Tooth movement histology Flashcards
Bone resorption and formation is regulated by what two things?
The dental follicle and the enamel organ!
Movement due to space vs movement due to facial growth
Space = mesial and occlusal
Growth = anterior and laterally
Leeway space definition
Replacement of larger primary molars with smaller permanent premolars.
How much space is gained due to leeway space in the maxilla and mandible
Maxilla = 1.5mm per quad
Mandible = 2.5mm per quad
Incisor liability definition
Permanent incisors are larger than primary!
Why is pain felt when mastication force is held for more than 1 second?
Periodontal fluid is squeezed out as the tooth is displaced
What is the PDL space?
.5mm around each root!
Response to orthodontic force is mediated by the ____
PDL!
Does collagen remodel during normal function? If so, how does it do so? Does alveolar bone remodel during normal function?
Collagen remodels during normal function continuously via fibroblasts and fibroclasts.
The alveolar bone also constantly remodels on a smaller scale!!
The PDL resists forces of ____ duration..
Short!
How does alveolar bone respond to heavy loads?
Force is absorbed and bends Piezoelectric currents.
PDL response to heavy forces…
<1 second =
1-2 seconds =
3-5 seconds =
<1 = PDL fluid is incompressible, alveolar bone bends, piezoelectrical signal generated
1-2 seconds = PDL fluid expressed, tooth moves within PDL
3-5 seconds = PDL fluid squeezed out, tissue compressed, PAIN
Pressure/tension
Pressure side = resorption with osteoclasts
Tension = apposition with osteoblasts
Heavy vs light forces
Light = osteoclasts recruited in 2 days, faster, frontal resorption!
Heavy = osteoclasts recruited in 7–14 days, slower, undermining resorption
How long does it take gingival fibers vs PDL fibers to rearrange?
Gingival = 1 year, PDL = few months
