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Ortho > Biomechanics 1 > Flashcards

Biomechanics 1 Flashcards

(74 cards)

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1
Q

first step in tx

A

PATHOLOGY should be controlled first

then ortho problems
- so treated in priority order

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2
Q

biomechanics - genreal

A

principles that reveal how to accomplish tooth movement

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3
Q

application of force –>

A

tissue response –> orthodontic movement

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4
Q

principles of bio of tooth movement

A
  • if prolonged pressure is applies to a tooth movement will occur
  • bone is selectively removed in some areas and added in others
  • tooth moves through the bone carrying its attachment apparatus with it
  • tooth movement is primarily a periodontal ligament phenomenom (so need this healthy structure for movement)
  • like no pdl ankylossis is incapable of movement
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5
Q

what is necessary for tooth movement? - clincial level

A

prolonged application of force

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6
Q

graph of movement at tissue level

A

1-3 days – displacement

2-10 weeks delay / long phase

then accelarates up to acceleration and linear

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7
Q

describe the initial strain / primary displacement

A
  1. initial reaction following force
  2. immediate movement within the viscoelastic pdl cradle
  3. fluid movement
  4. magnitude depends on root length/ bone height/ age/ pdl elasticity
  5. areas of pressure and tension are created
  6. pressure : pdl fibers and bone are compressed
  7. tension pdl is stretched
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8
Q

pressure

A

pdl fibers and bone is compressed

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9
Q

tension

A

pdl is stretched

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10
Q

time needed for movement

A

minimal of 6 hours for movement

more efficient movement with longer duration of force applied

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11
Q

dleay / lag phase general

A

Chain of reaction to allow within a few weeks of 2 -10 weeks to see the clinical movements

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12
Q

tooth closer to bone?

A

pressure vs farther away = areas of tension

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13
Q

delay / lag phase details

A

no movement but intense remodeling action around the tooth

relative force dependent (force applied per unit area)
- whats the ‘clincial root value’

partial or absolute occlusion of pdl blood vessels

structureal and biomechanical changes

bone remodeling

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14
Q

bone remodeling occurs

A

delay / lag phase

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15
Q

force determines

A

how long the delay / lag force lasts

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16
Q

partial occlusion

A

lower relative forces

blood vesels adaps to new environmnet

localized angiogenesisi to bypass occluded areas

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17
Q

absolute occlusion

A

higher forces

first time force is applied

complete occlusion of blood flow

temporary necrosis of immediate area

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18
Q

acceleration and linera phase - timing

A

LIGHT CONTINUOUS FORCES allow constant responsive state in tissues and more effective ortho movement

this is a response to adaption at bone/ pdl changes - directly affected by force magnitude - higher forces may show lag phase

rapid tooth displacement

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19
Q

frontal resorption

A

light forces distributed in large areas

  • right in front of root surface

transient ischemia

oxygenated is limited but still present (partial occlusion)

adaption and initiation of frontal resorption by pdl osteoclasts

movement occurs within 3-4 days

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20
Q

when does frontal resoprtion occur? by?

A

3-4 days by pdl osteoclasts

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21
Q

when does frontal resoprtion occur? by?

A

3-4 days by pdl osteoclasts

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22
Q

undermining resopriton details

A

larger forces applied

complete vascular occlusoin

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23
Q

tooth movement in undermining resorption

A

12-15 days after bone remodeling

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24
Q

pressure areas - more detailed

A

bone resorption from osteoclasts coming from the PDL

FRONTAL RESORPTION

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25
tension areas - more detailed
bone apposition by osteoblats coming from the PDL
26
osteogenesis
bone formed in soft tissue where it was never there before intramembranous and endochondral embryonic development ORTHO HAS NOTHING TO DO WITH THIS
27
BONE MODELING
bone formation on existin bone tissue over extended areas for significant periods of time growth and development change in shape of structure or translation of surface osteoclasts and osteoblsts act at different sites
28
which is a reparative mechanism?
bone remodeling with 4 different stages
29
4 stages of bone remodeling
1. activation 2. resorption 3. reversion 4. formation
30
light force
tooth contiues to mvoe with frontal resopriton
31
heavy force
repeated hyalinization - frontal resoprtion cycles
32
center or mass or gravity
point through which an applied force must pass for a FREE OBJECT to move linearly without rotation point of balance
33
center of resistance
point through which if an applied force must pass for a RESTRICTED BODY to move linearly movement without rotation in teeth - CR depends on the root length , morphology, and attachemnt levels 1/4 to 1/3 distance from CEJ to apec
34
Center of resistence in teeth
in teeth - CR depends on the root length , morphology, and attachemnt levels 1/4 to 1/3 distance from CEJ to apec usually around fircation in molars *
35
force in general
mass multiplied by acceleration vectors with magnitude (size) and direction direction -- line of action, sense and point of origin
36
resultant?
multiple vectors can be added
37
pure translation of tooth?
if forces passes through CR directly -- produce pure translation
38
ortho forces are applied where | + implication
on teh CROWN LEVEL | - so will generate rotation as well
39
center of rotation
a point about which a body appears to have rotated, as determined from its initial and final positions it can be located ANYWHERE on or off the tooth
40
center of resistance is where
always on the root
41
removable appliances produce
SINGLE FORCES
42
fixed appliances may produce
single forces and or couples | - more precise outcomes
43
types of tooth movement and result
tipping translation root movement rotation result from the application of moments and forces (moment/force) ratio
44
describe tipping
greater movement of the crown center of rotation is apical to center of resistance -- apex is staying more steady can be controlled or uncontrolled depending on location of Center of rotation
45
uncontrolled tipping
simplest movement single force non uniform stresses are generted greatest stress at CROWN AND APEX moment/ force ratio 0:1 to 5:1
46
0:1 to 5:1 ration
moment / force ratio within the uncontrolled tipping
47
in uncontrolled tipping where is the center of rotation adn resistenc e
center of rotation located between C of resistance and apex tip and apex move in OPPOITE DIRECTOIN
48
controlled tipping
very desirable - minimal stress at apex - less chances of root resorption moment/ force ratio 7:1 force AND COUPLE system of forces center of rotation AT APEX -- only major movement is at the crown
49
where is movement occuring in controlled tipping
movement at the CROWN -- the center of rotation at the apex moves very little
50
movement that allows for closure of space
translation
51
translation - basic
bodily movement
52
translation
single force at center of resistance system of forces -- force NOT passing through C resistance and couple moment / force ratio 10: 1
53
translaiton ratio and movement
10: 1 root and corwn moving in same distance in same HORIZONTAL DIRECTION center of rotation at infinity a lot of control
54
root movement general
toque movement
55
root movement moment/ force ratio
12:1
56
root movement changes what
the tooths axial incliniation - want the root position to change
57
greater stress where with root movement
greatest stress at apex level (may cause undermininig resorption and slow the movement) so greater stress at the apical level
58
greater stress where with root movement
greatest stress at apex level (may cause undermininig resorption and slow the movement) so greater stress at the apical level
59
movement in root movement
root moves while crown stays stationary -- center of rotation at the INCISAL EDGE OR BRACKET
60
ROTATION
pure rotation requires a couple if single force is sued, C of rotation is outside the tooth no net force acts at center of resistance need two forces opposing
61
rotation movement
single force not passing through center of resistnace c of roation outside of tooth
62
pure rotation
couple acts on tooth center of rotation is located at center of resistance - like on either sife of the tooth
63
when does Crot = CR
pure rotation
64
anchorage
resistance to unwanted tooth movemet
65
teeth move differently because
due to variations in their root surface -- more root surface more resistance to movement
66
more root SA?
harder to move -- more resistance
67
friction? - very general
opposes movement as well
68
friction - more detialed
it is resistance to the direction of movement, when moving a solid object tangentially against one another
69
sliding mechanics
teeth slide on the wire the higher the diameter the wire , the higher the friction, the greater the anchorage
70
relationship between wire and friction
higher diameter of wire -- the higher the friction -- the greater the anchorage
71
anchorage
resistance to unwanted tooth movement
72
examples of intraoral anchorage
TPA lingual arch
73
TPA
transpalatal arch connects the maxillary 1st molars and creates an anchor u nit of 6 roots
74
minimum force needed for movement
6 hours a day

Ortho (19 decks)

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