Dental Materials Flashcards
1
Q
Particles are made by thin cuts of alloy that are machine cut from a cast
A
Lathe-cut
2
Q
Particles are made by molten alloy blown through a nozzle
A
Spherical
3
Q
Particles are wetted with a lower mercury to allow ratio
A
Spherical particles
4
Q
which of the particles resist forces of condensation more
A
lathe-cut
5
Q
Alloy component that has a low creep value
A
Copper
6
Q
Alloy component that makes for a long last restoration
A
Copper
7
Q
amalgam alloy that doesn’t create concern about moister contamination
A
Zinc-free
8
Q
A slower setting type for amalgam is related to
A
Higher mercury
9
Q
how is the heat treatment of amalgam done?
A
by the manufacture
10
Q
relieves stress in the alloy particles
A
Heat treatment
11
Q
Provide manufacture control of setting time
A
heat treatment
12
Q
eliminates the compositional nonuniformities that exists in both types of particles
A
heat treatment
13
Q
when is there no free mercury found?
A
after setting
14
Q
what phase is the high-copper amalgam reaction missing?
A
Gamma 2
15
Q
What is the common phase of high-copper and low-copper amalgam?
A
Gamma 1
16
Q
Has a slower setting reaction because of the two sets process
A
High-Copper
17
Q
setting reaction disappearance of gamma 2 phase and formation of n’ phase?
A
High-copper
18
Q
Technique used for using amalgam
A
No-touch
19
Q
skin contact, inhalation of vapor, airborne droplets
A
mercury exposure
20
Q
set by US government to limit mercury exposure during the work week a@ 40 hr/week at 0.05 mg Hg/m3
A
Threshold limit value (TLV)
21
Q
any alloy made of Hg with a silverGtin alloy with varying amounts of copper and small amounts of zinc
A
Dental Amalgams
22
Q
Clinical benefits include long lasting restorations with a low creep value
A
High Copper amalgam
23
Q
Amalgam alloy that is more resistant to corrosion
A
High copper
24
Q
Results in a less plastic amalgam
A
Zn containing
25
Not economically feasible for manufacturer to eliminate what from amalgam
Zn
26
Makes lathe cut particles more brittle for machining
Zn
27
Improves amalgams resistance to corrosion
Zn
28
Mercury to alloy ratio
~ 0.05
29
silver --> Hg phase
Gamma 1
30
Tin --> Hg phase
Gamma 2
31
what us the major reaction phase in both low and high copper amalgams
Gamma 1
32
In what step of a high copper rxn does the gamma Gamma 2 phase not appear because is it replaced by n'
Second step
33
Why does high-copper have a slower setting rxn
two step process
34
When is the total delusional change to be complete for amalgam ( cannot detect change by explore or eye)
24hrs
35
Total dimensional change after 24 hr is limited by
ADA STD #1
36
Most modern amalgams undergo an overall _______ of setting mass
contraction
37
loss of anatomy and postoperative pain are possible problem with amalgam that exhibits
setting expansion
38
excessive setting contraction of amalgam can cause
mircoleakage
39
Incompletely consumed starting allow particle (gamma)
Strongest phase
40
Gamma 2 in lowGcopper amalgams (most corrosion prone)
Weakest phase
41
Amalgam is (brittle/ductile) under normal rates of loading
Brittle
42
Is the compressive or tensile strength of amalgam greater
Compressive
43
Amalgam needs proper dentinal support to resist forces of
Mastication
44
Fracture of ledge on poorly finished restoration readily occurs due to amalgams
poor edge strength
45
Fractures from amalgam being is caused by what
low tensile strength
46
What ratio for compressive strength divided by tensile strength is indicative of brittle material
High
47
The deformation that occurs as a result of constant force (load)
Creep
48
The only mechanical property correlated with clinical marginal fracture of low copper amalgam restorations
Creep
49
Which amalgam has a lowest creep value
High-copper
50
Boundary sliding of gamma 1 phase
Creep Mechanism
51
What is blocked by n' in high copper amalgam
Gamma 1
52
Margin-sealing capability that decreases microleakage with time is n advantage of
creep
53
corrosion protects of amalgam are advantageous for
Margin-sealing
54
Amalgam is relatively inexpensive than
Gold alloy
55
Amalgam corrosion at interproximal contacts with gold alloy restorations
Galvanic corrosion
56
Amalgam corrosion that occurs beach of multiple phases
Electrochemical corrosion
57
Amalgam corrosion at margins
Crevice corrosion
58
lower pH and oxygen concentration of
| saliva cause corrosion at
unpolished or secondary amalgam
59
Amalgam corrosion caused by low oxygen concentration due to
plaque build-up
60
Amalgam corrosion from reaction with sulfide ions at occlusal surface
Chemical corrosion
61
Cu6Sn5
n'
62
Minimizes amalgam corrosion
polishing
63
Scratches and pits trap debris, enhancing corrosion because
Low oxygen in areas
64
Clinical trials suggest hat _____ amalgam restorations have superior marginal integrity and longevity
Zn containing
65
EPA has set strict guidelines for
disposal of amalgam
66
Easy to please but has poor esthetic qualities
Amalgam
67
Good esthetic but is more difficult to place
Ceramics
68
flow into pits and fissures of tooth surface to prevent decay
Sealants
69
Often etching is recommended to prepare enamel before placing
Sealants
70
For sealants there needs to be Balance between ___ and ________
flow, sealing capability
71
Sealants are chemically the same as composites but there is no
Filler
72
What helps sealants flow into the pits and fissures more easily
Low viscosity
73
At surface of composites or thin materials like sealants, unpolymerized material must be removed
oxygen inhibition layer
74
What interferes with radical polymerizations - inhibits polymerization of methacrylates
oxygen
75
What is more problematic for thin layers like sealants
oxygen inhibition layer
76
Beneficial to make it possible to build up light curable composite in layers
oxygen inhibition layer
77
what needs t be done before a new layer is added?
curing
78
Used to make negative mold of dental structures
Impression material
79
What is starting to take the place of impression material
scanning for digital models
80
Irreversible hydrocolloid (alginate) are
water based
81
Hydrophobic, synthetic impression materials
Viscoelastic
82
Polysulfides, siloxane, polyethers
Viscoelastic
83
Used to make the cast from the impression
Gypsum
84
```
Low cost
Long shelf life
Biocompatibility
Pleasant to patient Dimensionally stable
Good handling properties
```
Ideal properties of impression material
85
Irreversible hydrocolloid impression material
Alginate
86
Used to make dental impressions for removable partial dentures, preliminary impressions for complete dentures, orthodontic models and study models
Alginate
87
Alginate is not used for crown and bridge impressions due to lack of
accuracy
88
water based materials for what in water
Sol
89
Resembles a solution, but is made up of colloidal particles dispersed in a liquid
Sol
90
Water based material that forms a sol
Alginate
91
What type cross-linking is formed with alginate
Calcium
92
Ties two chains together in a network of polymer chains
Calcium cross linking
93
sol ---> gel transformation
Setting rxn
94
How is alginate cured
mixing water with powder
95
water dissolved Ca ions that _____ alginate molecules
cross link
96
What can effect the properties of alginate
water temp
| water ratio
97
chemically alginate is
irreversible
98
Single poor only
quick pouring required
Limited detail reproduction
Low tear resistance
Disadvantages of alginate
99
```
Economical
Easy to use
Quick setting
Fair taste
Hydrophilic
Stock trays
Can displace blood and saliva
```
Advantages of alginate
100
Property of alginate that is effected why the amount of water int he environment
Dimensional stability
101
Loss of water to surroundings
Synersis
102
Gain of water from environment
Imbibition
103
Alginate impressions should be stored in a humid environment and poured quickly for
Least dimensional change & avoid distortion
104
Inherently hydrophobic materials
Polysiloxanes
105
addition type can be made hydrophilic
Polysiloxanes
106
Hydrophobic but chemically and dimensionally stable
Polysiloxanes
107
Can be added to Polysiloxanes to increase hydrophilic properties
surfactant
108
Polysiloxanes can be made more hydrophilic by the chemical incorporation of hydrophilic moieties into the
silicone backbone
109
Crosslinked of Polysiloxanes is done by
hydrosilation reaction
110
Polysiloxanes has ____ dimensional stability
Good
111
More stable than alginates or polysulfides
Polysiloxanes
112
What is used to improve detail registration and detail transfer for polysiloxanes
surfactant
113
surfactant makes Polysiloxanes more
Hydrophilic
114
Other than surfactant what can be used to improve Polysiloxanes' detail registration
Polyethers
115
Hydrophobic, but more hydrophilic on a hydrophobic scale than polysiloxanes
Polyethers
116
an additive that has a bad taste
Polyethers
117
fast setting slightly hydrophilic material
Polyethers
118
Dehydrate form of calcium sulfate found in a compact mass in nature
Gypsum
119
Dental gypsum products are manufactured by removing the water from what
calcium sulfate dehydrate
120
driving off part of the water of calcium sulfate dehydrate
calincation
121
a straightforward and reversible reaction
calincation
122
How is gypsum cured
water
123
calcium sulfate hemihydrate
stone powder
124
When calcium sulfate hemihydrate is added to water the hemihydrate is converted back to
dehydrate
125
What type of rxn takes place when the stone powder is added to water
reverse
126
what type of rxn is the conversion of calcium sulfate hemihydrate to dehydrate
exothermic rxn
127
Contributes to strength and dimensional change of gypsum
interlocking
128
Dental stone Requires less water, and are approx.. 2.5x stronger than
plaster
129
materials that are temporary and need to be removed
Provisional
130
Materials has dimethacrylates that crosslink the material
Denture base
131
Denture base needs to
last a long time
132
Denture base materials has
fillers
133
Denture base custom tray material
TRIAD and VLC
134
Visible light cured
VLC
135
Provisional materials are normally cured . .
chemically
136
A thermoplastic material that is designed to absorb impact
Mouthguard materials
137
Ways mouthguard materials can be processed?
Melted or pressure
138
Mouthguard materials has a ___ softening point
Low
139
Mouthguard materials is thermally processed with
hot water
140
Mouthguard materials is formed by
vacuum and dye
141
Copolymer or thermoplastic polymer
Mouthguard materials
142
Used to bind restorations of appliances to tooth structure
Cements
143
Glass ionomers
| Resin modified glass ionomers Zinc phosphates Zinc polyacrylate
Water based cements
144
Composites
| Compomers
Resin based cements
145
Zinc oxide eugenol
Oil based cements
146
Low viscosity but good mechanical properties and 25 um thickness are
Requirements for cements
147
More filler in Glass ionomer makes it have
more viscosity
148
A ratio of Powder to liquid in glass ionomer increase the working time
Low
149
For glass ionomers, it is the powder to liquid ratio P:L
2.7:1
150
Typically one component systems
Resin Cements
151
Viscosity and strength controlled by filer loading
Resin Cements
152
Used for ortho, ceramic crowns and bridges, veneers, inlays and onlays
Resin Cements
153
Increased filler increases or decreases viscosity
increases
154
How are glass ionomers cured
acid-base rxn
155
What does glass ionomer release
fluoride
156
adheres to the tooth structure well
glass ionomer
157
Glass ionomer has proven better retention than
composite
158
Is glass ionomer dimensionally stable
yes
159
```
Slow setting
Early dissolution
Optical properties
Stain resistance
Poor physical properties
```
disadvantages of glass Ionomer
160
Used to protect the pulp and minimize sensitivity
Bases and liners
161
Act as thermal and chemical barriers to the pulp
Bases and liners
162
Controls inflammation of pulp and movement of fluids
Bases and liners
163
relatively thin layer of material usedto protect dentin from residual reactants that diffuse out of the restoration or oral fluids that may penetrate leaky restoration interface
Liner
164
are used to provide thermal protection for the pulp and to supplement mechanical support for the restoration by distributing local stresses from the restoration across the underlying dentin surface during amalgam condensation (or cementation of indirect restorations)
Bases
165
Must have great mechanical properties bur viscosity is not as important
Bases
166
Is placed in a. thin layer so maters must have a low viscosity
Liner
167
Used for pulp caping with near or direct exposure
Calcium Hydroxide
168
Calcium Hydroxide is a
liner
169
odontoblasts will lay down what after pulp caping
defensive/ reparative dentin
170
Pain reduction=sedative restoration
ZOE
171
Intermediate restorative material
Reinforced ZOE
172
competent of ZOE that act as obtundent (dulls pain)
clove oil
173
can be used under composite
Reinforced ZOE
174
Inhibits polymerization
Reinforced ZOE
175
Expands when setting which increases sealing
Reinforced ZOE
176
What type of material is wax
Temporary
177
is was dimensionally stable?
must be
