Orthodontic Biomechanics

Question 1

Responsible for the three laws of motion:

Answer 1

Isaac Newton

Question 2

List Isaac Newtons three laws of motion:

Answer 2

Law 1: Law of inertia
Law 2: Law of acceleration
Law 3: Law of action & reaction

Question 3

An object at rest will remain at rest unless acted on by an unbalanced force; an object in motion will continue with constant speed and direction unless acted on by an unbalanced force

Answer 3

Law of inertia (1st law of motion)

Question 4

An object acted on by an unbalanced force will accelerate in the direction of the force:

Answer 4

Law of acceleration (2nd law of motion)

Question 5

T/F: according to the law of acceleration (2nd law of motion) the ball accelerates while your foot is in contact with it and in the air

Answer 5

False- the ball accelerates ONLY while your foot is in contact with the ball

Question 6

For every action, there is an equal & opposite reaction:

Answer 6

Law of action & reaction (3rd law of motion)

Question 7

The science that deals with the action of forces on the form & motion of the bodies:

Answer 7

mechanics

Question 8

Characteristics of a force include:

Answer 8

1. magnitude (grams)
2. direction (line of action)
3. sense

Question 9

Also known as center of gravity, the point in which an object or body is in equilibrium:

Answer 9

Center of resistance

Question 10

Relationship of the line of action of a force with the center of resistance:

Answer 10

movement of a free body

Question 11

A tooth is a _____

Answer 11

constrained body

Question 12

Since the tooth is a constrained body, the center of resistance will vary with:

Answer 12

alveolar height

Question 13

Measure of the tendency of a body to rotate around a point or axis perpendicular to any given plane:

Answer 13

moment

Question 14

List some simple forces:

Answer 14

1. pull (tension)
2. push (pressure)
3. extrude
4. intrude

Question 15

Point of application of the force in orthodontics is almost always at:

Answer 15

the CROWN LEVEL

Question 16

In orthodontics the direction of force is in:

Answer 16

THREE planes of space

Question 17

In orthodontics the amplitude of the force:

Answer 17

varies

Question 18

In regard to force systems in orthodontics, remember we must:

Answer 18

Move the ROOTS

Question 19

In orthodontics, a simple force applied to the crown of a tooth will result in:

Answer 19

TIPPING of the crown

Question 20

T/F: In orthodontics the crown will tip in the direction of the force (simple force), the apex will tip in the opposite direction

Answer 20

True

Question 21

What are the tooth movements that require more than a simple force?

Answer 21

1. translation
2. rotation

Question 22

Two forces equal in magnitude & opposite in direction acting on an object:

Answer 22

couple

Question 23

A couple occurs when two forces equal in magnitude & opposite in direction act on an object, this results in:

Answer 23

1. PURE MOMENT, since translators effect of the forces cancel
2. the object will SPIN AROUND its CENTER OF RESISTANCE (rotation)

Question 24

When an object spins around its center of resistance:

Answer 24

rotation (caused by a couple)

Question 25

Couples =

Answer 25

ALL rotation
NO translation

Question 26

Bodily movement in orthodontics is a result of:

Answer 26

translation

Question 27

What is often the movement of choice in orthodontics?

Answer 27

Translation

Question 28

What is required for translation to occur?

Answer 28

Combination of simple force and a moment of force

Question 29

Combination of force system=

Answer 29

translation