L3: Ceramics & Zirconia Flashcards
(186 cards)
1
Q
Ceramic applications include:
A
- all ceramic crowns, inlays, onlay, veneers & FPDs
- metal-ceramic crowns & FPDs
- implant abutments (and implants)
- denture teeth
- ceramic ortho brackets
2
Q
List the benefits of ceramics:
A
- enhanced esthetics
- physiologic gingival response
3
Q
Why is ceramics most beneficial for teeth with normally colored dentin?
A
Dentin color can affect restorations through the ceramic
4
Q
We see a physiologic gingival response with ceramics when properly:
A
contoured & 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 replication
- 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 include:
A
- flexural strength
- fracture toughness
- shrinkage
- thermal insulator
11
Q
Defined as the strength of a material bending:
A
flexural strength
12
Q
Stress on the outermost fibers of a bent 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:
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 the 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 material
A
low fracture strength
24
Q
Surface flaws act as _____ and cause widening and propagation of microcracks 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
A crack will propagate through material or until a particle is met which stops the crack growth:
crack propagation
28
Crack propagation & 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 & 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 produce through sintering?
feldspathic porcelain
35
Process of heating ceramic powder once molded:
sintering
36
Also called "firing" the ceramic:
sintering
37
The reduction of porosities between particles as the ceramic becomes more rubbery:
Sintering
38
Tg:
Glass transition temperature
39
A range of temperature where porcelain starts to become molten:
Glass transition temperature (Tg)
40
Glass transition temperature describes a transition from:
solid to rubbery
41
What is the typical glass transition temperature range of ceramics?
540 - 610 degrees celcius
42
It is important to note that the glass transition temperature of ceramics is:
BELOW the ceramic melting point
43
The glass transition temperature of ceramic is a range of temperature where porcelain starts to become:
molten
44
During firing (sintering) the space between the particle shrinks until the particles:
fuse together, resulting in dense/hard ceramic
45
Relies on external pressure to sinter and shape the ceramic at high temperature:
heat pressing
46
Heat pressing replies on _____ to sinter and shape the ceramic at high temperature
external pressure
47
During heat pressing, the restoration is made from a _____ (_____)
wax pattern (lost wax technique)
48
Heat pressing is also known as:
High temperature injection molding
49
CAD:
Computer aided design
50
CAM:
Computer aided manufacture
51
Involves a densely sintered material such as silicate, glass ceramics, and resin-based ceramics:
Hard milling (CAD/CAM)
52
Involves a partially sintered material such as zirconia, and lithium discillicate (e.Max) and the sintering is to be completed in oven AFTER manufacture:
Soft milling (CAD/CAM)
53
What type of milling involves sintering after the manufacture?
soft milling
54
What materials are used with hard milling?
1. silicate
2. glass ceramics
3. resin-based ceramics
(already densely sintered material)
55
What materials are used with soft milling?
1. zirconia
2. lithium discilicate (e.Max)
(partially sintered material)
56
For CAD/CAM, ____ are used for the milling process
blocks
57
What have improved esthetics with CAD/CAM?
1. Newer multishade blocks
2. a stain & glaze via furnace
58
List the types of blocks available for CAD/CAM:
1. Glass ceramics
2. Zirconia
3. Resin-ceramics
4. Resin
59
Classify the following blocks:
-vita mark 2
-IPS Emax CAD
-Celtra duo ultra
Glass ceramics
60
Classify the following blocks:
-IPS Emax ZirCAD
-3M Chairside zirconia
-CEREC zirconia
Zirconia
61
Classify the following blocks:
-Cerasmart
-Vita enamic
Resin-ceramics
62
Classify the following blocks:
-telio blocks
Resin
63
CAD/CAM systems include:
1. Itero
2. E4D
3. Trios
4. Planmeca
5. Carestream
64
T/F: More CAD/CAM systems come to the market every year
True
65
Ceramics that are predominately glass are considered:
veneers
66
Particle filled glass ceramics are considered:
eMax
67
Type of ceramics that have the most translucent optical properties:
Veneers (predominately glass)
68
What is considered the WEAKEST material?
Veneers (predominately glass)
69
Feldspathic porcelain is an example of:
Veneers (predominately glass)
70
Can you etch with Veneers (predominately glass)?
Yes
71
Type of ceramics that has less translucency than veneers but not the least amount of translucency:
Particle filled glass ceramic (eMax)
72
Particle filled glass ceramic (eMax) has a _____ strength
increased (compared to veneers but less than polycrystalline ceramic (zirconia))
73
Can you etch with Particle filled glass ceramic (eMax)?
Yes
74
Lithium discilicate is an example of:
Particle filled glass ceramic (eMax)
75
Type of ceramic with the LOWEST translucency:
Polycrystalline ceramic (zirconia)
76
Polycrystalline ceramic (zirconia) has the ____ strength
highest
77
Alumina & zirconia are examples of:
Polycrystalline ceramic (zirconia)
78
Can you etch Polycrystalline ceramic (zirconia)?
NOOOOO
79
Ceramic classification:
1. predominately glass
2. particle filled glass ceramic
3. polycrystalline ceramic
1. veneers
2. eMax
3. zirconia
80
Ceramic classification:
1. Highest translucency
2. Intermediate translucency
3. Lowest translucency
1. veneers
2. eMax
3. zirconia
81
Ceramic classification:
Can etch:
Cannot etch:
Can etch: veneers & eMac
Cannot etch: zirconia
82
Ceramic classification:
1. Highest strength
2. Intermediate strength
3. Lowest strength
1. zirconia
2. eMax
3. veneers
83
Give an example of each of the following:
1. Veneers
2. eMax
3. Zirconia
1. Feldspathic porcelain
2. Lithium discilicate
3. Alumina
84
The most beautiful, colorful, and most realistic false representation of natural tooth we have:
Ceramics
85
What are the negatives of ceramics?
Brittle & fracture prone
86
List some methods to strengthen ceramics:
1. resin bonding
2. reinforcement of crystalline structure of the ceramic
3. transformation toughening
87
T/F: you can use resin bonding to bond tooth to ceramic with the etchable ceramics
true
88
When resin bonding to strengthen ceramics, use of a ______ enhances bond strength
silane coupling agent
89
When resin bonding to strengthen ceramics, a resin cement used is either:
light-cured or dual-cured
90
Reinforcement of the crystalline structure of the ceramic to provide more strength involves the ____ phase which adds higher strength and is fracture resistance
dispersed crystalline phase
91
Lithium discillicate is an example of what method to strengthen ceramics?
reinforcement of the crystalline structure of the ceramic
92
Transformation toughening of ceramic to increase the strength involves:
A stress induced transformation
93
What form of ceramic strengthening is unique to zirconia:
Transformation toughening
94
In this process of strengthening ceramic, compressive forces at crack tip retard crack propagation:
Transformation toughening
95
How does porcelain break?
1. flexure
2. improper loading (askew occlusion)
96
Resin bonding is a high strength cementation procedure, so bonding ceramics will _____ the ability of the ceramic to flex. Therefore it ______
decrease; adds strength
97
Resin bonding with etchable glass ceramics provides a _____% increase in glass ceramic crown strength
50%
98
When resin bonding etchable glass ceramics, HF etched ceramic surface provides:
retention
99
When resin bonding etchable glass ceramics, the _____ (bifunctional monomers) forms a chemical bone
silane coupling agent
100
When resin bonding etchable glass ceramics, the etched enamel/dentin provides a:
adhesive layer
101
When resin bonding etchable glass ceramics, what layer is formed between the etched ceramic surface and the adhesive layer?
silane layer
102
How does resin cement work to strengthen ceramics?
The movement of the resin cement into the dentin tubules forms micro tags and moves into the porcelain spaces forming a matrix with great retention
103
Layer that contains resin microtags within the interlobular dentin and surrounding collagen fibers:
Hybrid layer
(created by resin bonding to ceramic)
104
A very thin "sheet" of porcelain as the as 0.3 to 0.5 mm (minimum thickness):
Veneers
105
What is the minimum thickness of veneers?
0.3-0.5mm
106
This tooth preparation is specific and aimed at providing aesthetics and physical support to this entity:
veneers
107
Veneers should not be used under:
Heavy occlusal loads
108
How are veneers bonded to the tooth?
Resin bonded to the enamel
109
Possibly the MOST esthetic dental restoration:
veneers
110
Veneers can be so thin that:
the underlying tooth color can affect optimal properties
111
By adding crystalline properties to the ceramic, ____ is much more difficult
Crack propagation
112
T/F: With crystalline reinforcement of ceramics cracks never begin
False- small cracks begin but then have a harder time causing catastrophic failure
113
What is the flexural strength?
a) enamel
b) feldspathic porcelain
c) leucite reinforced ceramic (empress)
d) e.Max
a) 300 MPa
b) 60-70 MPa (much lower)
c) 120-160 MPa
d) 360-500 MPa
114
An additional method to strengthen Feldspathic porcelain is to:
add a metal substructure
115
What material is ONLY used for veneers?
Feldspathic porcelain
116
Leucite reinforced ceramic:
Empress
117
Would you use leucite reinforced ceramic (empress) on a posterior crown?
No
118
Would you use leucite reinforced ceramic (empress) on a posterior inlay/onlay?
maybe- only where occlusal force is low
119
Would resin bonding help strengthen leucite reinforced ceramic (empress)?
Yes, it can be etched and therefore retention and strength is increased with resin bonding
120
Indications for leucite reinforced ceramic (empress):
anterior crowns & veneers
121
IPS empress esthetic & Ivoclar are examples of:
Leucite reinforced glass ceramic
122
Material that's flexural strength is stronger than enamel alone:
Lithium discilicate ceramic (e.Max)
(360-500 Mpa)
123
Lithium discilicate (e.Max) is used for:
1. veneers
2. anterior crowns
3. posterior crowns
4. anterior bridges (particular cases)
5. inlays/onlays with low occlusal forces
(due to its increased strength)
124
Can you use resin bonding on Lithium discilicate ceramic (E.Max)?
Yes- can use resin bonding AND other cements like RMGI
125
Should you use e.Max for a posterior three-unit bridge?
No- due to increased fracture of material
126
In the following image, we see a posterior three-unit FDP made of Lithium discilicate ceramic (e.Max). What went wrong to result in this?
You should not use e.Max for a posterior three-unit bridge due to increased fracture risk
127
Zirconia has a _____ structure
polycrystalline
128
The polycrystalline structure that comprises zirconia comprises:
1. increased strength
2. a surface that is not abrasive (like porcelain) & therefore is gentle on opposing dentition
129
What provides these properties of zirconia?
-increased strength
-a surface that is not abrasive (like porcelain) & therefore is gentle on opposing dentition
the polycrystalline structure
130
T/F: Resin bonding will NOT increase the strength of zirconia. Resin boning will increase the retention of zirconia.
Both statements true
131
What will resin bonding do for zirconia?
Increase the retention! But NOT strength
132
This material needs the internal restoration surface to be roughened since it cannot be etched:
Zirconia
133
T/F: Zirconia contains glass etch
False
134
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
135
What is needed for increased bonding of zirconia with resin cement?
A bonding primer
136
T/F: A bonding primer is needed for increased bonding of zirconia with resin cement
True
137
The original zirconia crown was from ______ 10 years ago
Glidewell
138
The original zirconia produced was a ____ zirconia crown called _____
3Y; Bruxir
139
Describe the first zirconia produced (3Y Bruxir):
1. horrible translucency esthetics
2. poorly defined occlusal anatomy
140
What was the flexural strength of 3Y Bruxir zirconia?
1200 Mpa
141
3Y Bruxir:
Zirconia (the original one)
142
T/F: Because of 3Y Bruxir zirconia's strength, any cement can be used
True
143
What has to be done to a 3Y Bruxir zirconia crown in order to fit?
Crown has to be "fired" and will shrink it about 25%
144
How are zirconia crowns so strong?
Transformational toughening
145
_____ is unique to zirconia
stress induced transformation
146
with stress induced transformation, ____ forces at crack tip retard the crack propagation
compressive forces
147
Describe what happens crack initiation of zirconia:
crack initiated --> tensile stress at crack tip causes a tetragonal to monoclinic shape change
148
Describe the shape change seen with crack initiation of zirconia:
tetragonal to monoclinic chape change
(transformational toughening)
149
What leads to crack closure associated with the compressive stresses in the vicinity of the crack tip
(zirconia transformational toughening)
volume increase associated with compressive stresses
150
To zirconia more translucent we can add ____.
What does this result in?
Yttria; decreased strength, increased translucency
151
Adding yttria to zirconia results in:
1. increased translucency
2. decreased strength
152
What type of zirconia is being described?
-100% tetragonal phase
-0% cubic phase
-HIGHEST mechanical properties (1200 MPa)
-LOWEST translucency
3Y Zirconia
153
What type of zirconia is being described?
-75% tetragonal phase
-25% cubic phase
-HIGH mechanical properties (850 MPa)
-HIGHER translucency
4Y Zirconia
154
What type of zirconia is being described?
-50% tetragonal phase
-50% cubic phase
-LOWEST mechanic properties (650 MPa)
-HIGHEST translucency
5Y Zirconia
155
In zirconia ______ phase helps with fracture toughness, while ____ phase helps with translucency
tetragonal (toughness); cubic (translucency/cuteness)
156
What formulation of zirconia is a 50;50 ratio of the tetragonal phase with the cubic phase?
5Y
157
PFZ:
Porcelain fused to zirconia
158
What is the purpose of a PFZ?
improve aesthetics with porcelain shell on top of zirconia core for strength
159
Monolithic options of zirconia are not very ____ but do not ____
esthetic; fracture easily
160
PFZ initially had failures, mostly in the:
posterior
161
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
162
If a patient comes in with a dark tooth (dentin) needing a crown, what may be a good option?
PFZ, because zirconia core can be used to mask dark dentin
163
T/F: Because zirconia is NOT brittle, any cement technique can be used
True
164
Zirconia copings can be as thin as ______ because zirconia is strong
0.4 mm
165
A ____ zirconia crown preparation can be very conservative similar to gold or PFM crown preps
monolithic zirconia
166
Describe the effects of zirconia on opposing teeth:
wear friendly
167
What type of finish lines can be used for zirconia crown preps?
chamfer or shoulder
168
Zirconia still needs appropriate ____ and ____ to survive in the oral cavity
thickness & occlusion
169
If you want the MOST esthetic anterior restoration restoration, what would you choose?
1. veneer:
2. crown:
1. feldspathic porcelain
2. e.Max or Empress
170
If you want the MOST esthetic posterior restoration, what material would you use?
1. Crown:
1. e.Max, or 5Y zirconia
171
If you have a bruxing patient, what posterior restoration material would you use?
3Y zirconia or gold
172
What is the MOST realistic anterior tooth replacement option?
Feldspathic porcelain veneer, resin bonded
173
Anterior teeth:
1. ____ occlusal forces
2. ____ strength requirement
3. ____ esthetic requirement
1. Lower
2. Less
3. Higher
174
Posterior teeth:
1. ____ occlusal forces
2. ____ strength requirement
3. ____ esthetic requirement
1. higher
2. higher
3. less
175
If the patient is NOT a grinder, what type of restoration material would we use in the posterior?
E.max or zirconia
176
Your patient is a bruxer/clencher and needs a bridge:
1. Best treatment option:
2. Middle treatment option:
3. NOT a great option:
1. monolithic zirconia (3Y) or PFM
2. monolithic material with buccal porcelain
3. fully veneered porcelain
177
When should you adjust glass ceramic veneers?
Only adjust AFTER seated & bonded with resin cement
(too fragile to adjust outside the mouth)
(internal surface should not be adjusted if possible)
178
When should you adjust e.Max (lithium discilicate)?
Adjustment outside the mouth is acceptable
(internal surface should not be adjusted if possible)
179
When should you adjust zirconia?
Adjustment outside the mouth is acceptable; internal surface needs either air abrasion or diamond bur roughening prior to cementation
180
After adjustment of ceramics with bur is done, what is the order for polishing?
1. coarse polisher
2. fine polisher
3. felt wheel or brush with fine diamond polishing paste
181
T/F: Resin cements do not require a moisture free environment
False- they DO require a MOISTURE FREE environment
182
MDP:
Methacryloyloxydecyl dihydrogen phosphate
183
Placed on zirconia to enhance the chemical bond to cements containing resin:
Primer containing MDP (used with resin cements)
184
Which of the following are contraindicated in LOW strength ceramics?
a) RMGI
b) resin cements
c) resin cements with MDP primer
a) RMGI
185
Why is an RMGI cement contraindicated with low strength ceramics?
because the water absorption with the setting of 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)
186
