Prosthodontics & Occlusion · single question
For the partial denture shown, where would the fulcrum line go?
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Correct answer: C. Mesial rest of 4 and 13
Mesial rest of 4 and 13 (C) is correct for the fulcrum line placement. The fulcrum line connects the most anterior abutment rests on each side — which in this Kennedy Class I configuration would be the mesial rests of teeth 4 (first premolar) and 13 (first premolar on the other side).
• The fulcrum line is critical in RPD design — it determines how the prosthesis will rotate when loaded. Indirect retainers must be placed anterior to the fulcrum line to resist rotation.
• Distal rests (A) would be placed on molars — posterior to the edentulous area — and are NOT used as the primary fulcrum for a Class I RPD.
• Mesial rests (B) of 5 and 12 are second premolars, not ideal for fulcrum reference in this case.
• The fulcrum line is critical in RPD design — it determines how the prosthesis will rotate when loaded. Indirect retainers must be placed anterior to the fulcrum line to resist rotation.
• Distal rests (A) would be placed on molars — posterior to the edentulous area — and are NOT used as the primary fulcrum for a Class I RPD.
• Mesial rests (B) of 5 and 12 are second premolars, not ideal for fulcrum reference in this case.
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