When the fit of a removable complete denture is diminished as a result of progressive alveolar bone reduction, relining or rebasing might be indicated. In clinical practice, a degree of confusion exists concerning the concepts relining, and rebasing. Relining is resurfacing the tissue side of a denture with a new material to fill the space which exists between the original denture contour and the altered tissue contour. Rebasing is resurfacing the fitting surface of a denture by replacing the entire denture base with new material, also to fill the space which exists between the original denture contour and the altered tissue contour. In particular, attention is given to 3 specific forms ofrelining and rebasing which serve to restore the maxillomandibular relationship, to extend effectively the palatal denture surface of the maxillary denture and to reline or rebase an implant-supported overdenture.