Crown And Bridge 114B: Unit Iii: Casting Finishing.

Front 1

1. Match the material used for finishing and polishing casting with its purpose.

Back 1

a. 1/2 round carbide bur i. Cuts of the sprue, may reduce sprue stump
b. Separating disc
ii. To be used with rouge
c. Heatless stone
iii. Reduces roughness of casting on its axial walls. Establishes proper axial contours. Establishes correct proximal contact areas. These are also best suited for the occlusal surface.
d. Sand Paper disc iv. Polishing compound, meant to be used with a Rubber Wheels soft felt wheel mounted on a mandrel.
Rubber points
e. Articulating film
v. removes nodules and positive defects; White Shoe Polish sharpens occlusal anatomy
f. Tripoli
vi. To be used in conjunction with Tripoli
g. Rouge
vii. Excellent choice for surfacing the occlusal areas of a casting prior to Tripoli
h. Mounted bristle brushes
viii. To disclose tight contact areas and occlusal
spots.
I. Felt wheel or
ix. Excellent choice for occlusal equilibration. chamois wheel
j. Mandrel mounted x. Polishing compound, meant to be used in wire brush combination with a mounted bristle brush.
k. Mounted white stone
xi. Shapes and re‐contours the sprue stump

Hint 1

ANSWER = (a=v); (b=i); (c=xi); (d=iii); (e=viii); (f=x); (giv);
(h=vi)
;(I=ii); (j=vii); (kix)

Front 2

2. T or F:
_____ Tripoli is a black compound, considered to be more course than rouge.

Back 2

True

Front 3

3. T or F:
_____Finishing procedures are the last steps required to complete a crown and bridge restoration

Back 3

True

Front 4

4. Arrange the steps for finishing a casting into their correct order.
a. Removing the sprue
b. Checking the casting in preparation for delivery
c. Machine or rough finishing the castings surface
d. Inspect the casting for defects
e. Test‐fitting the casting on the die
f. Cleaning and Pickling
g. Swaging and burnishing

Back 4

( f, d, e, a, g, c, b)

Front 5

5. All gross deposits of investment should be removed by the “digging out” process and
subsequent scrubbing with a stiff brush and water. This is known as _______________________

Back 5

d. the devesting process

Front 6

6. T or F:
_____ An ultrasonic cleaning unit filled with appropriate solution can effectively dislodge any residual investment debris

Back 6

True

Front 7

7. Circle all that apply:
An appropriate solution for an ultrasonic cleaning unit is:
a. hydrochloric acid
b. potassium citrate
c. commercial stone and investment remover
d. water

Back 7

B and C

Front 8

8. T or F:
_____Even the most minute investment particles remaining on a casting would
interfere with the fit of the restoration on the die, as well as the castings relation to the teeth around it,

Back 8

True

Front 9

9. The process of cleansing the casting of oxidation and other impurities from the metallic
surface by immersing it in a strong acid solution is called:
a. pickling
b. acidic‐ cleaning
c. canning
d. preserving

Back 9

A

Front 10

10. T or F
:_____Dental castings are pickled with the sprue and button still attached so that these portions will also be cleansed and ready for future reuse with another casting.

Back 10

True

Front 11

11. T or F:
TRU_____Pickling liquids and/or their fumes may cause personal physical damamge
and/or equiopment damage.

Back 11

True

Front 12

12. Noncorrosive pickling solutions such as ____________ can significantly reduce dangers.

Back 12

True

Front 13

13. T or F:
_____ ALL pickling procedures should be done in a well ventilated area, if possible
under a vent hood.

Back 13

True

Front 14

14. Circle all that apply: A 50% solution of____________ acid may be used for pickling:
a. Nitric
b. Hydrochloric
c. Citric
d. Sulfuric
e. Phosphoric
f. Acetic

Back 14

a, b, d, e (c and f help make lovely Vinagrette salad dressings though)

Front 15

15. A gold restoration may tarnish in the mouth because of:

Back 15

improper pickling

Front 16

16. Acids are _______ solutions and cause a plating of the casting if the solution is
contaminated.

Back 16

Electrolytic

Front 17

17. In your own words, describe why a gold casting would tarnish in the mouth as a result of
improper pickling:

Back 17

something to the effect of: “when a casting is placed in a contaminated pickling solution with metal tongs, an electric cell is formed. The tongs serve as one electrode and the gold casting as the other. The result is a flash plating of the casting
usually copper. This makes the casting look like copper instead of gold.

Front 18

18. T or F:_____ Even though most of a copper electroplate is removed when the casting is
polished, small pits will remain plated with copper when placed in the mouth.

Back 18

True

Front 19

19. T or F:
______ Saliva can act as an electrolytic solution, and will cause any small pits with
copper to corrode.

Back 19

TRUE

Front 20

20. List the 5 rules that prevent the possibility of electrocorrosion:

Back 20

1. Never use unprotected metal tongs to place or remove casting from any pickling solution.);
(2. When pickling solution becomes contaminated or discolored, safely discard and replace with fresh solution);
(3. Use a noncorrosive
pickling compound if possible); (4. Never mix different gold alloys in one casting);
(5. Store pickling solution in appropriate, well stoppered
bottles and observe precautions when handling acids.)

Front 21

21. T or F:_____ If plastic coated and glass beak tweezers are not available commercially,
regular tweezers can be covered and extended with selfcuring resin to provide protection

Back 21

true

Front 22

22. If regular acids are used for pickling, they must be:
a. stored carefully
b. used in an area remote from other equipment
c. used with an exhaust to draw vapors away
d. only used when boiling

Back 22

a, b, c

Front 23

23. With the correct solution in an appropriate beaker, made of er_____, _______, or _.

Back 23

plastic, glass, ceramic

Front 24

24. Conventionally, ceramic pickling dishes used to contain acid solution is warmed over
a _____ or ___.

Back 24

Bunsen flame or electric heating element

Front 25

25. Pickling must be continued or repeated:
a. 3 times
b. only once
c. 5 times
d. until all oxides are removed

Back 25

D

Front 26

26. T or F:
_____ Technique alloy metal should be pickled only once to remove oxides.

Back 26

FALSE (Since it will corrode, Technique alloy is not to be pickled)

Front 27

27. Castings are routinely checked for two types of defects________ and___ defects.

Back 27

Positive ; Negative

Front 28

28. T or F
:_____ Bubbles of metal or thin lacy protrusions or thin lacy protrusions from the castings are examples of positive defects.

Back 28

True

Front 29

29. T or F:
_____ Bubbles are caused by cracks in the investment and represent where metal had filled the cracks during the casting procedure.

Back 29

FALSE (this describes “fins”)

Front 30

30. T or F:
_____ If moisture collects along the margin most remote from the sprue, and is then cast, the molten metal can crush or crack the investment, resulting in a lacylike
fin pattern.

Back 30

True

Front 31

31. JEOPARDY QUESTION: Including voids in a casting known as porosity, these can also be through and through holes or even an incomplete casting.

Back 31

“What are negative defects?”

Front 32

32. Circle all that apply: Incomplete castings can be caused by:
a. incomplete filling of the mold at cast time
b. not enough metal in the melt
c. premature metal freezing
d. inadequate venting
e. excessive casting pressure
f. incomplete burnout
g. cracks in the investment.

Back 32

a, b, c, d, f

Front 33

33. T or F:
_____ Positive defects in a casting that are not on a margin line can be usually be
removed safely

Back 33

True

Front 34

34. T or F:
_____Negative defects can usually be corrected by filling the void area with solder.

Back 34

FALSE (Negative defects usually require a recast, unless the defect is VERY small)

Front 35

35. T or F:
_____ When inspecting a cast for defects, it is recommended that magnification be used.

Back 35

True

Front 36

36. All positive defects should be removed using a:
a. 84‐T bur
b. margin trimming bur
c. ½ round bur
d. ¼ round bur

Back 36

C

Front 37

37. T or F:
_____ The internal surface of a casting should be highly polished when positive
defects are removed.

Back 37

FALSE (never grind or polish the internal surface of a casting, only
remove the positive defects.)

Front 38

38. T or F:_
____ When placing a casting onto a die for a test fit, a little bit of “wobbling” is
considered normal, and can be corrected with burnishing.

Back 38

FALSE (the casting should fit the die smoothly, with no “forcing” or
wobbling needed).

Front 39

39. T or F:
_____ If a casting is warped or distorted, it must be rejected, and you have to start
over again.

Back 39

TRUE (break out the Picosep
and wat pots!)

Front 40

40. T or F:
_____ When test fitting a casting to a die, it is tremendously important to not damage the die in any way.

Back 40

TRUE (you must be extremely careful not to damage the die during test
fitting!)

Front 41

41. In your own words, briefly describe the best way to remove a sprue from a fitted casting:

Back 41

ANSWER = include the main points or something similar to: “use separating disk
mounted on mandrel and handpiece”; “leave a small uncut portion in the center”;
“Make the cut about twice as wide as the thickness of the disc to prevent binding”;
“Cut the sprue from both sides, not just one.”; “manually break off the last uncut portion of sprue.”; “avoid cutting the body of the casting”; “leave a little bit of sprue on the casting for recontouring

Front 42

42. T or F:
_____ If the sprue is cut completely through, control of the disc can be lost, causing damage to the casting, fingers, or both.

Back 42

True

Front 43

43. T or F:
_____ If no separating disks are available, heavyduty
metal shears or wire cutters
can be used to remove a sprue.

Back 43

FALSE (doing so could distort the casting).

Front 44

44. JEOPARDY QUESTION: “Related to abrading or polishing, this process involves firmly rubbing a hard metal point over a thin marginal surface to aid in adapting a casting to a die or tooth.”

Back 44

What is burnishing?

Front 45

45. Burnishing and other techniques to provide closer adaptation of the casting to the tooth or
die is called:
a. finishing
b. polishing
c. swaging
d. staging
e. none of the above

Back 45

c

Front 46

46. The best type of metal for a burnishing operation (either manual or handpiece burs) are:
a. copper
b. titanium
c. stainless steel
d. platinum

Back 46

C

Front 47

47. T or F:_
____ Gold and copper should not be used as burnishing tools because they will rub off on the surface of the casting and contaminate it.

Back 47

True

Front 48

48. An area of about ______ wide immediately adjacent to the entire length of the margin is usually the area to be burnished.

Back 48

1mm

Front 49

49. T or F:
_____ Burnishing cannot be done with the casting on the die, it must be off the die.

Back 49

FALSE (the casting can be on the die, but care must be taken to not
damage the die in any way).

Front 50

50. Tor F:
_____ When burnishing is complete, a marginal opening between the casting and the
die should only be observable under 10x magnification.

Back 50

FALSE (the marginal opening should not be detectable, even under magnification)

Front 51

51. Circle all that apply: Burnishing is particularly indicated for ______ castings.
a. inlay
b. ¾ crown
c. full crown
d. porcelain

Back 51

A and B

Front 52

52. T or F
:_____ Machining and surfacing or rough finishing of the casting surface may be
accomplished by using progressively finer abrasive polishing agents.

Back 52

True

Front 53

53. Any remaining portion of the sprue stump can be ground away and contoured with a stone like the _______.

Back 53

Heatless Stone

Front 54

54. Circle all that apply: Occlusal grooves of a casting are sharpened using:
a. #1 bur
b. ½ round carbide bur
c. small tapering white stone
d. flame shaped white stone
e. heatless stone

Back 54

A, B, C, D

Front 55

55. Arrange the materials needed for machining the entire surface of a crown in their correct
order of use:
a. sand paper discs
b. rubber wheels
c. rubber points
d. fine stones

Back 55

d, a, b, c

Front 56

56. T or F:
_____ Depending on the quality of the casting; you should start with the least abrasive instruments that will get the job done, and descend from there to the finest abrasives.

Back 56

True

Front 57

57. T or F:
_____ When finishing, the axial surfaces should be smoothed and contoured to within____ of the margins.

Back 57

1mm

Front 58

58. T or F:
_____ When polishing axial surfaces, you must be very careful not to grind away proximal contours in the proximal areas.

Back 58

True

Front 59

59. T or F:
_____ Mesial and Distal contacts must be adjusted one at a time.

Back 59

True

Front 60

60. Arrange the steps for equilibration of proximal contact areas into their proper order.
a. Remove the shiny spot with a medium grit rubber abrasive wheel
b. Inspect the die’s contact area to find the “shiny spot”
c. Place casting on the die and return to the proper position on the index base
d. Remove the adjacent pinned tooth

Back 60

d, c, b, a

Front 61

61. A “shiny spot” on the contact area of a casting is indicative of

Back 61

excessive contacting contour

Front 62

62. JEOPARDY QUESTION: “This material can be pulled between the casting and adjacent teeth to check and see if the contact points are well adjusted.”

Back 62

“What is mylar paper?”

Front 63

63. T or F
:_____ Mylar paper will leave a mark on the casting , disclosing where high spots and
contact areas are.

Back 63

FALSE (Articulating film does this, mylar paper is more of a “feel” for tightness)

Front 64

64. Once identified, areas of excessive contour can be removed from the casting by using:
a. separating disc
b. felt wheel with Tripoli
c. medium grit rubber wheel
d. heavy grit rubber disc

Back 64

C

Front 65

65. Circle all that apply:
A contact area on a casting is well adjusted when:
a. a thin piece of mylar paper can be pulled between the casting and adjacent tooth without
tearing, and only having minor resistance
b. a thin piece of mylar paper can be pulled between the casting and adjacent tooth, leaving
only a small amount of film residue on the casting.
c. A small piece of dental floss “snaps” gently between the contact areas without breaking.
d. Mylar paper can slide through the casting and adjacent tooth without any resistance.

Back 65

A and C

Front 66

66. JEOPARDY QUESTION: “Centric bite is checked on a model by placing a very thin layer of this material between the opposing teeth and occlusal surfaces of the casting.”

Back 66

What is articulating film?

Front 67

67. High spots marked by articulating film on the occlusal surfaces of a casting should be
ground away with:
a. separating disc
b. small white stone
c. carbide bur
d. rubber point

Back 67

B or C or D could be acceptable (D for smaller interferences)

Front 68

68. Circle the correct words to make the following statement true.
“As the occlusal surfaces
are adjusted, it is recommended that maxillary stamp cusps (contact / not contact) between maxillary and mandibular teeth on the balancing side.”

Back 68

Not contact

Front 69

69. T or F:
_____ In crown and bridge work, only fixed partial restorations should have
balancing side contacts.

Back 69

FALSE ( there are no balancing side contacts in crown and bridge work)

Front 70

70. Final smoothing of the casting is done with:
a. very fine sand paper discs
b. rubber wheels and points
c. the underside of a separating disc (non cutting surface)
d. fine grit wet sandpaper

Back 70

A and B

Front 71

71. T or F:
_____ All castings must be smooth and highly polished

Back 71

True

Front 72

72. Polishing a casting is important for:
a. good esthetics
b. friction for holding food in between cusps
c. comfort of the patient
d. prevents accumulation of debris from saliva and food
e. decreases the chance of tarnish, corrosion and recurrent decay

Back 72

a, c, d, e

Front 73

73. A properly polished casting will be absolutely smooth, free of scratches, and must__.
a. reflect light in a regular manner at any angle
b. reflect a non‐distorted image when looked at straight on (mirror effect)
c. reflect color corrected light, while dispersing UV light (for esthetics)
d. refract light at irregular angles to lessen reflections

Back 73

A

Front 74

74. Castings are first “_____” by using a succession of abrasive substances which scratch the surface of the restoration.

Back 74

surfaced

Front 75

75. T or F:_____ Surfacing produces smaller and smaller scratches on the surface of a casting to the point that the scratches become scarcely visible to the naked eye

Back 75

True

Front 76

76. List three materials used for polishing:___ ___ ___.

Back 76

Tripoli; Rouge; Bristle/wire brushes; mandrels (for mounting felt
wheels and wire brushes)

Front 77

77. T or F:
_____ Polishing agents are useless without the proper brush or wheel.

Back 77

True

Front 78

78. T or F:
_____ Rouge is courser than Tripoli polishing compound.

Back 78

FALSE (Tripoli is courser than Rouge)

Front 79

79. T or F:
_____ Tripoli is best used with a soft felt wheel.

Back 79

FALSE (it should be used with a bristle brush)

Front 80

80. ___ polishing compound is typically (but not always) a BBC clack compound.

Back 80

Tripoli

Front 81

81. When using Tripoli polishing agent, it should take about ______ minutes to remove the
polishing compound.

Back 81

2 to 3 minutes

Front 82

82. A soft felt wheel is best used with _____________ polishing compound

Back 82

Rouge

Front 83

83. List the steps needed to disinfect a casting for delivery to a dentist.
A.____
B.____
C._____
D_______________________

Back 83

A. Steam clean the casting and dies;
B. Clean castings in Ultrasonic cleaner.
C. Immerse castings in disinfecting solution
D. Package in proper packing material, label, and deliver

Front 84

84. When steam cleaning a casting, it should be held with:
a. gloved fingers.
b. locking tweezers
c. the die
d. on a Q‐tip

Back 84

B

Front 85

85. T or F:
_____ castings should be placed in the ultrasonic cleaner for 3 to 5 minutes in a soap
solution followed by an alcohol solution.

Back 85

True

Front 86

86. An average full coverage crown weighs approximately ________ dwt.

Back 86

2

Front 87

87. For a full coverage crown, 2 dwt of alloy will be needed for the crown, and an additional__ for the sprue and botton.

Back 87

2 (or twice the estimated weight of the casting.)

Front 88

88. There are ________ dwt in 1 Troy Oz.

Back 88

20

Front 89

89. There are _________dwt in 5 Troy ounces.

Back 89

100

Front 90

90. There are _______grains in 1 dwt.

Back 90

24

Front 91

82. A soft felt wheel is best used with _____________ polishing compound

Back 91

Rouge

Front 92

83. List the steps needed to disinfect a casting for delivery to a dentist.
A.____
B.____
C._____
D_______________________

Back 92

A. Steam clean the casting and dies;
B. Clean castings in Ultrasonic cleaner.
C. Immerse castings in disinfecting solution
D. Package in proper packing material, label, and deliver

Front 93

84. When steam cleaning a casting, it should be held with:
a. gloved fingers.
b. locking tweezers
c. the die
d. on a Q‐tip

Back 93

B

Front 94

85. T or F:
_____ castings should be placed in the ultrasonic cleaner for 3 to 5 minutes in a soap
solution followed by an alcohol solution.

Back 94

True

Front 95

86. An average full coverage crown weighs approximately ________ dwt.

Back 95

2

Front 96

87. For a full coverage crown, 2 dwt of alloy will be needed for the crown, and an additional__ for the sprue and botton.

Back 96

2 (or twice the estimated weight of the casting.)

Front 97

88. There are ________ dwt in 1 Troy Oz.

Back 97

20

Front 98

89. There are _________dwt in 5 Troy ounces.

Back 98

100

Front 99

90. There are _______grains in 1 dwt.

Back 99

24

Front 100

91. Circle all that apply: 1 gram is _____ of 1 dwt
a. 1/2
b. 2/3
c. 18 grains
d. 20 grains

Back 100

B and C

Front 101

92. The weight of gold needed for a restoration can be estimated by weighing the wax pattern
and multiplying by ______.
a. 12
b. 20
c. 15
d. 13
e. none of the above

Back 101

E (the pattern is weighed and multiplied by 17)

Front 102

93. T or F:
______ All gold alloys shrink as they cool to room temperature

Back 102

True

Front 103

94. Match the expansion % with the type of burnout or type of setup an invested ring can have
a. Bench Set i. Up to 1.4%
b. Hygroscopic Set ii. Up to 0.3 – 0.5%
c. Thermal low heat burnout iii. Up to 1.35%
d. High‐heat burnout iv. Up to 0.3% for benc‐set, 1.7% for Hygroscopic

Back 103

(a = ii); (b = i); (c = iv); (d = iii)

Front 104

95. Investment mold expansion can have an overall total of:
a. 1.4 – 1.85%
b. 1.50 – 2.0%
c. 1.25 % d. 1.70%

Back 104

A

Front 105

96. Gold alloy can experience a shrinkage rate of:
a. 1.4 – 1.85%
b. 1.50 – 2.0%
c. 1.25 – 1.70%
d. 5%

Back 105

C

Front 106

97. T or F:
_____ It is important that the investment mold expansion percentage match the gold allow shrinkage as closely as possible.

Back 106

True