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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
Amalgams. What advancement helped with marginal integrity, less creep, less tarnish, and better shine?
The change from high gamma-2 to high copper, low gamma-2.
26
What is creep?
Slow deformation under load - slow flow.
27
Why is corrosion a desired result with amalgam?
It makes a self-seal against tooth structure.
28
High copper, low gamma-2 has less tensile strength, on the order of 40-50 MPa after one day.
So, about ten-fold less than compressive strength. 1/10!
29
What is a resin?
A viscous liquid which is capable of hardening permanently.
30
What is polymerization?
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.
31
What is PMMA?
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
32
Epoxy polymers. What do they do?
Form a lot of chains, strong. Bisphenol A is used as a backbone for polycarbonate plastics
33
Bis-GMA, why do we use it so much?
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.
34
What is used sometimes instead of Bis-GMA?
UDMA
35
What is TEGDMA?
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.
36
What is HEMA?
It is hydrophilic and quite ALLERGENIC.
37
Resin based composites (RBCs) are what?
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)
38
What is used now to initiate curing?
Intense UV light.
39
Bonding RBCs to enamel or dentin is harder to do?
Dentin. It is more wet than enamel is live teeth.
40
RBCs shrink on curing, about how much?
About 1% or slightly more at best. How to overcome this? Pack incrementally, and know that RBCs shrink towards the curing light
41
T/F - Polymerization is ALWAYS incomplete.
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.
42
What do us and our staff need to be careful about?
We can become allergic to resins, especially HEMA. DO NOT LET THIS TOUCH THE SKIN
43
T/F - Bis-GMA is estrogenic.
True. However, there is more in plastic water bottles. More in a mother’s kiss.
44
Why do large RBC restorations fail earlier than other materials, like amalgam?
They shrink on curing, and they hydrolyze over time at the dentin interface from MMPs.
45
What pulpal depth is req’d for amalgam?
1.5 mm - also mech retention
46
What should we do to the matrix band before we use it?
Pre-contour with large ball burnisher
47
What kind of proximal surface offers the greatest resistance to fracture?
CONVEX
48
How do we separate for tight contacts?
Matrix and wedges completely close gingival margins.
49
Studies show which type of amalgam have the longest durability?
Lathe cut - silver/copper plus
50
What is the Half-Blood Prince’s “Speedball” technique?
Bring a large amount of amalgam over to the restoration and over fill
51
What are you supposed to do to the occlusal embrasure with the explorer?
Carefully carve and remove enough amalgam to prevent fracture on band removal.
52
What matrix do you use for composite restorations?
Sectional
53
What is the etch, peak, and cure req’s?
Etch - enamel 20 sec, dentin 10 sec Wash and blot dry, rub in Peak for 10 sec, light cure for 20 sec
54
Flowable - how thin of a layer?
0.5 mm. Light cure 20 seconds
55
T/F - composite is technique sensitive?
True.
56
What is the average life span of composites internationally? What about here at the school?
6 years 20 years
57
What is the average life span of amalgam internationally? Here at the school?
20 years 40 years
58
What is color?
Psychophysical sensation provoked in the eye by visible light and interpreted by brain.
59
What is value?
ACHROMATIC. Enables differentiation b/t the light and dark colors
60
What is hue?
The first chromatic coordinate. This enables differentiation b/t color families. Placed in a closed hue circle.
61
What is chroma?
2nd chromatic coordinate. Enables differentiation b/t pale and strong colors. Distance from vertical axis.
62
For our purposes, we are working in the color spectrum of how much?
0.016%
63
What is delta E?
Interaction of H/V/C differences. Basically, the color difference.
64
At a 50:50% acceptability threshold, what was delta E?
2.7
65
Over _______ of patients were aware of color difference.
80%
66
Correct match _____/16 pairs of tabs of two shade guides.
7.7
67
What was the average shade matching error?
4 vita shades
68
15 years ago, esthetic dentistry accounted for less than 20% of the money spent on dentistry. What is it now?
70%
69
What is psychophysics?
Science dealing w/ math relations b/t physical stimuli and sensations they cause
70
Where is the visible spectrum?
400-700 no
71
What is a light source? Primary? Secondary? Natural? Artificial?
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
What color rendering index (CRI) is desired for the dental office?
90 or more
73
D65 question.
All the above.
74
Absorption? Transparency? Translucency?
Light absorbed Passage of light thru an object w/ little distortion Passage of light but is distorted *Lighter does not mean more translucent
75
What is opacity?
Opposite of translucent
76
What is fluorescence?
Energy, usually UV, absorbed by certain chemical or material and re-emitted at other, longer, wavelengths
77
What is opalescence?
Material appears yellowish-red in transmitted light, but blue in scattered light perpendicular to transmitted light
78
Cones see what? Rods see what?
Color Black and white
79
1/12 males and 1/200 females are what?
Color deficient
80
What is metamerism?
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
What is additive mixing? What is subtractive mixing?
Additive: mixing of colored lights, mixture results in white Subtractive: mixing of colored substances and pigments, results in black
82
Cementation retention is achieved by 4 things. Name them.
``` Friction Adhesive joint Cement Restoration Or a combination ```
83
An effective interfacial seal depends on what?
Ability of cement to fill irregularities and resist the oral environment
84
Goal of cement?
Strong bond, prevent infiltration and caries and sensitivity
85
What is setting?
All chem rxns to finish
86
What is polymerization usually caused by?
UV light. H20 is the monomer(?)
87
What is chelation?
GI rxn w/ Ca2+ and other minerals - chem interaction w/ hydroxyapatite
88
Who found that acid etching of enamel increases bond strength in 1955?
Buonocore
89
Approx. _________ of all restorations placed are done to replace a defective or failed restoration.
50%
90
What are three reasons restorations fail?
Clinician factors, material properties, and patient factors.
91
Dentin, what are the tunnels, around tunnels, b/t tunnels?
Dentinal tubule, peritubular dentin, intertubular dentin
92
What is the comp of dentin?
50% mineralized apatite crystals 20% H20 30% orgo matrix
93
T/F - diameter and number of tubules increases near pulp.
SO DANG TRUE
94
The most desirable dentin to bond to is demineralized dentin that has not collapsed, right?
Correct. Demin dentin stiffened by orgo solvents in air
95
Over dried dentin results in what?
Bad cross linking
96
Overwetness of dentin cause what?
Failure
97
What is the smear layer composed of?
Bacteria, saliva, blood cells, denatured collagen
98
What is the hybrid layer?
Structure formed in hard tissues by demin of surface and subsurface, followed by infiltration of monomers and polymerization
99
What is the composition of dentin adhesives?
Primer - HYDROPHILIC monomer, like HEMA. H20, Acetone, Ethanol Adhesive - unfilled or lightly filled resin. This becomes the polymer.
100
4th gen. Name the process.
Remove smear layer. Primer Adhesive
101
5th Gen. Name it.
Remove smear layer | Combined primer and adhesive resin
102
6th gen. Name it.
Self-etching primer dissolves smear layer. | Adhesive.
103
Self-Etching Adhesives bond well to ______ enamel, but not as well to ________ enamel.
Cut | Uncut
104
7th gen. Name it.
One bottle. Dissolves smear layer, self-etch primer, and adhesive all in one bottle.
105
Adhesive systems are usually light cured and contain what?
An activator like camphorquinone and an organic amine. Dual-cured bonding agents include a catalyst to promote self-curing.
106
Some bonding agents contain:
Nanofiller Fluoride Antimicrobial ingredients Desensitizers
107
What is the most import mechanical property of bonding agents?
BOND STRENGTH
108
Enamel bonding occurs by ____________ retention after etching.
Micro mechanical.
109
What is the hybrid layer?
The structure formed in hard dental tissues by demineralization of the surface and subsurface followed by infiltration of monomers and subsequent polymerization
110
What is one of the most challenging problems of adhesive/dentin bonds?
Durability

Dental Materials - Final (1 decks)

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