Root canal treatment (also known as endodontic therapy, endodontic treatment, or root canal therapy) is a treatment sequence for the infected pulp of a tooth which is intended to result in the elimination of infection and the protection of the decontaminated tooth from future microbial invasion. Root canals, 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. Together, these items constitute the dental pulp.
Endodontic therapy involves the removal of these structures, disinfection and the subsequent shaping, cleaning, and decontamination of the hollows with small files and irrigating solutions, and the obturation (filling) of the decontaminated canals. Filling of the cleaned and decontaminated canals is done with an inert filling such as gutta-percha and typically a Zinc oxide eugenol-based cement. Epoxy resin is employed to bind gutta-percha in some root canal procedures. Another option is to use an antiseptic filling material containing paraformaldehyde like N2. Endodontics includes both primary and secondary endodontic treatments as well as periradicular surgery which is generally used for teeth that still have potential for salvage.
Diagnostics and Preparation
Before endodontic therapy is carried out, a correct diagnosis of the dental pulp and the surrounding periapical tissues is required. This allows the endodontist to choose the most appropriate treatment option, allowing preservation and longevity of the tooth and surrounding tissues. Treatment options for an irreversibly inflamed pulp (irreversible pulpitis) include either extraction of the tooth or removal of the pulp.
Removing the infected/inflamed pulpal tissue enables the endodontist to help preserve the longevity and function of the tooth. The treatment option chosen involves taking into account the expected prognosis of the tooth, as well as the patient’s wishes. A full history is required (which includes the patient's symptoms and medical history), along with a clinical examination (both inside and outside the mouth), and the use of diagnostic tests
There are several diagnostic tests that can aid in the diagnosis of the dental pulp and the surrounding tissues. These include:
- Palpation (this is where the tip of the root is felt from the overlying tissues to see if there is any swelling or tenderness present)
- Mobility (this is assessing if there is more than normal movement of the tooth in the socket)
- Percussion (TTP, tender to percussion; the tooth is tapped to see if there is any tenderness)
- Transillumination (shining a light through the tooth to see if there are any noticeable fractures)
- Tooth slooth (this is where the patient is asked to bite down upon a plastic instrument; useful if the patient complains of pain on biting as this can be used to localise the tooth)
- Dental pulp tests
In the situation that a tooth is considered so threatened (because of decay, cracking, etc.) that future infection is considered likely or inevitable, a pulpectomy (removal of the pulp tissue) is advisable to prevent such infection. Usually, some inflammation and/or infection is already present within or below the tooth. To cure the infection and save the tooth, the dentist drills into the pulp chamber and removes the infected pulp. To get freedom of bacteria the use of efficient antiseptics and disinfectants is necessary. One of the most effective is N2 root canal material which contains a small dose of paraformaldehyde. The nerve is either drilled out of the root canal(s)with engine driven files or with long needle-shaped hand instruments known as files
Endodontic treatment may fail for many reasons: one common reason for failure is inadequate chemomechanical debridement of the root canal. This may be due to poor endodontic access, missed anatomy or inadequate shaping of the canal, particularly in the apical third of the root canal, also due to the difficulty of reaching the accessory canals which are minute canals that extend in from the pulp to the periodontium in a random direction. They are mostly found in the apical third of the root.
Exposure of the obturation material to the oral environment may mean the gutta-percha is contaminated with oral bacteria. If complex and expensive restorative dentistry is contemplated then ideally the contaminated gutta percha would be replaced in a retreatment procedure to minimise the risk of failure.
The type of bacteria found within a failed canal may differ from the normal infected tooth. Enterococcus faecalis and/or other facultative enteric bacteria or Pseudomonas sp. are found in this situation.
Endodontic retreatment is technically demanding; it can be a time consuming procedure, as meticulous care is required by the dentist. Retreatment cases are typically referred to a specialist endodontist. Use of an operating microscope or other magnification may improve outcomes.