• radicular – refers to tooth root
• radiograph – also known as an x-ray, image of bone and tooth structures produced through exposure to ionizing radiation
• reimplantation – reinsertion of tooth into its socket following trauma that partially or completely removed it
• reline – resurfacing of the tissue side of a removable denture to correct issue with fit
• resin – material used in dental restorations and other dental treatments
• resorption – loss of bone or structure
• retainer – appliance used to ensure teeth do not return to prior misaligned state following orthodontic treatment
• root – portion of the tooth that attaches the tooth to the gums and socket
• root canal – pulp cavity inside the tooth root
• root canal therapy – treatment of disease or injury to the tooth pulp, generally involves the removal of part or all of the pulp and replacement with inert material
• root planing – a procedure used in the treatment of periodontal disease, involves deep cleaning of teeth at the roots to remove calculus and other substances
• rubber dam – latex sheet used to isolate part of the mouth from saliva and potential contaminants during surgery