Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ORTHO I > lecture 7 > Flashcards

lecture 7 Flashcards

1
Q

Why can we move teeth with
orthodontic appliances?

A
  • Because the teeth are not bonded to bone but
    rather “held” in position by the periodontal
    ligament
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what bone is easier to move teeth in?

A

cancellous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

PDL components

A
  • Mesenchysmal cells
  • Fibroblasts (main cell type)
  • Osteoblasts
  • Cementoblasts
  • Blood vessels
  • Nerve endings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

mesenchymal cells

A

precursor cell to all PDL cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

nn endings at PDL role

A

used for proprioception and pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

root resorb with ortho?

A

usually always occurs, amount is variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Fibroblasts

  • Important role in?
A

Fibroblasts
* Important role in response to mechanical loading due to occlusal forces
* The architect, builder and caretaker of the PDL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Periodontal ligament (PDL)
* turnover of tissue?
*Collagen synthesis?
*Constant thickness at mm?

A

Periodontal ligament (PDL)
* High rate of turnover of tissue within the PDL
*Collagen synthesis reported highest in PDL tissue
than any other connective tissue in body
*Constant thickness at 0.18 to 0.25 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Periodontal ligament functions
support and shock

A
  1. Supportive: Attach teeth to the alveolar bone with the principal fibers
  2. Shock absorber
    – Fluid displacement: light to moderate forces
    – Principal fibers: heavier forces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how does PDL change with ortho

A

pressure placed on it will change widths and cause it to alter tooth posiiotn with bone apposition and resorb to resume width

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

increased PDL size on PA with tx?

A

may app enlarged but actually just has osteoid in space yet to be mineralized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

PDL function: Remodeling:

A
  1. Remodeling:
    – Tissue formation: Mesenchysmal cells will
    differentiate into osteoblasts, cementoblasts,
    fibroblasts (signaling factors)
    – Tissue resorption: Same cells will transform into
    osteoclasts, cementoclasts
    – Compensate for tooth wear and attrition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

PDL function: Sensory

A
  1. Sensory:
    – Nerve ending to provide
    * Pain
    * Pressure
    * Spatial control of the lower dentition in relation to the upper (rest position)
    * Tmj location
    * Mastication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PDL Fluids

A
  • Shock absorbing effect
  • If a tooth is subjected to large force for <1 second, there is expression of fluid and the tooth moves within alveolus. The principal fibers take over
  • If a tooth is subjected to a large force for more than 3-5 seconds, there is compression of the PDL by the root against the alveolar bone and pain
  • Light and continuous forces will also express tissue fluids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

desired forces for ortho tx

A

light and continuous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The PDL is essential
for tooth:

A

The PDL is essential
for tooth movement
and adjustment to
the occlusal changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Physiologic Tooth Movement

A

✓Tooth migration or eruption
–Resorptive bone wall
–Depository bone wall

18
Q

Tooth migration throughout life

A
  1. Constant mesial shift caused by the wear of
    contact points (depends on the occlusion)
  2. Adjustment to occlusal wear ( teeth stay in
    contact)
19
Q

Resorptive Bone Wall

A
  • Alveolar bone resorption on tooth-moving side
  • Osteoclasts in scattered lacunae on the alveolar bone
    wall
20
Q

Resorptive Bone Wall
* Resorption stops when?
* Osteoblasts?

A
  • Resorption stops when the tooth is in occlusal or neuro muscular balance
  • Osteoblasts form new bone where new fibrils will attach.
21
Q

Reconstruction of PDL
*Fiber attachment is?
*Appears that same undifferentiated mesenchymal cells can become?

A

Reconstruction of PDL
*Fiber attachment is re-established
*Appears that same undifferentiated mesenchymal cells can become osteoclasts or osteoblasts

22
Q

Depository Bone Wall
*Mainly apposition of ? and rearrangement of ?
* The PDL will maintain its?
*Thickness proportional to?

A

*Mainly apposition of bone and rearrangement of PDL fibers
* The PDL will maintain its normal width of 0.25mm (key to bone remodeling.
*Thickness proportional to cellular activity

23
Q

goals of ortho tx

A

*Goal is to use the physiologic capabilities of the PDL to achieve desirable orthodontic movements.
*A force is placed on the tooth resulting in mechanical pressure or tension.
*The PDL will respond by bone resorption and remodeling of the periodontium

24
Q

Primary bone resorption
* Mimics?
* Resorption of the alveolar bone wall on the?
* Bone formation by the PDL on the?
* forces are needed to achieve this goal?

A

primary goal of ortho
* Mimics the physiologic bone remodeling process
* Resorption of the alveolar bone wall on the
pressure side
* Bone formation by the PDL on the tension side
* Light forces are needed to achieve this goal

25
Q

Pressure Side
* blood flow?
*direct resorption of alveolar bone wall by?
* may begin ? hours after force
application, but usually at about ? hours

A

*reduction of blood flow in the “pressure side”
*direct resorption of alveolar bone wall by osteoclasts coming form the PDL
* may begin 12 hours after force application, but usually at about 40 hours

26
Q

pain with ortho tx

A

usually due to excessive force bringing bone and root together which cuts off blood supply to PDL cauisng necrosis

27
Q

Pressure Side
*in contrast to physiologic tooth movement?

A

*in contrast to physiologic tooth movement, there is complete breakdown of old fibers and fiber bundles with formation of new fiber elements

28
Q

Tension Side
*cellular activity increases after ? hours of applying orthodontic force
* new mineralized layer?
* after some time what will cover this area?
* mineralization of?

A

*cellular activity increases after 30-40 hours of applying orthodontic force
* new mineralized layer close to alveolar bone wall
* after some time, osteoid produced by osteoblasts will cover this area
* mineralization of osteoid

29
Q
  • The goal of the PDL response is to:
A
  • The goal of the PDL response is to maintain a constant width (0.18-0.25mm)
30
Q

Amount of pressure
* Response is related to?
* As the pressure increases?

A
  • Response is related to the amount of pressure that is applied on the alveolar wall.
  • As the pressure increases, there is a dramatic reduction in blood flow in the PDL on the pressure side.
31
Q

“Excessive orthodontic force” what occurs

A

“Excessive orthodontic force”
* Instead of primary bone resorption,
hyalinization of the PDL occurs

32
Q

can we avoid hyalinization

A

Unavoidable in Clinical Orthodontics

33
Q

Hyalinization
* The most frequent?
* dependent on?
* how does this occur?

A
  • The most frequent “complication” in orthodontic movement
  • Force dependent
  • Forces of high magnitude press the root against the alveolar bone wall occluding the blood vessels
34
Q

Hyalinization
* PDL responds with?

A
  • PDL responds with local degeneration and sterile necrosis instead of the desired proliferation and differentiation of cells
35
Q

Hyalinized Zone
*occurs in about what time period?
* bone resorption is?
* tooth movement?

A

*occurs in about 1-2 days
* bone resorption is indirect or undermining because there are no living cells in hyalinized area
* tooth will not move until hyalinized zone has been cleaned up and adjacent alveolar bone wall is resorbed

36
Q

repair with hyalinization
* Osteoclasts from?
* Osteoclasts from?
* Elimination of debris by?
* Reorganization of ?

A
  • Osteoclasts from surrounding PDL
  • Osteoclasts from adjacent marrow spaces
  • Elimination of debris by scavenger cells and
    phagocytosis
  • Reorganization of the PDL
37
Q

Factors Influencing Orthodontic Tooth
Movement

A
  • Character of bone (cancellous or cortical)
  • Force application
  • Applied force and time
38
Q

Character of Bone

A
  • Spongy, cancellous bone has the best characteristics for tooth movement
    *“Old” bone is more difficult to resorb than “young” bone
  • Dense cortical bone is much harder to resorb.
39
Q

Deleterious Effects of Orthodontic
Force

A
  • Root resorption
  • Long-term periodontal health specially in adults
40
Q

Conclusions
* Primary bone resorption?
* Impossible to achieve?
* Use the ? force as possible
* Hyalinization may promote?

A
  • Primary bone resorption is the method of choice for tooth movement
  • Impossible to achieve consistently with fixed orthodontics
  • Use the smallest force as possible
  • Hyalinization may promote root resorption (severity of the cellular response?)

ORTHO I (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions