Local anesthesia is used to prevent the sensation of pain in a specific area of your mouth where treatment is being performed. Local anesthesia works by blocking the nerves that sense or transmit pain. A topical anesthetic may be applied prior to administering a local anesthesia injection to eliminate the pain caused by the needle. Local anesthesia is used in procedures such as fillings, treatment of gum disease, while preparing teeth for crowns, etc. Depending upon the dental treatment that you have undergone, you may need pain-relieving medication after the effect of anesthesia wears off.