I'm wondering how long does it take for dental anaesthetic to wear off?

1-3 hr average: If you had a routine treatment, most anesthetics used in dental treatment wears off within 3 hours or so. There are several kinds, and some are designed to work only for a short term and wears off in 1-2 hours. Most others usually lasts about 3 hours. If a dentist determines a prolonged anesthesia is beneficial, s/he may have used a long-lasting type, which may last 10 hours before wearing off.