Preparation guidelines, Preparation guidelines for multi-unit bridges – Ivoclar Vivadent Zenostar User Manual
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Preparation guidelines
Before commencing the design process, make sure that the preparation is suitable for the placement of a ceramic restoration.
Successful results can only be achieved with Zenostar if the relevant guidelines and layer thicknesses are strictly observed.
Basically, the following preparation guidelines apply:
no angles or sharp edges,
a shoulder preparation with rounded inner edges or a chamfer is ideal,
the indicated dimensions reflect the minimum thicknesses for Zenostar restorations,
the edges of the prepared tooth should have a diameter of at least 1 mm (milling tool geometry) to permit optimum milling in
the CAD/CAM unit.
Preparation guidelines for single crowns – 3-unit bridges
Evenly reduce the anatomical shape and observe the stipulated minimum wall thicknesses. Ideally, a shoulder with rounded inner
edges or a chamfer is prepared; the width of the shoulder or chamfer should be 1 mm.
The incisal or occusal aspect of the crown should be reduced by at least 1.5 mm.
The labial and/or lingual aspect of anterior and posterior crowns should be reduced by at least 1.2 mm.
If a conventional or self-adhesive cementation method is used, retentive surfaces must be created.
Preparation angle: 6-8° for conventional cementation; >6° for adhesive cementation
Preparation guidelines for multi-unit bridges
Evenly reduce the anatomical shape and observe the stipulated minimum wall thicknesses. Ideally, a shoulder with rounded inner
edges or a chamfer is prepared; the width of the shoulder or chamfer should be 1 mm.
The incisal or occusal aspect of the crown should be reduced by at least 2 mm.
The labial and/or lingual aspect of anterior and posterior crowns should be reduced by at least 1.5 mm.
If a conventional or self-adhesive cementation method is used, retentive surfaces must be created.
Preparation angle: 6-8° for conventional cementation; >6° for adhesive cementation
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6°
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