.....never heard of this and always made sure I took plenty of VitC before any procedures including extractions-wisdoms and molars-always get "local" and the dentists were always able to give me excellent local without resorting to extra injections.
I would question their "technique" and expertise as I have had 2 exquisitely miserable experinces with 2 different dentists and 1 guy was so bad i walked out.(ran was more like it,too much xylocaine with epi on board ! !!!made me more nervous)