Ivoclar Vivadent SR Nexco Paste - Manual (Page 30)

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mEtaL framEWorK faBrIcatIon
there are two types of frameworks, i.e. frameworks for full-coverage veneers (ideal space) and frameworks for partial
veneers (limited space). Basically, it is advisable to design a full wax-up and then fabricate a silicone key to check the
space conditions during contouring. When fabricating the frameworks, make sure that the minimum wall thickness after
finishing is 0.3 mm for single crowns and 0.5 mm for bridge abutments. these dimensions are the prerequisite for a
stable metal framework and a durable bond between the metal and composite. If the stipulated framework and
connector dimensions are not observed, delamination and cracking may occur.
Contouring
the framework reflects the reduced anatomical tooth shape (see page 26 for tooth shape-supporting contouring).
as a result, the lab composite can be applied in an even layer and will consequently be appropriately supported. the
requirements of the different alloys have to be taken into account.
Full contouring of the anatomical tooth shape
Reducing the model portions and checking using the silicone key.
If the metal framework is too small, the veneering composite is not adequately supported, which
may lead to cracks, delamination and esthetically compromised results. Mechanical retentions
are generally beneficial and advisable, as they support the chemical bond between metal and
composite.