Forces moving teeth Flashcards

1
Q

What are the 2 types of tooth movement?

A

Physiological tooth movement (eruption)

Orthodontic from externally generated forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the stages in tooth eruption?

A
  • pre-eruptive tooth movement (small, random)
  • intra-osseous eruption (after crown forms, slow) aka erupting through the bone
  • mucosal penetration (fast)
  • pre-occlusal eruption (slow)
  • post occlusal eruption (very slow)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is the dental follicle important for tooth eruption?

A

Its important for bone resoprtion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What other factors are important for eruption?

A

Deciduous tooth resorption

Apical blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How can interceptive ortho treatment help ectopic canines?

A

Interceptive extraction of the deciduous canines at the correct stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When is the right time/correct stage to interceptively extract deciduous canines to help treat ectopic canines?

A

When the permanent has 1/2-2/3rds of roots development

Pateint will be between 10-12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When should GPD’s be looking for ectopic canines? Why is it important to refer then?

A

Around age 9 and refer

Because if dont extract on time will need surgery to move them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the physiological basis of orthodontics? e.g. how does the tooth move

A

If an external force is applied to a tooth, the tooth will move as the bone around it remodels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The bony remodelling in orthodontic tooth movement is mediated by what?

A

The PDL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When will a tooth note move?

A

If it doesnt have a PDL or is ankylosed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What role does cementum play in tooth movement? (how is it affected?)

A

Cementum is muchmore resisitant to resorption than bone, although some degree of root resorption after orthodontics should be expected

If there was no cementum then teeth would exfoliate post treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Appliances transmit forces to the PDL and bone and osteoclasts ‘herd’. What happens if there is an osteoclast that isnt working optiminally?

A

Macrophage will phagocytose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the different theries for how orthodontic tooth movement occurs?

A
  • differential pressure theory
  • piezo-electric theory
  • mechano-chemical theory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the differential pressure theory.

A

You get tension on one side where there is bone deposition

Get compression on other side/parts and get resorption from osteoclasts here

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the piezoelectric current theory.

A

-piezoelectric currents are generated when crystalline structure, such as bone, are defomed

These currents have been suggested as the prime mechanism by which tooth movement is modulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the mechano-chemical pressure theory.

A

mechanical stress

  • release of neuropeptides from nerve endings
  • stimulate fibroblasts, endothelial cells and alveolar bone
  • fibroblasts also communicate with osteoblasts and osteoclasts
  • alveolar bone and PDL remodelling
  • tooth movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the diff types of ortho appliances? (3)

A
  • removables
  • functional
  • fixed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the different types of tooth movement?

A
  • tipping
  • bodily movement
  • intrusion
  • extrusion
  • rotation
  • torque (is like tipping but moving the root instead of the crown)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the ideal force tot tip a tooth? (exam Q)

A

35-60 grams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are functional orthodontic appliances used to treat?

A

To correct class II occlusions (bring the mandible forward)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do functional appliances work?

A
  • The mandible is postured away from its normal rest position
  • the facial musculature is stretched which generated forces transmitted to the teeth and alveolus
  • there may be an effect on facial growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Give an example of how a functional appliacne may work with a Class II.

A
  • restrict maxillary growth
  • promote mandibular growth
  • remodel the glenoid fossa
23
Q

Describe the skeleton changes that occur with functional appliance.

A

Mandible is postured away from its normal rest position

24
Q

Describe the dental changes that occur with a functional appliance.

A
  • upper teeth tip back (maxillary restriction of growth)
  • lower teeth tip forward (wouldnt do on patient with lowers tipped forward)
25
Q

How long do you tend to wear a functional appliance for?

A

6 months full time then 6 months just at night

26
Q

Summarise the mode of action of functional appliances and the changes that they cause. (4 main points)

These changes together achives what?

A
  • skeletal change (30%)
    • Growth of mandible
    • Restriction of maxilla
  • dentoalveolar change (70%)
    • retroclination of the upper teeth
    • proclination of the lower teeth
  • Mesial migration of the lower teeth
  • Distal migration of the upper teeth

Achieves Class I

27
Q

What kind of tooth movement can fixed applianced facilitate?

A

All types (tipping, bodily movement, intrusion, extrusion, rotation, torque)

28
Q

What is the ideal force for bodily movement of a tooth?

A

150-200grams

29
Q

What does bodily movement of a tooth mean?

A

Moving the tooth at the same angle it is at

30
Q

What type of wire is needed for bodily movement?

A

rigid stainless steel wire that can bend

31
Q

Describe what happens in bodily movement of a tooth. (bone remodelling etc)

A
  • Apply force to a tooth (150-200g)
    • Get bone resorption on side of tooth that is moving
    • Get deposition of bone on the opposite side of the tooth

There is co-ordinated bone modelling and remodellling in response to the applied force.

Osteoclasts and osteoblasts play a big role in this

32
Q

What is the ideal force to intrude a tooth?

A

10-20grams

33
Q

Describe how an orthodontic appliance is used to intrude a tooth.

A

Gentle small force and the tooth will intrude

-pressure on the supporting structures is evenly distributed, and bone resorption is necessary, particularly at the apical area and alveolar crest

34
Q

What is the ideal force to extrude a tooth?

A

35-65grams

35
Q

How are teeth extruded with orthodontic appliances?

A

Tension is induced in the supporting structures and bone deposition happens to maintain tooth support

36
Q

What is the ideal force for rotation of a tooth?

A

35-60grams

37
Q

How do teeth rotate from ortho appliances?

A

Need a force couple

FOrces going in different directions and will have a centre of rotation

38
Q

What is the ideal force for apical root torque?

A

50-100grams

39
Q

How is apical root torque achiveed with ortho appliances?

A
  • is really difficult on any fixed appliance
  • is like a force couple
  • the crown doesnt move much but root does
40
Q

Summarise the optimum forces for different types of tooth movements.

A
  • Tipping = 30-60g
  • Bodily movement = 150-200g
  • Intrusion = 10-20g
  • Extrusion = 35-60g
  • Rotation = 30-60g
  • Torque = 50-100g
41
Q

How would you describe the kind of force in orthodontics generally?

A

Light force

42
Q

We use light forces as we want what to happen?

A

Frontal resorption

43
Q

Describe what histologically changes happen during orthodontics when light/ideal forces are used. (7 points)

A
  • hyperaemia within the PDL
  • appearance of osteoclasts and osteoblasts
  • resorption of lamina dura from pressure side (osteoblasts)
  • Apposition of osteoid on tension side (osteoblasts(
  • remodelling of socket ‘frontal resorption’
  • Periodontal fibres reorganise
  • gingival fibres appear not to become reorgnaised ut remain distorted
44
Q

What would happen if moderate force was applied to try and move a tooth?

A
  • Would have occlusion of vessels of PDL on pressure side
    • Leads to cell free areas (hylinsation)
    • Isnt dead but cant resorb the bone anymore
  • Hyperaemia of vessels of PDL on tension side
  • Period of stasis (bone is just there and no tooth movement)
  • Increased endsteal vascularity
    • UNDERMINING RESORPTION (bad)
    • Osteoclasts underneath the area causing this
  • Relatively rapid movement on tooth with bone deposition on the tension side
    • Tooth may become slightly loose
  • HEaling of PDL - reorganisation and remodelling

The teeth dont move efficiently

45
Q

What would happen if you tried to move a tooth with excessive force?

A
  • necrosis
  • undermining resorption
  • pain
  • permanent change

Would get no movement then a ‘clunk’

46
Q

What are the 4 factors affecting the response to orthodontic force? (is really only 3)

A
  • age
  • magnitude
  • duration
  • anatomy
47
Q

How does duration affect the response to ortho force?

A

Get bettwe results when worn 24hours a day

48
Q

What anatomical factors can effect the response to ortho forces?

A
  • bone wasting/cleft
  • alveolar necking
  • soft tissues
  • mid-palatal suturre
49
Q

What is alveolar necking and how does it affect ortho?

A

Tooth removed and the two alveolar plates are very close together

Almost impossible to move teeth through here

50
Q

Are teeth that have been root treated a problem?

A

If there is no pathology then no

51
Q

What are the deleterious effects/side effects of using orthodontic force?

A
  • Pain and mobility
  • Pulpal changes
  • Root resorption
  • Loss of alveolar bone support
  • Relapse
52
Q

What amount of tooth movement is though to be ideal?

A

1mm per month

It takes time!!

53
Q

What is the treatment time for fixed appliances?

A

24 months