post-natal craniofacial development

Question 1

soft tissue studied?

Answer 1

poorly studied

will adapt bone development

Question 2

main determinant of bone formation

Answer 2

genetic, however environment can play a role

Question 3

endochondral growth
occurs mainly in?
use of?

Answer 3

occurs in long bone mainly, use of growth centers/plates
replacement of cartilage matrix with osseous matrix at ossification centers (1 and 2)
forms cancellous, cortical bone and bone marrow (formed with blood vessel penetration)

Question 4

how do secondary oss centers from

Answer 4

blood vessel invasion

Question 5

another name for endo oss

Answer 5

indirect growth

Question 6

growth centers and plates

Answer 6

site of bone formation in endo oss

•Where the cartilage matrix is replaced by immature bone

primary formed initially in the middle of the cartilage matrix and secondary formed with vessel invasion

genetically programmed=growth pre-determined
highly organized centers of growth
at the plate: cartilage matrix replaced with immature bone

Question 7

facial bone growth?

Answer 7

not endochondral oss except for the cranial base, mainly intramembraneous

Question 8

cranial base growth
mechanism?
precursor?
portions? 
forms? influences?

Answer 8

responds to long bone growth, separate the cranial vault from the craniofacial structures, cartilage matrix=chrondrocranium
anterior: completed at 6 yrs
posterior: completed at 12-15 yrs
both anterior and posterior form the cranial angle which can influence facial structure and occlusion

Question 9

intramem bone growth
bones?
steps?
results in?

Answer 9

all of skull except the base
mesenchymal cells receive signal to dif into osteoblasts and form oss centers> produce osteoid (unmineralized)> become calcified/ osteocytes are formed which then create cortical/cancellous bone> marrow formed with blood vessel invasion

intramembranous growth will result in displacement of other structures in space

Question 10

where does bone formation occur in intramem formation

Answer 10

The bone formation occurs directly in a

vascularized mesenchyme.

Question 11

bone remodeling

Answer 11

occurs thru life with balance of apposition and resorbtion

can also help in the growth of bones as well

Question 12

Resorption-Apposition
always proportional?
where is bone formed/ resorbed?
mandible growth example

Answer 12

New bone forms on the external aspect of the bone while bone is resorbed on the internal aspect

The ratio is not always proportional as some structures must increase in size during growth.

Question 13

V principle of Enlow

Answer 13

• A bony structure will be displaced during growth.
• In order to preserve the shape, parts of the bone will receive new bone and parts will resorb.
• Placing a V on a growing osseous structure will determine the direction of growth
• The V is placed on the growth surface. Apposition surfaces are in the center of the V while resorbing surfaces are located outside the V

this also allows the shape of the bone to be kept

Question 14

Growth Mechanisms of the cranio-facial structures (not
base)
what process displaces bone?
drift principle, allows?

Answer 14

• Intramembranous (direct)
• Displacement of bone in space by resorption-apposition
• Drift principle: allows volume increase and displacement in space while maintaining the proper shape

Question 15

drift principle

Answer 15

based on resorption and apposition

movement of structure/growth due to a mix of resorb and appo

Question 16

Displacement by apposition -resorption
maxilla example
malocclusions?

Answer 16

movement of facial structure with apposition and resorb, such as cranail base causing the movement of the maxilla down and forward typically, if a more vertical path is taken by the maxilla it may result in malocclusion

Question 17

what occurs at sutures

Answer 17

positive remodeling