Dental Materials Ch. 9

Question 1

the desirable strength of gypsum materials is _________ related to the amount of water used.

a) directly
b) indirectly
c) not
d) partially

Answer 1

a) directly

Question 2

for gypsum products, a suitable accelerator and retarder, respectively, would be:

a) Ethyl alcohol and Oleic acid
b) Oleic acid and glycerin
c) borax and potassium sulfate
d) potassium sulfate and borax

Answer 2

d) potassium sulfate and borax

Question 3

the gypsum material known as “high-strength stone” may also be referred to as:

a) Plaster
b) Dental stone
c) Type III stone
d) Improved stone

Answer 3

d) Improved stone

Question 4

the final setting time for gypsum products typically is:

a) 15-30 mins
b) 30-45 mins
c) 45-90 mins
d) 90-120 mins

Answer 4

b) 30-45 mins

Question 5

to make a correct mix for dental stone when using 50 g of powder, the amount of water would be approximately:

a) 10-12 ml
b) 14-15 ml
c) 28-30 ml
d) 45-50 ml

Answer 5

b)14-15 ml

Question 6

Cathy and her parents will meet with an orthodontist to discuss an orthodontist treatment plan. At a previous appointment, the orthodontist took impressions of Cathy’s maxillary and mandibular arches. the replicas made from watch impression to discuss the treatment plan are termed:

a) casts
b) dies
c) study models
d) molds

Answer 6

c) study models

Question 7

decreasing the setting time of a dental material results in a product that:

a) will set faster
b) will set slower
c) does not affect the setting time
d) enhances the properties

Answer 7

a) will set faster

Question 8

the weakest gypsum product is:

a) improved stone
b) dental stone
c) plaster
d) die stone

Answer 8

c) plaster

Question 9

when excess water is not present in gypsum product, it is known as the:

a) wet strength
b) Dry strength
c) initial setting time
d) surface strength

Answer 9

b) Dry strength

Question 10

the best way to mix products is to:

a) “eyeball” amount of powder added to water
b) add water to the powder
c) add powder to the water
d) add powder and water to bowl simultaniously

Answer 10

c) add powder to the water

Question 11

initial and final settlement times of gypsum can be determined with the use of Gilmore needles. a practical, easy method to determine final setting time in a dental office would be to:

a) set timer for 20 mins.
b) observe the change from wet to dry strength
c) watch for the loss of gloss
d) attempt to penetrate the material with the metal spatula

Answer 11

d) attempt to penetrate the material with the metal spatula

Question 12

when the setting time of a dental material is increased which of the following is true?

a) the material sets slower
b) the material sets faster
c) the setting reaction does not change
d) the setting reaction is increased

Answer 12

a) the material sets slower