A root canal is indicated when the pulp or nerve of the tooth becomes infected and/or inflamed. The most common cause for the inflammation are deep cavities, fractures or cracks in teeth, trauma and repeated dental procedures. If the tooth is left untreated, the infection can cause pain and lead to an abscess and tooth loss. Generally infected teeth will display prolonged sensitivity to temperature, discoloration of the tooth and tenderness around the tooth and surrounding gums.