Jesus, if the infection is bad enough the numbing meds won’t cross the blood/brain barrier. I had that happen with a broken upper rear tooth that started to abscess, knot in the roof of my mouth, jesus christ that was rough.. numbing meds/lidocaine didn’t really work. I had to cowboy up while this tiny Filipino dentist yanked that ****er out. All that puss went flying across the room, but I felt instant relief.E5...6 numbing shots...nothing....E7.....let me do it again...seriously? LOL! My heartbeat was in my big toe for hours and hours.