theories of craniofacial growth

Question 1

suture theory

Answer 1

1) bone at sutures is primary determinant of own growth
2) pressure of new bone at suture pushes bone apart and intramembranous bone can determine their own growth
3) now we know it is sites of growth, not centers
- sutures fail to grow with translocation
- react to manipulation

Question 2

cartilage theroy

Answer 2

1) cartilage is primary determinant with bone and sutures reacting passively
2) cartilage determines growth at areas even distant from the cartilages
- believes the condylar cartilage is like a growth center
- location of septal cartilage would pull maxilla down and forward (pacemaker)
3) experiments clarified
- transplantation: nasal septum sometimes, mandibular condyle never, epiphyseal plate well
- surgical removal of cartilage affects growth
*nasal septum is a growth center in PART

Question 3

functional matrix theory

Answer 3

1) soft tissue matrix is primary determinant, and bone and cartilage matrix are secondary followers
2) growth of cranium and face is a response to functional needs
3) cranial vault
- the pressure of the brain separates the bones at sutures, and new bone passively fills in

Question 3

growth site

Answer 3

1) location of growth

Question 4

center of growth

Answer 4

1) location where independent (genetically controlled) growth is occurring

Question 5

mandibular condyle

Answer 5

1) very fragile and can be resorbed over a period of time
2) however, studies show
- 75% of condyle regenerates, which means no growth deficit
- 25% altered growth after injury => growth deficit occurs
3) lost condyles give no support to idea that it is a growth center

Question 6

form and function

Answer 6

1) form follows function
2) function determines, controls, and regulates form

Question 7

cranial sutures

Answer 7

1) edge to edge
- no force loading
2) beveled suture
- hear force
3) serrated suture
- intermittent tension force
4) beveled and serrated
- intermittent tension and shear force
5) butt ended
- intermittent compressive force

Question 8

size of head is a accurate representation of the

Answer 8

size of the brain

Question 9

hydrocephaly

Answer 9

1) buildup of intracranial pressure from CSF
2) enlarged cranial vault

Question 10

mandibular condyle with functional matrix theory

Answer 10

1) if proper function is obtained, loss of condylar cartilage would have no effect
2) 75% of children who suffer a condylar fracture have no issues with mandibular growth
3) 25% of children…?
- maybe the function was not obtained in these
-ankylosis of the mandible, which means motion is limited

Question 11

clinical examples

Answer 11

1) ear infection caused scarring of TMJ and limited ROM
2) mandibular growth severely altered

Question 12

catch up growth

Answer 12

1) only occurs if function is restored