L3- Ceramics and Zirconia Flashcards
(185 cards)
1
Q
Ceramic applications include:
A
- All ceramic crowns, inlays, onlays, veneers and FPDs
- Metal-ceramic crowns and FPDs
- Implant abutments (and implants)
- Denture teeth
- Ceramic orthodontic brackets
2
Q
List the benefits of ceramics:
A
- enhanced esthetics (due to absence of metal and improved light transmission)
- physiologic gingival response
3
Q
Why are ceramics most beneficial for teeth with normally colored dentin?
A
dentin coli can affect restoration through the ceramic
4
Q
We see a physiologic gingival response with ceramics when properly:
A
contoured and highly glazed/polished
5
Q
____ is the most realistic restoration that looks like a tooth
A
ceramics
6
Q
Why and how does ceramic look so much like a real tooth?
A
- color replcation
- refraction
- translucency
7
Q
Describe the color replication of ceramics that makes it look so much like a real tooth:
A
ceramics can be tinted/colored to produce nearly any tooth shade
8
Q
Describe the refraction of ceramics that makes it look so much like a real tooth:
A
ceramics reflect and absorb light rays simulating enamel
9
Q
Describe the translucency of ceramics that makes it look so much like a real tooth:
A
type of porcelain (incisal/dentin/opaque)
10
Q
Important properties of ceramics includes:
A
- flexural strength
2 fracture toughness - shrinkage
- thermal insulator
11
Q
Defined as the strength of a material in bending:
A
flexural strength
12
Q
Stress on the outermost fibers of a ben test specimen, at failure:
A
flexural strength
13
Q
Describe the flexural strength of ceramic:
A
brittle!
14
Q
Defined as the resistance to fracture when a crack is present:
A
fracture toughness
15
Q
_____ have high fracture toughness due to plasticity at tip of crack, absorbs energy, making crack propagation more difficult
A
Metals
16
Q
Describe the fracture toughness of ceramics:
A
low fracture toughness - little plasticity
17
Q
What happens to ceramics as they are fired?
A
they shrink!
18
Q
Meaning a poor conductor of heat:
A
thermal insulator
19
Q
Ceramic is a thermal insulator meaning it is:
A
a poor conductor of heat
20
Q
The coefficient of thermal expansion in ceramic is ___. This means that:
A
low; ceramics do not expand and contract much with heat and cold
21
Q
CTE:
A
Coefficient of thermal expansion
22
Q
What is a major limitation of ceramics?
A
They are brittle
23
Q
A.A. Griffith (1921) suggested that the ___ of glass is due to the presence of microscopic flaws in the bulk of material.
A
low fracture strength
24
Q
Surface flaws act as ___ and cause widening and propagation of micro cracks through the ceramic material.
A
Stress initiators
25
Ceramic limitations:
1. ____ in porcelain propgate cracks
2. damage from ____ & ____ propagate cracks
3. these porosities can be ___ or ___
1. porosities
2. grinding & heat
3. external or within the material
26
Why do ceramics fail at lower than expected stress?
crack propagation
27
Crack will propagate through material, or until a particle is met which stops the crack growth:
crack propagation
28
Crack propagation and stress corrosion are both limitations of:
ceramic
29
____ describes how strength is reduced in a moist environment
stress corrosion
30
_____ is reduced in a moist environment
strength
31
A stress-dependent chemical reaction between water vapor and crack tip, causing crack growth and fracture with comparatively little occlusal loading (over long periods)
Stress corrosion
32
Stress corrosion is a ____ reaction between ___ & ___, causing crack growth and fracture with relatively little ____ (over long periods)
stress-dependent chemical reaction; water vapor & crack tip; occlusal loading
33
Ceramic powder/liquid is built up and molded (feldspathic porcelain)
sintering
34
What type of ceramic is produced through sintering?
Feldspathic porcelain
35
Process of heating ceramic powder once molded, (also called firing the ceramic)
sintering
36
The reduction of porosities between particles as the ceramic becomes more rubbery:
sintering
37
Tg:
Glass transition temperature
38
A range of temperatures where porcelain starts to become molten:
Glass transition temperature (Tg)
39
Glass transition temperature describes a transition from:
sold to rubbery
40
What is the typical glass transition temperature range of ceramics?
540-610 degrees Celsius
41
It is important to note that the glass transition temperatures of ceramics is:
BELOW the ceramic melting point
42
The glass transition temperature of ceramic is a range of temperature where porcelain started to become:
molten
43
During firing (sintering), the space between the particles shrinks until the particles:
fuse together, resulting in dense/hard ceramic
44
Relies on external pressure to sinter and shape the ceramic at high temperature:
heat pressing
45
Heat pressing relates on ____ to sinter and shape the ceramic at high temperature
external pressure
46
During heat pressing, the restoration is made from a ____ (____)
wax pattern (lost wax technique)
47
Heat pressing is also known as:
high temperature injection molding
48
CAD:
computer aided design
49
CAM:
Computer aided manufacture
50
Involves an already densely sintered material such as silicate, glass ceramics, & resin-based ceramics:
hard milling (CAD/CAM)
51
Involves partially sintered material such as zirconia, lithium discilicate (e. max) & the sintering is to be completed in oven AFTER manufacture:
soft milling (CAD/CAM)
52
What type of milling involves sintering AFTER the manufacture?
soft milling
53
What materials are used with hard milling?
1. silicate
2. glass ceramics
3. resin-based ceramics
(already densely sintered material)
54
What materials are used with soft milling?
1. zirconia
2. lithium distillate (e. max)
(partially sintered material)
55
For CAD/CAM, ___ are used for the milling process
blocks
56
What has improved esthetics with CAD/CAM?
1. newer multi-shade blocks
2. a stain and glaze via furnace
57
List the types of blocks available for CAD/CAM
1. glass ceramics
2. zirconia
3. resin-ceramics
4. resin
58
Classify the following blocks:
- Vita Mark 2
- IPS Emax CAD
- Celtra Duo Ultra
Glass ceramics
59
Classify the following blocks:
- IPS Emax ZirCAD
- 3M Chairside Zirconia
- CEREC Zirconia
Zirconia
60
Classify the following blocks:
- Cerasmart
- Vita Enamic
Resin-ceramics
61
Classify the following blocks:
- Tell blocks
Resin
62
CAD/CAM systems include:
1. Itero
2. E4D
3. Trios
4. Planmeca
5. Carestream
63
T/F: More CAD/CAM systems come to the market every year
True
64
Ceramics that are predominately glass are considered:
veneers
65
Ceramics that are particle filled glass ceramics are considered:
Emax
66
Type of ceramics that have the most translucent optical properties:
Veneers (predominately glass)
67
What is considered the weakest material?
Veneers (predominately glass)
68
Feldspathic porcelain is an example of:
Veneers (predominately glass)
69
Can you etch with Veneers (predominately glass)?
Yes!
70
Type of ceramics that have less translucency than veneers but not the leas amount of translucency
Particle filled glass ceramic (eMax)
71
Particle filled glass ceramic (eMax) has a ____ strength
increased (compared to veneers but less than polycrystalline ceramic zirconia)
72
Can you etch Particle filled glass ceramic (eMax)?
Yes!
73
Lithium disilicate is an example of:
Particle filled glass ceramic (eMax)
74
Type of ceramic with the LOWEST translucency:
Polycrystalline ceramic (zirconia)
75
Polycrystalline ceramic (zirconia) has the ____ strength
highest
76
Alumina and zirconia are examples of:
Polycrystalline ceramic (zirconia)
77
Can you etch Polycrystalline ceramic (zirconia)?
NOOOOO!
78
Ceramic classification:
1. Predominately glass
2. Particle filled glass ceramic
3. Polycrystalline ceramic
1. Veneers
2. Emax
3. Zirconia
79
Ceramic classification:
1. Highest translucency
2. Intermediate translucency
3. Lowest translucency
1. Veneers
2. Emax
3. Zirconia
80
Ceramic classification:
Can etch:
CANNOT etch:
can etch: veneers & max
cannot etch: zirconia
81
Ceramic classification :
1. Highest strength
2. Intermediate strength
3. Lowest strength
1. Zirconia
2. Emax
3. Veneers
82
Give an example of each of the following:
1. Veneers
2. Emax
3. Zirconia:
1. Feldspathic porcelain
2. Lithium disilicate
3. Alumina
83
The most beautiful, colorful, and the most realistic false representation of natural tooth we have:
Ceramics
84
What are the negatives of ceramics?
brittle and fracture prone
85
List some methods to strengthen ceramics:
1. resin bonding
2. reinforcement of the crystalline structure of ceramic
3. transformation toughening
86
T/F: You can use resin bonding to bond tooth to ceramic with the etchable ceramics
True
87
When resin bonding to strengthen ceramics, use of a ______ enhances bond strength
Silane coupling agent
88
When resin bonding to strengthen ceramics, a resin cement used is either:
light cured or dual cured
89
Reinforcement of the crystalline structure of the ceramic to provide more strength involves the ____ phase which adds higher strength and fracture resistance
dispersed crystalline phase
90
Lithium disilicate is an example of what method to strengthen ceramics?
Reinforcement of the crystalline structure of the ceramic
91
Transformation toughening of ceramic to increase the strength involves:
stress induced transformation
92
What form of ceramic strengthening is unique to zirconia?
transformation toughening
93
In this process of strengthening ceramic, compressive forces at crack tip retard crack propagation:
Transformation toughening
94
How does porcelain break?
1. flexure
2. improper loading (askew occlusion)
95
Resin bonding is a high strength cementation procedure , so bonding ceramics will ____ the ability of the ceramic to flex. Therefore it ____.
decrease; adds strength
96
Resin bonding with etchable glass ceramics provides a ___ in glass ceramic ceramic crown strength
50% increase
97
When resin-bonding etchable glass ceramics, HF etched ceramic surface provides:
retention
98
When resin-bonding etchable glass ceramics, the ____ (bifunctional monomers) forms a chemical bond
silane coupling agent
99
When resin-bonding etchable glass ceramics, etched enamel/dentin provides a:
adhesive layer
100
When resin-bonding etchable glass ceramics, what layer is formed between the etched ceramic surface and the adhesive layer?
silane layer
101
How does resin cement work to strengthen ceramics?
The movement of the resin cement into the dentin tubules forms microtags and moves into the porcelain spaces forming a matrix with great retention
102
Layer that contains resin microstags within the interlobular dentin and surrounding collagen fibers:
Hybrid layers
(created by resin bonding to ceramic)
103
A very thin sheet of porcelain as thin as 0.3 to 0.5 mm (minimal thickness)
veneers
104
What is the minimal thickness of veneers?
0.3 to 0.5 mm
105
This tooth preparation is specific and aimed at providing esthetics and physical support to this entity:
veneers
106
Veneers should not be used under:
heavy occlusal loads
107
How are veneers bonded to the tooth?
resin bonded to the enamel
108
Possibly the MOST esthetic dental restoration:
veneers
109
Veneers can be so thin that the:
underlying tooth color can affect the optical properties
110
T/F: With crystalline reinforcement of ceramics cracks never begin
False- small cracks begin but then have a harder time causing catastrophic failure
111
By adding crystalline aspects to the ceramic, ____ is much more difficult
crack propagation
112
Flexural strength of:
A) enamel
B) feldspathic porcelain
C) leucite reinforced ceramic
D) E. Max
A)300 MPa
B) 60-70 MPa (much lower)
C) 120-160 MPa
D) 360-500 MPa
113
An additional method to strengthen feldspathic porcelain is to:
add a metal substructure
114
What material is ONLY used for veneers?
feldspathic porcelain
115
Leucite reinforced ceramic:
empress
116
Would you use leucite reinforced ceramic on a posterior crown?
No
117
Would you use leucite reinforced ceramic on an onlay/inlay?
Maybe- only where occlusal force is low
118
Would resin bonding help strengthen leucite reinforced ceramic?
Yes- it can be etched and therefore retention and strength is increased with resin bonding
119
Indications for leucite reinforced ceramic (empress)
anterior crowns & veneers
120
IPS, Empress, Esthetic, and Ivoclar are all examples of:
leucite reinforced glass ceramic
121
Material that's flexural strength is stronger than enamel alone:
Lithium disilicate ceramic (E. Max) (360-500 MPa)
122
Lithium Discilicate (E. Max) is used for:
1. veneers
2. anterior crowns
3. posterior crowns
4. anterior bridges (particular cases)
5. inlays & only with low occlusal forces
(due to its increased strength)
123
Can you use resin bonding on lithium discilicate ceramic (E. max)?
Yes - can use resin bonding AND other cements like RMGI
124
Can you use E. Max for a posterior 3-unit bridge?
No due to increased fracture of material
125
In the following image, we see a posterior 3 unit FDP made from lithium disilicate ceramic (E. Max)... What went wrong to result in this?
You should NOT use E. max for a posterior bridge
(due to increased fracture risk)
126
Zirconia has a ____ structure:
polycrystalline
127
The polycrystalline structure of zirconia provides:
1. increased strength
2. a surface that is not abrasive (like porcelain) and therefore is gentle on opposing dentition
128
What provides these properties of zirconia?
- increased strength
- a surface that is not abrasive (like porcelain) and therefore is gentle on opposing dentition
The polycrystalline structure of zirconia
129
T/F: Resin bonding will NOT increase the strength of zirconia. Resin bonding will increase the retention of zirconia.
Both statements true
130
What will resin bonding do for zirconia?
Increase the retention! (but not the strength)
131
This material needs the internal restoration surface to be roughened since it cannot be etched:
Zirconia
132
T/F: Zirconia contains glass etch
False
133
Zirconia needs the internal restoration surface to be roughened since it cannot be etched. How might this be accomplished?
1. Air abrasion
2. Diamond bur
134
What is needed for increased bonding of zirconia with resin cement?
bonding primer
135
T/F: A bonding primer is needed for increased bonding of zirconia with resin cement
True
136
The original zirconia crown was from ___ 10 years ago
Glidewell
137
The original zirconia produced was a ___ zirconia crown called ___
3Y; Bruxir
138
Describe the first zirconia produced (3Y zirconia aka Bruxir):
1. horrible translucency esthetics
2. poorly defined occlusal anatomy
139
What was the flexural strength of 3Y Bruxir?
1200 MPa
140
3Y Bruxir:
Zirconia (the original one!)
141
T/F: Because of 3Y Bruxir zirconia strength, any cement can be used
true
142
What has to be done to a 3Y Bruxir Zirconia crown in order to fit?
crown has to "fired" and will shrink to fit; will shrink it about 25%
143
How are zirconia crowns so strong?
transformational toughening
144
____ is unique to zirconia
stress induced transformation
145
With stress induced transformation ____ forces at crack tip retard the crack propogation
compressive forces
146
Describe what happens following crack initiation of zirconia:
Crack initiation --> tensile stress at crack tip causes a tetragonal to monoclinic shape change
147
Describe the shape change with crack initiation of zirconia?
tetragonal --> monoclinic shape change
(transformational toughening)
148
What leads to crack closure associated with the compresses stresses in the vicinity of the crack tip (zirconia transformational toughening)
volume increase associated with the compressive stresses
149
To make zirconia more translucent we can add ___. What does this result in?
Yttria; decreased strength
150
Adding Yttria to zirconia results in:
1. increased translucency
2. decreased strength
151
What type of zirconia is being described?
- 100% tetragonal phase
- 0% cubic phase
- HIGHEST mechanical properties (1200 MPa)
- LOWEST translucency
3Y zirconia
152
What type of zirconia is being described?
- 75% tetragonal phase
- 25% cubic phase
- HIGH mechanical properties (850 MPa)
- HIGHER translucency
4Y zirconia
153
What type of zirconia is being described?
- 50% tetragonal phase
-50% cubic phase
- LOWEST mechanical properties (650 MPa)
- HIGHEST translucency
5y zirconia
154
In zirconia, ____ phase helps with fracture toughness, while ____ phase helps with translucency
tetragonal = toughness
cubic= translucency (cuteness)
155
What formulation of zirconia is a 50/50 ratio of the tetragonal phase with the cubic phase?
5Y
156
PFZ:
porcelain fuzed to zirconia
157
What is the purpose of a PFZ?
improve esthetics with the porcelain shell on tope of the zirconia core for strength
158
Monolithic options of zirconia are not very ___ but do not ____.
Esthetics; fracture easily
159
PFZ crowns initially had failures, mostly in the:
posterior
160
List some reasons PFZ crowns failed? Specifically the porcelain aspect that would fail:
1. lack of porcelain support in zirconia substructure
2. OCCLUSION
3. Bond between zirconia and porcelain would not be able to overcome the difference in coefficient of thermal expansion between the zirconia core and the veneering porcelain
161
If a patient comes in with a dark tooth (dentin) needing a crown, what may be a good option?
PFZ because the zirconia core can be used to mask the dark dentin
162
T/F: Because zirconia is NOT brittle, any cement technique can be used
true
163
Zirconia copings can be as thin as ___ because zirconia is strong
0.4
164
A _____ zirconia crown preparation can be very conservative similar to gold or PFM crown preps
monolithic zirconia
165
Describe the effects of zirconia on the opposing teeth:
wear friendly
166
What type of finish lines can be used for zirconia crown preps?
chamfer or shoulder
167
Zirconia still needs appropriate ____ and ____ to survive in the oral cavity
thickness & occlusion
168
If you want the MOST esthetic anterior restoration what material would you choose?
1. veneer
2. crown
1. feldspathic porcelain
2. E. Max or Empress
169
If you want the MOST esthetic posterior restoration, what material would you use?
1. Crown
Emax or 5Y zirconia
170
If you have a bruxing patient, what posterior restoration material would you use?
3Y zirconia or Gold
171
What is the most realistic anterior tooth replacement option?
Feldspathic porcelain veneer resin bonded
172
Anterior teeth:
1. ____ occlusal forces
2. ____ strength requirement
3. ____ esthetic requirement
1. lower
2. less
3. higher
173
Posterior teeth
1. ____ occlusal forces
2. ____ strength requirement
3. ____ esthetic requirement
1. higher
2 higher
3. less
174
If the patient is NOT a grinder, what type of restoration material would we use in the posterior?
E. max or Zirconia
175
Your patient is bruxer/clencher and needs a bridge.
1. Best treatment option:
2. Middle treatment option:
3. Not a great option:
1. Monolithic zirconia or PFM
2. monolithic material with buccal porcelain
3. fully veneered porcelain
176
When should you adjust glass ceramic veneers?
Only adjust AFTER seated and bonded with resin cement (too fragile to adjust outside the mouth) and the internal surface should NOT be adjusted if possible
177
When should you adjust E. Max (lithium disilicate)?
adjustment outside the mouth is acceptable and the internal surface should not be adjusted if possible
178
When should you adjust zirconia?
Adjustment outside the mouth is acceptable; internal surface needs either air abrasion or diamond bur roughening prior to cementingA
179
After adjustments of ceramics with bur, what is the order for polishing?
1. coarse polisher
2. fine polisher
3. felt wheel or burns with fine diamond polishing paste
180
T/F: Resin cements do not require a moisture free environment
False- They DO require a moisture free environment
181
MDP:
Methacryloyloxydecyl dihydrogen phosphate
182
Placed on zirconia to enhance the chemical bond to cements containing resin
Primer containing MDP (used with resin cements)
183
Which of the following are contraindicated in LOW strength ceramics?
A) RMGI
B) Resin cements
C) Resin cements with MDP primer
A- RMGI
184
Why is an RMGI cement contraindicated with low strength ceramics?
Because the water absorption with the setting of the cement leads to slight expansion and possible fracture of ceramic at thin margin area
(however because zirconia is a strong ceramic it can be used with zirconia)
185
