The root canal procedure.
This page describes the steps a dentist follows when they perform root canal treatment (endodontic therapy). Use the blue tabs on the right to access information that answers individual questions about this procedure.
The steps of having root canal -
Step 1 - Placing the rubber dam.
After numbing you up, your dentist will "isolate" your tooth by way of placing a rubber dam. A "rubber" dam is simply a thin sheet of latex (about 6" x 6").
Your dentist will punch a hole near the center of this sheet. They'll then slip it over your tooth so it alone sticks through. A metal clamp is then positioned to hold the dam in place.
The portion of the tooth that sticks through the dam now lies in a region where its environment can be controlled. The tooth can be washed and dried and kept saliva-free.
Why is tooth isolation important?
One of the fundamental goals of root canal therapy is removing contaminates from within the tooth.
Since saliva contains bacteria and other debris, a rubber dam acts as a barrier that keeps the tooth dry so contamination from saliva isn't a problem.
Step 2 - Creating the access cavity.
As the starting point for performing your tooth's treatment, your dentist will need to gain access to its nerve space. This step is called creating an "access cavity."
Your dentist will use their dental drill to making a hole that extends through the surface of your tooth to its pulp chamber. This is the hole through which they will perform their work.
For back teeth, the access cavity is made right through the tooth's chewing surface. For front ones, it's made on their backside.
When creating the access cavity, the dentist will also remove any tooth decay and loose or fragile tooth parts or fillings that are present.
Step 3 - Measuring the length of the tooth.
Your dentist's goal will be to treat the entire length of your tooth's nerve space but not beyond. To be able to work within these confines, your dentist must measure the length of your tooth. This measurement is typically calculated to the nearest 1/2 millimeter (about 1/50th of an inch).
How does a dentist make this calculation?
A dentist has two methods they can use to measure a tooth.
a) Radiographic measurements:
Traditionally, dentists have established/confirmed/documented the length of a tooth by way of taking an x-ray of it after a root canal file has been positioned in its canal. (Since root canal files are metal, they show up distinctly on an x-ray.)
The actual measurement is taken by reading markings etched on the file. The x-ray is simply used to confirm that the file is positioned properly (extends the full length of the tooth).
b) Electronic measurements:
In recent decades, electronic length-measuring devices have come into common usage.
The dentist will clip one of the unit's wire leads to a root canal file that has been inserted into the tooth. They will then tuck its second lead inside the patient's lip (to complete a circuit).
As the dentist slides the file further and further into the root canal, the electronic unit signals (via digital readout or beeping sound) when it has reached the canal's end (tip of the root). Once again, the measurement is read from the markings on the file. The electronic unit simply indicates that the file is in the proper position.
Using one of these units may sound unpleasant but in practice it isn't. In fact it's desirable. You won't feel a thing. And using it is very quick and accurate.
Several individual measurements may be needed for a tooth.
A separate length measurement will need to be made for each of the tooth's individual root canals. (Teeth can have several canals and/or roots.)
Step 4 - Cleaning and shaping the tooth's root canals.
The next step of the root canal process involves "cleaning and shaping" the interior of the tooth (the pulp chamber and each of its root canals).
In regard to this step:
- Its cleaning aspect removes bacteria, toxins, nerve tissue, and related debris that are harbored inside the tooth. (Here's more information about why this is needed.)
- Shaping refers to a process where the tooth's canals are enlarged and flared, so they have a shape that's ideal for the procedure's filling and sealing step.
What instruments are used to clean inside a tooth?
For the most part, a tooth is cleaned and shaped using root canal files.
Files look like tapered straight pins but close inspection you can feel that their surface is rough, not smooth. These instruments literally are miniaturized rasps.
How are files used?
A dentist will work a file up and down, with a twisting motion, in each of a tooth's root canals.
This action scrubs, scrapes and shaves the sides of the canals, thus cleaning and shaping them.
Your dentist will use several files.
This same motion will be used with an entire series of files (probably six or more), each of which has a slightly larger diameter. (The color of a file's handle indicates its diameter.)
The idea is that each of the files, when used in order, slightly increases the overall dimensions of the root canal. Since some canal contaminates are embedded within a canal's walls, this enlargement produces both a cleaning and shaping effect.
Your dentist may have a handpiece that can manipulate the files for them.
Traditionally, root canal files have been used as hand instruments (manipulated by the dentist's fingers). Your dentist may, however, have a special dental drill (handpiece) that holds the files and produces the needed filing motion for them.
Tooth irrigation is an important part of the cleaning and shaping process.
While performing their work, your dentist will also periodically irrigate (flush out) your tooth. This floats and washes away accumulated debris and contaminants.
Step 5 - Sealing the tooth.
Once the interior of the tooth has been thoroughly cleansed and properly shaped, it is ready to be sealed (have its hollow interior filled in).
In some cases, the dentist will want to place the filling material immediately after they have finished cleaning the tooth. With other cases, they may feel that it is best to wait about a week before performing this procedure.
[ Related content: How many appointments will your root canal therapy take? ]
If the latter case is chosen, your dentist will need to place a temporary filling in your tooth, so to keep contaminates out during the time period between your appointments. (Precautions you should take.)
What type of root canal filling material is used?
The most frequently used root canal filling material is a rubber compound called gutta percha. It comes in preformed cones whose dimensions match the size (diameter, taper) of the files that have been used to shape the tooth's canals.
A root canal sealer (a thin paste) is usually used with the gutta percha. It simply helps to fill in any voids or spaces inside the tooth that the gutta percha can't.
Placing the gutta percha.
At this point, individual cones of gutta percha are placed inside the tooth to fill in and seal off that area that has been cleansed.
Sealer is either applied to each gutta percha cone as it is placed into its canal, or else applied inside the root canal itself before the cone is inserted. Several, even many, individual cones may need to be placed before the interior of the tooth is fully filled.
A dentist will often soften up the gutta percha by touching a hot instrument to it. This way it can be packed down so it closely adapts to the shape of the tooth's interior.
As an alternative, a dentist may place the gutta percha via the use of a "gun." This apparatus is somewhat similar to a hot-glue gun. It warms a tube of gutta percha. The softened material can then be squeezed out into the tooth.
Placing a temporary filling.
Once your dentist has finished sealing your tooth, they will place some type of temporary filling. It will seal off the access cavity created at the beginning of your procedure, therefore protecting the work that's just been completed. (Precautions you should take.)
Step 6 - The root canal process has now been completed but your tooth still requires additional work.
At this point, the individual steps of performing the root canal procedure have been finished but your tooth's treatment is not yet complete. A permanent restoration must still be placed.
Choosing an appropriate type of dental restoration, and having it placed promptly, will help to insure the long-term success of your tooth's endodontic therapy.