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AU14 Orthodontics > Mechanical Properties of Orthodontic Archwires > Flashcards

Mechanical Properties of Orthodontic Archwires Flashcards

1
Q

Most orthodontic archwires are what kind of materials

A

elastic

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2
Q

What two phases of archwires are important

A

elastic and plastic phases

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3
Q

What does the force/deflection curve represent

A

how much the wire will bend before breaking

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4
Q

force/deflection curve changes with what

A

archwire diameters and materials

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5
Q

This is force/area (F/A)

units; newton/square mm, pascal, etc.

A

stress (σ)

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6
Q

This is the change in length/original length (ΔL/L)

units; none; described as a percentage

A

strain (ε)

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7
Q

What is the elastic modulus (E)

A

stress/strain E (σ/ε)

units; newton/square mm, pascal

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8
Q

What is the difference between the stress/strain curve and a F/D curve

A

stress/strain curve removes the geometric factor

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9
Q

Which curve, the S/S or F/D includes the includes the geometry of the specimen in the calculation

A

F/D

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10
Q

The stiffness measured by an F/D curve is called what

A

extrinsic stiffness

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11
Q

The stiffness measured by an S/S curve is called what

A

intrinsic stiffness

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12
Q

Which curve will vary depending upon the items size/diameter. For example, if examining the same material with two different diameters, the graph will change

A

F/D

S/S curve is the same regardless of size

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13
Q

How many different curves will one homogenous material of different dimensions have

A

one S/S curve

many F/D curves

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14
Q

This is the slope of the linear portion of the F/D curve or elastic modulus in the S/S curve

A

stiffness

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15
Q

This is 1/stiffness

A

springiness

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16
Q

This is the ability to return to the original shape; clinical useful can be beyond the elastic limit

A

springback

17
Q

This is the distance a wire can be bent elastically before permanent deformation

A

range

18
Q

This is the stiffness x range

A

strength

19
Q

This is the area under the S/S curve out to the proportional limit

A

resilience

20
Q

This is the amount of permanent deformation a wire can withstand before failure

A

formability

21
Q

This property of ideal archwires is to produce desired force magnitude without excessively deflecting the AW

A

high strength

22
Q

This property of ideal archwires is to produce a relatively constant force

A

low stiffness

23
Q

This property of ideal arch wires is to deflect the arch wire to a great extent without causing permanent deformation

A

high range

24
Q

This is not a direct mechanical property of ideal archwires

A

capability of taking weld/solder

25
Q

What are the two arch wire variables affecting mechanical property

A

size and shape

26
Q

Shape is more important for which property

A

shear (torsion) force, but not for bending; the diameter is important for bending

27
Q

Tying an arch wire tightly to the brackets increases this, but decreases these two properties

A

increases strength

decreases springiness and range

28
Q

Adding loops (increase in length) to an arch wire increases what

A

its range and springiness

29
Q

Which wire has the highest strength, stainless steel, TMA, M-NiTi

A

Stainless Steel > TMA and M-NiTi

30
Q

Which wire has the highest stiffness, stainless steel, TMA, M-NiTi

A

Stainess Steel > TMA > M-NiTi

31
Q

Which wire has the highest range, stainless steel, TMA, M-NiTi

A

M-NiTi&raquo_space;> TMA > Stainless Steel

32
Q

This wire has low stiffness, good strength, high range, but very poor formability

A

M-NiTi

33
Q

This is not considered a typical elastic material; a wide range of constant force is produced during austenitic ⇔ martensitic phase transition

A

Superelastic NiTi (A-NiTi)

34
Q

Which arch wire is chosen for initial alignment

A

small size NiTi

35
Q

Which arch wire is chosen for the leveling phase

A

relatively large size TMA or stainless steel

36
Q

What arch wire is chosen for the torquing phase

A

large size rectangular stainless steel or TMA

37
Q

What arch wire is chosen for the finishing phase

A

stainless steel or TMA, size can vary depending on the purpose

38
Q

Loops are helices are used in arch wires primarily to
A. align teeth
B. increase force of the wires
C. increase flexibility of the wires
D. hold soft tissues away from orthodontic brackets

A

C. increase flexibility of the wires

AU14 Orthodontics (11 decks)

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