Facial Growth 2 Flashcards
What cells make the majority of the face?
Neural crest cells (ectomesenchyme)
What processes develop the facial skeleton?
- Frontonasal processes
- Maxillary + mandbular process
- From the 1st brachial arch
What is formed by intramembranous ossification? (2)
- Vault of skull
2. Mandible + maxilla
What is formed by endochondral ossification?
Base of skull
Define a suture
Specialised fibrous joints between intramembranous bone
What does each suture contain?
Each suture is a band of connective tissue
- With osteogenic cells in the centre
List sites of facial growth (3)
- Sutures
- Synchondroses
- Surface deposition
Where are synchondroses found?
Found in the midline
Between the ethmoid, sphenoid + occipital bones
What makes up the cranial vault? (4)
Frontal
Occipital
Temporal
Parietal bones
What 2 ways does growth at the cranial vault occur?
- Bone growth at sutures
2. External + internal surfaces remodelled through surface deposition + resorption
How many fontanelles are present at birth?
6
When do fontanelles close?
By 18 months
What makes up the cranial base? (4)
Frontal
Occipital
Ethmoid
Sphenoid
How does growth occur in the cranial base?
- Endochondral ossification at synchondroses
2. Surface remodelling at synchondroses
When does half of the cranial base growth occur by?
Age 3
When does the spheno-ethmoidal synchondrosis fuse at?
7yrs
When does the spheno-occipital synchondrosis close at?
13-15yrs in females
15-17yrs in males
Fuses by age 20
How is the maxilla displaced?
Maxilla is displaced downwards + forwards relative to the anterior cranial base
Where does surface deposition and resorption occur in the maxilla/nasomaxillary complex? (2)
DEPOSITION
- Lower border of hard palate + alveolar process
RESORPTION
- On the floor of the nasal cavity + floor of orbits
How is the mandible displaced?
Grows downwards and forwards
How does growth occur by surface remodelling in the mandible?
RESORPTION
- Anteriorly + lingually
DEPOSITION
- Posteriorly + laterally
Results in an increase in height of the ramus + increase in length of the dental arch
Compare lengths of mandible and maxilla
MANDIBLE
Increases in length by 26mm in males
Increases in length by 20mm in females between ages 4-20
MAXILLA
Increases in length by 8mm in males
Increases in length by 5.5mm in females between ages 4-20
At what age does the growth of the maxilla begin to proceed very slowly?
After 7 years
When does growth of the mandible slow down?
17 in females
19 in males
When does growth of maxilla slow down?
12
When is tx that utilises the growth of the mandible most effective?
During pubertal growth spurt
When is tx that utilises the growth of the maxilla most effective?
Before the circumaxillary sutures + palate have fused - early teens
How can growth be utilised to help ortho tx?
- Functional appliances
- Rapid maxillary expansion
- Protraction headgear
What is a growth rotation due to?
Imbalance in the growth of the anterior + posterior face heights
What does a forward growth rotation lead to?
Short face
Deep bite
What does a backward growth rotation lead to?
Long face
AOB
