Lec 2.1: Archwires

Question 1

It is one of the active components of fixed orthodontic appliances, which when used, brings about various tooth movements (tipping, bodily, torque, rotational and vertical movements) through the medium of brackets and welded buccal tube on the palatal aspect of the molar band.

Answer 1

Archwire

Question 2

Tooth movements that archwires can bring (5)

Answer 2

*Tipping
*Bodily
*Torque
*Rotational
*Vertical

Question 3

4 Extrinsic properties of archwires?

Answer 3

1. Size
2. Wire geometry
3. Shape (rectangular/round)
4. Length

Question 4

5 Intrinsic properties of archwires?

Answer 4

1. Yield strength
2. Modulus of Elasticity
3. Elastic/Proportional Limit
4. Ultimate tensile strength
5. Fracture/failure point

Question 5

4 Key properties of wires?

Answer 5

1. Strength
2. Stiffness
3. Low stiffness slope
4. Range

Question 6

Determine how much stress a material can withstand before it starts permanent deformation.

Answer 6

Yield strength

Question 7

Flexibility or stiffness

Answer 7

Modulus of elasticity

Question 8

First permanent deformation;
Point at which material starts to deform permanently.

Answer 8

Elastic proportional limit

Question 9

Maximum load; point of clinical loading

Answer 9

Ultimate tensile strength

Question 10

Maximum load a wire can sustain and still be clinically useful.

Answer 10

Springback

Question 11

Wire breaks

Answer 11

Fracture/failure point

Question 12

Materials that do not strain much beyond elastic limit; breaks right away.

Answer 12

Brittle

Question 13

Those that deform a great deal before breakage.

Answer 13

Ductile

Question 14

Maximum force that can be obtained from a wire.

Answer 14

Strength

Question 15

Formula for strength?

Answer 15

S=SXR (Stiffness x Range)

Question 16

Amount of force produced per activation.

Answer 16

Stiffness

Question 17

Ability to apply lower force.
Greater ease and accuracy in applying force.
A more constant force over time as the wire deactivates.

Answer 17

Low stiffness slope

Question 18

Distance wire will bend elastically before permanent deformation occurs.

Answer 18

Range

Question 19

Clinically measured to the ultimate tensile strength.

Answer 19

Spring back / Working range

Question 20

PROPERTIES OF AN IDEAL ARCHWIRE:
a. ____ strength
b. ____ stiffness (____ springiness)
c. ____ range
d. ____ formability
e. ____ resilience
f. ____ surface friction
g. _______
h. ________
i. _________
j. _________

Answer 20

1. High strength
2. Low stiffness / High springiness
3. High range
4. High formability
5. High resilience
6. Low surface friction
7. Biocompatibility
8. Environmentally friendly
9. Joinability (weldable/solderable)
10. Reasonable cost