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Ortho Midterm 1 (AU2017) > Lecture 5- mechanical properties of orthodontic archwires > Flashcards

Lecture 5- mechanical properties of orthodontic archwires Flashcards

1
Q

Force/Deflection (F/D) curve changes with archwire … and …

A

diameters and materials

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2
Q

What does the Stress/Strain (S/S) curve account for that Force/Deflection (F/D) does not?

A

area

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3
Q

Stress= …

A

Force/Area

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4
Q

F/D …. include geometry of specimen in the calculation so the stiffness measured by an F/D curve is called…

A

DOES NOT

Extrinsic stiffness

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5
Q

S/S curve … the geometry out so the stiffness measured by an S/S curve is called…

A

normalizes

Intrinsic stiffness

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6
Q

… is the slope of linear portion of the F/D curve or elastic modulous in S/S curve

A

Stiffness

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7
Q

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

A

Range

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8
Q

Strength =

A

Stiffness x Range

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9
Q

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

A

Resilience

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10
Q

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

A

Formability

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11
Q

Ideal orthodontic archwires will have

... strength
... stiffness
... range
... formability
capability of taking ...
A

HIGH strength

LOW stiffness

HIGH range

HIGH formability

Capability of taking weld/solder

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12
Q

If you increase the diameter of a wire then you…
.. strength
… springiness
… range

A

increase strength

decrease springiness

decrease range

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13
Q

If you increase length of a wire then you…
… strength
… springiness
… range

A

decrease strength

increase springiness

increase range

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14
Q

adding loops to an archwire increases … and …

A

range

springiness

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15
Q 
NiTi wires have...
... stiffness
.... strength
... range
.... formability
A

LOW stiffness

GOOD strength

HIGH range

POOR formability

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16
Q

Loops and helices are used in arch wires primarily to…. (4)

A

align teeth

increase force of the wires

increase flexibility of the wires

hold soft tissues away from brackets

17
Q

Center of resistance is NOT at the center of gravity, rather it is the approximate midpoint of … (or halfway between the … and …)

A

embedded portion of root

halfway btn apex and alveolar crest

18
Q

The center of resistance of a tooth varies with … and …

A

alveolar bone height
and
root length

19
Q

T/F the center of resistance varies with an orthodontic force

A

False

20
Q

If there is alveolar bone loss, center of resistance moves…

A

apically

21
Q

If there is root resorption, center of resorption moves…

A

coronally

22
Q

If the line of action of a force does NOT pass through the center of resistance, the force will produce some … of the tooth. This potential for… is measured as a ….

A

rotation

rotation

moment

23
Q

A … is two forces that are equal magnitude, parallel and mom-collinear and opposite direction

A

couple

24
Q

A couple produces…

A

a pure rotation

25
Q

… produces bodily tooth movement which means all points on an object move in the same direction at the same rate

A

Translation

26
Q

To produce translation, the line of action of a single force needs to pass through

A

the center of resistance

27
Q

The center of rotation for translation is…

A

infinity

28
Q

The center of rotation for uncontrolled tipping is…

A

slightly apical to the center of resistance (one third root length from the apex)

29
Q

The center of rotation for controlled tipping is the…

A

apex

30
Q

The center of rotatin for root movement (torque) is the …

A

incisal edge

31
Q

The center of rotation for pure rotation is …

A

the center of resistance

32
Q

Herbst and MARA are … appliances for growth modification to correct…

A

fixed

class 2

33
Q

Forsus is a … appliance to correct …. occlusion but only correct dentally

A

fixed

class 2

34
Q

Are fixed or removable more commonly used?

A

fixed

Ortho Midterm 1 (AU2017) (5 decks)

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