Root canal is a term which is used for describing your natural cavity that lies within the center of your tooth. The nerves of the tooth lie in the root canal. When the nerve tissue or the pulp of your tooth gets damaged, it will break down, resulting in multiplication of bacteria in the pulp chamber.The presence of bacteria and the decayed debris may cause a tooth infection. It can also cause a swelling that sometimes spreads to the other parts of the neck, face or head. If you are experiencing pain, tooth discoloration, swelling or a feeling of tenderness in your lymph nodes, there may be a chance that you require a root canal treatment.