Biology of ortho treatment Flashcards
(99 cards)
1
Q
what is the goal of ortho apliances
A
To move the tooth via biological remodeling NOT mecahnical force
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
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
4
Q
how does the tooth move in bitting
A
Relative to the jaw, but not moving against the alveolar bone
5
Q
why is bone bending important for the jaw
A
stop decalcification of the bone
6
Q
what does bone bending do
A
- Force against crystalline structure mechanically distorts crystals
- production of rapid current flow as electrons move
- force removed allows the crystals to come back to OG position
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
8
Q
what is the flow of electrons due to the rhythmic loading of bone
A
piezo-electric currents
9
Q
is the piezo-electric current needed for ortho tooth movement
A
No
10
Q
is electric current needed for ortho tooth movement
A
Yes, needed to alter cell membrane potentials
11
Q
what theory do we use to do ortho movement
A
Pressure-tension theory
12
Q
what happens if heavy force is sustained
A
PAIN
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
14
Q
what kind of signal is used for the pressure-tension expalanation
A
Chemical
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
16
Q
what happens as the PDL is increasing compressed
A
Blood flow is completely cut off
-necrosis
17
Q
how long does pressure take to change CO2 and O2 levels and Prostaglandin/cytokine release
A
minutes
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
19
Q
when does remodeling occur after pressure applied
A
About 2 days
20
Q
time for blood Vessels within PDL to become occluded in the pressure side due to heavy pressur
A
3-5 sce
21
Q
time for Blood flow to be cut off in compressed PDL under heavy pressure
A
minutes
22
Q
time for cell death in compressed area under heavy pressure
A
hours
23
Q
time for Cell differentiation in adjacent marrow spaces undermining resorption begins under heavy pressure
A
3-5 days
24
Q
time for undermining resorption removing lamina dura adjacent to compresses PDL and tooth movement occurs under pressure
A
7-14 days
25
where are cells coming from to remodel in the case of heavier sustained pressure
Area adjacent to PDL not necrotic
| one marrow spaces outside the lamina dura
26
what does undermmining resorption get its name
Large nectrotic areas in the PDL needed for osteoclasts to resorb the lamina dura
27
what does the necrotic area in the PDL of the undermining resorbing send
chem signals to stimulate formation of osteocalasts
28
what produces more movement, heavy or light force initiation
light force
29
how do yo u know if force is tooth heavy
if the tooth is loose(loss of lamina dura)
30
why does tooth tipping occur
When a single force is applied to the crown of a tooth
| - resistance comes from the root
31
where is the center of resistance when pulling on a crown
Center of root
32
how do you do bodily movement on the tooth
Apply two forces simultaneously to the crown to load entire area of the PDL
33
how much force is needed to do body movement compared to tiping
2x as much (100g vs 50g)
34
how much loading occures during extrusion
loads the entire PDL volume
35
how much force is needed to extrude or rotate a tooth
The same as tiping
36
why does rotation or extruding not require more force than tipping
Roots are irregularly shapped, so any force lead to tipping somewhat
37
Force needed to rotate, extrude, and tip
50g for all of them
38
what is torque
Tooth movement where root apex is moved further than crown in a desired dirction
39
how much is needed for torque
about 75 g
40
how can we do intrusion
V. light compression at the apex (10g)
41
why do you need a light force in intrusion
force is concentrated in one small area so small force compresses more
42
how long must you wear an appliance to lead to movement
at least 4-8 hours a day
43
what is the best way to move a tooth
Light continuous force
44
how does light force cause a tooth to move
frontal resorbtion on the PDL side of the lamina dura
45
what is interrupted force
a spring with poor force decay where force drops to zero before reactivation
46
does undermining resorption occur in all patients
Yes, but just slightly
47
is heavy interrupted force okay
May be clinically acceptable even though it may cause pain
48
is continuous force possible with removable appliances
No
49
what force does a removable appliance create
Intermittent force
| - maybe with some interrupted force
50
what is the appointment interval for ortho
4-6 weks
- movement takes 7-14 days
- 2 weeks to recover
51
does heavy or light force springs need more intervals
Heavy needs more interval checkups
| - without will lead to tissue damage
52
should there be pain if you do the correct amount of force
not immediately, but later may feel aching for 2-4 days and leaves until appliance is reactivated
53
what leads to pain in ortho devices
ischemic areas in the PDL going to sterile necrosis
54
how to allivate some pain
chew gum of bite repeatedly on plastic wafer
55
what happens to the pulp initially after ortho appliances are installed
some inflammation at the root apex due to mild pulpitis
56
what is the effect of mild pulpitis in the tooth after ortho appliances are installed
no significance, with no loss of tooth vitality
57
why might a tooth lose vitality after initial ortho treatment
- 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
can you move endo teeth
Yes
59
can clasts attack the root
yes, but can get repaired
60
what protects tooth against osteoclasts
- Uncalcified cememtum in non necrotic PDL
61
what parts of the tooth tend to get attacked by osteoclasts
cememntum adjacent to necrotic area
62
what happens to the attacked root eventually
New cememntum is formed to fill defect
63
does root remodling occur in ortho
Yes
64
when would apical root resorption not restore itself
Leads to coalscence of creates
| - islands of root structure separated from root surface
65
where does loss of root structure tend to occur
Apex
66
how much root resorption occurs per year in a fixed appliance
about 1 mm (nota problem)
67
how much can a root resorb
- Mild to moderate generalized resoprtion
- Severe generalized
- severe local resorption
68
what is severe generalized resorbting
Loss of most of the roots on most teeth (rare)
69
what is severe localized resorption
loss of 1/4 of root in some teeth (2-3% of ortho patients)
70
what teeth tend to get severe localized resorption
Max incisors
71
what may lead to severe localized resoprtion
bring root apicies into contact with cortical bone
| - movement linguallly (tipping crown facially)
72
when should you take x-rays to help be sure of severe localized resorption
6-9 months after ortho tretament begins
73
what do you do if severe localized resorption occurs
Keep treatment short, and compromise treatment goals
74
can ortho affect jaw bone growth
Yes
75
can you modify jaw if its not growing
No ( treat at period of rapid growth/adolescent growth spurt)
76
what is the ideal for tooth movement when growth modification is desired
No tooth movement( goal is not corection of maloclusion in growth mod treatment, correction of improper jaw relationship is)
77
when does skeletal growth occur
between early evening and midnight ( should wear at all hours)
78
what does excessive maxillary growth lead to
Class II
| Long face problems
79
what is done to restrain maxillary growth
headgear
80
how much force to use for headgear
250g per side minimum to the maxilary first molars
81
when should headgear be worn
Early evening and at night (but not during the day) for about 12 hours
82
how often is headgear treatment successful
75% (some based on patient coperation
83
how can we speed up maxillary growth
Face mask (not very successful due to lack of force and suture shape)
84
why does the suture shape keep maxillary growth from occuring
Very well interdigitiated
85
when is a good time to spur growth of the maxilary
At an early age, before sutures lock up
86
can you restrict mandibular growth
not really, but can get the chin to rotate down and back
87
why does restriction of mandibular growth occur
children don't like to ear it
difficult to load the whole TMJ
painful
88
what is the only way to stop mandibular grwoth
Surgery
89
how do you use class III elastics to restrain mandibular growth
elastics from miniplates at the base of zygomatic arch to mandibular canines
90
when to use elastics to mdoify mandibular growth
10-11 years old (need good bone, but early as possible )
| - later than the facemask
91
how much force to use for modifying mandibular growth with elastics
150g on each side(worn all the time)
92
what is the rsult of soft tissue pulling the mandible foward
condylar process grows up and back
93
what are the major reasons for retetion
- 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
how long after removal does it take from the PDL to reorganize
3-4 months
95
how are the teeth while PDL reorganizes
unstable ungainst occlusal and soft tissue pressures
96
what can gignival fibers do if no retainer used
Are stretched and can rotate a tooth back to og position
97
how can one help with gingival fiber pull for aggressive rotations
sever the gingival fiber network aroudn the teeth before braces are moved (leading the interdental papilla
98
how far can teeth be moved to cause a change in the effect of soft tissue pressures
```
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
how can growth afect treatment
Growth continues after treatment regardless of how you changed it during appliance use
mandibular growth forward, presses incisors against teeth so you get movement
