# Overdentures > Overdentures for BDS Prosthodontics — retained root advantages, canine abutment selection, copings, attachments and the McGill consensus. - Canonical URL: https://prepelephant.com/topics/bds/prosthodontics/overdentures-basics - Exam / course: BDS · Subject: Prosthodontics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Overdentures", PrepElephant, https://prepelephant.com/topics/bds/prosthodontics/overdentures-basics ## Direct answer Overdentures are removable prostheses that cover and rest on one or more retained natural roots or teeth, most often endodontically treated canines. Retaining roots preserves alveolar bone around them, keeps periodontal proprioception that guides functional load, and offers superior support, stability and retention — through copings, studs, bars or magnets — compared with conventional complete dentures. The classic cephalometric evidence is Crum and Rooney's finding of roughly 0.6 mm of mandibular ridge loss over five years under overdentures against several millimetres under conventional dentures. ## What you must remember - Definition: a removable dental prosthesis that covers and rests on one or more remaining natural teeth and/or roots (Glossary of Prosthodontic Terms wording). - Bone preservation: residual ridge resorption is markedly reduced around retained roots — Crum and Rooney's classic study measured about 0.6 mm of mandibular ridge change over five years with overdenture abutments versus about 5 mm with complete dentures. - Proprioception: intact periodontal ligament mechanoreceptors give odontally guided fine control of occlusal loads, which complete denture patients lack. - Canines are the abutments of choice — longest roots, bulky bone, positioned at the corner of the arch near the denture's rotation axis; mandibular canines are the classic pair retained. - Abutment criteria: endodontically treatable and restorable, periodontally healthy with at least half the root length supported by bone (crown-root ratio approaching 1:1), minimal mobility, and bilaterally symmetric positions. - Retention options in increasing complexity: simple domed copings, stud attachments (for example Dal-Ro type), bar-and-sleeve (Dolder/Hader) designs splinting abutments, and rare-earth magnets (samarium-cobalt, neodymium-iron-boron with a keeper). - Copings rise 2 to 4 mm above the gingiva as polished domes; the overdenture is relieved and cushioned over them with a resilient liner initially. - Main late failures are root caries and periodontal breakdown of abutments — prevented by meticulous hygiene, daily fluoride (gel or varnish) and chlorhexidine, with regular recall. - The McGill consensus statement (2002) declared the two-implant mandibular overdenture the first-choice standard of care for the edentulous mandible — quote it when comparing options. ## A worked abutment decision A 58-year-old man has a badly resorbed mandible with only two firm canines, both carious to gum level but with sound roots and over two-thirds bone support. The temptation is to extract and deliver a conventional denture; the reasoning says otherwise. Endodontic treatment of both canines is straightforward, and their retention alone justifies the effort: bone stays around each root, the denture gains two pillars of support, and the patient keeps proprioceptive feedback that translates into easier adaptation. After endodontics, cast domed copings are cemented, or simple amalgam or composite domes are built if cost constrains; attachments are added only if retention demands, since each adds plaque traps and prosthesis cost. The overdenture is fabricated over the copings with an acrylic flange kept thin labially, checked and relieved with pressure indicating paste over the abutments, and lined with a short-term soft liner during settling. His recall combines denture checks with abutment care: fluoride application, scaling and radiographs. If the canines later fail, the same prosthesis converts to an implant overdenture — the design logic (two pillars in the canine region) carries straight across. ## Viva angles on abutments Viva examiners ask "why the canine?" and accept only stacked reasoning: longest root, best bone, keystone position at the arch's corner, distant from the pooled plaque of the lingual sulcus and useful for both support and retention. The second trap is over-prescribing attachments — a magnetic or bar system on a poorly motivated patient trades a modest retention gain for plaque accumulation and abutment loss, whereas a plain coping overdenture with good hygiene outlasts it. Remember also that an overdenture patient is a maintenance patient for life, not a case completed at insertion. ## Frequently asked questions ### Why do overdentures preserve alveolar bone? Functional load transmitted through retained roots maintains the periodontal apparatus and stimulates the surrounding bone; classic long-term studies show only a fraction of the ridge loss seen under conventional dentures. ### Which teeth are preferred as overdenture abutments and why? Canines, for their long roots, dense surrounding bone, favourable position at the arch corner near the denture rotation axis and generally low caries experience compared with other anterior teeth. ### What attachments can retain an overdenture? Domed copings, stud attachments, rigid or resilient bar-and-sleeve systems splinting abutments, and rare-earth magnets; choice balances retention needed, hygiene access and cost. ### What is the McGill consensus statement? The 2002 consensus that a two-implant-retained mandibular overdenture should be the first-choice standard of care for the edentulous mandible, because it dramatically improves function and quality of life over a conventional lower denture. ### How are overdenture abutments protected from caries? Daily fluoride gel or periodic varnish, chlorhexidine rinses, meticulous brushing of the domes, and recall scaling — root caries and periodontitis are the principal reasons overdentures fail late.