How many anaesthetic injections would someone need to have a molar root canal carried out?

A few: Some patient are harder ot numb than others. Lower molars are harder ot numb than upper molars. Sometimes a series of injections must be repeated on or more times before successful anesthesia.

Varies: Sometimes a patient can have a root canal performed without an injection if the tooth nerve has completely died. But to be comfortable, and when a rubber dam is placed around the tooth to protect from infection, some injections may be needed. With a infected or hyperactive tooth (especially lower molars, ) sometimes additional injections are necessary.