<正> It is reported in this article that the mandibular unilateral distal-extension remova-ble partial dentures with wrvught wtre retentive clasp arm

cast circumferential retentive arm andI-bar retentive arm were tested under vertical loading

and the stresses around the root of thetooth adjacent to the extension base were ovserved by means of photoeiastic stress analysis.The results showed that the retentive clasp arm or reciprocal clasp arm in distal-extension remov-able partial denture does not affect the magnitude and direction of the abutment tooth force

that there is no obvious difference among the wrought wire clasp arm

cast circumferential clasparm and I-bar clasp on the abutment tooth force

and that the force created due to loading of re-movable partial denture is transmitted to the primary abutment tooth mainly through theocclusal rest.