Root canal local anesthesia how long does it last?

Can vary: Depends on the area as well as how the anesthesia was given..Cob be as less as 45 min to as long as 6 to 8 hours.Sometimes anesthesia is given as infiltration ...Sometimes as nerve block which can take longer..Especially for back molars..Also depends on location as well as course of the nerve..

Depends: Various anesthetics have different therapeutic effects. These effects are dependent on physiologic responses by the patient. Each patient will have slightly different reactions to these medications. Anesthetics have a working time and a lingering time. The needs of the procedure should dictate the type of anesthetic to be used. Ask you doctor what is best for the procedure you have planned.

Varies: Some anesthetics are made to last longer than others so your dentist will use what is best for your condition.