Anchorage Flashcards
What is anchorage?
Resistance to unwanted reciprocal tooth movements
What is the rate of tooth movement related to? And what is this theory called?
Differential theory stages that: level force per unit root area over a certain range of force
What are the sources of intraoral anchorage?
root surface area teeth in same arch palate opposing teeth implants/TAD
What is EO anchorage and What are sources of E/O anchorage?
This is when the force to move the teeth is from the outside head gear attaching onto cranial bones
What is loss of anchorage?
movement of the anchor teeth during orthodontic treatment
What is excessive loss of anchorage?
UNWANTED movement of anchor teeth during orthodontic treatment which prevents dsired tooth movement from occurring
How can we prevent LOA?
move small number of teeth at any one time
keep active forces light
make anchorage root area as large as possible
Which requires more anchorage, full bodily movement or tipping?
full bodily movement as there is more area for which bone has to resorb
What is the disadvanage of intermaxlliary anchorage?
this can sometimes lead to the over eruption of posterior teeth and reduction of the overbite
What are the groups os intra oral traction?
simple: one tooth
compound: several teeth
reciprocal: 2 groups of teeth are pitted against eachother so get movements in both sets, this is needed in palatal expasion
When would we use head gear?
to move all teeth distally
when there is not enough I/O anchorage
What are the two types of head gear?
cervical pull
high pull
How does cervical pull work?
this is at the level of the occlusal plane and causes the upper molars to extrude so cannot be used in people with increases lower facial height
How does high pull head gear work?
this is placed above the occlusal place
How long does the head gear need to be worn?
10/12 hours
How much force is exerted by hed gear?
200-250g
WHat do TAD create?
temporary anchorage device
they provide absolute anchorage
Tooth moving forces create equal and opposite forces according to who?
Newtons third law
How can we monitor anchorage?
By recording each visit the extent of movements you want to happen
What is the root surface area of upper incisor?
Central: 2.2cmsq
Lateral: 1.8cmsq
What is the root surface area of an upper canine?
2.7cmsq
What is the root surface area of an upper second premolar?
2.3cmsq
What is the root surface area of an upper molar?
4.6cmsq
Anchorage within one jaw is known as what?
Intra maxillary
Anchorage across jaws is knows as?
Intermaxilliary
What are the components of head gear?
- Headcap
- Elastic bands
- Facebow/whiskers
- J Hooks
How much force is needed to tip a tooth?
25-60g
How much force is needed to bodily move a tooth?
50-120g
How much force is needed to torque a tooth?
50-100g
How much force is needed to rotate a tooth?
35-60g
How much force is needed to extrude a tooth?
34-60g
How much force is needed to intrude a tooth?
10-20g
What level of force must be not exceeded during tooth movement?
30mmHg
Because this is the pressure in capillaries and above this the capillaries will occlude and this then leads to hyalinasation of the pdl
How does bone resorb under physiological conditions ie. When the amount of force exerted by the brace does not exceed the capillary force?
- Osteoclasts are formed by the fusion of blood monocytes which then resorb bone under the control of osteoblasts
How does bone resorb in ortho when there has been death of the pdl?
Osteoblasts and osteoclasts that would be returned from the pdl are not available and for frontal resorption of bone
This means bone remodelling would be otherwise performed by cells migrating from Undamaged areas of pdl which may take several days therefor in these circumstances bone is resrobed outward a by osteoclasts lining the marrow spaces from the cancellous bone to the pdl.
What is the type of bone resorption that takes place in hylanisee pdl?
Undermining resorption
Osteoclasts resorb the bone from the cancellous bone to the pdl
When the pdl is hylainsee bone resorption is faster. T/F
F
Delay of 10-14 days
What is there more likely to be as a consequence of hylaisation?
LOA
This is because the force maybe too strong or the tooth in question but form the remaining anchor teeth the force maybe just the right level
Why does bodily movement have greater optimal force levels that the other types of movements?
Because a greater area of pdl is involved and thus more force can be applied
What happens if toot much force is used to intrude teeth?
Since only a small amount of pdl is involved
- Root resorption
- Tooth devitalisation as the apical blood is constricted
What does class 2 Intermaxilliary anchorage look like?
From upper 3’s to lower 6’s
What does class 3 Intermaxilliary anchorage look like?
Fro lower 3’s to upper 6’s
