Lecture 3 Flashcards
1
Q
What are composite resins cured by?
A
Visible light
2
Q
Esthetic direct restorative
A
Composite resin
3
Q
What is the primary benefit of composite resins?
A
Esthetics and ease of placement
4
Q
- Easy to Place
- Excellent Clinical Outcomes
- Poor Esthetics
A
Amalgams
5
Q
- Good Esthetics
- Excellent Clinical Outcomes
- More Difficult to Process
A
Ceramics
6
Q
- Easy to place
- Moderate clinical outcomes
- Good esthetics
A
Composite
7
Q
Hybrid Material of an organic phase (resin) and an Inorganic (filler) phase
A
Composite
8
Q
Are teeth composites?
A
Yes
9
Q
Are composites direct restoration?
A
Yes
10
Q
Advantages of Both Organic and Inorganic
Components
A
Composites
11
Q
Tend to be Tougher but not as Strong or Wear Resistant
A
Organic polymers
12
Q
Tend to be Strong and Wear Resistant but Brittle
A
Inorganic Materials
13
Q
Second Component of
the ‘Ease of Use’ in resin
A
Visible light curing
14
Q
Allows for long working time in resins
A
Command set
15
Q
What does curing develop?
A
Mechanical properties
16
Q
One of the Most Important Processes in Dental
Polymers
A
Polymerization
17
Q
Another name for polymerization
A
crosslinking
18
Q
How do you change crosslink density?
A
Number of crosslinking groups and the degree of crosslinking
19
Q
Another name for degree of crosslinking
A
Degree of curing
20
Q
Types of curing
A
Mixing (chemical)
Heat
Light
21
Q
- Operator Dependent – Working Time
- No Special Tools
- Chairside
A
Mixing (chemical) curing
22
Q
- Consistent, High Degree of Cure
- Not good In Vivo
A
Heat curing
23
Q
- Command Cure
- Good In Vivo
- Lower Degree of Cure – Limited Thickness
A
Light curing
24
Q
- Resin System
- Filler
- Bonding Agent
- Visible Light Initiator
A
Components of composite resin
25
Most common resin system
BisGMA-TEGDMA
26
Stuctural component and diluent
Resin system
| BisGMA-TEGDMA
27
- Activation of initiator molecule to generate free radical
- Initiation of monomer to generate a free-radical
- Propagation of Free-Radical with Four Monomers
- Termination of Free- Radical
Polymerization Process
28
Why type of bonds are polymer bonds?
Covalent
29
Do polymer bonds have a high of low molecular weight
High
30
Long molecules composed principally of nonmetallic
| elements (organic chemistry C,O,N,H)
Polymer bonds
31
Entangled long chains
Polymers
32
Derive strength and properties from the entanglement
Polymer bonds
33
Allows for the relative ease of processing
Resin system
34
Unpolymerized resin ...
Flows like honey
35
Provides the physical properties to resin systems
BisGMA
36
How is the viscosity in resin systems?
Very high and cannot be used alone
37
What is used with resin systems?
A reactive diluent (TEGDMA)
| -30%-50%wt
38
More stain stiffness =
More viscosity
39
- Silica or Zirconia Based Inorganics
- 50-80 wt% of the Composite
- Has Surface Hydroxyl Groups
Filler
40
Types of fillers
- Micron (fine)
- Nano (microfine)
- Nano (microfine) in polymer matrix
41
Higher filler loading results in a
Higher modulus
42
- Teeth are Nanocomposites
- Smaller Fillers Should have Better Wear Properties
- Allows for betting Polishing and Finish
- Expectation of Better Mechanical Properties
Why smaller filler size
43
- Early Composites Had 20-30 µm Filler Particles
- Fine Fillers 3-0.5 µm
- Can be loaded at 77-88 wt percent in a Composite
Micron (fine) particles
44
- Typically 0.2-0.04 µm in Size
- Very High Surface Area
- Tendency to Aggregate
- Maximum Loading 38 wt%
Nano (microfine) filler
45
Filler with very high surface area
Nano (microfine) filler
46
Filler with tendency to aggregate
Nano (microfine) filler
47
-Microfine Fillers Polymerized in Matrix and Ground to 20-30 µm Particles
-Allows for Inorganic Loading up to
50-60 wt %
-Reduces Aggregation
-Poorer Filler to Matrix Bonding - No
Coupling Agent
Nano (microfine) in polymer matrix
48
Filler that reduces aggregation
NANO (MICROFINE) IN POLYMER MATRIX
49
Poorer filler to matrix bonding- no coupling agent
NANO (MICROFINE) IN POLYMER MATRIX
50
- Mixtures of Filler Sizes
- Can Take Advantage of Having Some Microfill
- Still have Loading of 70%
Hybrid composites
51
Perma flow is a
Flowble composite
52
Low viscosity composites have
better handling
53
- Low Viscosity – Better Handling
- Lower Filler Content
- Low Modulus
- Higher Shrinkage
- Cervical Abfraction Areas
Flowable composites
54
- Contains both 0.4 µm and 0.02-0.05 µm Fillers
- 78% Filled
- Nanofiller is Prepolymerized
Herculite Ultra- microhybrid (nanohybride)
55
Nanofiller is prepolymerized in
- Herculite ultra- microhybrid (nanohybrid)
| - Filtrek Supreme (nanofill)
56
Prepolymerized Nanofiller
| 78% Filled
Filtrek supreme (nanofill)
57
Results from a Density Change of Monomer to Polymer
Polymerization shrinkage
58
Inherent Property of Double Bond Polymerization
Polymerization shrinkage
59
Has Less Molecular
Volume than the Sum
The Two Monomers
Methacrylate dimer
60
How is polymerization shrinkage measured?
Density change
61
Density change
Dilatometer
62
-Important for Direct Composite Restoratives
-Important for any Material that Required Dimensional
Stability
Polymerization shrinkage
63
What are the effects of polymerization shrinkage
- Stress on tooth structure
| - Microleaks and lead to secondary carries
64
Has Both Hydrophobic and Hydrophilic Character
Adhesive layer
65
Water sorption mechanisms of degradation
- Hydrolysis of coupling agent
| - Hydrolysis of TEGDMA
66
Most of the lab data is focused on
Mechanical properties
67
Components of biomechanical unit
- Restorative material
- Tooth structure
- Interface
- -stress transferred
68
Two component cement
Glass ionomer cement
69
Two components of glass ionomer
- Acidic polymer in aqueous solution
| - Basic glass
70
What is glass-ionomer cement cured by
Acid-base reaction
71
What does glass ionomer cement release?
Fluoride
72
What does glass ionomer have good adhesion to?
Tooth structure
73
- Polyacid
- Basic Glass
- Water
- Modifiers (+) tartaric acid
Components of glass ionomer
74
-Aluminafluorosilicate Glass
-Components Sintered at 1100-1500 oC
-Molten Glass Poured on Metal Surface and
Cooled in Water ‘Shock Cooling’
-Ground into 45 µm particles
Basic glass
75
Reacts with basic glass
Poly Acid
76
Is all glass consumed in the setting reaction?
No
77
Form from the polyacid and glass
Salt bridges
78
Not a well characterized process
Setting reaction
79
- Cleans smear layer
| - Leaves smear plugs
Condition dentin
80
Dissolves periphery of glass in glass ionomer reaction
Acid matrix
81
What ions does glass release
Ca2+, Al3+, F-
82
Quickly chelate with
| acid polymer chain
Divalent Ca ions
83
- Al+3 replace Ca+2
- Increase strength
- F- released
24-72 hours into glass ionomer reaction
84
What do acid side groups chelate with?
Glass and HA
85
Attacks the surface of the glass. No coupling agent needed
Polyacid after glass ionomer setting
86
Released upon setting
Sodium and Flouride ions
87
Continue to be released over time
Na and F
88
Hybrid Between Glass Ionomer and Compostie
| Resin
Resin modified glass ionomer
89
Has Both VLC and Acid-Base Curing
| Mechanisms
Resin modified glass ionomers
90
What does resin modified glass ionomers increase
Physical properties
91
What does resin modified glass ionomers decreased
Initial solubility of GI in solution
92
Improved over glass ionomer but inferior to composit resin
Resin modified glass ionomer
93
Shows Initial Polymerization Shrinkage but
| Expansion Upon Water Sorption
Resin modified glass ionomer
94
-Will Release Fluoride at Levels Similar to
Conventional Glass Ionomers
-Will Have Some Polymerization Shrinkage but
Offset by Swell
Physical properties of RMGI
