ORTHO801: Biomechanics

What is the #1 requirement to move teeth?

PDL

The ___ is the #1 requirement to move teeth?

PDL

PDL tension/stretch results in ___

osteoblasts forming bone

Osteoblasts forming bone is due to ___

PDL tension/stretch

PDL compression results in __

osteoclasts removing bone

Osteoclasts removing bone is due to __

PDL compression

What is the ideal force to move a tooth?

light continuous force

Types of Orthodontic Tooth Movement

Tip

Translate

Torque

Intrude

Extrude

Rotate

Tipping of teeth involves___ and __

angulation & inclination

Translation

bodily movement without rotation

Torque

M-D angulation / B-L angulation from a couple

Intrude

moving tooth in

For a deep bite, sometimes true intrusion is not always the answers, therefore it is called ___

"relative" intrusion

Extrude

move teeth out

How much force does Tipping require?

35-60

How much force does Bodily Translation require?

70-120

How much force does Root Uprighting require?

50-100

How much force does Rotation require?

35-60

How much force does Extrusion require?

35-60

How much force does Intrusion requirement?

10-20

Which Orthodontic tooth movement requires the least amount of force?

Intrusion

Which Orthodontic tooth movement requires the most amount of force?

Bodily Translation

Force

a push/pull on an object with mass that causes it to change velocity (motion)

Force =

mass * acceleration

1 Newtown = ___ ounces

3.6

1 Newton = ___ grams

102

1 Ounce = ___ grams

28.3

To understand biomechanics you must be able to answer these two questions:

1. Where will this force(s) move a tooth (teeth) to?

2. To move a tooth (teeth) to a planned position, what forces(s) must be applied?

Single Force

a load (push/pull) applied to a tooth that will tend to change its position

A single fore has what 4 components?

1. Point of Application

2. Line of Action

3. Sense

4. Magnitude

Center of Resistance (CRES)

a fixed point on a tooth that defines where a maximum resistance to movement is mathematically concentrated. Where a force applied will result in translation or bodily movement of a tooth.

When a force is applied to the CRES, ___ will result

translation

A Center of Resistance (CRES) of an object is the same as its ____ when the object is in free space

Center of Mass (balance point)

A tooth is a ___ object within a periodontium

restrained

T/F: A tooth in the PDL has its CRES = CMAS

FALSE

CRES is located ___ from the alveolar crest and is relative to root length and crestal bone height.

1/3-1/2

CRES is about ___ mm from average bracket height on a tooth

10 mm

Mandibular Molars CRES is estimated to be ___ a length of its root from the alveolar crest viewed from a facial and mesio-distal perspective (near bifurcation), and near its ___ from an occlusal perspective

1/3-1/2

center

Maxillary Molars CRES is estimated to be ____ a length of its root from the bony crest from facial and mesio-distal perspective (near a bifurcation), and near its ___ from an occlusal perspective

1/3-1/2

palatal root

Single Rooted Teeth CRES is estimated to be ___ length of its root from the bony crest from a facial and mesio-distal perspective, and neat its ___ from an occlusal perspective

1/3-1/2

center

Tendency

likelihood of occuring, whether or not a probable action or effect actually occur

Tipping

rotational movement caused by a single force applied at a point away (excentric) from the tooth's center of resistance

Tipping is what kind of movement?

Rotational

How many grams to tip a tooth ?

50 grams

Center of Rotation (CROT)

point about which a tooth will rotate

The Center of Rotation is a ___ point and not ___

fluid

fixed

The two types of orthodontic forces

Single Force

Couple

A ___ applied to a crown of a tooth will have a tendency to create a moment at a center of rotation just apical to a center of resistance

single force

A single force will have a tendency to create a moment at the CRot just ___ to the CRES

apical

Moment

a measurement of a tendency for a tooth to rotate when a force is applied away from the tooth's center of resistance

A moment is ___ a force

NOT

T/F: a moment is a force

FALSE

Pure "Uncontrolled" Tipping has some ___ along with the rotational movement, occurs with the CROT being just apical to the CRES

bodily movement

Moment Equation

Force x Distance

Couple

a system of two parallel forces of equal magnitude acting on oppositie directions

Torquing

rotating a tooth by applying a twisting force created by a force couple

A ___ applied to a crown of a tooth will have a tendency to create a moment about a center of resistance

couple of forces

A couple of forces will have the Moment at the __

Center of Resistance

___ can only result from an applied couple to an object

pure rotation

Translation

bodily movement of a tooth without rotation in any of the three dimensions

Translation results from a ____ with a line of action through its CRES

single force

T/F: a single force can be applied to a tooth with a line of action through its center of resistance

FALSE

Translation requires___

Equivalent Force system

How many grams to translate a tooth?

100 grams

Equivalent Force System

single force + couple of forces

Single Force Applied

Uncontrolled tipping

Single Force + Couple Applied

Controlled Tipping

Translation

Root torqing

Couple Applied

Pure rotation

Biomechanics can only be described

instantaneously

What is the 4th dimension?

time