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MODULE 3: CLINICAL SCIENCES “B” 65Q > Orthodontic Materials / Physical Principles 8% 5Q > Flashcards

Orthodontic Materials / Physical Principles 8% 5Q Flashcards

1
Q

Equation for stress =

A

force / area

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2
Q

Equation for strain =

A

deflection / unit strength

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3
Q

Equation for strength =

A

stiffness x range

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4
Q

Equation for springiness =

A

1 / stiffness

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5
Q

The stress strain curve shows the __________ behavior of a material

A

elastic

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6
Q

the point at which any permanent deformation is first observed:

A

elastic limit / proportional limit

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7
Q

Deformation of 0.1% is observed

A

yield strength

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8
Q

Maximum Load / Ultimate Tensile Strength

A

maximum load the wire can sustain after some permanent deformation

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9
Q

area of the curve up to the proportional limit. (Energy Storage)

A

Resilience

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10
Q

amount of permanent bending a wire can stand before breaking

A

Formability

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11
Q

distance a wire will bend elastically before permanent deformation

A

Range

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12
Q

Ideal AW properties:

( High / Low ) strength

( High / Low ) Stiffness

( High / Low ) Range

( High / Low ) Formability

A

High strength

Low Stiffness

High Range

High Formability

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13
Q

In terms of surface roughness which AW materials have the most asperities

A

NiTi > TMA > SS

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14
Q

Which AWs have the most friction to sliding mechanics

A

TMA > NiTi > SS

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15
Q

Frictionless mechanics with closing loops is done with which material?

A

TMA

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16
Q

An increase in wire length x 2 has what effect on strength?

A

decrease x 2

1/X

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17
Q

An increase in wire length x 2 has what effect on stiffness?

A

decrease x 8

1/X3

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18
Q

An increase in wire length x 2 has what effect on springiness?

A

increase x 8

X3

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19
Q

An increase in wire length x 2 has what effect on range?

A

increase x 4

X2

20
Q

An increase in wire diameter x 2 has what effect on range?

A

decrease x 2

1/X

21
Q

An increase in wire diameter x 2 has what effect on strength?

A

increase x 8

X3

22
Q

An increase in wire diameter x 2 has what effect on stiffness?

A

increase x 16

X4

23
Q

An increase in wire diameter x 2 has what effect on springiness?

A

decrease x 16

1/X4

24
Q

what is another name for the material Elgiloy

A

cobalt chromium

25
Q

Elgiloy can be softer and thus more:

A

formable

26
Q

Elgiloy can be heat treated, which would increase its strength to that of _________________ by increasing the UTS and resilience

A

stainless steel

27
Q

Nitinol has no phase change, is not superplastic and is also known as

A

M-NiTi

28
Q

NiTi is superplastic, meaning it has shape ___________; it ( does / does not ) have the ability to change molecular structure

A

memory

does

29
Q

Name the 2 ways to get a phase change in NiTi

A

Pseudoelasticity/Superelasticity

Thermoelasticity

30
Q

Due to the thermoelasticity of NiTi, heat induces change from the ___ → ___ state while cold induces change from the ___ → ___ state.

A

heat: M → A
cold: A → M

31
Q

Due to the superelasticity of NiTi, stress induced martensite (SIM) induces change from the ___ → ___ state while deactivation induces change from the ___ → ___ state.

A

SIM A → M

Deactivation M → A

32
Q

NiTi is formed at high temps (state ___ ), when cooled (state ___ ) can then be plastically deformed.

This means its original shape restored when ( cooled / heated )

A

A

M

heated

33
Q
  • ( A / M ) NiTi is the stabilized form of NiTi with no application of phase transition effects
A

M (Martensitic)

34
Q

Flexibility: A-NTi ___ M-NiTi

A

A < M

35
Q

Stiffness: A-NTi ___ M-NiTi

A

A > M

36
Q

what is manifested by very large reversible strains and a non-elastic stress-strain or force-deflection curve

A

superelasticity

37
Q

In A-NiTi wires, the initial archwire should exert (more / less / same ) force whether it were deflected a relatively small or large distance

A

the same

38
Q

The unique force-deflection curve for A-NiTi wire occurs because of a ______________________ in grain structure from austenite to martensite in response to an applied force (not to a temperature change).

A

phase transition

39
Q

Beta NiTi is aka

A

Copper NiTi

40
Q

which material guarantees Temperature Transition Range (TTR) so you know exactly at what temperature the phase transition occurs?

A

Beta NiTi

41
Q

the ideal temperature for the phase transition of Beta NiTi

A

35° C

42
Q

Bending moment vs deflection plot for 16 mil orthodontic wires

Note that after an initial force is reached, ___-NiTi has a considerably flatter load-deflection curve and greater springback than ___-NiTi, which has greater springback than steel

A

A

M

43
Q

The concept that the unloading force is different (less) than the loading force. After untyting, retying increases the amount of force delivered.

A

Hystersis

44
Q

Small-round NiTi wires should be ___-NiTi, while larger rectangular ones often perform better if made from ___-NiTi. M-NiTi which remains useful, primarily in the later stages of treatment when flexible but larger and somewhat stiffer wires are needed

A

A

M

45
Q

TMA is aka

A

Titanium Molybdenum

46
Q

Compared to Nitonol, TMAis, ( smoother / rougher ), ( can / cannot ) be welded, has good formability

A

smoother

can

47
Q

What AW material offers remarkable strength and springiness, making it an excellent choice for auxiliary springs and for intermediate and finishing wires

A

TMA

MODULE 3: CLINICAL SCIENCES “B” 65Q (7 decks)

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