I'm allergic to to all local anesthetics. Proved by an allergist. Will nitrous oxide be enough for a root planning? I don't want to feel it?

I'm allergic to local anesthetics, and need to be put under for simple procedures. I need to have a root planning, my dentist recommends nitrous oxide, will I still feel the pain? I'm a big baby in the chair because I've almost died from allergic reactions twice. anaphylaxis

I need a deep cleaning root planning, not a root canal. I did talk to a doctor and many dentists, they don't believe me, even with a note from my allergist. I was told to go to a hospital or use gas. Just want to know what peoples experiences are with gas??