Nobody likes to hear they need a root canal, but what exactly is it? Each individual tooth has living tissue inside it. If a tooth is damaged it can affect the living tissue inside. Bacteria will then live inside the tooth which can lead to pain and swelling around the tooth. When root canal treatment is completed it works similar to a stopper in a sink. We clean out the dying tissue and bacteria and then fill the canals with a material that stops bacteria from being able to get back into the tooth and allows the tissues to heal.