8: Gypsum materials


Gypsum materials

Figure 8.1 Effect of drying time on compressive strength of dental plaster.


Figure 8.2 Effect of the W/P ratio (shown above the columns) on the strength of gypsum materials.


Figure 8.3 Wet and dry compressive strengths of gypsum materials.


Table 8.1 Dental gypsum products

ANSI/ADA specification nomenclature Traditional nomenclature
Type I—Plaster, impression Impression plaster
Type II—Plaster, model Model or laboratory plaster
Type III—Dental stone Class I stone; model stone
Type IV—Dental stone, high strength Class II stone; die stone
   Low expansion (ISO Type 4)
   High expansion (ISO Type 5)

Table 8.2 Water-to-powder (W/P) ratios for gypsum materials

Product W/P ratio
(g water/100 g powder)
Plaster 40–50
Dental stone 25–30
Die stone 19–24

Table 8.3 Effect of W/P ratio on characteristics of mixed gypsum materials


Table 8.4 Comparative properties of dental gypsum products


8.1 Dental gypsum materials

Widely used in dentistry, gypsum materials are obtained from natural deposits of gypsum, CaSO4·2H2O, which when heated loses 1.5 g mol of water and converts to the hemihydra/>

Only gold members can continue reading. Log In or Register to continue

Jan 1, 2015 | Posted by in Dental Materials | Comments Off on 8: Gypsum materials
Premium Wordpress Themes by UFO Themes