How can i not gag when i get impressions made at the dentist?

Few things: Sometimes swishing with a mouth wash to numb your mouth helps. I tell my patients to breath through their nose and wiggle their toes. This often does the trick.

Fast set : I often use fast set impression material and also use a type of mouthwash called breath deodorant (ok, sounds funny, ) but it works. I also would recommend that the assistant takes the lower impression first, which is easier for the patient and helps build confidence. Breathe short quick breathes through the nose too.