Orthodontics - Physiology of Tooth Movement Flashcards

1
Q

name the types of tooth movements. (2)

A

physiological:
eruption
mesial drift

orthodontic

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2
Q

name the 2 subgroups of physiological tooth movement.

A

tooth eruption

mesial drift

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3
Q

list the types of physiological tooth eruption movements. (4)

A

pre-eruptive

intra-osseous

mucosal

post occlusal

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4
Q

describe when pre-eruptive movement occurs.

A

Starts when crown is forming, ends when crown is complete and root starts to form

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5
Q

describe how quickly intraosseous movement occurs.

A

As soon as roots start to develop the tooth moves 1mm every 3 months

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6
Q

describe how quickly mucosal movement occurs.

A

just reaches the mucosa and it come through really fast 1-2mm per month

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7
Q

describe when post occlusal movement occurs, how fast is this?

A

Once tooth hits something hard i.e. the opposing tooth, the PDL becomes establish and there are very slow movements

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8
Q

describe the suggested mechanism of tooth eruption. (3)

A
  • Root elongation and pressure around the apex from secretions
  • Alveolar bone remodelling and the action of the dental follicle
  • Reorganisation of the PDL membrane fibres and the role of fibroblasts
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9
Q

name the important factors in the eruption process. (3)

A

the dental follicle

apical blood flow

genetic factors i.e parathyroid receptor gene

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10
Q

how do you analyse ectopic canines on a radiograph?

A
  • Height
  • Closeness to the midline/how much is it overlapping the adjacent tooth
  • Angle : bad prognosis = > 30 degrees or horizontal
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11
Q

what angle of an ectopic canine has poor prognosis?

A

> 30 degrees

horizontal

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12
Q

what structure allows a tooth to move? (1)

A

a PDL

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13
Q

name the mechanism responsible for orthodontic tooth movement?

A

Mechano-chemical pressure

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14
Q

describe the Mechano-chemical pressure mechanism of orthodontic tooth movement. (5)

A
  • Mechanical stress applied to the tooth there are areas compression and tension on the tooth
  • Neuropeptides are released from nerve endings
  • Neuropeptides stimulate fibroblasts, endothelial cells and alveolar bone.
  • Fibroblasts communicate with osteoclasts and osteoblasts
  • The activation of the osteoblasts and osteoclasts = alveolar bone and PDL remodelling
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15
Q

where does resorption take place in tooth movement?

A

in areas of compression - in front of the tooth

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16
Q

where does deposition take place in tooth movement?

A

in areas of tension - distal aspect of a tooth moving forward

17
Q

name the types of tooth movements that we can achieve. (6)

A
  1. Tipping - URAS = 35-60g
  2. Bodily movements – root moved with the crown 150-200g
  3. Intrusion = 10-20g
  4. Extrusion = 35-60g
  5. Rotation = 35-60g
  6. Torque = 50-100g
18
Q

what movement do URA’s use?

A

tipping

19
Q

how much pressure is required for tipping movements?

A

35 – 60g

20
Q

how much pressure is required for bodily movements?

A

150 - 200g

21
Q

describe bodily movements.

A
  • Coordinated bone modelling and remodelling: allows resorption on one side and deposition on the other
22
Q

how much pressure is required for intrusion?

A

10-20g

23
Q

how much pressure is required for extrusion?

A

35-60g

24
Q

how much pressure is required for rotation?

A

35-60g

25
Q

how much pressure is required for apical torque?

A

50 – 100g

26
Q

name the histological changes occur in the application of light orthodontic forces?

A

Frontal Resorption

27
Q

name the histological change that occurs in the application of moderate orthodontic forces? (1)

A

undermining resorbtion

28
Q

what happens if excessive orthodontic force is applied? (5)

A
  • Necrosis
  • Undermining resorption
  • Resorption of root surfaces
  • Pain
  • Permanent change
29
Q

what factors affect the response to orthodontic forces?

A
  1. Magnitude (the force applied)
  2. Duration of wear
  3. Age
  4. Anatomy
30
Q

what anatomical features influence the response to orthodontic treatment? (3)

A

• Volume of bone
- Alveolar neck (from lost teeth) composed of 2 dense cortical plates: takes a long time to move tooth through this bone.

  • Effects of the tongue – acts against the appliances
  • Digit habits
31
Q

what are the deleterious effects of orthodontics? (5)

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