Sometimes cavities or dental caries start to damage tooth layers through dentin and enamel. This works its way to the pulp which holds arteries and nerves of the tooth. As cavities enter the pulp, the tooth can become sensitive to hot and cold and severe pain can develop. When this occurs the dentist drills deep into the tooth to eliminate all the bacteria and cleans the pulp chamber with tools. This procedure can take one or two visits but will result in a tooth that’s pain free.