Gypsum Products I

Which of the following gypsum product is manufactured by Dry

calcination

• Type II

• Type III

• Type IV

• Type V

What is the main difference between dental stone and dental plaster

• Chemical composition

• Shelf life

• Shape and size of particles

• Solubility in water

Impression plaster containing potato starch is called as

• Plaster of paris

• Soluble plaster

• Anti – expansion solution

• Die stones

Type III Dental gypsum product is

• Class III stone or Crystocal

• Class II Stone or Densite

• Class I stone or hydrocal

• Model or lab plaster

What product is obtained by calcining gypsum under steam pressure at

120-130°C in the presence of sodium succinate

• Type I

• Type II

• Type III

• Type IV

ADA specication number of gypsum products is

• 15

• 20

• 25

• 30

The β (Beta) hemihydrate of gypsum requires more water for mixing

because

• They are more regular in shape and dense

• They are more regular in shape and highly porous

• They are more irregular in shape and porous

• They are more dense and prismatic in shape

The main ingredient in dental plaster is

• Calcium sulphate hemihydrate

• Calcium phosphate

• Calcium anhydrate

• Calcium sulphate dihydrate

Water of reaction needed to convert 100g of calcium sulphate

hemihydrates to calcium sulphate dihydrate is

• 18.6ml

• 22.2ml

• 30.4ml

• 45.3ml

Gypsum product having least expansion

• Type I - Impression plaster

• Type II - Model plaster

• Type III - Stone plaster

• Type IV - Die stone