Anesthetic can take anywhere between 45 minutes and 2 hours to typically wear off depending on the type of anesthetic used and the amount used.
Some anesthetics have longer acting components where the numbing sensation can last between 5-8 hours. These longer acting anesthetics are typically only used for longer procedures that involve extensive surgery.
The important part to remember here is that, patients should not eat solid foods until the effects of the anesthetic have fully disappeared in order to avoid injuring or gnawing on their cheeks and/or lips and not realize it. Also, patients should avoid hot foods while they are numb because they cannot gauge how hot something is and therefore can easily burn themselves.