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Why use the big spacer?????
For overdenture constructions---whether it is the Preci
Clix, Preci Ball, Sphero Flex, or Ceka--it is often asked, "Why use the big tin spacer?"
First, the tin spacer is used over the
crown--or coping--during processing to block out excess acrylic from locking in
the attachment female. This is helpful, but not the major reason for using
the big tin spacer.
The real reason for using the big spacer can be
understood by viewing figures A and B.
A |
Figure A is a Ceka overdenture
case fabricated using only the small spacer. Using only the small spacer eliminates
all movement of the prosthesis--it is a rigid attachment. As you can see, the denture base is in direct contact with the
post coping (arrow). Forces are directed to the post coping abutment
This same principle applies to all overdentures and bars
with post copings. |
B |
Figure B is the same Ceka overdenture case, only this time
both the small and large spacers were used. Using both spacers allows for movement of
the prosthesis--it is now a resilient attachment.
During processing, the large spacer creates a free space between the prosthesis and the
post coping to allow this free movement and direct the forces to the tissue.
The greater the area the forces are spread over, the less force that is generated on
the abutment. |
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