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WorksheetsGypsum Product III
Total questions: 20
Worksheet time: 25mins
Working time of gypsum products can be increased by
Using slurry water for mixing
Faster spatulation
Increasing the water: powder ratio
Increasing the time of mixing within practical limits
The length & Diameter of Vicat penetrometer are
(a)Accelerators and retarders are used with gypsum products mainly to control
(a)Which is the most commonly used accelerator in gypsum product?
(a)A gypsum cast can be safely removed from the impression at the end of
(a)A retarder can slow down the setting reaction of dental stone by the following mechanism:
Enhancing the solubility of hemihydrate
Increasing the precipitation of dihydrate
Inhibiting the crystal growth
Providing greater number of nuclei of crystallization
The main purpose of adding modifiers to gypsum products is to modify their
(a)Using higher water: powder ratio while mixing Type II gypsum product will increase it’s
(a)Shorter setting time of impression plaster compared to dental stone is mainly due to
Difference in their chemical composition
Difference in their mixing time
Higher water:powder used for mixing dental stone
Presence of chemical modifiers in impression plaster
Mixing dental plaster in unclean bowl which contains fine gypsum particle residues should be avoided mainly because it
Affects the color of plaster
Decreases the time available for manipulation
Lowers the setting expansion
Lowers the strength of dental plaster
The normal setting expansion of gypsum products can be reduced by
(a)Balanced stone is dental stone in which
Accelerators or retarders have been added according to need
Amount of water of hydration is controlled
Normal setting expansion is equal to hygroscopic setting expansion
α and β hemihydrate crystals are present in equal proportions
What is the weight of heavier Gilmore needle (in grams)?
(a)
Increase in number of nuclei of crystallization will
(a)Longer mixing within practical limits
(a)What is the effect of higher W:P ratio on setting time and normal setting expansion respectively?
(a)Using slurry water for mixing dental stone will
(a)What is terra alba ?
(a)What is the conseuence of mixing plaster of paris with boiling water
(a)The diameter of lighter & heavier Gillmore needles are
(a)
