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Dental Materials - Final > Final > Flashcards

Final Flashcards

1
Q

What is resilience?

A

Energy req’d to resist perm change.

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2
Q

What is fracture toughness?

A

Resistance to fracture

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3
Q

What is flexibility?

A

Small stress/strain relationship

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4
Q

What is the highest tensile strength?

A

Dentin

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5
Q

What is corrosion?

A

Desired in amalgam, chem breakdown of metal

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6
Q

Definition of setting time?

A

Time for chemicals to completely react in a material

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7
Q

Which are limitations for testing materials in the lab?

A

All the above

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8
Q

Which are patients and tech?

A

All the above

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9
Q

With Intraoral scanners, what does open connection mean?

What about trusted connection?

A

Open: Send files to lab or any CAD/CAM system, has options for clear aligners and night guards

Trusted: In-office mills, digital implant workflows, orthodontic appliances, access to digitally produced SLA working models

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10
Q

What are some training req’s for intraoral scanning in office?

A

Scanning and hole filling
Margin marking design
Lab script completion
File transfer to lab

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11
Q

Selection of restorative materials: CEREC vs PlanMill.

A

All yes, EXCEPT PlanMill no on Feldspathic porcelain

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12
Q

What is the work flow from CAD/CAM working with a lab?

A

Dental office does digital scan. Scan is then sent to lab. Lab designs restoration.

Or,

Impression or model is sent in, model/impression is scanned. Restoration is design. Milling center or lab used.

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13
Q

Dyes are fabricated using what?

A

SLA 3D printing

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14
Q

Lava COS vs Elastomeric Impressions. Occlusion numbers.

A

Lava. Elastomeric

Perfect: 74%. 48%

High: 18%. 46%

Light: 8%. 6%

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15
Q

What factors are present in the selection of CAD/CAM ceramics?

A

Strength - 120 to 1500 MPa

Esthetics - Ant vs Post

Patient factors

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16
Q

CAD/CAM Ceramics. Name the three types and strengths.

A

Feldspathic Porcelain - 100-120 MPa

Leucite-reinforced porcelain - 120-140 MPa (Best for Ant veneers)

Lithium distillate ceramic - 500 MPa (IPS e.max CAD) (Esthetic and strong)

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17
Q

CAD/CAM non-silica based ceramics.

A

Zirconia

Strength: 500-1500 MPa

Veneered core and framework and full-contour restorations

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18
Q

What is high strength Zirconia?

A

Y-TZP

> 90% ZrO2
Stabilized with 3.0%-5.4% Y2O3, HfO2, Al2O3
Small grains w/ no glassy phase
NO SILICA

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19
Q

Zirconia has improved ______________ but lower ______________ strength.

A

Translucency

Flexural

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20
Q

Cubic zirconia is what?

A

> 95% ZrO2
Small grains w/ no glassy phase
No silica

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21
Q

Know that BruxZir # of units sold increased from 10,000/month in 2010 to 143,000/month in 2016, while PFM stayed relatively the same with 25,000/month in 2010 to 19,000/month in 2016.

A

Almost done with this class jack.

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22
Q

Zirconia crowns and bridges at 5 yrs.

A

Most had no chipping or fracture. One crown and two implant failures.

Excellent esthetics for B1 shade

3% deboned and were recemented.

Minimal wear on crown and opposing, while some wear was shown on opposing gold crowns

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23
Q

Stump shade is important!

A

Yes!

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24
Q

Which ceramics are popular in Japan and what is their translucency and flexural strength?

A

Milled Resin
High translucency
Low flexural strength

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25
Q

Amalgams. What advancement helped with marginal integrity, less creep, less tarnish, and better shine?

A

The change from high gamma-2 to high copper, low gamma-2.

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26
Q

What is creep?

A

Slow deformation under load - slow flow.

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27
Q

Why is corrosion a desired result with amalgam?

A

It makes a self-seal against tooth structure.

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28
Q

High copper, low gamma-2 has less tensile strength, on the order of 40-50 MPa after one day.

A

So, about ten-fold less than compressive strength. 1/10!

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29
Q

What is a resin?

A

A viscous liquid which is capable of hardening permanently.

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30
Q

What is polymerization?

A

The opening of the double bond b/t two carbons, linking two molecules into one, and then adding more to create a polymer.

EX - the vinyl group can be opened and linking can occur.

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31
Q

What is PMMA?

A

It’s our “go to” for dentures, but not used for fillings.

**O2 inhibition - if curing happens in air, then the surface layer remains monomer-rich, which is very useful, b/c add’l material will bond chemically when it cures

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32
Q

Epoxy polymers. What do they do?

A

Form a lot of chains, strong. Bisphenol A is used as a backbone for polycarbonate plastics

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33
Q

Bis-GMA, why do we use it so much?

A

Main resin component of most dental filling resins. It is strong.

*It is highly viscous, and must be diluted w/ a more fluid resin to make it workable.

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34
Q

What is used sometimes instead of Bis-GMA?

A

UDMA

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35
Q

What is TEGDMA?

A

Low viscosity - it is the diluent in resin composites that allow Bis-GMA to be workable. It polymerizes, but quite a lot leaches out in the days following placement.

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36
Q

What is HEMA?

A

It is hydrophilic and quite ALLERGENIC.

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37
Q

Resin based composites (RBCs) are what?

A

A mixture of filler particles and resins. They add strength, create color, influence surface finish.

The particles are mostly silica with a mixture in sizes. Usually silane coupling happens (a chemical coating on silica particles - increases the bond b/t resin and filler particles)

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38
Q

What is used now to initiate curing?

A

Intense UV light.

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39
Q

Bonding RBCs to enamel or dentin is harder to do?

A

Dentin. It is more wet than enamel is live teeth.

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40
Q

RBCs shrink on curing, about how much?

A

About 1% or slightly more at best.

How to overcome this? Pack incrementally, and know that RBCs shrink towards the curing light

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41
Q

T/F - Polymerization is ALWAYS incomplete.

A

TRUE.

What comes out and what does it do?

Mostly TEGDMA, some HEMA. It kills some pulpal cells, and causes some hypersensibility. The body clears this in about a day.

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42
Q

What do us and our staff need to be careful about?

A

We can become allergic to resins, especially HEMA. DO NOT LET THIS TOUCH THE SKIN

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43
Q

T/F - Bis-GMA is estrogenic.

A

True. However, there is more in plastic water bottles. More in a mother’s kiss.

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44
Q

Why do large RBC restorations fail earlier than other materials, like amalgam?

A

They shrink on curing, and they hydrolyze over time at the dentin interface from MMPs.

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45
Q

What pulpal depth is req’d for amalgam?

A

1.5 mm - also mech retention

46
Q

What should we do to the matrix band before we use it?

A

Pre-contour with large ball burnisher

47
Q

What kind of proximal surface offers the greatest resistance to fracture?

A

CONVEX

48
Q

How do we separate for tight contacts?

A

Matrix and wedges completely close gingival margins.

49
Q

Studies show which type of amalgam have the longest durability?

A

Lathe cut - silver/copper plus

50
Q

What is the Half-Blood Prince’s “Speedball” technique?

A

Bring a large amount of amalgam over to the restoration and over fill

51
Q

What are you supposed to do to the occlusal embrasure with the explorer?

A

Carefully carve and remove enough amalgam to prevent fracture on band removal.

52
Q

What matrix do you use for composite restorations?

A

Sectional

53
Q

What is the etch, peak, and cure req’s?

A

Etch - enamel 20 sec, dentin 10 sec

Wash and blot dry, rub in Peak for 10 sec, light cure for 20 sec

54
Q

Flowable - how thin of a layer?

A

0.5 mm. Light cure 20 seconds

55
Q

T/F - composite is technique sensitive?

A

True.

56
Q

What is the average life span of composites internationally? What about here at the school?

A

6 years

20 years

57
Q

What is the average life span of amalgam internationally? Here at the school?

A

20 years

40 years

58
Q

What is color?

A

Psychophysical sensation provoked in the eye by visible light and interpreted by brain.

59
Q

What is value?

A

ACHROMATIC. Enables differentiation b/t the light and dark colors

60
Q

What is hue?

A

The first chromatic coordinate. This enables differentiation b/t color families. Placed in a closed hue circle.

61
Q

What is chroma?

A

2nd chromatic coordinate. Enables differentiation b/t pale and strong colors. Distance from vertical axis.

62
Q

For our purposes, we are working in the color spectrum of how much?

A

0.016%

63
Q

What is delta E?

A

Interaction of H/V/C differences. Basically, the color difference.

64
Q

At a 50:50% acceptability threshold, what was delta E?

A

2.7

65
Q

Over _______ of patients were aware of color difference.

A

80%

66
Q

Correct match _____/16 pairs of tabs of two shade guides.

A

7.7

67
Q

What was the average shade matching error?

A

4 vita shades

68
Q

15 years ago, esthetic dentistry accounted for less than 20% of the money spent on dentistry. What is it now?

A

70%

69
Q

What is psychophysics?

A

Science dealing w/ math relations b/t physical stimuli and sensations they cause

70
Q

Where is the visible spectrum?

A

400-700 no

71
Q

What is a light source?

Primary?
Secondary?
Natural?
Artificial?

A

Any area or body emitting radiation in the visible spectra range.

Light to look at
Look at tooth reflecting primary light
Sun, moon, stars
Any other light source

72
Q

What color rendering index (CRI) is desired for the dental office?

A

90 or more

73
Q

D65 question.

A

All the above.

74
Q

Absorption?

Transparency?

Translucency?

A

Light absorbed

Passage of light thru an object w/ little distortion

Passage of light but is distorted

*Lighter does not mean more translucent

75
Q

What is opacity?

A

Opposite of translucent

76
Q

What is fluorescence?

A

Energy, usually UV, absorbed by certain chemical or material and re-emitted at other, longer, wavelengths

77
Q

What is opalescence?

A

Material appears yellowish-red in transmitted light, but blue in scattered light perpendicular to transmitted light

78
Q

Cones see what?

Rods see what?

A

Color

Black and white

79
Q

1/12 males and 1/200 females are what?

A

Color deficient

80
Q

What is metamerism?

A

Change of color matching of two objects viewed under diff light sources
Two color samples appear to match under one condition but not under another
Conditional match
Non-spectral match

81
Q

What is additive mixing?

What is subtractive mixing?

A

Additive: mixing of colored lights, mixture results in white

Subtractive: mixing of colored substances and pigments, results in black

82
Q

Cementation retention is achieved by 4 things. Name them.

A 
Friction
Adhesive joint
Cement
Restoration
Or a combination
83
Q

An effective interfacial seal depends on what?

A

Ability of cement to fill irregularities and resist the oral environment

84
Q

Goal of cement?

A

Strong bond, prevent infiltration and caries and sensitivity

85
Q

What is setting?

A

All chem rxns to finish

86
Q

What is polymerization usually caused by?

A

UV light. H20 is the monomer(?)

87
Q

What is chelation?

A

GI rxn w/ Ca2+ and other minerals - chem interaction w/ hydroxyapatite

88
Q

Who found that acid etching of enamel increases bond strength in 1955?

A

Buonocore

89
Q

Approx. _________ of all restorations placed are done to replace a defective or failed restoration.

A

50%

90
Q

What are three reasons restorations fail?

A

Clinician factors, material properties, and patient factors.

91
Q

Dentin, what are the tunnels, around tunnels, b/t tunnels?

A

Dentinal tubule, peritubular dentin, intertubular dentin

92
Q

What is the comp of dentin?

A

50% mineralized apatite crystals
20% H20
30% orgo matrix

93
Q

T/F - diameter and number of tubules increases near pulp.

A

SO DANG TRUE

94
Q

The most desirable dentin to bond to is demineralized dentin that has not collapsed, right?

A

Correct. Demin dentin stiffened by orgo solvents in air

95
Q

Over dried dentin results in what?

A

Bad cross linking

96
Q

Overwetness of dentin cause what?

A

Failure

97
Q

What is the smear layer composed of?

A

Bacteria, saliva, blood cells, denatured collagen

98
Q

What is the hybrid layer?

A

Structure formed in hard tissues by demin of surface and subsurface, followed by infiltration of monomers and polymerization

99
Q

What is the composition of dentin adhesives?

A

Primer - HYDROPHILIC monomer, like HEMA. H20, Acetone, Ethanol

Adhesive - unfilled or lightly filled resin. This becomes the polymer.

100
Q

4th gen. Name the process.

A

Remove smear layer.
Primer
Adhesive

101
Q

5th Gen. Name it.

A

Remove smear layer

Combined primer and adhesive resin

102
Q

6th gen. Name it.

A

Self-etching primer dissolves smear layer.

Adhesive.

103
Q

Self-Etching Adhesives bond well to ______ enamel, but not as well to ________ enamel.

A

Cut

Uncut

104
Q

7th gen. Name it.

A

One bottle. Dissolves smear layer, self-etch primer, and adhesive all in one bottle.

105
Q

Adhesive systems are usually light cured and contain what?

A

An activator like camphorquinone and an organic amine. Dual-cured bonding agents include a catalyst to promote self-curing.

106
Q

Some bonding agents contain:

A

Nanofiller
Fluoride
Antimicrobial ingredients
Desensitizers

107
Q

What is the most import mechanical property of bonding agents?

A

BOND STRENGTH

108
Q

Enamel bonding occurs by ____________ retention after etching.

A

Micro mechanical.

109
Q

What is the hybrid layer?

A

The structure formed in hard dental tissues by demineralization of the surface and subsurface followed by infiltration of monomers and subsequent polymerization

110
Q

What is one of the most challenging problems of adhesive/dentin bonds?

A

Durability

Dental Materials - Final (1 decks)

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