#4 Tooth Movement Flashcards
What is the width of the PDL?
0.5mm (perio says 0.25mm ….)
The PDL is adapted to resist ______ duration forces.
short (seconds)
Force magnitude and duration are both very important because a force as little as ____ gm can induce tooth movement.
2 gm
T or F, PDL fibers need to be remodeled for tooth movement.
True, the remodeling mostly done by fibroblasts.
_____ is required for tooth moment beyond the PDL space.
Bone resorption
_______ are responsible for bone resorption.
Osteoclasts (multinucleate, produce acid and enzymes that remove bone)
What are the theories of tooth moment?
- The bioelectrical theory - bony changes caused by electric signals:
- Force induces induces piezoelectical signals
- Bioelectrical potential changes cell activity - The pressure-tension theory = bony changes caused by chemical signals
- pressure and tension alter blood flow.
- formation and release of chemical messengers
- Chemical messengers change cell activities.
How long does it take to displace tooth in PDL space?
1-2 secs light pressure
How long does it take to alter blood flow?
3-5 sec of light pressure
What happens after minutes of sustained light pressure?
Oxygen tension at compression side decreases -> Prostaglandins (PG-E) and cytokines (IL1) release)
What happens after hours of sustained light pressure?
Chemical messengers cause metabolic change; second messengers (such as cAMP) release –> osteoclasts recruitment (from blood), maturation and activation –> frontal bone resorption (good)…
How long does it take for tooth to move beyond the PDL space with sustained light pressure?
2 days
What happens within minutes of heavy sustained pressure?
Blood flow is cut off to compressed PDL and after a few hours cell death occurs in compressed area.
What happens within 3-5 days of heavy sustained pressure?
Osteoclasts recruitment from bone marrow), maturation and activation –> undermining bone resorption (Bad)
How long does it take for tooth to move beyond PDL space with heavy sustained pressure?
7-14 days
How is the movement of movement of teeth different over time with heavy vs. light force?
Light force = continued steady movement
Heavy force = Choppy, stop and go movement
How many hours a day of sustained force is needed to activate cellular activity?
4-8 hrs/day *longer duration produces more efficient tooth movement
The compression area larger during _____ that ______.
Translation than tipping *Greater force is needed to produce the same pressure.
Is movement faster in the Maxilla or mandible?
Maxilla * Bone density
What drugs inhibit tooth moment?
Prostaglandin inhabiters: NSAID, Corticosteroids
Bisphosphates
What methods can accelerate tooth Movement?
Local injury: regional acceleratory phenomenon (RAP)
Corticotomy Assisted tooth movement (Wilckodontics)
Is anchorage needed for reciprocal space closure?
No! because both teeth are moving to close a gap.
What is stationary anchorage control?
Only allows bodily movement of the molars, which requires stronger pressure.
What is skeletal anchorage?
Use temporary anchorage devices (TAD’s) to prevent unwanted movement.
Can teeth with RCT be moved orthodontically?
Yes (Generally pupal reaction is minimal with movement)
Where might permanent loss of root structure occur after movement?
Primarily at the apex
What teeth are more prone to root reabsorption due to movement?
incisors and second premolars
What are the risk factors for excessive resorption?
Abnormal root morphology: conical roots, pointed apices, diacerations
Prolonged treatment time, excessive and prolonged orthodontic forces
History of root resorption
What are the effects of orthodontic treatment on Alveolar bone height?
Usually
T or F, Active periodontal disease must be controlled before orthodontic treatment.
true
