| 摘要 |
No extractor tool is completely satisfactory. By using a novel systemincorporating an insert into the crowns or the bridges themselves, the cementholding the crowns can be easily broken. A cylindrical resin tube 7 isintended to be positioned in the wax of a future moulded crown 12 or a bridgeto be moulded in the substance of the crown 12 to form a passage 13 andserving as the bed for a metal tube 1. This piece 1 will be cemented into thepassage 13 formed in the crown 12. The crown formed in this fashion will thenbe used as the basis for the internal horizontal extractor. A screwpenetrates into the insert 1 and encounters the two half-cylinders foldedagainst each other. By continuing to turn the screw it will spread the twohalf-cylinders and thus by means of same, will break the cement that holdsthe cemented crown. |
