Facial Growth II

Question 1

What are the sites of facial growth?

Answer 1

• sutures
• synchondroses
• surface deposition

Question 2

What are sutures?

Answer 2

Specialised fibrous joints situated between intramembranous bone
- band of connective tissue

Question 3

what cells are found within the connective tissue in sutures?

Answer 3

osteogenic cells

Question 4

What are synchondroses?

Answer 4

A cartilage found in the midline between the ethmoid, sphenoid and occipital bones
- new cartilage is formed in the centre of a synchondrosis as cartilage, the periphery is transformed into bone

Question 5

What type of ossification does the base of the skull form by?

Answer 5

Endochondral ossification

Question 6

What do the bones of the vault form by?

Answer 6

Intramembranous ossification

Question 7

What is the change in position of a bone due to remodelling known as?

Answer 7

“drift”
cortical drift

Question 8

For how many years does the cranial vault expand for?

Answer 8

Expands in response to the growing brain until age 7

Question 9

When is rate of growth greatest in the cranial vault?

Answer 9

first 3 years of life

Question 10

How does growth in the cranial vault occur?

Answer 10

• bone growth at the sutures
• external and internal surfaces are remodelled through surface deposition and resorption to displace the bone radially

Question 11

After neural growth ceases, why does the forehead continue to enlarge?

Answer 11

In response to accommodate expanding air sinuses

Question 12

How many fontanelles are present at birth?

Answer 12

6

Question 13

When does the sphenoid-ethmoidal synchondrosis fuse? (roughly)

Answer 13

around 7 years

Question 14

When does the sphenoid-occipital synchondrosis close? (roughly)

Answer 14

13-15 years in females
15-17 years in males

Question 15

When does the sphenoid-occipital synchondrosis fuse? (roughly

Answer 15

20 years old

Question 16

What does the shape or angle of the cranial base affect?

Answer 16

The jaw relationship

Question 17

Why is there forward displacement of the maxillary complex?

Answer 17

To create space posteriorly for development of the maxillary tuberosities and space for eruption of molar teeth

Question 18

In what direction does the mandible grow?

Answer 18

Downwards and forwards

Question 19

Where does growth occur in the mandible?

Answer 19

At the condylar cartilage & occurs by surface remodelling (resorption and deposition of bone)

Question 20

Resorption during growth of the mandible mainly occurrs where?

Answer 20

Anteriorly and lingually

Question 21

Deposition during growth of the mandible mainly occurrs where?

Answer 21

posteriorly and laterally

Question 22

By how much does the mandible increase in length between ages 4-20?

Answer 22

Males = 26mm (approx)
Females = 20mm (approx)

Question 23

By how much does the maxilla increase in length between ages 4-20?

Answer 23

Males = 8 mm
Females = 5.5mm

Question 24

When does growth of the mandible increase significantly?

Answer 24

During pubertal growth spurt

Question 25

When does growth slow of the mandible?

Answer 25

Females = 17 years old Males = 19 years old

Question 26

When does growth of the maxilla slow?

Answer 26

Around 12 years old

Question 27

What type of growth (of the maxilla and mandible) slows first?

Answer 27

Width slows first —> then length —> then height

Question 28

When is treatment the utilises the growth of the mandible best carried out?

Answer 28

During pubertal growth spirt

Question 29

When is treatment the utilises the growth of the maxilla best carried out?

Answer 29

before the circumaxillary sutures and palate have fused (early teenage years)

Question 30

Can we predict facial growth?

Answer 30

Not really

Question 31

What controls growth?

Answer 31

Combination of genetic and environmental influences

Question 32

What impact does facial growth have on orthodontic treatment?

Answer 32

Can affect the severity of a malocclusion (improving or making worse)

Question 33

Why do growth rotations occur?

Answer 33

Due to an imbalance in the growth of the anterior and posterior face heights

Question 34

What does forward rotation lead to?

Answer 34

Short face

Question 35

What does backwards rotation lead to?

Answer 35

long face

Question 36

How does adult facial growth present?

Answer 36

- continues slowly though life - tendency to see increased overall length & prominence of nose & chin - lips become thinner & more retrusive

Question 37

What are examples of measurements that can note facial growth changes?

Answer 37

- casts of face - cephalometry - 3D laser scanning - 3D photogrammetry

Question 38

What are the indications for taking a lateral cephalogram?

Answer 38

- to aid diagnosis (skeletal class or vertical discrepancy etc) - treatment planning - progress monitoring

Question 39

What are lateral cephalograms? why are they good?

Answer 39

Standardised lateral radiographs of the face & base of skull - reproducible

Question 40

What analysis is involved when looking at lateral cephs?

Answer 40

- relationship between jaws & cranial base - relationship between upper & lower jaw - position of teeth relative to the jaws - soft tissue profile

Question 41

What are some reference landmarks on a lateral cephalogram?

Answer 41

- sella - nasion - anterior nasal spine - posterior nasal spout - pogonion - menton - gonion - porion

Question 42

What reference lines are relevant in lateral cephalograms?

Answer 42

- Sella-nasion - Frankfort plane - Maxillary plane - Occlusal line - Mandibular plane

Question 43

What measures the anterior-posterior position of the maxilla and mandible relative to the base of the skull?

Answer 43

Eastman analysis

Question 44

What does the eastman analysis measure?

Answer 44

- antero-posterior position of the maxilla and mandible relative to the base of skull - position of mandible relative to maxilla - angulation of teeth to maxilla and mandible - vertical facial proportions

Question 45

What errors can be present in cephalometry?

Answer 45

- radiographic projection errors - error is within the measuring system - errors in landmark identification

Question 46

What can the SNA and SNB angle tell us?

Answer 46

measures the antero-posterior positon of the maxilla and mandible relative to the base of skull

Question 47

What can the ANB or the MMPA / FMPA tell us?

Answer 47

Position of mandible relative to maxilla