A complete or partial denture provided with additional retention or support by being placed over or attached to existing retained teeth, tooth roots, or implants. Overdentures may be tooth (or implant) supported or tooth (or implant) and tissue supported. Benefits of overdentures can include prevention of alveolar bone loss by retention of teeth or tooth roots, improved speech, management of tooth wear, improved jaw alignment, and improved masticatory efficiency. Retention (resistance to vertical displacement) and stability (resistance to lateral or rotational displacement) are enhanced in comparison with conventional complete or partial dentures. A high standard of oral hygiene must be maintained to minimize the risk of caries on the root faces.