Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Fixed Prosthodontics > Crown Preparations- margin design > Flashcards

Crown Preparations- margin design Flashcards

1
Q

Parts of a crown preparation:

A
  1. axial wall
  2. interproximal wall
  3. finish line
  4. occlusal anatomy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

A full coverage restoration can survive in the biologic environment of the oral cavity only if:

A

the margins are closely adapted to the surface finish line of the preparation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The design of the preparation ______ dictates the shape and bulk of restorative material in the marginal area of the restoration

A

finish line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Types of finish line design include:

A
  1. knife edge
  2. chamfer (light and heavy)
  3. shoulder
  4. beveled should
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

A chamfer finish line can be described as:

A

light or heavy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Finish line design that is used primarily for full metal crowns only. (Especially gold crowns):

A

Knife edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Most conservative preparation design for the finish line :

A

Knife edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What may be used to create a knife edge finish line?

A

Flame or needle-shaped diamond bur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The disadvantages of knife edge finish lines include:

A
  1. difficult to see finish line in an impression or scan
  2. metal can be thin & susceptible to distortion under heavy occlusal load
  3. often leads to an over-bulking of crown material to compensate for thinness along margin
  4. easy to miss creating distinct end of finish line and instead acial wall never terminates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

This image shows a knife edge finish line. What is the disadvantage to B?

A

Margin thin and susceptible to distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

This image shows a knife edge finish line. What is the disadvantage to C?

A

To compensate for thin marginal area, labs will overbulk crown at margin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the indications for the use of knife edge margin finish lines?

A
  1. generally NOT indicated
  2. in certain instances like a tipped molar, a knife edge margin is possible to be conservative in an abnormal area
  3. must have an excellent lab technician
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In certain instances, like a tipped molar, a _____ margin is possible to be conservative in an abnormal area

A

knife edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Label the following types of margin finish lines:

A

(left to right)
1. shoulder
2. chamfer
3. knife edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is required for a knife edge finish line?

A

An excellent lab technician

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two types of chamfer margins?

A
  1. heavy chamfer
  2. light chamfer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What types of crowns use a light chamfer?

A

Metal crowns & zirconia crowns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What types of crowns use a heavy chamfer?

A

-Ceramic crowns
-Zirconia crowns
-Metal-ceramic crowns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What type of bur can be used to create a chamfer finish line?

A

Round-end tapered diamond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

A heavy chamfer will work for what type of crowns?

A

Any type of crown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When creating a chamfer margin finish line axial depth more than 1/2 the bur, can create ____ of the margin, which leave ____ likely to chip or break leaving an open and exposed margin

A

lipped edges; unsupported enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the advantages of a chamfer margin finish line? (5)

A
  1. chamfer is well suited to full metal crowns & zirconia crowns
  2. ease of seating & placing crown
  3. ease of detecting margin on impression/scan
  4. if full metal, chamfer is easy to wax & cast
  5. provides adequate thickness of restoration material at margin area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A light chamfer is ______ deep in axial wall

A light chamfer produces a _____ degree margin with rounded internal angle

A

0.3-0.5 mm

30-45 degree margin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

A light chamfer produces a a ____ internal angle

A

Rounded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Type of margin finish line that combines knife edge burnish-ability with bulk of material for all metal crowns:

A

Chamfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Label the parts of the following crown prep:

A

a) chamfer finish line
b) functional cusp bevel
c) planar occlusal reduction
d) rounded angles
e) axial reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

the chamfer finish line promotes:

A

marginal integrity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

the functional cusp bevel promotes:

A

structural durability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

the planar occlusal reduction promotes:

A

structural durability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

the rounded line angles promote:

A

structural durability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

the axial reduction promotes:

A

retention and resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

A heavy chamfer provides room for:

A

thicker ceramic margin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

The ______ of the heavy chamfer decreases material stress in the margin area

A

internal rounded angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the measurements of a heavy chamfer?

(How deep)

A

1.0-1.2mm deep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What bur is used to accomplish a heavy chamfer?

A

typically a large round-ended diamond bur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Label which chamfer is light and which is heavy:

A

Left- light
Right- heavy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

A ______ margin design produces a close to 90 degree angle

A

shoulder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

A shoulder margin design produces a close to _____ degree angle

A

90

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

A shoulder margin design is used primarily for ______ crowns and ______ crowns where thickness of material is important but can also be used for ___ crowns

A

metal ceramic & all ceramic; zirconia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

A modified shoulder produces a _____ angle

A

rounded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

A shoulder margin is typically created with:

A

flat-end diamond burs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

In a shoulder margin design, the angle of the axial wall and finish line is close to 90 degrees and this functions to:

A

decrease stresses on restoration material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

A shoulder margin designs primarily used for _____ and ____ crowns

A

metal-ceramic & all ceramic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Label the different margins shown:

A

Left: shoulder margin
Right: beveled shoulder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Some shoulder finish lines can include a bevel at a _____ degree angle

A

30-45

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

A shoulder with a bevel is often used for _____ and _____

A

inlays and onlays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What type of margin can be used for metal ceramic crowns where there is a metal collar?

A

beveled shoulder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

A beveled shoulder margin allows for _____ of metal to ensure marginal fit

A

adaptability

49
Q

Significant roughness of preparation finish line can prevent:

A

close adaptation of crown margin

50
Q

Rough margin = ______ = _____

A

plaque accumulation; recurrent decay

51
Q

Finish line designs vary based on: (3)

A
  1. restoration material
  2. location in the mouth
  3. desired results
52
Q

The type of tooth preparation in which the finish line forms a 90-degree angle with the unprepared tooth surface:

53
Q

The advantage of this margin includes:

-less distortion of crown margins
-provides adequate bulk
-good crown contours
-can attain good esthetics

54
Q

The disadvantages of this margin includes:

-marginal adaptation can be affected
-more tooth structure needs to be removed

55
Q

Indications of this type of margin include:

-all ceramic crowns
-PFM crowns

56
Q

This type of margin is similar to a shoulder but has a bevel placed at the border:

A

beveled shoulder

57
Q

Indications of this type of margin include:

-gingival finish line on the proximal box of inlays or onlays
-occlusal shoulder of onlays and mandibular three-quarter crowns
-the finish line for extremely short walls
-the posterior margin for metal-ceramic crowns with a supra gingival margin

A

beveled shoulder

58
Q

The advantages of this type of margin include:

-to get proper marginal adaptation
-the bulk of the material in border

A

beveled shoulder

59
Q

The disadvantages of this type of margin include:

-more tooth structure is removed
-less conservative approach
-preparation should be extended apically

A

beveled shoulder

60
Q

A finish line design for tooth preparation in which the gingival aspect meets the external axial surface at an obtuse angle:

61
Q

Indications for this type of margin include:

-cast metal restorations
-lingual margin of metal-ceramic restorations

62
Q

Advantages of this type of margin include:

-conservative tooth prep
-good marginal adaptation
-provides bulk to the restoration

63
Q

Disadvantages of this type of margin include:

-technique sensitive
-any defect in fabrication can lead to unsupported tip of the crown

64
Q

Similar to chamfer finish line but comes with a 90 degrees cavosurface angle with a large radius rounded internal angle:

A

heavy chamfer

65
Q

In cases of metal restorations using a chamfer margin, a ____ is added to the finish line

66
Q

Indications for this type of margin include:

-ceramic crowns
-metal crowns with a bevel

A

heavy chamfer

67
Q

Advantages for this type of margin include:

-best finish line for a ceramic crown

A

heavy chamfer

68
Q

Disadvantages for this type of margin include:

-technique sensitive
-little discrepancy can lead to the formation of a lip or unsupported fragile enamel

A

heavy chamfer

69
Q

Also considered a thin-edge margin or feather-edge:

A

knife edge

70
Q

Indications for this type of margin include:

-young patients
-metal restorations
-MOD onlay
-inaccessible areas
-when the finish line extends to the cementum
-the lingual surface of mandibular posterior teeth
-pin ledge 3/4 quarter crown

A

knife-edge/feather-edge

71
Q

Advantages for this type of margin include:

-conservative
-helps in preserving tooth structure
-ideal for marginal adaptation
-useful in gold & metal crowns/restorations as it lets you burnish it to a fine finish
-considered an ideal finish line

A

knife-edge/feather-edge

72
Q

Disadvantages for this type of margin include:

-distinct or proper finish is not visible
-waxing
-polishing and casting become critical
-overcontouring of restorations to obtain a bulk is a usual complication

A

knife-edge/feather-edge

73
Q

Crown preparation concerns:

Scientists seem to oscillate back and forth as to whether heat produced during a crown preparation will:

A

kill the pulp

74
Q

Crown preparation concerns:

It is agreed that the _____ becomes irritated and inflamed during _____

A

pulp; crown preparations

75
Q

Crown preparation concerns:

A rise in the pulp temperature by ____ degrees significantly increases the chance of _____

A

10 degrees; pulpal necrosis

76
Q

Crown preparation concerns:

Because of the concerns with overheating the pulp during a crown preparation we should: (7)

A
  1. use lots of water
  2. use sharp burs
  3. use light pressure
  4. use high speed
  5. use diamond burs
  6. avoid desiccation of the teeth
  7. if visibility is compromised, with an assistant, with water off from the hand piece, an assistant can use air and small amounts of water to help keep tooth cool.
77
Q

The main cause of postoperative inflammation or necrosis of the pulp is probably the injury of ______, a tissue in direct functional and physiological connection with the pulp

78
Q

Margin design instrumentation:

For the preparation, what is used? (3)

A
  1. high-speed handpiece
  2. air/water spray
  3. diamond burs
79
Q

Margin design instrumentation:

For finishing the preparation, what is used? (3)

A
  1. slow-speed handpiece
  2. fine diamond burs (possibly some carbide burs)
  3. hand instruments
80
Q

Margin design instrumentation:

For caries removal of the crown preparation, what is used? (2)

A
  1. slow-speed with 2, 4 or 6 round bur
  2. spoon excavators
81
Q

Burs that function to remove enamel and dentin by grinding it away:

A

diamond burs

82
Q

Burs that function to remove tooth by shearing it away:

A

carbide burs

83
Q

______ burs are most efficient, 2-3x faster than _____ burs

A

diamond; carbide

84
Q

What type of bur is being described?

-cut precision prep features with smooth surfaces
-often used to place extra retentive features in a crown preparation such as a seating groove

A

Carbide burs

85
Q

_____ can be used to help smooth finish lines

A

hand instruments

86
Q

Hand instruments that can be used to help smooth finish lines include: (4)

A
  1. chisel
  2. hatchet
  3. hoe
  4. margin trimmer
87
Q

Advantages of full metal crowns:

Gold and many metal crowns are:

A

soft metals

88
Q

Full metal crowns are _____ to opposing teeth

89
Q

Advantages of full metal crowns:

metal is strong so:

A

material can be quite thin

90
Q

Describe the preparations involving a full metal crown:

A

very conservative preparations

91
Q

Advantages of full metal crowns:

Metals have some antibacterial properties making:

A

recurrent decay less likely

92
Q

Describe the effects of most gold and full metal crowns on the gingiva:

93
Q

______ crowns are very durable even if worn through or with an endo access

A

metal crowns

94
Q

In metal crown if the contact is missing:

A

you can add material to the contact to re-establish it

95
Q

List the disadvantages of full metal crowns:

96
Q

Discuss the margin design for a full metal crown preparation:

A

Can use knife-edge margin, but usually a light chamfer is recommended (0.3-0.5 mm)

97
Q

In a full metal crown preparation, axial walls are reduced to create a tapered wall between ____ to ____ degrees ideally, but can have TOC up to ____ degrees

A

6 to 10; 20

98
Q

In a full metal crown preparation, axial walls can be reduced as little as ___ but can be reduced more if needed

99
Q

Discuss the occlusal reduction in a full metal crown preparation:

A

uniform occlusal reduction depth of 1.0 to 1.5mm following tooth anatomy

100
Q

Nothing is _____ in dentistry except for our tools

101
Q

In a full metal crown preparation, line angles and corners need to be rounded to prevent:

A

pressure points and possible fracturing of a restorative material

102
Q

In a full metal crown preparation, rounded preparations make the:

A

crown fabrication process easier

103
Q

In a full metal crown preparation, prepared surfaces and finish line are smoothed with a fine grit diamond bur, what does this ensure?

A

Preparation walls are scored, but with a smoother more consistent shape for seating and longevity of the restoration

104
Q

Full metal crown summary:

A) Chamfer finish line: _____
B) Axial reduction: _____
C) Total occlusal taper: _____
D) Occlusal clearance: _____
E) _____ of all line angles

A

A) 0.3-0.5mm
B) as little as 0.5mm
C) 6-10 degrees
D) 1.0-1.5mm
E) rounding

105
Q

Label the various tooth preparations:

A

(Left to right)
Metal or all-zirconia
PFM
All-ceramic

106
Q

A relatively new material that is tooth-colored and ceramic-like:

107
Q

Zirconia is considered _____ free

108
Q

Zirconia can have similar properties to:

109
Q

Zirconia can be described as very:

A

hard and tough

110
Q

Compare the appearance of zirconia to natural teeth:

A

less translucent

111
Q

What material is seen in the following crown?

112
Q

The original zirconia that was very tough and very ugly:

113
Q

Why have new iterations of zirconia been created?

A

to make zirconia more esthetic

114
Q

What is the problem with making new iterations of zirconia that are more esthetic?

A

In order to make them more esthetic the strength of the zirconia is reduced

115
Q

Depending on the type of zirconia crown, the preparation can be:

A

as minimal as a full metal crown prep or as extensive as an all ceramic crown prep

116
Q

Zirconia is rapidly changing still so what is extremely important?

A

knowing which kind of zirconia your lab is using so you can prep appropriately

117
Q

The more esthetic your zirconia is, the more ______ will be needed

Fixed Prosthodontics (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions