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Dental Materials > Quiz 1: Lecture 1+ 2 > Flashcards

Quiz 1: Lecture 1+ 2 Flashcards

1
Q

What is enamel made up of?

A

Rods and Interrods.

***Rod sheath= narrow space around 3/4 of each rod Keyhole shape

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2
Q

What is Intertubular dentin?

A

Structural component of the hydroxyapatite-embedded collagen matrix- bulk of the dentin

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3
Q

What is Peritubular dentin?

A

Limited to the lining of the tubular walls- little organic matrix densely packed w/ apatite crystals

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4
Q

What is the strongest and simplest bond within atoms?

A

Covalent;

Example 2 H+ bonds overlapping

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5
Q

What is the Biological type of properties for materials?

A

toxicity and sensitivity reactions that occur locally or systemically within associated tissues.

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6
Q

What is surface energy ?

A

A LOW surface energy liquid will readily spread over a HIGH surface energy substance

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7
Q

What is Wetability?

A

The measure of the affinity of a liquid for a solid as indicated by the spreading of a drop

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8
Q

What is Adsorption?

A

Dissilimar substance in intimate contact with the surface of a solid= adhere
**HIGH energy surfaces will adsorb molecules more readily than LOW energy surfaces

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9
Q

What is Absorption?

A

The uptake of a liquid by a bulk solid. The substance absorbed diffuses into the solid material

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10
Q

Describe the Biocompatibility usage test?

A

Material is placed in a situation identical to its intended clinical use. In animals or humans (clinical trials)

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11
Q

What is Microleakage?

A

Materials may not bond with sufficient strength to resist contraction on polymerization, wear, thermal cycling

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12
Q

What does the gap between the tooth and restoration allow?

A

Allows influx of materials that may irrigate the pulp

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13
Q

Acids used to remove smear layer are potential source of irritation.. Depends on:

A

1) ****Remaining Dental Thickness (RDT) - 0.5mm min
2) Strength of the acid
3) Degree of etching

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14
Q

How is stress measured?

A

The force & the area to which it is applied are measured and stress is calculated from the
RATIO OF FORCE PER AREA* (F/A)

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15
Q

What are the types of stress? Specifically Tension?

A

**Elongation!
Forces are directed away from each other in the same straight line
(Axial- Molecules resist being pulled apart)

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16
Q

What is Compression force?

A

***Shrinkage!
Forces directed toward each other in the same straight line
(Molec. resist being forced more closely together)

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17
Q

What is a Shear force?

A

Forces directed parallel to each other **NOT along the same straight line
(One portion resists sliding past the other)

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18
Q

What is a Torsion force?

A

Twisting forces

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19
Q

What is bending forces?

A

Results from a bending moment

20
Q

What is Strain?

A

*****Deformation CAUSED by STRESS **

Deformation = deformation/length

21
Q

What is the proportional limit?

A

The greatest stress sustained without deviation from the linear proportionality of the dress and strain

22
Q

What is Elastic limit?

A

The greatest stress sustained without permeant deformation

23
Q

Elastic deformation is __________?

A

***NON-permanent

24
Q

Plastic deformation is __________?

A

**PERMANENT

25
Q

What is Yield Strength?

A

The stress at which the material begins to function in a plastic manner. Limited permanent strain has occurred

26
Q

Is Permanent Deformation a good or bad thing?

A

BOTH***

Destructively: filings, crowns, bridges, can be deformed casing improper occasion
Constructively: Ortho appliances adjustment to fix bite..etc

27
Q

What is Ultimate Strength?

A

-Max stress that a material can withstand in tension or compression.

-Greatest stress occurs at the HIGHEST POINT
(center of graph (C)

28
Q

What is Fracture Strength?

A
  • Stress at which a brittle material fractures

- At the END of graph where it FAILS (BREAKS) (D )

29
Q

What is Elongation?

A

-Deformation that results from the application of TENSILE FORCE
-Takes in the WHOLE CURVE
(***Indicates the workability of alloy)

30
Q

What is Elastic Modulus? (Young’s Modulus)

A
  • **The measure of elasticity
  • **The HIGHER the value of E, the MORE STIFF/RIGID the material

(Represents the stiffness/rigid/flexible of a material within the elastic region)

31
Q

What is Resilience?

A
  • **Resistance of a material to permeant deformation
  • The amount of energy needed to deform the material to theproportional limit

(Area under the Elastic portion)

32
Q

What is Toughness?

A
  • **The resistance of material to fracture
  • **Indicates the amount of energy needed to cause fracture
  • ** Combination of yield strength, ultimate strength, strain INCREASING any of these, INCREASES TOUGHNESS!

(-Area under the elastic & plastic area )

33
Q

What is Fracture Toughness?

A

Fracture Mechanics- Characterizes the behavior of materials with cracks or flaws

34
Q

What do Defects generally do to material ?

A

**Weaken material and may result in fractures at stresses well below the yield stress.
(larger the flaw, less stress need to create flaw)

35
Q

What is Tensile properties of Brittle Materials ?

A

Tensile properties of brittle materials, hard to measure so **Diametral Compression Test

36
Q

When creating “Compression strength” of brittle material, what is the pastil response like?

A

The plastic response is small

37
Q

What is Fatigue strength?

A

The stress at which a material fails under repeated loading

***DEPENDS OF MAGNITUDE of the LOAD & the # of LOADINGS

38
Q

What is Endurance Limit?

A

Stress at which the material can be loaded an infinite number of times WITHOUT FAILING

39
Q

What is Viscoelasticity?

A

***RATE of LOADING is important for many materials. (alginate, elastomeric immersion materials, waxes, amalgam, polymers)

40
Q

Materials with mechanical properties dependent on loading rate are termed?

A

***Viscoelastic

41
Q

What is Viscosity?

A

-The resistance of a fluid to flow

***time and temp DEPENDENT

42
Q

What is CREEP?

A

Increase in strain in material under constance stress (amalgam)

43
Q

What is Tear Strength?

A

Resistance to tearing forces

rapid loading = higher value (less likely to tear

44
Q

What kind of bonds to Ceramics have?

A

-Ionic bonds - crystalline (leucite) and amorphous (glass)

45
Q

What kind of bonds do Metals have?

A

Metallic bonds- crystalline

46
Q

What kind of bonds do Polmers have?

A

Molecular solids -covalent and secondary bonds

Dental Materials (1 decks)

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