Occlusal Scheme Selection for an Implant-Supported Mandibular Overdenture
A 72-year-old woman with a severely resorbed mandible (Cawood and Howell class V) and a maxillary complete denture requests a mandibular implant overdenture. She has two implants placed at the canine positions with locator attachments. The maxillary denture is 10 years old, has worn teeth, and shows reduced vertical dimension. She reports difficulty eating and sore spots under the maxillary denture. She has adequate bone for the two implants but declines additional surgery.
1. What occlusal scheme would you choose for the mandibular overdenture, and why?
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Recommendation: A bilateral balanced occlusion is generally preferred for a mandibular implant overdenture opposing a maxillary complete denture, especially with two implants and a resilient attachment. Balanced contacts in excursions reduce tipping forces on the implants and improve stability of the maxillary denture.
Considerations:
- With two implants, the overdenture can rotate anteriorly; balanced occlusion and a properly designed attachment help control dislodgement.
- Lingualized occlusion is an alternative that can improve esthetics and reduce lateral forces, but balanced contacts remain important.
- Monoplane occlusion may be considered if the ridge is severely resorbed and esthetics allow, but it reduces chewing efficiency and may not suit this patient's desire for improved function.
Maxillary denture: The worn maxillary denture and reduced vertical dimension should be addressed. Fabricating a new maxillary denture with a balanced occlusal scheme coordinated with the mandibular overdenture is likely necessary for optimal outcomes. Simply retrofitting the old denture may perpetuate sore spots and instability.
2. How do you sequence treatment and address the sore spots and reduced vertical dimension?
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Sequencing:
- Assessment: Evaluate the maxillary denture for fit, occlusion, and vertical dimension. Sore spots may be due to ill-fitting denture base, occlusal imbalance, or reduced vertical dimension.
- Provisional phase: Reline or adjust the maxillary denture to restore comfort and evaluate a corrected vertical dimension with a trial acrylic or record base. Use a verification jig and occlusal records.
- Implant overdenture fabrication: After implant healing and attachment placement, fabricate the mandibular overdenture with balanced occlusion against the maxillary prosthesis.
- Definitive maxillary denture: If the old denture cannot be adequately adjusted, fabricate a new maxillary complete denture coordinated with the mandibular overdenture.
Sore spots: Identify and relieve pressure areas; check for occlusal interference and excessive vertical dimension. If reduced vertical dimension is contributing, increase it gradually and verify patient tolerance before finalizing.
Patient communication: Explain that a new maxillary denture may be needed and that the overall plan aims to improve comfort and function, not just replace the lower denture.