enlargement coefficient or shrinkage?

The measurements of the final dental prosthesis must be known before milling the pre-sintered components.
Some machines use the multiplication (enlargement) coefficient, while others use shrinkage.

If the MULTIPLICATION COEFFICIENT method (enlargement coefficient) is used, each final measurement must be multiplied by this coefficient, specified for each lot.

If PERCENTAGE SHRINKAGE is used, the formula is:
[(pre-sint. - sint.) / (pre-sint.)]*100
(shrinkage of the pre-sintered product during sintering referred to the initial measurements of the pre-sintered product).
If this method is used, each measurement of the final prosthesis must therefore be multiplied by the following value:
100 /(100 – percentage shrinkage), specified for each lot.

The results obtained following one of the two methods indicate the dimensions which the pre-sintered prosthesis must have before being fired in the oven.
These values are based on the experience of CO.N.CE.P.T. following various tests conducted considering machinability, density of the “green” (unsintered) product and final density.

Minimum element thickness
The values indicated are references for the technician in preparation of the prosthetic elements. However, designing of the prosthetic element is the responsibility of the dentist and the dental technician, who must check the sizing of the prosthetic structure case by case.

The wall strength should be at least

ANTERIOR TEETH

  • incisal/occlusal thickness 0.7mm
  • circular thickness  0.5mm

POSTERIOR TEETH

  • occlusal thickness = 1.5 mm – circular thickness = 0.5mm

ABUTMENT crowns for bridge framework with 2 pontics

  • incisal/occlusal thickness =1mm
  • circular thickness = 0.7mm

The connector surface should be at least
Anterior bridge

  • with 1 pontic= 7mm 2
  • with 2 pontics = 9mm2

Posterior Bridge

  • with 1 pontic = 9mm2
  • with 2 pontic= 12mm”
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