This document provides information about relining and rebasing dentures. It begins with definitions of relining and rebasing. Relining involves adding new base material to the existing denture base to refit the denture. Rebasing replaces all the base material of a denture while keeping the original teeth arrangement. Common indications for relining and rebasing include alveolar ridge resorption and loose or ill-fitting dentures. Materials, pretreatment procedures, techniques, and chairside methods are described for both relining and rebasing dentures.