Prosthodontics & Occlusion · single question
A patient has a Kennedy Class I RPD. Regarding the fulcrum line placement, which answer is correct? (See the photo of the RPD model)
Show answer and explanation
Correct answer: B. Distal rest of teeth #4 to #13
- A. Distal rests on #5 and #12 would place the fulcrum line in the anterior segment — not the recommended position for Class I RPD.
- B. For a Kennedy Class I (bilateral distal extension) RPD, the fulcrum line connects the DISTAL rests of the most posterior abutment teeth — the distal rests of #4 and #13 (upper first premolars bilaterally). This gives the most posterior fulcrum line, minimizing rotational forces on the denture base.
- C. Mesial rests in some Class I designs are possible but the optimal fulcrum line uses distal rests on the most posterior abutments (#4 and #13).
- D. Using a cingulum rest on an anterior tooth significantly changes the fulcrum line position and is not standard for this case configuration.
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