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Ortho 2 > MECHANICAL CONCEPTS IN ORTHODONTICS > Flashcards

MECHANICAL CONCEPTS IN ORTHODONTICS Flashcards

1
Q

load on an object causing it to move in direction of application

A

FORCE

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2
Q

→ Newtowns
→ grams or ounces

A

FORCE

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3
Q

balance point of a free body where all mass of an object is concentrated

A

CENTER OF GRAVITY OR MASS

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4
Q

point on the body where a single force (at this point) results in translation

A

CENTER OF RESISTANCE

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5
Q

pint through which an applied force must pass for an object (tooth) to move linearly without rotation

A

CENTER OF RESISTANCE

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6
Q

1-2 mm apical to the bifurcation along the long axis of the tooth

A

Multirooted Tooth

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7
Q

1⁄3 to 1⁄2 of the length of the root from the crest of the alveolar bone along the long axis of the tooth

A

Monorooted Tooth

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8
Q

point about which the object circles around a certain point

A

CENTER OF ROTATIO

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9
Q

T/f

CENTER OF ROTATION controlled with couple and force

A

T

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10
Q

used to create bodily movement

A

CENTER OF ROTATION

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11
Q

CENTER OF ROTATION location:

A

o at the center of resistance
o apical to it
o at the root apex
o infinity

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12
Q

product of force times the perpendicular distance from point of force application and center of resistance (Cres)

A

MOMENT

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13
Q

longer roots have center of resistance more ____ located

A

apically

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14
Q

unit of MOMENT

A

: gm-mm

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15
Q

force will tend to translate and rotate around the object around Cres

A

MOMENT

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16
Q

tendency for a force to produce rotation or tipping of a tooth

tendency to tilt or rotate

A

MOMENT

17
Q

ortho tooth movement is not applied on the center of the rotation of the tooth but it is delivered through the crown

A

MOMENT OF THE FORCE (𝑀𝑓)

18
Q

T/f

MOMENT OF THE FORCE (𝑀𝑓), not pure linear movement but some rotational movement (moment of the force) will be present

A
19
Q

two equal, opposite, noncollinear but parallel forces separated at a distance

A

COUPLE

20
Q

two forces equal in magnitude but opposite in direction and parallel to each other

A

COUPLE

21
Q

T/f

overcome the moment WILL force applied to the crown

A

T

22
Q

T/f

decrease the magnitude of the moment → apply force closer to the center of resistance

A

T

23
Q

T/f

in orthodontics:
o impractical to apply the force directly to the root

o similar effect could be achieved by constructing a rigid attachment that projected upward from the crown

A

T

24
Q

T/f

ROTATION requires a couple

A

T

25
Q

Movement of tooth around its own center of resistance

A

Rotation

26
Q

T/f

forces passing through the center of resistance do not produce a moment, because the distance to the center of resistance is zero; hence, the tooth does not rotate

A

T

27
Q

A _____ archwire fitting into a rectangular
bracket slot on the tooth is most widely used because the entire force system can be produced with a single wire

A

rectangular

28
Q

T/f

in orthodontics, equivalent force systems produce the same effect if the force system was placed at the center of resistance or at the crown (bracket/tube)

A

T

29
Q

US wire dimensions: thousandths of an ____

European wire dimensions: in ____

A

inch

millimeters

30
Q

COMMON TOOTH MOVEMENTS

Translation

Tipping (Uncontrolled)

Tipping (Controlled)

Torque

A

10 - 20 gms

35- 60 gms

50 - 100 gms

100- 150 gms

31
Q

• Crown and root apex moves in the same distance and the same horizontal direction

• requires the most
orthodontics force to achieve

A

Translation

32
Q

tooth moves in the same amount in the same direction

force through the center of resistance or through the whole alveolar bone surface

one area of tension and one area of pressure

A

TRANSLATION (BODILY MOVEMENT)

33
Q

Movement of crown but root apex position is maintained

•Crot at root apex

A

Controlled Tipping

34
Q

Root apex and crown move in opposite directions

•Crot below Cres (near each other)

A

Uncontrolled Tipping

35
Q

• displacement of the tooth from the socket in the direction of eruption
• Only areas of tension

A

Extrusion

36
Q

•movement into the socket along the long axis of the tooth
•difficult to accomplish

A

Intrusion

37
Q

force is applied at the bracket and an even larger couple is applied to prevent tipping of the crown caused by the force

A

ROOT MOVEMENT (TORQUE)

Ortho 2 (4 decks)

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