Ivoclar Vivadent IPS d.SIGN - Manual (Page 25)

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When fabricating porcelain shoulders, make sure that the
framework is supported by the prepared tooth rather than
the veneer. To achieve this the framework is reduced exactly
to the inner edge of the chamfer or shoulder preparation. In
this way, functional support of the framework by the
prepared tooth is achieved. A framework that accuractly fits
the prepared tooth is essential in order to keep the ceramic
material from getting on the inner surface of the framework.
2. Framework design for porcelain shoulders
wrong correct
Single connector width
= single stability
Double the width of the
connector
= double the stability
Double the height of the
connector at single width
= eightfold the stability
3. Framework stability
The dimensions of the interproximal connector greatly
influences the stability of the restoration during the
laboratory procedure as well as the clinical long-term success
after cementation. Therefore, the dimension of the
connector area must be adequate for the alloy being used.
This is especially important if a bio-alloy or high-gold alloy is
to be used.