Exam 1 - Biomechanics1

Question 1

Bone resorption from osteoclasts coming form the PDL (Frontal resorption)

Answer 1

Pressure areas

Question 2

bone apposition by osteoblasts coming from the PDL

Answer 2

Tension areas

Question 3

What three things cause bone turnover and orthodontic movement?

Answer 3

1. osteogenesis
2. Bone modeling
3. Bone remodeling

Question 4

Bone formed in soft tissue where there was never bone before
Intramembranous and endochondral
responsible for: Embryonic development, early growth and healing

This has nothing to do with orthodontic movement

Answer 4

Osteogenesis

Question 5

Bone formation on existing bone tissue
Over extended areas for significant periods of time
growth and development
change in shape of structure or translation of surface
Osteoclasts and osteoblasts act different sites

Answer 5

Bone modeling

Question 6

Reparative mechanisms
Ca homeostasis
Physiologic mechanism for maintaining and repairing structural integrity of bone
Four different stages: Activation, resorption, reversion, formation
Osteoblasts and osteoclasts activities found on same site (bone shape maintained)

Answer 6

Bone remodeling

Question 7

Tooth continues to move with frontal resorption

Answer 7

Light force

Question 8

Repeated hyalinization-frontal resorption cycles

Answer 8

Heavy force

Question 9

Action applied to a body
Mass x acceleration

Vectors: Magnitude and direction

Direction: line of action, sense and point of origin

Answer 9

Force

Question 10

What is a resultant?

Answer 10

when multiple vectors are added

Question 11

Forces passing through center of resistance produce pure?

Answer 11

Translation

Question 12

Orthodontic forces are applied where?

Answer 12

AT THE CROWN

not through the center of resistance of the tooth

This results in some ROTATIONAL movement also

Question 13

Orthodontic forces produce what types of movement

Answer 13

Translation and some rotational movement

Question 14

A point about which a body appears to have rotated, as determined from its initial and final positions

It can be located anywhere, on or off the tooth

Answer 14

Center of rotation

Question 15

Removable appliances produce?

Answer 15

Single forces

Question 16

Fixed appliances may produce?

Answer 16

single forces and/or coupled forces

Question 17

Four types of tooth movement

Answer 17

1. Tipping
2. Translation
3. Root movement
4. Rotation

Question 18

movement of the crown

Center of rotation is apical to center of resistanec

Can be controlled or uncontrolled depending on location of Center of rotation

Answer 18

Tipping

Question 19

Uncontrolled tipping

Answer 19

Simplest movement to produce

Single force

Non uniform stresses are generated

Greatest stress at crown and apex

Movement/Force ratio 0:1

Question 20

Where is the center of rotation located in uncontrolled tipping?

Answer 20

Between Center of resistance and apex.

Tip and apex move in opposite direction

Question 21

Controlled Tipping”

Answer 21

Very desirable movement

System of forces

Force AND couple

Force to move crown, couple to control apex position

Movement/Force ratio 7:1

Question 22

Where is the center of rotation located in controlled tipping?

Answer 22

at the APEX

Only major movement is of the crown

Question 23

“Bodily movement”

Single force at center of resistance

System of forces: Force not passing through Center of resistance AND couple

Movement/force ratio 10:1

Answer 23

Translation

Question 24

Root and crown move the same distance in same horizontal direction in what movement?

Answer 24

Translation

Question 25

Where is the center of rotation located in Translation

Answer 25

Center of rotation at infinity

Question 26

“Torque”

Change in tooth’s axial inclination

System of forces: Force AND couple

Movement/Force ratio 12:1

Answer 26

Root Movement

Question 27

Root moves while crown stays stationary

Answer 27

Root movement

Question 28

Where is the center of rotation located in Root Movement?

Answer 28

At the incisal edge or bracket

Question 29

Requires a couple
if single force is used, C rotation is OUTSIDE tooth

No net force acts at center of resistance

Viewed occlusally

Answer 29

Rotation