Endodontics

Endodontic (Root Canal) Treatment

Endodontic Treatment, also known as Root Canal Treatment, is a dental procedure in which the diseased or damaged pulp (core) of a tooth is removed and the inside areas (the pulp chamber and root canals) are filled and sealed.

Purpose

Inflamed or infected pulp (pulpitis) most often causes a toothache. To relieve the pain and prevent further complications, the tooth may be extracted (surgically removed) or saved by root canal treatment. Root canal treatment has become a common dental procedure; more than 14 million are performed every year, with a 95% success rate, according to the American Association of Endodontists.

Precautions

Once root canal treatment is performed, the patient should have a crown placed over the tooth to protect it. The cost of the treatment and the crown may be expensive. However, replacing an extracted tooth with a fixed bridge, a removable partial denture, or an implant to maintain the space and restore the chewing function is typically even more expensive.

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Below, you can see a schematic tooth showing the anatomical structures usually associated with a Root Canal Procedure. Click on the image and you can see schematically, when a Root Canal Procedure becomes necessary.

To the left is a schematic cross section of a molar tooth. The Pulp Chamber is the place where all nerve and blood vessels come together. The Main Canals are the conduits for the nerves and blood vessels (also called NVB - Neuro Vascular Bundle) running through it. Often Lateral Canals come off the Main Canals. The PDL (Periodontal Ligament Space) is composed of fibers, that act as shock absorbers for the tooth, and nerves and blood vessels. A dead nerve does NOT mean a "dead" tooth. The PDL is what keeps the tooth alive. The nerve is merely an information "relay" system for the tooth. Hover and Click on the image.

The image to the left shows a tooth which has been accessed and cleaned out for a root canal procedure. The three "black" holes are the Main Canals. At this point the dentist can fill the canals with a filling material, which will seal the root. Click on the image to see the canals filled.

Description (there are a set of images illustrating this procedure below)

Root canal treatment may be performed by a general dentist or by an endodontist, a dentist who specializes in endodontic (literally "inside of the tooth") procedures. Inside the tooth, the pulp's soft tissue contains the blood supply, by which the tooth gets its nutrients, and the nerve, by which the tooth senses hot and cold. This tissue is vulnerable to damage from deep dental decay, accidental injury, tooth fracture, or trauma from repeated dental procedures (such as multiple fillings over time). If a tooth becomes diseased or injured, bacteria build up inside the pulp, spreading infection from the natural crown of the tooth to the root tips in the jawbone. Pus accumulates at the ends of the roots, forming a painful abscess which can damage the bone supporting the teeth. Such an infection may produce pain that is severe, constant, or throbbing, as well as prolonged sensitivity to heat or cold, swelling and tenderness in the surrounding gums, facial swelling, and discoloration of the tooth. However, in some cases, the pulp may die so gradually that there is little noticeable pain.

Root canal treatment is performed under local anesthesia. A thin sheet of rubber, called a rubber dam, is placed in the mouth to isolate the tooth. The dentist removes any tooth decay and makes an opening through the natural crown of the tooth into the pulp chamber. Creating this access also relieves the pressure inside the tooth and can dramatically ease pain.

The dentist determines the length of the root canals, usually with a series of x rays. Small wire-like files are then used to clean the entire canal space of diseased pulp tissue and bacteria. The debris is flushed out with large amounts of water (irrigation). The canals are also slightly enlarged and shaped to receive an inert (non-reactive) filling material called gutta percha. However, the tooth is not filled and permanently sealed until it is completely free of active infection. The dentist may place a temporary seal, or leave the tooth open to drain, and prescribe an antibiotic to counter any spread of infection from the tooth. This is why root canal treatment may require several visits to the dentist.

Once the canals are completely clean, they are filled with gutta percha and a sealer cement to prevent bacteria from entering the tooth in the future. A metal post may be placed in the pulp chamber for added structural support and better retention of the crown restoration. The tooth is protected by a temporary filling or crown until a permanent restoration may be made. This restoration is usually a gold or porcelain crown, although it may be a gold inlay, or an amalgam or composite filling (paste fillings that harden).

Preparation

There is no typical preparation for root canal treatment. Once the tooth is opened to drain, the dentist may prescribe an antibiotic, then the patient should take the full prescribed course. With the infection under control, local anesthetic is more effective, so that the root canal procedure may be performed without discomfort.

Aftercare

The tooth may be sore for several days after filling. Pain relievers, such as ibuprofen (Advil, Motrin) may be taken to ease the soreness. The tissues around the tooth may also be irritated. Rinsing the mouth with hot salt water several times a day will help. Chewing on that side of the mouth should be avoided for the first few days following treatment. A follow-up appointment should be scheduled with the dentist for six months after treatment to make sure the tooth and surrounding structures are healthy.

Risks

There is a possibility that the root canal treatment will not be successful the first time. If infection and inflammation recur and an x ray indicates retreatment is feasible, the old filling material is removed and the canals are thoroughly cleaned out. The dentist will try to identify and correct problems with the first root canal treatment before filling and sealing the tooth a second time.

In cases where an x ray indicates that retreatment cannot correct the problem, endodontic surgery may be performed. In a procedure called an apicoectomy, or root resectioning, the root end of the tooth is accessed in the bone, and a small amount is shaved away. The area is cleaned of diseased tissue and a filling is placed to reseal the canal.

In some cases, despite root canal treatment and endodontic surgery, the tooth dies anyway and must be extracted.

Below you can see what the individual steps in a root canal treatment are, beginning at the stage where the pulp chamber has been cleaned out. The perspective of the images represents a top view down into the pulp chamber of a molar.

After the pulp chamber (see schematic above) has been cleaned out, you dentist (or endodontist) uses a succession of files in increasing diameter, to enlarge and shape the root canals. This is to prepare them for the root canal filling material. You can see the thin yellow file on the left image.

Once the canals have been cleaned and shaped properly, the filling material can be placed. These are individual cones if a rubber compound that get inserted into the canals and either condensed or heated (some doctors use preheated injectable compound). This will provide the mechanical seal to the canal.

Once enough cones are placed, the excess is seared off with a heated instrument and molded in place to seal the canal completely. This will prevent bacteria from entering the canal system at either end.

The doctor has to make sure that all the canals are properly sealed. This is often the most time consuming part of the entire procedure.

Here you can see all the canals filled and sealed. The final step is to fill the access hole with a base material, usually composite or a more accessible material.

Once the access hole is filled, the tooth is ready for a crown preparation. A crown is usually recommended after a root canal procedure, which has weakened the structure of the tooth dramatically. The crown will "brace" the tooth and protect it from fracturing under heavy load.

The final x-ray shows the molar with the root canal filling in place. Note that this x-ray shows a negative image for better visibility of the root canal filling (black).