Prosthodontics & Occlusion · single question
Where should the indirect retainer be placed on a Kennedy Class I removable partial denture?
Show answer and explanation
Correct answer: C. Perpendicular to and anterior to the fulcrum line
- A. Midline placement only works if it happens to be anterior to the fulcrum line; the defining characteristic is its relationship to the fulcrum, not the midline.
- B. Placing the indirect retainer on the most posterior abutment would be at or near the fulcrum line — this provides no indirect retention benefit.
- C. Correct. An indirect retainer must be placed ANTERIOR to the fulcrum line (the imaginary line connecting the two principal abutment teeth) AND perpendicular to it. This placement creates a lever arm that prevents the distal extension denture base from rotating away from the tissue (lifting) when occlusal forces act on the anterior portion of the denture.
- D. The indirect retainer should be anterior, not on the same side as the edentulous space.
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