R

reline
plastic buildup of denture to compensate for bone loss

restoration (prosthetic restoration)
any tooth filling, crown, denture, or other dental device that restores or replaces lost tooth structure

root
the part of the tooth located in the gums, connecting it firmly to the jaw

root canal therapy
removing the pulp of a heavily decayed tooth and replacing it with a filling material

root resections
removing the root of a tooth while retaining the crown

root retention
a procedure to remove the crown of a root canal treated tooth while keeping enough of the root and gums to hold a prosthesis