I’ve found that as I got older Novocaine is metabolized faster. Though I have no idea what dosages were used at various times, in my 20’s I would remain numb for an hour after any dental procedure. Now in my 50’s, despite asking for increased dosages and multiple shots, I seldom remain numb for more than 10 minutes.
When I was a teen I had an operation on both feet. It was supposed to have been able to be done with local. After it was over the doctor said it took 25 times more than he had ever given anyone.
Post-op I was feeling sharp pain again in about an hour. He said with as much as he gave me, it with as much as he gave it should have been about 4 to 6 hours.
Next office visit he said he had checked with an anesthesiologist who said his experience showed about 2 to 5% of the patients he saw had metabolisms that seem to absorb it and process it out of their systems very fast.
All my dental stuff was painful every time except for one older dentist. After the first visit, he used to bring me in an 45 minutes early to start the injections. I always thanked him and he said it was rather unusual but not unknown. Just that most doctors/dentists don’t want to wait the time it takes.
Not a great way to be different than other people!