The lever systems

By Dr.Swathi Pai on Saturday 17 January 2009 with 0 comments



Class I: the “see-saw”

-resistance – fulcrum – effort

-resistance is the clasp

-fulcrum is the terminal rest

-effort is downward force on the distal extension

-like KII, where resistance is on the contralateral side of the arch from the fulcrum and effort


Class II: the “wheel-barrel”

-fulcrum – resistance – effort

-effort is upward force on the distal extension

-otherwise, the clasp would disengage

-like KI

Class III: the “fishing pole”

-fulcrum – effort – resistance

-does not occur in RPD design

-TMJ muscles and teeth act as a class III lever

-cantilever: when fulcrum and resistance are connected on the same body

Category: Prosthodontics Notes

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