Orthodontic Biomechanics Flashcards
Responsible for the 3 laws of motion:
Isaac Newton
List Isaac Newton’s 3 laws of motion:
- Law of intertia
- Law of acceleration
- Law of action & reaction
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.
Law of inertia (1st law of motion)
An object acted on by an unbalanced force will accelerate in the direction of the force:
The law of acceleration (2nd law of motion)
T/F: According to the law of acceleration (2nd law of motion), the ball accelerated while your foot is in contact with it and in the air.
False- the ball accelerates ONLY while your foot is in contact with the ball
For every action there is an equal and opposite reaction:
Law of action & reaction (3rd law of motion)
The science that deals with the action of forces on the form and motion of bodies:
mechanics
Characteristics of a force include:
- magnitudes (grams)
- direction (line of action)
- sense
Also known as center of gravity; point in which an object or body is in equilibrium:
Center of resistance
Relationship of the line of action of the force with the center of resistance:
movement of a free body
A tooth is a ____.
constrained body
Since the tooth is a constrained body, the center of resistance of a tooth with vary with:
alveolar height
Measure of the tendency of a body to rotate around a point or axis perpendicular to any given plane:
moment
List some simple forces:
- pull (tension)
- push (pressure)
- extrude
- intrude
The point of application of the force in orthodontics is almost always at:
crown level
In orthodontics, the direction of force is in:
3 planes of space
In orthodontics, the amplitude of the force:
varies
In regard to force systems in orthodontics, remember we must:
move the roots
In orthodontics, a simple force applied to the crown of a tooth will result in:
TIPPING of the crown
T/F: IN orthodontics, the crown will tip in the direction force (simple force), the apex will tip in the opposite direction:
TRUE
Tooth movements needing more than a simple force:
- translation
- rotation
Two forces equal in magnitude and opposite direction acting on an object:
couple
A couple occurs when two forces equal in magnitude and opposite in direction act on an object. this results in:
- PURE MOMENT, since translators effect of the forces cancel
- The object will spin around its center of resistance (ROTATION)
When an object spins around its center of resistance:
rotation
Couples =
ALL rotation; NO translation
Bodily movement in orthodontics is a result of:
translation
What is often the movement of choice in orthodontics?
translation
What is required for translation to occur?
combination of simple force and a moment of force
Combination of force system =
translation
