Anesthesia is the temporary loss of sensation or pain in one part of the body produced by a topically applied or injected agent without depressing the level of consciousness.
In dentistry, the most commonly used local anesthetic is lidocaine (also called xylocaine or lignocaine), a modern replacement for procaine (also known as novocaine). Its half-life in the body is about 1.5–2 hours.
Dental anesthetics fall into two groups: Esters (procaine, benzocaine) and Amides (lidocaine, mepivacaine, prilocaine and articaine).
Esters are no longer used as injectable anesthetics; however, benzocaine is used as a topical anesthetic