Deck 16: Gypsum and Wax Products

Question 1

For regular-set gypsum products,the initial set occurs within _____ minutes from the beginning of the mix.

A) 1 to 2
B) 3 to 5
C) 7 to 9
D) 12 to 14

Answer 1

7 to 9

Question 2

Model plaster has a water-to-powder ratio of approximately _____ (mL/g).

A) 0.15
B) 0.45
C) 1.00
D) 2.50

Answer 2

0.45

Question 3

Which of the following is true regarding trimming of models with a model trimmer?

A) The occlusal plane should be perpendicular with the base.
B) Bases and anatomic portions should be soaked for 5 to 10 minutes before trimming.
C) The anterior portion of both the maxillary and mandibular arch models should be trimmed to a point at the midline.
D) The casts should be trimmed so that proportionately the base makes up one third and the anatomic portion two thirds of the total depth.

Answer 3

The casts should be trimmed so that proportionately the base makes up one third and the anatomic portion two thirds of the total depth.

Question 4

An increase in the recommended water-to-powder ratio will result in a _____ accurate model.

A) stronger,more
B) stronger,less
C) weaker,more
D) weaker,less

Question 5

Which of the following will accelerate the setting of gypsum products?

A) Saliva
B) Blood
C) Alginate
D) Set gypsum particles

Question 6

Which of the following statements is true regarding dimensional accuracy of gypsum products?

A) Plaster has the least amount of setting expansion.
B) Plaster has the least amount of setting contraction.
C) High-strength stones have the least amount of setting expansion.
D) High-strength stones have the least amount of setting contraction.

Question 7

Which of the following is true concerning the chemical properties of gypsum materials?

A) Chemically,the mineral gypsum is a hemihydrate of calcium carbonate.
B) To form the raw material into a powder,the manufacturer heats it and adds water.
C) When the dihydrate is again mixed with water,a product with a viscosity capable of flowing is produced.
D) The amount of water required to mix the calcium sulfate hemihydrate is greater than the amount required for the chemical reaction.

Question 8

Which of the following gypsum products is ideal for making full or partial denture models,orthodontic models,and casts requiring higher strength and abrasive resistance?

A) Impression plaster (Type I)
B) Model plaster (Type II)
C) Dental stone (Type III)
D) Dental stone,high strength (Type IV)

Question 9

As the temperature of the wax increases,the _____ of the wax decreases until the wax becomes a liquid.

A) melting point
B) flowability
C) stability
D) viscosity

Question 10

When proportioning gypsum products,the water should be measured with a graduated cylinder and the powder should be:

A) mixed by guess and by golly.
B) weighed on a scale.
C) measured with the use of scoops.
D) measured with a graduated cylinder as well.

Question 11

β-Hemihydrate is commonly used for:

A) die stone.
B) working casts.
C) diagnostic models.
D) dental investment.

Question 12

When working models for cast restorations are being made,a die of high-strength stone (Type IV)is often poured with a base and adjacent teeth of Type _____ stone.

A) I
B) II
C) III
D) V

Question 13

Which material is able to withstand the high heat and stress produced when molten metal is forced into molds to form indirect restorations?

A) Dental investment
B) Model plaster
C) Dental stone
D) Die stone

Question 14

An increase in spatulation time and rate will _____ the setting time and _____ the rate of setting expansion.

A) lengthen;increase
B) lengthen;decrease
C) shorten;increase
D) shorten;decrease

Question 15

Which of the following statements is true concerning the mixing of plaster and stone materials?

A) The measured amount of powder is placed into the mixing bowl and the water is slowly sifted into the powder.
B) The measured amount of powder is placed into the mixing bowl and the water is dumped into the powder.
C) The measured amount of water is placed into the mixing bowl and the powder is slowly sifted into the water.
D) The measured amount of water is placed into the mixing bowl and the powder is dumped into the water.

Question 16

Which of the following is true of the double-pour method for fabricating and trimming diagnostic/working casts?

A) This technique involves two separate mixes.
B) After the impression is poured,the remaining material is used for the base.
C) One mix of gypsum is produced to pour the anatomic and art portions of the cast.
D) The material in the inverted impression may slump away from the impression,causing distortion of the cast or trapping or air voids.

Question 17

Which of the following dental gypsum products will require the least water for mixing and will have the highest final density?

A) Impression plaster (Type I)
B) Model plaster (Type II)
C) Dental stone (Type III)
D) Dental stone,high strength (Type IV)

Question 18

The _____ the particles of gypsum powder are,the weaker and less resistant to abrasion is the final product.

A) smaller,more irregular,and denser
B) smaller,more regular,and more porous
C) larger,more irregular,and more porous
D) larger,more regular,and denser

Question 19

What does it mean when freshly mixed gypsum loses its gloss?

A) Beginning of the working time
B) Final compressive strength
C) Initial set
D) Final set

Question 20

Increased porosity of the gypsum particles makes it necessary to use _____ water to convert the _____ when mixing gypsum products.

A) more;hemihydrate particles back to dihydrate particles
B) less;hemihydrate particles back to dihydrate particles
C) more;dihydrate particles back to hemihydrate particles
D) less;dihydrate particles back to hemihydrate particles

Question 21

Which of the following represents the correct sequence for creation of a casting using the lost wax technique?
1)The pattern and sprue are encased in an investment ring.
2)A wax or plastic sprue is attached to the pattern.
3)A wax pattern of the restoration is carved on the die.
4)The enclosed pattern and sprue are heated in a burnout oven at high temperatures.

A) 3,1,2,4
B) 3,2,1,4
C) 2,3,1,4
D) 3,2,4,1

Question 22

Match the items with the correct description below.
Models

A)Replicas of the prepared teeth that are generally removable from the working cast
B)Hard replicas of hard and soft tissues of the patient's oral cavity made from gypsum products
C)Casts generally made from dental plaster or stone and used for patient education,treatment planning,and tracking of the progress of treatment

Question 23

Wax patterns should be invested within _____ of carving.

A) minutes
B) hours
C) days
D) weeks

Question 24

List and describe the use of the different types of gypsum products used in dentistry.

Question 25

Which kind of wax is used to construct the metal framework of partial and complete dentures?

A) Utility wax
B) Boxing wax
C) Casting wax
D) Baseplate wax

Question 26

Which of the following is an example of a pattern wax?

A) Inlay wax
B) Sticky wax
C) Boxing wax
D) Bite registration wax

Question 27

Utility wax may be used to:
1)adapt the periphery of an impression tray.
2)provide a better fit into the vestibule of the impression material.
3)cover sharp brackets and wires for orthodontic patients.

A) 1,2,3
B) 1,2
C) 2,3
D) 1

Question 28

Match the items with the correct description below.
Study models

A)Replicas of the prepared teeth that are generally removable from the working cast
B)Hard replicas of hard and soft tissues of the patient's oral cavity made from gypsum products
C)Casts generally made from dental plaster or stone and used for patient education,treatment planning,and tracking of the progress of treatment

Question 29

Match the items with the correct description below.
Diagnostic casts

A)Replicas of the prepared teeth that are generally removable from the working cast
B)Hard replicas of hard and soft tissues of the patient's oral cavity made from gypsum products
C)Casts generally made from dental plaster or stone and used for patient education,treatment planning,and tracking of the progress of treatment

Question 30

Which of the following kinds of waxes is used to adhere components of metal,gypsum,or resin together temporarily during fabrication and repair?

A) Inlay wax
B) Sticky wax
C) Boxing wax
D) Corrective impression wax

Question 31

Match the items with the correct description below.
Dies

A)Replicas of the prepared teeth that are generally removable from the working cast
B)Hard replicas of hard and soft tissues of the patient's oral cavity made from gypsum products
C)Casts generally made from dental plaster or stone and used for patient education,treatment planning,and tracking of the progress of treatment

Question 32

Match the items with the correct description below.
Casts

A)Replicas of the prepared teeth that are generally removable from the working cast
B)Hard replicas of hard and soft tissues of the patient's oral cavity made from gypsum products
C)Casts generally made from dental plaster or stone and used for patient education,treatment planning,and tracking of the progress of treatment

Question 33

Which of the following is true of boxing wax?

A) A strip of boxing wax is 3 inches wide.
B) Boxing wax is difficult to manipulate at room temperature.
C) Boxing wax is slightly tacky at room temperature.
D) Boxing wax comes in ropes that are easily manipulated at room temperature.

Question 34

In the lost wax technique for casting gold for dental restorations,a _____ is attached to the pattern to form the channel into which the molten metal will be forced.

A) die
B) sprue
C) casting
D) crucible

Question 35

What could occur if excess residue remains in the investment mold after the wax pattern is melted out?

A) This will create a harder and denser product.
B) The melting temperature of the wax will increase.
C) The melting temperature of the wax will decrease.
D) This may result in inaccuracies in the object being produced.

Question 36

Which of the following statements is true of inlay waxes?

A) Most dentists prefer to use the direct waxing technique.
B) These waxes are generally in light colors of white or yellow.
C) Type I inlay wax is melted onto a die outside the mouth in a direct technique.
D) They may be used directly in the mouth and placed onto the prepared tooth in the direct waxing technique.

Question 37

Sheets of baseplate wax are usually layered to:

A) produce patterns for metal castings using the lost wax technique.
B) construct the metal framework of partial and complete dentures.
C) produce the form on which denture teeth are set.
D) form the base portion of a gypsum model.