Gypsum stone classifications

By Dr.Swathi Pai on Tuesday 13 January 2009 with 0 comments



-Type I: impression plaster

-Type II: plaster

-Type III: yellow stone

-Type IV: green die-stone (high compression strength)

-Type V: die-stone (high expansion and high compression strength)

The gypsum (CaSO4) has 2 forms:

-alpha CaSO4 = soluble anhydrite

-beta CaSO4 = insoluble anhydrite

-the higher the density of the stone, the less water required for hydration.


Basic technique for recording centric relation is an anterior deprogrammer. Functions of an anterior deprogrammer :

  1. relax the musculature

  2. eliminate engrams

Deprogrammer should be in place for 20-30min. Once this occurs, the mandible can be more easily manipulated so that the condyles are seated in the most superior and anterior portion of the glenoid fossa. The deprogrammer should span teeth #s 8 & 9.

Category: Prosthodontics Notes

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