facial growth 2 Flashcards
How are bones of the face formed
intramembranous or endochondral
ossification
What are the pre-existing cartilaginous skeletons for the face
nasal capule and meckels cartlidge
What of the mandilbe dissapears shortly after birth
condylar cartilage
wha are the differences between an adult and an neonatal face
The infant the face is small compared to
the cranium the eyes are large and the ears
are low set.
The forehead is upright and bulbous and
the face appears broad.
The nasal region is vertically shallow, with
the nasal floor close to the inferior orbital
rim. In the adult the midface expands and
the nasal floor has descends
What are the sites of facial growth
Sutures
Synchondroses
Surface deposition
Talk about sutures
Specialised fibrous joints situated between intramembranous bone
Each suture is a band of connective tissue which has osteogenic cells in the centre and the most peripheral of these cells provide new bone growth
Growth at the sutures occurs in response to growing
structures separating the bone
When facial growth is complete they fuse together
Talk about Synchondroses
These are found in the midline
They exist between the ethmoid, sphenoid and
occipital bones
A cartilage – based growth centre with growth
occurring in both directions
New cartilage is formed in the centre of a synchondrosis as cartilage at the periphery is transformed into bone
Talk about surface deposition
New bone is deposited beneath the periosteum over the surfaces of the both the cranial and facial
bones
The change in position of a bone due to remodelling is known as “drift”. (cortical
drift)
In order for bones to maintain their shape as they grow resorption is also taking place
This process of deposition and resorption is known as remodelling
When does the cranial vault stop growing and what are the two ways in which it grows
7 years
Bone growth at the sutures
External and internal surfaces are remodelled through surface
deposition and resorption to displace the bones radially
What bones consist of the cranial base
Frontal, ethmoid, sphenoid , temporal and occipital bones
What bones consist of the cranial base
Frontal, ethmoid, sphenoid , temporal and occipital bones
How does growth in the cranial base occur
Endochondral ossification
Surface remodelling
Why is growth of cranial base relevant
Growth occurs between the ages of 4 to 20 years and causes an overall increase in
length of the cranial base. However, the anterior cranial base is relatively stable after the age of 7 years and so has been used for superimposition in cephalometric analysis
The cranial base plays an important role in determining how the maxilla and mandible relate to each other. The shape or angle of the cranial base affects the
jaw relationship
The maxilla articulates with the anterior cranial base and the mandible is closely associated with the posterior cranial base being suspended beneath the middle cranial fossa
What angles relate to what skeletal relationship
A small angle is more likely to be associated with a class III skeletal relationship
A large angle more likely to be associated with a class II skeletal pattern
How does the mandible grow
Grows downwards and forwards
Growth occurs at the condylar cartilage
Growth occurs by surface remodelling (resorption
and deposition of bone)
Resorption mainly anteriorly and lingually and
deposition posteriorly and laterally
Results in increase in height of the ramus and
increase in length of the dental arch to
accommodate the permanent teeth
