Hi there,
I've had Sedation dentistry before, they gave me one Valium to take the night before and one Halcion to take an hour before my appointment. Worked like a charm :)

The Valium is just to keep you "calm" the night before. I think the Halcion is the important one. Not sure if that would work for you? They will give you as much as you need once you are there. The one you take at home is just to get you "started". My dentist kept checking with me, to see how I was feeling.