What about nitrous oxide for root canal? Also my BAD marijuana experience

So after a 3.5 year taper off 10 mgs valium which I finally completed several years ago, I was feeling great and mostly recovered when I did the stupidest thing ever. I tried a pot candy to see if it helped with sleep. After noticing nothing for two hours, I finally went to bed and woke in the middle of the night wasted out of my mind. I had lots of internal shivering (a withdrawal sx I'd long said goodbye to), felt completely drunk and had a full-blown anxiety attack when I tried to get up to go to the bathroom. (Hadn't had one of those in years.)

But even worse, when I stood up from the toilet, my blood pressure plummeted and I started to pass out. I then fell--face first, on my two front teeth--on my mom's wooden hope chest. That was 8 weeks ago and I've been seeing lots of dental specialists since then to see if my teeth can be saved. Unbelievable right?

I think I might be headed for two root canals at this point and am experiencing lots of dental anxiety. I've had them in the past, but I'm just not sure I can manage it this time. I've never had nitrous oxide so is it on the approved list post benzo or not? I seem to be super sensitive to drugs these days. Dammnit!