Increasing sensitivity of a tooth, spontaneous sharp pain and discomfort when chewing are the most common symptoms that could indicate the need for root canal treatment. In those cases, a cavity in a tooth becomes very deep and reaches the nerve in the root of the tooth. The root canals, which contain the nerve and blood vessels that supply the tooth, can become infected. Root Canal Treatment is to remove an infection, and often the damaged nerve. It is usually carried out over one, two or more stages, and can save your tooth from having to be taken out.