“Full mouth restoration” involves treating all the teeth if missing or decayed with a recommended choice of treatment.
If all the teeth are “missing” then they can be “fixed” by utilizing support from “dental implants” or can be a “removable prosthesis” like “dentures”.
If the bite (the way the upper and lower teeth meet each other) is collapsed due to attrition or missing posterior or anterior teeth causing difficulty in biting and chewing.
If all the teeth have some amount of “attrition” or decay like “cavities” then they can be “root canal treated” if required or they can be “capped or crowned”.