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ortho > Biology of ortho treatment > Flashcards

Biology of ortho treatment Flashcards

1
Q

what is the goal of ortho apliances

A

To move the tooth via biological remodeling NOT mecahnical force

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2
Q

why does the tooth not move to bite force but does to light ortho force?

A
  • PDL is a shock absorber in the alveolar bone
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3
Q

what allows the PDL to act as a shock absorber

A

The fluid in the PDL

  • uncompressible, with bending alveolar bone
  • squeezes out and cellular elements feel pressure
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4
Q

how does the tooth move in bitting

A

Relative to the jaw, but not moving against the alveolar bone

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5
Q

why is bone bending important for the jaw

A

stop decalcification of the bone

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6
Q

what does bone bending do

A
  1. Force against crystalline structure mechanically distorts crystals
  2. production of rapid current flow as electrons move
  3. force removed allows the crystals to come back to OG position
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7
Q

what is alveolar bone lost when a tooth is extracted

A

No rhythmic loading needed to generate piezo-electric currents, resulting in decalcification and resorption

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8
Q

what is the flow of electrons due to the rhythmic loading of bone

A

piezo-electric currents

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9
Q

is the piezo-electric current needed for ortho tooth movement

A

No

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10
Q

is electric current needed for ortho tooth movement

A

Yes, needed to alter cell membrane potentials

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11
Q

what theory do we use to do ortho movement

A

Pressure-tension theory

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12
Q

what happens if heavy force is sustained

A

PAIN

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13
Q

how does sustained pressure effect the tooth/alveolar bone

A

Puts pressure on the tooth then alveolar bone pushes back leading to a movement relative to the alveolar bone

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14
Q

what kind of signal is used for the pressure-tension expalanation

A

Chemical

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15
Q

how does pressure-tension lead to chemical release

A
  • Mechanical distoration of cells in pDL leads to release of cellular contents
  • decrease in Blood flow in pDL opposite of force applied changes O2 and CO2 levels in PDL releasing chemical
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16
Q

what happens as the PDL is increasing compressed

A

Blood flow is completely cut off

-necrosis

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17
Q

how long does pressure take to change CO2 and O2 levels and Prostaglandin/cytokine release

A

minutes

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18
Q

how long does it take for metabolic changes/cAMP changes/cell differeations to occur in cells when pressure is changed

A

about 4 hours

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19
Q

when does remodeling occur after pressure applied

A

About 2 days

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20
Q

time for blood Vessels within PDL to become occluded in the pressure side due to heavy pressur

A

3-5 sce

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21
Q

time for Blood flow to be cut off in compressed PDL under heavy pressure

A

minutes

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22
Q

time for cell death in compressed area under heavy pressure

A

hours

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23
Q

time for Cell differentiation in adjacent marrow spaces undermining resorption begins under heavy pressure

A

3-5 days

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24
Q

time for undermining resorption removing lamina dura adjacent to compresses PDL and tooth movement occurs under pressure

A

7-14 days

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25
Q

where are cells coming from to remodel in the case of heavier sustained pressure

A

Area adjacent to PDL not necrotic

one marrow spaces outside the lamina dura

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26
Q

what does undermmining resorption get its name

A

Large nectrotic areas in the PDL needed for osteoclasts to resorb the lamina dura

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27
Q

what does the necrotic area in the PDL of the undermining resorbing send

A

chem signals to stimulate formation of osteocalasts

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28
Q

what produces more movement, heavy or light force initiation

A

light force

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29
Q

how do yo u know if force is tooth heavy

A

if the tooth is loose(loss of lamina dura)

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30
Q

why does tooth tipping occur

A

When a single force is applied to the crown of a tooth

- resistance comes from the root

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31
Q

where is the center of resistance when pulling on a crown

A

Center of root

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32
Q

how do you do bodily movement on the tooth

A

Apply two forces simultaneously to the crown to load entire area of the PDL

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33
Q

how much force is needed to do body movement compared to tiping

A

2x as much (100g vs 50g)

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34
Q

how much loading occures during extrusion

A

loads the entire PDL volume

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35
Q

how much force is needed to extrude or rotate a tooth

A

The same as tiping

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36
Q

why does rotation or extruding not require more force than tipping

A

Roots are irregularly shapped, so any force lead to tipping somewhat

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37
Q

Force needed to rotate, extrude, and tip

A

50g for all of them

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38
Q

what is torque

A

Tooth movement where root apex is moved further than crown in a desired dirction

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39
Q

how much is needed for torque

A

about 75 g

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40
Q

how can we do intrusion

A

V. light compression at the apex (10g)

41
Q

why do you need a light force in intrusion

A

force is concentrated in one small area so small force compresses more

42
Q

how long must you wear an appliance to lead to movement

A

at least 4-8 hours a day

43
Q

what is the best way to move a tooth

A

Light continuous force

44
Q

how does light force cause a tooth to move

A

frontal resorbtion on the PDL side of the lamina dura

45
Q

what is interrupted force

A

a spring with poor force decay where force drops to zero before reactivation

46
Q

does undermining resorption occur in all patients

A

Yes, but just slightly

47
Q

is heavy interrupted force okay

A

May be clinically acceptable even though it may cause pain

48
Q

is continuous force possible with removable appliances

A

No

49
Q

what force does a removable appliance create

A

Intermittent force

- maybe with some interrupted force

50
Q

what is the appointment interval for ortho

A

4-6 weks

  • movement takes 7-14 days
  • 2 weeks to recover
51
Q

does heavy or light force springs need more intervals

A

Heavy needs more interval checkups

- without will lead to tissue damage

52
Q

should there be pain if you do the correct amount of force

A

not immediately, but later may feel aching for 2-4 days and leaves until appliance is reactivated

53
Q

what leads to pain in ortho devices

A

ischemic areas in the PDL going to sterile necrosis

54
Q

how to allivate some pain

A

chew gum of bite repeatedly on plastic wafer

55
Q

what happens to the pulp initially after ortho appliances are installed

A

some inflammation at the root apex due to mild pulpitis

56
Q

what is the effect of mild pulpitis in the tooth after ortho appliances are installed

A

no significance, with no loss of tooth vitality

57
Q

why might a tooth lose vitality after initial ortho treatment

A
  • history of previous trama or poor control of heavy ortho forces
  • large movements of tooth after undermining resorption leading sever of vessels at apex through the labial cortical plate
58
Q

can you move endo teeth

A

Yes

59
Q

can clasts attack the root

A

yes, but can get repaired

60
Q

what protects tooth against osteoclasts

A
  • Uncalcified cememtum in non necrotic PDL
61
Q

what parts of the tooth tend to get attacked by osteoclasts

A

cememntum adjacent to necrotic area

62
Q

what happens to the attacked root eventually

A

New cememntum is formed to fill defect

63
Q

does root remodling occur in ortho

A

Yes

64
Q

when would apical root resorption not restore itself

A

Leads to coalscence of creates

- islands of root structure separated from root surface

65
Q

where does loss of root structure tend to occur

A

Apex

66
Q

how much root resorption occurs per year in a fixed appliance

A

about 1 mm (nota problem)

67
Q

how much can a root resorb

A
  • Mild to moderate generalized resoprtion
  • Severe generalized
  • severe local resorption
68
Q

what is severe generalized resorbting

A

Loss of most of the roots on most teeth (rare)

69
Q

what is severe localized resorption

A

loss of 1/4 of root in some teeth (2-3% of ortho patients)

70
Q

what teeth tend to get severe localized resorption

A

Max incisors

71
Q

what may lead to severe localized resoprtion

A

bring root apicies into contact with cortical bone

- movement linguallly (tipping crown facially)

72
Q

when should you take x-rays to help be sure of severe localized resorption

A

6-9 months after ortho tretament begins

73
Q

what do you do if severe localized resorption occurs

A

Keep treatment short, and compromise treatment goals

74
Q

can ortho affect jaw bone growth

A

Yes

75
Q

can you modify jaw if its not growing

A

No ( treat at period of rapid growth/adolescent growth spurt)

76
Q

what is the ideal for tooth movement when growth modification is desired

A

No tooth movement( goal is not corection of maloclusion in growth mod treatment, correction of improper jaw relationship is)

77
Q

when does skeletal growth occur

A

between early evening and midnight ( should wear at all hours)

78
Q

what does excessive maxillary growth lead to

A

Class II

Long face problems

79
Q

what is done to restrain maxillary growth

A

headgear

80
Q

how much force to use for headgear

A

250g per side minimum to the maxilary first molars

81
Q

when should headgear be worn

A

Early evening and at night (but not during the day) for about 12 hours

82
Q

how often is headgear treatment successful

A

75% (some based on patient coperation

83
Q

how can we speed up maxillary growth

A

Face mask (not very successful due to lack of force and suture shape)

84
Q

why does the suture shape keep maxillary growth from occuring

A

Very well interdigitiated

85
Q

when is a good time to spur growth of the maxilary

A

At an early age, before sutures lock up

86
Q

can you restrict mandibular growth

A

not really, but can get the chin to rotate down and back

87
Q

why does restriction of mandibular growth occur

A

children don’t like to ear it
difficult to load the whole TMJ
painful

88
Q

what is the only way to stop mandibular grwoth

A

Surgery

89
Q

how do you use class III elastics to restrain mandibular growth

A

elastics from miniplates at the base of zygomatic arch to mandibular canines

90
Q

when to use elastics to mdoify mandibular growth

A

10-11 years old (need good bone, but early as possible )

- later than the facemask

91
Q

how much force to use for modifying mandibular growth with elastics

A

150g on each side(worn all the time)

92
Q

what is the rsult of soft tissue pulling the mandible foward

A

condylar process grows up and back

93
Q

what are the major reasons for retetion

A
  • Gingival and perio tissues require tmie for reorganization after ortho appliancecs removed
  • teeth may be inherently unstable
  • changes produce growth that can alter tratment
94
Q

how long after removal does it take from the PDL to reorganize

A

3-4 months

95
Q

how are the teeth while PDL reorganizes

A

unstable ungainst occlusal and soft tissue pressures

96
Q

what can gignival fibers do if no retainer used

A

Are stretched and can rotate a tooth back to og position

97
Q

how can one help with gingival fiber pull for aggressive rotations

A

sever the gingival fiber network aroudn the teeth before braces are moved (leading the interdental papilla

98
Q

how far can teeth be moved to cause a change in the effect of soft tissue pressures

A 
2mm for front incicors facially
0-1mm fo canines facially
2mm for the 1st premolars facially
2-3mm for 2st premolars facially
3mm for molars facially

all in the mandible

99
Q

how can growth afect treatment

A

Growth continues after treatment regardless of how you changed it during appliance use
mandibular growth forward, presses incisors against teeth so you get movement

ortho (22 decks)

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