Dental Materials Part II, Test I Flashcards Preview

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Flashcards in Dental Materials Part II, Test I Deck (64):
1

Class I cavities include what?

(5 points here)

All pit and fissure cavities

Occlusal Surfaces

Premolars/Molars

Occlusal 2/3 of Facial/LIngual surfaces

LIngual Max Incisors

2

Define Class II cavities

Proximal surfaces

Premolars/Molars

3

Class III cavities:

Proximal surfaces

Incisors/Canines

Do NOT involve incisal angle

4

Class IV cavities:

Proximal surfaces

Incisors/Canines

Involve Incisal angle

5

Class V cavities:

Gingival 1/3

Facial/Lingual

All teeth

*non pit/fissure cavities

6

Class VI cavities:

Incisal edge Anterior teeth

Occlusal cusp heights Posterior teeth

7

In enamel bonding, what 2 structures are identifiable after etching with phosphoric acid gel?

Microtags

Macrotags

8

What are the 3 procedures of Dentin Bonding?

Etching

Priming

Bonding

9

What % of Dentin is water?

25%

10

What are 4 functions of Etching in Dentin Bonding?

(removes 2 things, exposes 2 things)

Removes the smear layer

Removes HA from outer dentin layer

Exposes a collagen sponge layer

Exposes dentin tubules

11

During the Etching process, what must be done to keep the collagen sponge layer from collapsing?

Prevent drying

12

In Dentin Bonding, the resin component part of the primer's attachment to the dentin is called what?

Hybrid Layer Formation

13

4 principles of adhesion in Dentin Bonding:

Hybrid Layer variable thickness

Mechanically weak if incomplete adherence with primer

Primer Solvents enhance wetting (monomers > tags)

To get monomers deep, many primer layers may be needed (as solvent evaporates)

14

What are the 2 parts of Primer that make it a Bifunctional Monomer?

Hydrophilic collagen

Hydrophobic resin

15

What is an example of a Bifunctional monomer?

HEMA

16

The self-etch two-step process has combined what?

Conditioner and Primer

17

Most bonding is a result of ________ retention

Micro-mechanical

18

Currently the best bonding takes place on a _____ surface and agents containing ______ and ______.

Moist

MDP and Ethanol

19

What are the 4 Major Components of Resin Composite restorative material?

Organic polymer matrix

Inorganic filler particles

Coupling agent

Initiator-accelerator system

20

The Organic Polymer Matrix that make up resin composite are made up of what?

Oligomers

21

What are 3 examples of Oligomers?

Bis-GMA

U-DMA

TEG-DMA

22

What is the most common photoinitiator in Visible-Light Activation?

What wavelength does it absorb?

Camphorquinone

Blue light (400-500 nm)

*reacts w/ activator, forms free radicals, polymerization

23

T/F
The surface layer of resin composite's exposure to air may inhibit double bonds

True

24

What percentage of resin composite may be unreacted double bonds at the air contact surface layer?

75%

25

What is present in bond failure interface in resin composite?

Microgap formation

26

In resin composite, what is Polymerization Shrinkage a direct function of?

Volume Fraction of Polymer

27

Because Microfilled composite has a higher volume percentage of polymer, there is more/less shrinkage?

More

28

Why does Microhybrid composite have less shrinkage?

Less polymer matrix

29

Thermally speaking, why does Microfilled resin composite have More Expansion?

More polymer present

30

Compared to highly filled Fine Particle Composites, what is the E value of Microfilled composites?

1/4 to 1/2 E value

*microfilled not as good as highly filled fine particle

31

How is Irradiance (radiate exitance) measured?

# photos per second per unit area

mW/cm2

32

How is Energy Density measured?

Irradiance x time

J/cm2

33

What is the most common photo-absorbing material?

Camphorquinone

34

What is the maximum spectrum sensitivity of Camphorquinone?

465-47- nm

Blue range

35

What are 5 factors that determine how long it takes to adequately cure a composite?

Energy Density (irradiance of light x time)

Distance from composite

Collimation of light (focusing/narrowing)

Wavelengths emitted and absorbed

Composite type

36

What is the Reciprocity principle in terms of Total Energy Density?

Increase irradiance, Decrease time

Decrease irradiance, Increase time

37

What 2 types of light will lower irradiance and therefore increase curing time?

LED

Halogen

38

What type of light will increase irradiance and therefore decrease curing time?

Plasma arc

39

Other than lowering Irradiance, name 5 factors that will Increase curing time

Microfil composites

Darker shades

Flowable composites

greater distance

poor collimation

40

Other than increasing irradiance with plasma arc, name 4 factors that will Decrease curing time

Hybrid composites

Lighter shades

Close distance

Good collimation

41

What instrument part fits into the handpiece and provides the rotary motion to the bur?

Shank

42

What connects the head to the shank?

Neck

*usually tapers

43

What is the working part of the instrument?

Head

44

How are Rotary Cutting Instruments classified?

(2)

Shape

Number (which I think is size)

45

If the rake face is ahead of the radius, the bur has a ....

Negative Angle

46

A negative rake angle is used for cutting hard brittle materials because it...

Minimizes fracture of the cutting edge

47

Increasing the Clearance Angle ________

Decreases the Edge Angle

48

What provides space for the chips formed ahead of the following blade?

Clearance Angle

49

Why are Carbide burs at around 90 degrees and need more of a rake angle?

This angle is considered?

Carbide is brittle

Negative

50

T/F
Clearance angles are either curved or have 2 surfaces to provide low clearance angles and greater clearance space ahead of the following blade.

True

51

What does a Coupling Agent ensure?

Bond forms between Inorganic filler and Oligomer during setting

52

What is an example of a Coupling Agent?

Silane

53

T/F
Coupling Agent like Silane is applied to the surface of the filler before it is mixed with Oligomer

True

54

When the Oligomer sets, the double bonds from the Silane react with the Oligomer to bridge a link between what?

Filler > Coupling Agent > Oligomer > polymer matrix

55

Compared to a Microhybrid, a Microfil will have more Matrix Resin in it. What are 5 consequences for Microfil?

Take up more water

More soluble in mouth

More polymerization shrinkage

Higher rate of Thermal Expansion

Lower Elastic Modulus

***overall, decreased properties

56

Where would Microfils most likely be used?

Where would Microhybrids most likely be used?

*one Doesn't go into heavy load-bearing areas

Aesthetics

Load bearing

***Microfils shouldn't be used on load bearing interface - will stress tooth-composite bond because of "squishyness"

57

Round burs are measured from ____ to _____

Pear shaped bur common measurement:

Tapered fissure burs common measurement:

1/4 to 8

330, 329 (230-232)

169 (700-703)

58

What happens to the edge angle if you increase the clearance angle?

Edge angle decreases

59

What happens when we etch dentin?

What happens when we etch enamel?

Prevent drying, hybrid layer, collagen

Microtags/Macrotags

60

What are the 4 components common to all bonding?

Etching

Primer

Adhesive

Initiator

61

How is the Hybrid layer formed?

Resin in Primer > Etched Dentin

62

Look at HEMA molecule

OK

hydrophobic/hydrophilic

63

Polymerization of composites:

Initiation, Propagation, Termination

64

T/F
Microhybrids are blends of fine materials

True

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