dentist treats (cleans out and then seals off) that space inside a tooth originally occupied by its "nerve."

[Dentists refer to a tooth's "nerve" as its "pulp tissue." On our pages we use both terms interchangeably.]


2) What does root canal treatment accomplish? / What's its purpose?

Root canal therapy is used to treat pathological conditions inside a tooth that have affected its nerve tissue, and often the tissues that surround its root too.

Necrotic pulp tissue removed from a tooth.

This is nerve tissue that's been pulled out of a tooth's root canal.

By completing treatment ...

  • A dentist both resolves the tooth's internal (nerve space) problems (by way of removing dead or dying pulp tissue, clearing up infection, sanitizing the tooth's root canal system, etc...) ...
  • ... and also sets the stage so the person's body's healing process can successfully return those tissues that surround the tooth's root that have been affected by its internal condition, back to a normal healthy state.

The procedure itself is primarily a two-stage process.

  • A) Cleansing the tooth's interior. - This first portion of the procedure involves removing compromised tissues (infected, necrotic, degenerating), microorganisms, and associated debris and contaminates, from within a tooth's nerve space (root canal system).
  • B) Sealing off the treated area. - The procedure is then completed by filling in and sealing off the tooth's cleansed internal space, so contaminates can't leak back into or out of it.

Details -

A) Cleaning the tooth. - What does this step accomplish?

Background.

Dentists use root canal treatment to resolve a wide range of nerve-related problems. For example, this same fix is used when a tooth's pulp tissue is: 1) Acutely inflamed, 2) In the process of dying, or 3) Completely necrotic (dead). It's also used when the tooth's interior harbors an active infection (acute flare-up).

And although each of these conditions is different, what they each have in common is that they all involve (or ultimately will) a situation where the tooth's nerve space harbors contaminates that will leak out of the tooth's root tip and persistently irritate (inflame) the tissues that surround it.

The goal.

So, the underlying purpose of the cleaning portion of the root canal procedure is for the dentist to sanitize the interior of the tooth as effectively as possible.

To do so, they'll remove the remaining remnants of the tooth's pulp tissue (live or dead), the organic debris left over from the breakdown of this tissue, microorganisms (bacteria, fungi) and the toxins and other byproducts that they have created.

B) Sealing off the tooth's interior. - Why is this important?

The sealing aspect of the root canal procedure has to do with filling in and sealing off the (now empty and sanitized) nerve space inside the tooth. Related to this goal, there are two objectives.

  • One of them is for the filling material to create a seal that prevents contaminates from seeping back into the tooth, so it's not recontaminated/reinfected.
  • The other goal is just the opposite. The seal prevents any irritants still trapped within the tooth's root canal system from seeping out and causing persistent irritation of the tissues that surround the root.

A tooth's canal system can have many branches.

How a dentist cleanses a tooth.

How is it that things can seep out? Hasn't the tooth's interior been cleansed?

Root canals don't really have a precise shape like we show in our illustrations.

They're more like a river where the main channel may give birth to small divisions that wander away and then return. Or else branch off and follow a different route entirely.

The problem this poses.

Due to this convoluted configuration, and despite a dentist's best efforts, it's always possible that some debris still remains. And in fact, the reality of the matter is that studies have shown that the root canal system of a tooth really can't be completely cleaned and disinfected. (Hargreaves)

So, the sealing process insures that these (hopefully minimal level of) contaminates that remain are entombed within the tooth and can't seep out and persistently irritate the tissues that surround its root.


3) Why are contaminates harbored within a tooth such a big issue?

Your body's ability to handle infections inside teeth is different than with other parts of your body. That's because teeth are hard, cavernous objects.

A comparison -

A) Soft-tissue infections.

As an example, imagine that your finger has a cut that's become infected. If so, your body's immune system will kick into gear.

By way of your blood and lymphatic vessels, the area will be flooded with white blood cells that will combat the invading bacteria. And, in most cases, your cells will win. They will kill off the offending microorganisms and clear away their associated debris.

B) Infections inside teeth.

Now, consider the scenario with teeth. Once a tooth's nerve tissue has started to degenerate (die off), and bacteria have taken up residence inside the tooth's empty nerve space, it's difficult for white blood cells to effectively get at the microorganisms to combat them.

A tooth whose nerve has dies provides a prime location for bacteria to live.

Necrotic (dead) teeth make a nice home for bacteria.

There's limited transportation available.

Due to the deteriorated state of the tooth's pulp tissue, the blood and lymphatic vessels inside the tooth that might be used to transport these cells directly to where they are needed, either no longer exist or have been compromised.

That means the nerve space inside a tooth (especially when fully necrotic) can provide a nice cozy cave-like location for bacteria because it's a place where your body's defense mechanisms have a hard time getting at them and being effective. (Ingle)

The consequences.

With this scenario, at best your body will only be able to cordon off the infection stemming from inside your tooth, via setting up a perimeter of defensive tissues and cells around the tooth's root.

As a worst case, the infection will massively overwhelm your body's wall of defenses, resulting in pain and swelling (an acute tooth abscess).

What actually happens is often a mixture of both. One where the tooth's infection remains quite (cordoned off and controlled) most of the time, with periods of (hopefully minor) flare-ups where some level of tenderness, pain or swelling is noticed.

So, here's what root canal treatment accomplishes.

Endodontic therapy provides for a third outcome, one where an infection associated with a tooth is not just cordoned off but instead can actually be cleared up by your body's defense mechanisms.

  • The root canal treatment assists your body's infection-fighting process by removing (disinfecting) and sealing off (entombing) bacteria and contaminates inside your tooth that it would otherwise have difficulty dispensing with.
  • Following the completion of your tooth's treatment, no further leakage of irritants from its root should occur.
  • Any microorganisms and contaminates that have already exited, and as a result have inflamed the tissues that surround your tooth's root, can be dealt with in normal fashion by your body's immune system.
  • The expectation is that this clean up and healing process will be successful. The result will be an inert tooth root (one that doesn't leak irritants) surrounded by normal healthy tissues.

 Reference: 

Hargreaves KM, et al. Cohen's Pathway of the pulp. Chapter: The core science of endodontics. - Linked above.

Other things you need to know to understand root canal treatment.

Where precisely in a tooth is its nerve?

A tooth's nerve tissue (pulp) is housed in its canals and pulp chamber.

Total tooth nerve space = Canal(s) + Pulp chamber

Teeth are not solid. Instead, inside every tooth lies a hollow space filled with the tooth's pulp tissue ("nerve"). Dentists use the following terms to refer to various portions of this nerve space:

a) The pulp chamber.

This is a cavern that lies pretty much in the center of a tooth's crown (the portion that is visible above the gum line).

b) Root canals.

Root canals are tiny tunnels that run the length of a root. (From the tooth's pulp chamber down to the root's apex (tip).)

As a rule, every tooth root (note: some teeth have more than one) will contain at least one root canal. But a root having more than just one is possible, and commonplace with some kinds of teeth. (For more in depth information, visit our page: How many roots and root canals do teeth have?)

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Isn't it important for a tooth to have a nerve?

No, not really. A tooth's pulp tissue plays a role in the its formation and development. But once that's been completed, it's not so vitally important. So, having it removed during root canal treatment isn't that big of a deal.

You don't really get much "feeling" input from a tooth's nerve.

Under normal circumstances, the nerve tissue inside our teeth provides us with comparatively little information.

Yes, when subjected to pressure or temperature extremes, or exposed to severe insult (like advancing tooth decay or the formation of a crack), teeth do respond with a painful sensation. But other than that, the nerves inside our teeth remain relatively unresponsive.

Proprioception.

You might think that when you push on your teeth, or else close them together, the pressure sensation that you feel (proprioception) is a signal from within your tooth.

Actually, most of this sensation (around 70%) comes from the nerve fibers found in the tissues that surround your tooth's root, with the remainder originating from its pulp tissue (Eliyas). On a practical level however, this loss is not usually noticed.

 Reference: 

You'll never miss your tooth's nerve.

Due to the above, from a standpoint of normal function, the presence of live nerve tissue within a tooth is pretty much optional. If it's present and healthy, then wonderful. But if it's been removed as a part of root canal treatment, then that's fine too. You'll never miss it.

 

Last revision/review: 12/26/2018 - Revision with content added.

 
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