Prosthodontics & Occlusion · single question
What is the purpose of rest seats in a removable partial denture?
Show answer and explanation
Correct answer: A. Support
Rest seats are prepared on abutment teeth to provide vertical SUPPORT for the RPD framework, directing occlusal forces along the long axis of the abutment tooth and preventing the denture base from sinking into/impinging on the soft tissue. Stability and retention are functions of other RPD components (like reciprocal/guide planes and retentive clasp arms, respectively), not the rest seat's primary role.
- A. INCORRECT. Stability (resistance to horizontal displacement) is provided primarily by the rigid components of the major connector and the bracing arms of clasps — not rest seats.
- B. INCORRECT. Retention (resistance to removal along the path of insertion) is provided by the retentive tip of the clasp engaging the undercut of the abutment tooth.
- C. INCORRECT. 'Structure' is not an RPD design principle. The four RPD principles are: Support, Stability, Retention, and Reciprocation.
- D. CORRECT. Rest seats provide SUPPORT — they prevent the denture from moving toward the tissue (vertically/apically) and distribute occlusal forces to the abutment teeth along their long axes.
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