biomechanics of tooth movement Flashcards
tooth movement catagories
physiological
orthodontics
physiological types of tooth movement
pre eruptuve
eruptive
post eruptive
where do permanent teeth tend to form
lingual/palatal side of primary teeth
rate of eruptive tooth movemnt
1mm per month
post eruptive movement
accommodate to growing jaws
accommodate for occlusal wear
compensate for interproimal wear - mesial drift
when can you move a tooth
need vital PDL
- tooth cannot be ankylosed
PDL consists of
cells
extracellular components
what may be responsible in the PDL for relapse after tx
collagen fibre bumdles
oxytalan fibres
what occurs on the pressure side of the moving tooth
where the PDL is being compressed
- differentiation of osteoclasts
collagen fibre remodelling
tension side of moving tooth
bone deposition
collagen fibre remodelling
stages of movement
initial compression
delay phase (2-14) - cells need to move to area and activate
tooth movment
initial compression
slight movement against wall of PDL
tooth moves through PDL
delay phase
loss of cells from area
new cells move in
bone resorption
tooth movement
PDL has new cels
bone resoprtion
collagen fibre remodelling
threshold duration of fore
min 6hrs per day
longer force applied more efficient the movement
excessive force application consequenes
blood vessels occluded on pressure side
cell death, delay in recruitment, have to be recruited outside the PDL
OC recruited from endosteal surface of bone, slower movement
hylinization and undermining resoprtion(described above)
risks with excessive force application
1) delay in tooth movement
2) pain
3) loss of vitality
4) mobility
5) root resorption
6) loss of anchorage
what does optimum force depend on
size of tooth
type of movement
continuous or intermittent
orthodontic anchorage
control of unwanted tooth movement
- there is an equal and opposite force pushing other teeth eg the molar which a tooth may be anchored to
types of movement
tipping bodily movement rotation torque vertical movement (extrusion, intrusion)
what type of movement do removable appliances do
only tipping
fixed do all (3D movement)
types of movement and their ideal forces
bodily movement 70-120 root uprighting 50-100 rotation - 35-60 extrusion 35-60 tipping 35-60 intrusion 10-20
cellular event in responce to mechanical loading
matrix strain and fluid flow in the alveolar bone and PDL
cell strain as a result of matrix strain and fluid flow
cell activation and differentiation
remodelling of PDL and alveolar bone
how and what is hylinization /how does it occur
force applied to tooth exceeds pressure in capillaries 30mmHg capillaries will occlude
cell dealth in PDL
sterile necrosis
- which is hylainzation
