Growth & Development

Question 1

Describe the growth at the symphysis?

Answer 1

Lingual apposition at the symphysis

Question 2

Primary failure of eruption is seen more frequently in the anterior region.

When orthodontic extrusion forces are applied, ankylosis often occurs with such teeth.

Answer 2

False / True

Primary failure of eruption (PFE)
Is only seen in POSTERIOR teeth
Genetic/familial predisposition
Can affect one tooth or all the teeth distal to it causing posterior open bite
Tx if just one tooth: extract and bone graft/implant
If multiple teeth: osteotomy (limited success)

Question 3

Moss Functional Matrix Theory

Answer 3

*Sutural growth is related to the functional matrix. Sutural growth is affected by *response to soft tissue.

SUTURAL growth is *appositional not periosteal
Translation is due to the capsular matrix (passive growth)
Palate grows by 1) sutural, 2) lingual apposition, 3) superior resorption

*Transformation and *BONE GROWTH is due to the periosteal matrix (active growth, muscles)
Bone only grows appositionally, not interstitially. Mandible body grows primarily by apposition.

Question 4

Frontonasal process gives rise to:

Answer 4

Forehead
Nose (bridge, septum, columella, ala)
Philtrum (MNP)

FNP gives rise to MNP and LNP and structures:
Ala of the nose (LNP)
Pre-maxilla and primary palate (MNP)

NOT:
Maxillary process
Secondary palate (forms from maxillary process)
Lateral lip
Vermillion??

Question 5

Maxillary process gives rise to:

Answer 5

Upper jaw, lip, orbital floor

Question 6

Primary growth SITES:

Primary growth CENTERS:

Answer 6

Sites: 
*Condyle 
*Sutures
NOT synostosis (bony fusion)
Syndesmosis (fibrous joint i.e. ankle, wrist) is not a growth center in the craniofacial complex

Centers:

• Synchondrosis
• Ephiphyseal plates
• Nasal septum

Question 7

Pure Intramembranous

Pure Endochondral

Mixed

Answer 7

Intramembranous: *frontal, *parietal, maxilla, palatine, zygomatic, lacrimal, nasal, vomer, body of mandible

Endochondral growth = growth at synchondroses
Cranial base therefore develops at synchondroses
Hyoid *Ethmoid Incus Stapes Inferior Concha

Mixed =
Mandible (body is intramembranous, condyle is endochondral), malleus, occipital, sphenoid, temporal

Question 8

Maxilla growth

Mandible growth

Answer 8

Maxilla: displaced down and forward (growth is up and back)
Apposition *superior and *posterior
Resorption *anterior

Palate:
Resorption *nasally
Deposition *orally
So that the palate grows down

Mandible: displaced down and forward (condyle grows up and back)
Apposition *posterior ramus and *lingual symphysis NONE at pogonion
Resorption *anterior ramus (increase md corpus length) and *B point

Question 9

Ossification of sesamoid bone at SMI 4

CVMS II

Answer 9

Ossification of sesamoid bone at SMI 4 = maximum growth spurt will occur within 1 year (60-70% growth remains)
CVMS II: peak mandibular growth will occur within 1 year