Anchorage Flashcards

1
Q

What is anchorage?

A

Resistance to unwanted reciprocal tooth movements

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2
Q

What is the rate of tooth movement related to? And what is this theory called?

A

Differential theory stages that: level force per unit root area over a certain range of force

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3
Q

What are the sources of intraoral anchorage?

A
root surface area
teeth in same arch
palate
opposing teeth
implants/TAD
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4
Q

What is EO anchorage and What are sources of E/O anchorage?

A

This is when the force to move the teeth is from the outside head gear attaching onto cranial bones

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5
Q

What is loss of anchorage?

A

movement of the anchor teeth during orthodontic treatment

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6
Q

What is excessive loss of anchorage?

A

UNWANTED movement of anchor teeth during orthodontic treatment which prevents dsired tooth movement from occurring

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7
Q

How can we prevent LOA?

A

move small number of teeth at any one time
keep active forces light
make anchorage root area as large as possible

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8
Q

Which requires more anchorage, full bodily movement or tipping?

A

full bodily movement as there is more area for which bone has to resorb

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9
Q

What is the disadvanage of intermaxlliary anchorage?

A

this can sometimes lead to the over eruption of posterior teeth and reduction of the overbite

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10
Q

What are the groups os intra oral traction?

A

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

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11
Q

When would we use head gear?

A

to move all teeth distally

when there is not enough I/O anchorage

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12
Q

What are the two types of head gear?

A

cervical pull

high pull

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13
Q

How does cervical pull work?

A

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

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14
Q

How does high pull head gear work?

A

this is placed above the occlusal place

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15
Q

How long does the head gear need to be worn?

A

10/12 hours

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16
Q

How much force is exerted by hed gear?

A

200-250g

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17
Q

WHat do TAD create?

A

temporary anchorage device

they provide absolute anchorage

18
Q

Tooth moving forces create equal and opposite forces according to who?

A

Newtons third law

19
Q

How can we monitor anchorage?

A

By recording each visit the extent of movements you want to happen

20
Q

What is the root surface area of upper incisor?

A

Central: 2.2cmsq
Lateral: 1.8cmsq

21
Q

What is the root surface area of an upper canine?

A

2.7cmsq

22
Q

What is the root surface area of an upper second premolar?

A

2.3cmsq

23
Q

What is the root surface area of an upper molar?

A

4.6cmsq

24
Q

Anchorage within one jaw is known as what?

A

Intra maxillary

25
Q

Anchorage across jaws is knows as?

A

Intermaxilliary

26
Q

What are the components of head gear?

A
  1. Headcap
  2. Elastic bands
  3. Facebow/whiskers
  4. J Hooks
27
Q

How much force is needed to tip a tooth?

A

25-60g

28
Q

How much force is needed to bodily move a tooth?

A

50-120g

29
Q

How much force is needed to torque a tooth?

A

50-100g

30
Q

How much force is needed to rotate a tooth?

A

35-60g

31
Q

How much force is needed to extrude a tooth?

A

34-60g

32
Q

How much force is needed to intrude a tooth?

A

10-20g

33
Q

What level of force must be not exceeded during tooth movement?

A

30mmHg
Because this is the pressure in capillaries and above this the capillaries will occlude and this then leads to hyalinasation of the pdl

34
Q

How does bone resorb under physiological conditions ie. When the amount of force exerted by the brace does not exceed the capillary force?

A
  1. Osteoclasts are formed by the fusion of blood monocytes which then resorb bone under the control of osteoblasts
35
Q

How does bone resorb in ortho when there has been death of the pdl?

A

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.

36
Q

What is the type of bone resorption that takes place in hylanisee pdl?

A

Undermining resorption

Osteoclasts resorb the bone from the cancellous bone to the pdl

37
Q

When the pdl is hylainsee bone resorption is faster. T/F

A

F

Delay of 10-14 days

38
Q

What is there more likely to be as a consequence of hylaisation?

A

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

39
Q

Why does bodily movement have greater optimal force levels that the other types of movements?

A

Because a greater area of pdl is involved and thus more force can be applied

40
Q

What happens if toot much force is used to intrude teeth?

A

Since only a small amount of pdl is involved

  1. Root resorption
  2. Tooth devitalisation as the apical blood is constricted
41
Q

What does class 2 Intermaxilliary anchorage look like?

A

From upper 3’s to lower 6’s

42
Q

What does class 3 Intermaxilliary anchorage look like?

A

Fro lower 3’s to upper 6’s