Exam 1 - Biomechanics1 Flashcards
Bone resorption from osteoclasts coming form the PDL (Frontal resorption)
Pressure areas
bone apposition by osteoblasts coming from the PDL
Tension areas
What three things cause bone turnover and orthodontic movement?
- osteogenesis
- Bone modeling
- Bone remodeling
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
Osteogenesis
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
Bone modeling
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)
Bone remodeling
Tooth continues to move with frontal resorption
Light force
Repeated hyalinization-frontal resorption cycles
Heavy force
Action applied to a body
Mass x acceleration
Vectors: Magnitude and direction
Direction: line of action, sense and point of origin
Force
What is a resultant?
when multiple vectors are added
Forces passing through center of resistance produce pure?
Translation
Orthodontic forces are applied where?
AT THE CROWN
not through the center of resistance of the tooth
This results in some ROTATIONAL movement also
Orthodontic forces produce what types of movement
Translation and some rotational movement
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
Center of rotation
Removable appliances produce?
Single forces
Fixed appliances may produce?
single forces and/or coupled forces
Four types of tooth movement
- Tipping
- Translation
- Root movement
- Rotation
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
Tipping
Uncontrolled tipping
Simplest movement to produce
Single force
Non uniform stresses are generated
Greatest stress at crown and apex
Movement/Force ratio 0:1
Where is the center of rotation located in uncontrolled tipping?
Between Center of resistance and apex.
Tip and apex move in opposite direction
Controlled Tipping”
Very desirable movement
System of forces
Force AND couple
Force to move crown, couple to control apex position
Movement/Force ratio 7:1
Where is the center of rotation located in controlled tipping?
at the APEX
Only major movement is of the crown
“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
Translation
Root and crown move the same distance in same horizontal direction in what movement?
Translation
Where is the center of rotation located in Translation
Center of rotation at infinity
“Torque”
Change in tooth’s axial inclination
System of forces: Force AND couple
Movement/Force ratio 12:1
Root Movement
Root moves while crown stays stationary
Root movement
Where is the center of rotation located in Root Movement?
At the incisal edge or bracket
Requires a couple
if single force is used, C rotation is OUTSIDE tooth
No net force acts at center of resistance
Viewed occlusally
Rotation
