A tooth is a complex structure containing several different types of tissues. The hard, shiny outside is the enamel. Under the enamel is the dentin, the microporous tissue that makes up most of the tooth. The bottom of the tooth (below the gum line) is the root. The root anchors the tooth in position. A tooth can have more than one root.
While the outside of a tooth is solid and hard, the inside contains soft tissue, called pulp. The pulp contains blood vessels, nerves, and connective tissue and supplies nourishment for the tooth. The pulp lie in a chamber that extends down through the root in a passageway called the root canal.
Root Canal Treatment
A cavity (tooth decay) occurs when acids from sugar-eating bacteria erode an area of a tooth. When a cavity is found, the dentist uses a drill to remove the decayed tissue and replaces the hole with a dental filling. If the cavity is not detected until the decay reaches the pulp chamber, bacteria can infect the pulp and nerve tissue. If not treated, the pulp can die and the infection can spread from the root to the bone, causing bone damage.
Once decay reaches the pulp, a root canal treatment may be needed to save the tooth. A typical root canal is performed over several visits. First, the dentist (or endodontist, a specialist in root canal procedures) administers a local anesthetic. Then a tiny opening or hole is made through the crown of the tooth. The pulp is removed with tiny files or a dental drill and the interior of the canal root is cleaned and reshaped. Medications may be placed inside the pulp chamber and root to sterilize the area and eliminate remaining bacteria. Next, a temporary filling is placed inside the hole to seal the opening and keep out saliva and bacteria. In the next visit, the temporary filling is removed and the pulp chamber and root canal are recleaned and filled with a permanent material and sealed. In some cases, a metal post may be inserted into the root canal to give the tooth more structure and support. In the next visit, a porcelain or gold crown is placed over the top of the tooth.
According to the American Academy of Endodontists, about 14 million root canals are performed annually in the U.S. The only alternative to a root canal is extraction (pulling) of the tooth. After extraction, a bridge or implant is needed to prevent the teeth from shifting.
Direct Pulp Capping
Dentists often recommend a root canal when a cavity exposes the nerve in the tooth, even if the infection hasn't damaged the nerve. However, some dental professionals say a full root canal may not be necessary and are offering another procedure, called direct pulp capping. First, an opening is made in the crown to remove the cavity. Then, the exposed pulp is sealed with a liquid filler that dries to a solid form. It's the same type of material used to make contact lenses for the eyes. Once dry, the filler forms an airtight seal over the area. While a typical root canal can take several visits and may cost up to several thousand dollars, direct pulp capping can be done in a single visit for under $500. The procedure adds only about 15 to 20 minutes onto the time needed for a traditional filling procedure.
Dental experts caution direct pulp capping is not for all patients – only those in whom the tooth nerve is still healthy. Once the nerve has been damaged, a traditional root canal is needed. In some cases, patients who receive direct pulp capping may still eventually need a root canal if some bacteria remain or the infection has spread further than anticipated.