Mandibular Overdenture Strategy in a Patient on Long-Term Bisphosphonate
A 74-year-old woman attends for replacement of her 12-year-old complete dentures. The maxilla is edentulous; the mandible retains only the two canines (33 and 43). The lower denture is retentive only with adhesive and causes recurrent sore spots. Both canines have 5–6 mm probing depths, grade II mobility, and cervical caries; radiographs show about 50% bone support. The mandibular anterior ridge is severely resorbed, but a CBCT suggests 9–10 mm of bone height between the mental foramina. Her medical history includes osteoporosis treated with alendronate for 8 years, hypertension controlled with amlodipine, and an eGFR of 55 mL/min. She requests “fixed teeth” and is strongly opposed to another removable denture. She has no history of radiotherapy or malignancy.
1. Compare retaining the canines as overdenture abutments with extracting them and placing an implant-supported mandibular prosthesis. Which factors dominate your decision?
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The decision is dominated by the prognosis of the canines, the patient's medical risk, and her prosthetic demands. Retaining 33 and 43 as overdenture abutments avoids mandibular surgery and may be attractive in a patient with 8 years of alendronate exposure. However, both teeth have 5–6 mm pockets, grade II mobility, caries, and only about 50% bone support; their long-term prognosis is guarded. They would need endodontic treatment if the pulp is involved, caries removal, and cast copings or attachments, and the patient must be able to clean them. Extracting them and placing an implant-retained overdenture would give more predictable retention, and the CBCT shows adequate anterior bone height. The main concern is MRONJ risk, although the risk with oral implants is low. A fixed implant prosthesis would require more implants and possibly grafting, and her severe resorption makes it less predictable. I would present both options, recommend periodontal and endodontic assessment of the canines, and avoid promising fixed teeth. If the canines are restorable and hygiene is good, an overdenture on natural abutments is a reasonable lower-risk first option; if they fail, implant placement can be considered after risk assessment.
2. What would you tell the patient about MRONJ risk if implants are placed, and how would you document consent?
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I would explain that long-term oral bisphosphonate use is associated with a small but real risk of MRONJ after oral surgery, including implant placement. The risk is lower with oral than with intravenous agents and with shorter duration, but 8 years of alendronate means the risk is not negligible. I would not rely on a drug holiday as a guaranteed risk reduction; the evidence is limited, and any decision to interrupt treatment must be made with her physician. I would document that she understands the alternatives (retained canines with overdenture, conventional denture, no treatment), the risks of infection, implant failure, and MRONJ, and that implant treatment is not guaranteed to give fixed teeth. I would also document that she was advised about hygiene and follow-up. Consent should be explicit and written, with a clear statement that she can decline surgery.
3. If you retain 33 and 43, describe the prosthetic and periodontal plan.
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If 33 and 43 are retained, they should be managed as overdenture abutments. Caries is removed and the teeth are endodontically treated if needed; cast post-and-core copings or amalgam cores are placed, and the crowns are reduced to about 2 mm above the gingival margin to leave room for the denture base and attachments. The abutment teeth should be splinted only if mobility requires it; otherwise independent copings with resilient attachments are preferred. The denture is relieved over the abutments, border-moulded, and relined or remade with a stable occlusion. Hygiene access must be designed into the prosthesis, and the patient needs instruction and a 3-month recall. Probing depths and mobility are recorded at each visit; if a pocket persists or the tooth becomes symptomatic, the abutment is re-evaluated and may be extracted.