Lecture 5- mechanical properties of orthodontic archwires

Question 1

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

Answer 1

diameters and materials

Question 2

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

Answer 2

area

Question 3

Stress= …

Answer 3

Force/Area

Question 4

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

Answer 4

DOES NOT

Extrinsic stiffness

Question 5

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

Answer 5

normalizes

Intrinsic stiffness

Question 6

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

Answer 6

Stiffness

Question 7

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

Answer 7

Range

Question 8

Strength =

Answer 8

Stiffness x Range

Question 9

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

Answer 9

Resilience

Question 10

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

Answer 10

Formability

Question 11

Ideal orthodontic archwires will have

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

Answer 11

HIGH strength

LOW stiffness

HIGH range

HIGH formability

Capability of taking weld/solder

Question 12

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

Answer 12

increase strength

decrease springiness

decrease range

Question 13

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

Answer 13

decrease strength

increase springiness

increase range

Question 14

adding loops to an archwire increases … and …

Answer 14

range

springiness

Question 15

NiTi wires have...
... stiffness
.... strength
... range
.... formability

Answer 15

LOW stiffness

GOOD strength

HIGH range

POOR formability

Question 16

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

Answer 16

align teeth

increase force of the wires

increase flexibility of the wires

hold soft tissues away from brackets

Question 17

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

Answer 17

embedded portion of root

halfway btn apex and alveolar crest

Question 18

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

Answer 18

alveolar bone height
and
root length

Question 19

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

Answer 19

False

Question 20

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

Answer 20

apically

Question 21

If there is root resorption, center of resorption moves…

Answer 21

coronally

Question 22

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 ….

Answer 22

rotation

rotation

moment

Question 23

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

Answer 23

couple

Question 24

A couple produces…

Answer 24

a pure rotation

Question 25

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

Answer 25

Translation

Question 26

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

Answer 26

the center of resistance

Question 27

The center of rotation for translation is...

Answer 27

infinity

Question 28

The center of rotation for uncontrolled tipping is...

Answer 28

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

Question 29

The center of rotation for controlled tipping is the...

Answer 29

apex

Question 30

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

Answer 30

incisal edge

Question 31

The center of rotation for pure rotation is ...

Answer 31

the center of resistance

Question 32

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

Answer 32

fixed class 2

Question 33

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

Answer 33

fixed class 2

Question 34

Are fixed or removable more commonly used?

Answer 34

fixed