Tooth movement and appliances Flashcards

1
Q

what is described in the aim of an ortho URA prescription sheet

A

description of what the APPLIANCE is aiming to achieve
Not the aim of the whole treatment

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2
Q

what process does tooth movement via orthodontics rely on

A

bone remodelling by osteoclasts and osteoblasts which is controlled by PDL fibres
if a prolonged force is applied, tooth movement will occur

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3
Q

differential pressure theory of orthodontic tooth movement

A

applying force to the crown creates stresses in the periodontal ligaments
Compression areas see bone resorption and tension areas see bone deposition

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4
Q

mechano-chemical theory of orthodontic tooth movement

A

cells (osteoblasts) undergo shape changes in response to tension and pressure
Compression areas see osteoblasts bunched up exposing osteoid layer to osteoclasts resulting in resorption
Tension areas see osteoblasts stretched and flattened preventing osteoclasts reaching the osteoid layer and allowing for bone deposition to occur

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5
Q

what movement can removable appliances create

A

tipping of teeth

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6
Q

example of a functional appliance

A

twin block

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7
Q

what patients might be given a functional appliance

A

patients with skeletal discrepancies who are still growing
(must be still growing for them to work)

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8
Q

what force is required to tip teeth

A

dependent on size of tooth , 35-60g

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9
Q

what is bodily movement of a tooth and how much force is required for this to be done

A

bodily movement is moving the whole tooth, crown and root, as one. Requires a fixed appliance
force required in 150-200g

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10
Q

what force is required to intrude teeth and why is it so low

A

10-20g
high forces would risk root resorption

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11
Q

what force is required to rotate teeth

A

35-60g

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12
Q

what force is required to extrude teeth

A

35-60g

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13
Q

what is torque movement of a tooth and how much force is required to do this

A

torque refers to moving the root of the tooth with minimal movement of the crown
requires force of 50-100g

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14
Q

what change to blood flow is caused by orthodontics using light pressure

A

hyperaemia in pressure and tension areas
(increased blood flow)

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15
Q

what happens to PDL and gingival fibres when a tooth is moved orthodontically using light pressure

A

the PDLs have enough time to reorganise
Gingival fibres remain distorted and dont reorganise - a main reason for relapse post treatment if a retainer isnt worn

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16
Q

what changes to blood flow is seen during orthodontics using moderate forces

A

sees hyperaemia on tension side but occlusion of blood vessels on the compression side

17
Q

if moderate forces are being used, what occurs on the compression side of a tooth being moved

A

compression side sees hyalinisation a process seeing cell death due to occlusion creating a cell free zone

18
Q

how does movement occur when moderate forces are used to move teeth

A

periods of stasis then sudden rapid tooth movements - unideal

19
Q

name 3 possible consequences of using excessive force to move teeth

A

root resorption , anchorage loss, loss of vitality

20
Q

why do teeth move slower in older patients receiving ortho

A

bone becomes denser as we age and there is slower cell turnover

21
Q

to promote eruption of a permanent tooth if extracting a deciduous tooth early , what is the ideal time

A

when one half to two thirds of the permanent root is formed