Conversion of CVC Preparations

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Conversion of CVC Preparations
Dr Saj Jivraj DDS,MSEd Dr TJ Ahn DDS
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Preparation

• Differences of a PFM from a CVC
• More (1.5 mm) mid-facial thickness.
• More (1.3 mm) gingival axial reduction.
• More (2.0 mm) occlusal reduction total for
  porcelain bearing areas.
• Shoulder margin (90 degrees to the external
  surface of the tooth) for strength of both
  porcelain and tooth.
• Gingival extensions at 0.5 mm supra-gingival
  pre-clinically. At or below tissue clinically
  due to esthetics.

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Porcelain Occlusion
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Metal Occlusion
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Metal Occlusion
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2.0mm Reduction for porcelain
1.5mm for Metal
0.65mm for metal
1.0-1.3mm depending on tooth size
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Gold 0.3-0.5mm
Opaque 0.2mm
Body 0.5-0.7mm
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For Porcelain Occlusion reduction Would be 2mm
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Place depth grooves into facial surface using
6782-016 diamond. You have previously reduced
0.65mm gingival axial reduction, with a 1mm mid
buccal axial thickness. Insert the bur to 0.5
mm at the tip. Place the margin so that final
termination will be 0.5mm supragingival.
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Remove tooth structure between the grooves.
Measure depth Of shoulder with a 13 hatchet.
Shoulder should be 1.3mm.
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Smooth the shoulder with a bin angle chisel in a
pulling motion. Ensure shoulder is 90 degrees to
the external surface of the tooth.
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Margin
90 degrees to External surface Of tooth.
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You will also have to reduce more tooth structure
from the second plane to allow room for
porcelain. Sink the bur to half its depth at the
tip and finish reduction Of the second plane from
mesial to distal transitional line angle.
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Evaluate shoulder and second plane