Root Canal Treatment

February 20, 2011 by Dr. Ng SN

What is root canal treatment

Root canal treatment on front teeth

Root canal treatment or sometimes refers as RCT is a treatment used to repair and save a tooth that is badly decayed or becomes infected. During a root canal procedure, the nerve and pulp are removed and the inside of the tooth is cleaned and sealed. Without treatment, the tissue surrounding the tooth will become infected and abscesses may form (below).

Gum abscess

What is root canal?

Root canal is the term used to describe the natural cavity within the center of the tooth. The pulp or pulp chamber is the soft area within the root canal. The tooth’s nerve lies within the root canal.
A tooth’s nerve is not vitally important to a tooth’s health and function after the tooth has emerged through the gums. Its only function is sensory — to provide the sensation of hot or cold. The presence or absence of a nerve will not affect the day-to-day functioning of the tooth.

What Damages a Tooth’s Nerve and Pulp in the First Place?

Big decay

A tooth’s nerve and pulp can become irritated, inflamed, and infected due to:

  • deep decay
  • repeated dental procedures on a tooth and/or large fillings
  • a crack or chip in the tooth
  • or trauma to the face.

How does dentist know whether the tooth needs RCT?

There are several symptoms that usually lead dentist to conclude that the tooth requires RCT:


Tooth Discolouration


  • Pain which is severe and prolong that affect  daily activities
  • Throbbing pain that usually disturb sleep at night
  • Feel painful when biting on the affected side
  • Prolonged sensitivity/pain to heat or cold temperatures (after the hot or cold has been removed)
  • Discoloration (a darkening) of the tooth
  • Swelling and tenderness in the nearby gums
  • A persistent or recurring pimple on the gums (gum abscess)

From dental examination:

Pulp testing

  • A very large cavity or deep restoration on that tooth
  • Feels very painful on percussion on that tooth
  • Not responsive to the vitality test using a Pulp Tester
  • A radiolucency lesion over the tip of the root on radiograpghic examination

How does Root Canal Treatment done?

Step-by-step of root canal treatment

A) Placing the rubber dam.

After local anaesthetic is given, dentist usually need to “isolate” your tooth. He will first punch a small hole in a sheet of rubber. Then, he will then slip this sheet over the affected tooth and position a small tooth clamp to hold it there. The purpose of a rubber dam is to keep the tooth saliva-free therefore, avoid contamination of bacteria from saliva .

B) Creating the access cavity.

The tooth was isolated using rubber dam and a hole was made (cavity access) to reach the pulp chamber

As a starting point for performing  root canal treatment, dentist must first gain access to the nerve space (or the pulp chamber) within the tooth.
He do this by using a dental drill to create an access cavity. This hole will extend into the interior of the tooth to its pulp chamber. It’s the hole through which the dentist will perform their work.
On the molar teeth, the access cavity is made on the chewing surface of the tooth and for the front teeth, the access hole is made on the tooth’s backside.
The overall size of the access cavity will vary according to factors such as the location of the individual canals and how hard it was for the dentist to find them. Additionally, beyond just that portion of the tooth that must be removed for access, the dentist will also need to remove any decay that’s present and any loose or exceptionally fragile tooth parts or fillings.

C) Cleaning and shaping the tooth’s root canals.

The next step of the root canal process involves “cleaning and shaping” the interior of your tooth (the pulp chamber and all root canals). In regard to the cleaning process, its purpose is to remove bacteria, toxins, nerve tissue, and related debris that are harbored inside the tooth.
The shaping process refers to how the tooth’s canals are enlarged and flared, so the have a shape that facilitates the filling and sealing process.

What instruments are used?

Endodontic file

For the most part, a tooth is cleaned and shaped using endodontic files. These files look like straight pins but on closer inspection you will find that their surface is rough, not smooth. These instruments literally are files and are used as such.

How are the files used?

Dentist works the file up and down, with a twisting motion, in each of your tooth’s root canals. This action will scrub, scrape and shave the sides of the canals, thus cleaning and sculpting them. He will perform this same type of action using a series of files, each having a slightly larger diameter.
The idea is that each consecutive file is used to slightly increase the overall dimensions of the root canal. Since some canal contaminates are embedded within a canal’s walls, this enlargement assists with both the procedure’s cleaning and shaping goals.
While performing this work, the dentist will also periodically flush out (irrigate) the tooth. This helps to wash away accumulated debris and contaminants. While a number of different solutions can be used for this purpose, sodium hypochlorite (bleaching agent) is the most common one. An added benefit of bleach is that it is a disinfectant.

Some dentist may have a handpiece that can manipulate the files for them.

Traditionally, files have been hand instruments. This simply refers to the fact that the dentist creates their filing action by manipulating them with their fingers. Some dentist may, however, have a special dental drill (handpiece) that produces the needed file motion for them.

Rotary Endodontic System

As a variation on this same theme, there is yet another type of dental handpiece that produces a cleaning motion by way of holding a root canal file and vibrating it vigorously.

Measuring the length of the root canals.

Determine the length of root canal with a radiograph

The goal of root canal treatment is to achieve cleaning of the entire length of each of the tooth’s root canals, but not beyond.
As a means of determining the precise length of a canal, dentist will use apex locator to get the measurement for the length of the tooth (from the crown to the tip of the root). By doing so, the dentist wouldn’t go beyond during cleaning.
Usually, he will confirm the measurement by taking a x-ray of the tooth with a file placed in the tooth. The x-ray picture will show if the file extends the full length of the canal or not.

D) Sealing the tooth – Placing the filling material.

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.

What type of root canal filling material is used?

Sealing of the root canals

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 paste) is usually used with the gutta percha. It is either applied to a cone’s surface before it is placed into a canal, or else applied inside the root canal itself before the cone is inserted. Several individual cones of gutta percha may be needed to fully fill the interior of the tooth.
Dentist will warm the gutta percha (either before or after it has been placed into the tooth) to soften it. This way it can be molded to closely adapt 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.
Once your dentist has finished sealing your tooth, they will place a temporary filling, so to seal off the access cavity created at the beginning of your treatment.

How long does root canal treatment take?

The total amount of time that’s needed for a tooth’s root canal therapy will of course hinge on how many appointments are needed (one visit, or two or more) and how long each one will take. Usually, root canal treatment for molar usually take about 3 to 4 visits. Each visit takes around an hour. For the front teeth, usually take fewer visits as they are simpler and located at the front region.

Summary of Root Canal Treatment:

Cases of root canal treatments

RCT on upper left first molar

RCT on lower right first molar

RCT on lower right first molar

RCT on lower rigth first molar


E) Post Root Canal Treatment

At this point, while the individual steps of performing the root canal process have been finished, the tooth’s treatment is not yet complete. The tooth is no longer alive since the pulp has been removed. And this can make the tooth brittle and more prone to fracture.
Therefore, a permanent restoration must still be placed. Choosing the right type of dental restoration, and having it placed promptly, will help to insure the long-term success of the tooth’s endodontic therapy.
There are a few options:
1) Crown (recommended) as it is strong, durable and more aesthetic
2) Dental filling – cheap, can be done on the spot (doesn’t required 2 visits)

F) Final words…

Tooth infection can recur in treated teeth (even RCT treated tooth), hence, good oral hygiene, including brushing, flossing and regular dental examination are necessary to prevent further problems. For more info on good oral hygiene click here.

More info on General Dental Treatment

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