Because the tooth will not heal by itself. Without treatment, the infection will spread, bone around the tooth will begin to degenerate, and the tooth may fall out. Pain usually worsens until one is forced to seek emergency dental attention. The only alternative is usually extraction of the tooth, which can cause surrounding teeth to shift crookedly, resulting in a bad bite. Though an extraction is cheaper, the space left behind will require an implant or a bridge, which can be more expensive than root canal therapy.
Treatment often involves from one to three visits.
This is all done under local anesthesia. Contrary to popular myth a root canal is causes very little discomfort. Once it is determined that treatment is successful, the tooth needs either a filling or a crown to protect it from possible future breakage, because root canal filled teeth are brittle. It is estimated 24 million teeth are treated per year with root canal therapy. If the teeth were instead removed, the options of replacing them are usually more costly and less natural.