Can you get a canker sore after a tooth extraction?

Yes: Canker sores can form in response to many forms of stress, including surgical stress. An oral ulcer may form at the site of the tooth extraction, at the site of the local anesthetic injection, or at any site in the mouth. These usually respond to oral rinses such as saline solution (salt water) or antiseptic mouthwash. If it persists, return to see your oral surgeon or dentist for evaluation.

????: Yes, but the extraction is not the cause of the canker sore. The virus that causes the sores is in your system. The extraction just "stresses" the body to react to the virus.