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When is a root canal necessary?

This treatment is necessary when there is extensive tooth decay or damage by an injury to your mouth.

When the nerve becomes infected, the infection can spread through the root canal system and eventually lead to an abscess causing a great deal of discomfort. Root canal therapy is carried out to clean, disinfect and fill the insides of the tooth. This type of therapy alleviates pain, prevents permanent damage to decayed teeth, and is often the alternative to a tooth extraction. A standard rubber dam is used for maximal patient comfort to prevent re-infection and contamination of the canals with pathogenic microorganisms.

Root canal treatment is a skilled and time-consuming procedure. Most courses of treatment will involve two or more visits.

What is endodontic treatment?

Endodontic therapy is treatment to the nerve in a tooth, which acts to eliminate infection and to protect the decontaminated tooth from future microbial invasion. This is commonly referred to as a “root canal”.

Root canals inside teeth and their associated pulp chamber are the physical hollows within a tooth that are naturally inhabited by nerve tissue, blood vessels and other cellular entities. Endodontic therapy involves the removal of these structures, the subsequent shaping, cleaning, and decontamination of the hollows with tiny files and irrigating solutions and the obturation (filling) of the decontaminated canals with an inert filling such as gutta percha and typically an antimicrobial cement.

To cure the infection and save the tooth, the dentist drills down to the pulp chamber and removes the infected pulp and then cleans the nerve out of the canal(s). After this is done, the dentist fills each of the canals and the chamber with an inert material and seals up the opening. This procedure is known as root canal therapy.

For some patients, root canal therapy is one of the most feared dental procedures, perhaps because of a pain that necessitated the root canal procedure. However, dental professionals assert that modern root canal treatment is relatively painless because the pain can usually be controlled with a local anesthetic during the procedure and pain control medication can be used before and/or after treatment.

In some cases it may be very difficult to achieve pain control before performing a root canal and antibiotics may be used to reduce the infection before root canal treatment is undertaken.

Success and prognosis

Root canal treated teeth may fail to heal, for example if the dentist is not able to find, clean and fill all of the root canals within a tooth.

On a maxillary (upper) molar, there is a more than 50% chance that the tooth has four canals instead of just three. But the fourth canal tends to be very difficult to see and often requires special instruments and magnification in order to see, and in fact can sometimes be blocked and be unable to be properly instrumented.

This infected canal may cause a continued infection or “flare up” of the tooth. Any tooth may have more canals than expected, and these canals may be missed when the root canal is performed.

  • Sometimes canals may be unusually shaped, making them impossible to clean and fill completely; some infected material may remain in the canal.
  • Sometimes the canal filling does not fully extend to the apex of the tooth, or it does not fill the canal as densely as it should.
  • Sometimes a tooth root may be perforated (the root damaged with a hole in it to the outside) while the root canal is being treated, or due to the original infection, making it difficult or impossible to fill the tooth. The perforation may be filled with a root repair material.

A specialist can often re-treat failing root canals, and these teeth will then heal, often years after the initial root canal procedure. However, the survival or functionality of the endodontically-treated tooth is often the most important aspect of endodontic treatment outcomes, rather than apical healing alone.

Recent studies indicate that substances commonly used to clean the root canal space incompletely sterilize the canal. It is accepted that it is unlikely that all of the bacteria can possbly be removed from the nerve space. The remaining bacteria become sealed inside the space with no available food supply from the mouth. The theory is that these bacteria become dormant and irrelevant. This has been an accepted theory in the science of root canals for over 50 years.

A properly restored tooth following root canal therapy yields long-term success rates near 97%. In a large scale Dental Study of over 1.6 million patients who had root canal therapy, 97% had retained their teeth 8 years following the procedure, with most untoward events, such as re-treatment, apical surgery or extraction, occurring during the first 3 years after the initial endodontic treatment.

Endodontically treated teeth are prone to extraction mainly due to non-restorable decay, and to a lesser extent to endodontic-related reasons such as endodontic failure, vertical root fracture, or perforation. With the removal of nerves and blood supply from the tooth, it is best that the tooth be fitted with a crown which increases the prognosis of the tooth by six times.

Procedural accidents

It is possible that an instrument may separate (break) during root canal treatment, meaning a small portion of the metal file used during the procedure is separated inside the tooth.

The file segment may be left behind if an acceptable level of cleaning and shaping has already been completed and attempting to remove the segment would risk damage to the tooth. While potentially disconcerting to the patient, having metal inside of a tooth is relatively common, such as with metal posts, amalgam fillings, gold crowns, and porcelain fused to metal crowns.

The occurrence of file separation is proportional to the narrowness, curvature, length, calcification and number of roots on the tooth being treated. Complications resulting from incompletely cleaned canals, due to blockage from the separated file, can be addressed with surgical root canal treatment by a specialist.