Dental Materials Part II, Test I Flashcards Preview

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

Class I cavities include what?

5 points here

A

All pit and fissure cavities

Occlusal Surfaces

Premolars/Molars

Occlusal 2/3 of Facial/LIngual surfaces

LIngual Max Incisors

2
Q

Define Class II cavities

A

Proximal surfaces

Premolars/Molars

3
Q

Class III cavities:

A

Proximal surfaces

Incisors/Canines

Do NOT involve incisal angle

4
Q

Class IV cavities:

A

Proximal surfaces

Incisors/Canines

Involve Incisal angle

5
Q

Class V cavities:

A

Gingival 1/3

Facial/Lingual

All teeth

*non pit/fissure cavities

6
Q

Class VI cavities:

A

Incisal edge Anterior teeth

Occlusal cusp heights Posterior teeth

7
Q

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

A

Microtags

Macrotags

8
Q

What are the 3 procedures of Dentin Bonding?

A

Etching

Priming

Bonding

9
Q

What % of Dentin is water?

A

25%

10
Q

What are 4 functions of Etching in Dentin Bonding?

removes 2 things, exposes 2 things

A

Removes the smear layer

Removes HA from outer dentin layer

Exposes a collagen sponge layer

Exposes dentin tubules

11
Q

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

A

Prevent drying

12
Q

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

A

Hybrid Layer Formation

13
Q

4 principles of adhesion in Dentin Bonding:

A

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
Q

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

A

Hydrophilic collagen

Hydrophobic resin

15
Q

What is an example of a Bifunctional monomer?

A

HEMA

16
Q

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

A

Conditioner and Primer

17
Q

Most bonding is a result of ________ retention

A

Micro-mechanical

18
Q

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

A

Moist

MDP and Ethanol

19
Q

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

A

Organic polymer matrix

Inorganic filler particles

Coupling agent

Initiator-accelerator system

20
Q

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

A

Oligomers

21
Q

What are 3 examples of Oligomers?

A

Bis-GMA

U-DMA

TEG-DMA

22
Q

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

What wavelength does it absorb?

A

Camphorquinone

Blue light (400-500 nm)

*reacts w/ activator, forms free radicals, polymerization

23
Q

T/F

The surface layer of resin composite’s exposure to air may inhibit double bonds

A

True

24
Q

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

A

75%

25
Q

What is present in bond failure interface in resin composite?

A

Microgap formation

26
Q

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

A

Volume Fraction of Polymer

27
Q

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

A

More

28
Q

Why does Microhybrid composite have less shrinkage?

A

Less polymer matrix

29
Q

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

A

More polymer present

30
Q

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

A

1/4 to 1/2 E value

*microfilled not as good as highly filled fine particle

31
Q

How is Irradiance (radiate exitance) measured?

A

photos per second per unit area

mW/cm2

32
Q

How is Energy Density measured?

A

Irradiance x time

J/cm2

33
Q

What is the most common photo-absorbing material?

A

Camphorquinone

34
Q

What is the maximum spectrum sensitivity of Camphorquinone?

A

465-47- nm

Blue range

35
Q

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

A

Energy Density (irradiance of light x time)

Distance from composite

Collimation of light (focusing/narrowing)

Wavelengths emitted and absorbed

Composite type

36
Q

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

A

Increase irradiance, Decrease time

Decrease irradiance, Increase time

37
Q

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

A

LED

Halogen

38
Q

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

A

Plasma arc

39
Q

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

A

Microfil composites

Darker shades

Flowable composites

greater distance

poor collimation

40
Q

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

A

Hybrid composites

Lighter shades

Close distance

Good collimation

41
Q

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

A

Shank

42
Q

What connects the head to the shank?

A

Neck

*usually tapers

43
Q

What is the working part of the instrument?

A

Head

44
Q

How are Rotary Cutting Instruments classified?

2

A

Shape

Number (which I think is size)

45
Q

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

A

Negative Angle

46
Q

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

A

Minimizes fracture of the cutting edge

47
Q

Increasing the Clearance Angle ________

A

Decreases the Edge Angle

48
Q

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

A

Clearance Angle

49
Q

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

This angle is considered?

A

Carbide is brittle

Negative

50
Q

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.

A

True

51
Q

What does a Coupling Agent ensure?

A

Bond forms between Inorganic filler and Oligomer during setting

52
Q

What is an example of a Coupling Agent?

A

Silane

53
Q

T/F

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

A

True

54
Q

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

A

Filler > Coupling Agent > Oligomer > polymer matrix

55
Q

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

A

Take up more water

More soluble in mouth

More polymerization shrinkage

Higher rate of Thermal Expansion

Lower Elastic Modulus

***overall, decreased properties

56
Q

Where would Microfils most likely be used?

Where would Microhybrids most likely be used?

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

A

Aesthetics

Load bearing

***Microfils shouldn’t be used on load bearing interface - will stress tooth-composite bond because of “squishyness”

57
Q

Round burs are measured from ____ to _____

Pear shaped bur common measurement:

Tapered fissure burs common measurement:

A

1/4 to 8

330, 329 (230-232)

169 (700-703)

58
Q

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

A

Edge angle decreases

59
Q

What happens when we etch dentin?

What happens when we etch enamel?

A

Prevent drying, hybrid layer, collagen

Microtags/Macrotags

60
Q

What are the 4 components common to all bonding?

A

Etching

Primer

Adhesive

Initiator

61
Q

How is the Hybrid layer formed?

A

Resin in Primer > Etched Dentin

62
Q

Look at HEMA molecule

A

OK

hydrophobic/hydrophilic

63
Q

Polymerization of composites:

A

Initiation, Propagation, Termination

64
Q

T/F

Microhybrids are blends of fine materials

A

True

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