What is the minimum number of implants generally recommended to support an implant-retained maxillary overdenture?

Correct answer: D. Four

• A. A single implant is not a recognised protocol for an overdenture.
• B. Two implants is the accepted minimum in the mandible, where the anterior bone is dense and a two-implant overdenture performs well.
• C. Six implants gives excellent support and is often preferred for a fixed maxillary prosthesis, but four is the stated minimum for an overdenture.
• D. Correct. The maxilla requires at least four implants, because its bone quality is poorer (types III and IV) and the arch must resist greater rotational forces.

Note: For a fixed full-arch maxillary prosthesis the usual recommendation rises to six or more, depending on cantilever length and bone quality.