Facial Growth 2

Question 1

How would you describe the size of the face on a baby compared to the head?

Answer 1

The face is small compared to the overall size of the head in newborns

Question 2

Describe the differences between and adult and neonatal skull.

Answer 2

• infant face is small compared to the cranium, eyes are large and the ears are low set (face takes up 1/2 of face whereas in adult 3/4)
• 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 (height of maxilla less)
• in the adult, the midface expands and nasal floor desends

Question 3

What are the 3 different types of sites of growth/types of growth in the face?

Answer 3

• sutures
• synchondroses
• surface deposion

Question 4

What is a suture?

Answer 4

It is a specialised fibrous joint situated between intramembranous bone.

Question 5

Describe the structure of a suture.

Answer 5

A band of connective tissue which has osteogenic cells in the centre and the most peripheral of these cells provide new bone growth

Question 6

Growth at sutures occurs due to what? Describe how it works.

Answer 6

Growth occurs in response to growing structures separating the bone (e.g. calvarium in response to development of brain)

Where the bones are pushed apar, new bone forms in the suture

Suture growth happens in areas of TENSION

Question 8

Where are synchondroses found?

Answer 8

In the midline

They exist between the ethmoid, sphenoid and occipital bones

Question 9

Describe how growth happens at synchondroses.

Answer 9

Has a cartilage based growth centre with growth occuring in both directions

The bones on either side of the sychondrosis are moved apart as growth takes place

New cartilage is formed in the centre of a synchondrosis as cartilage at the periphery is transformed into bone

Question 10

Describe the bone growth in the face via surface deposition.

Answer 10

New bone is deposited beneath the periosteum over the surfaces of both the cranial and facial bones

Question 11

How is the shape of bones maintained during growth?

Answer 11

Resorption also takes place

(the process of growth and deposition is also known as remodelling)

Question 12

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

Answer 12

Drift

e.g. cortical drift

Question 13

What bones is the cranial vault composed of?

Answer 13

Frontal bone

Temporal

Occipital

Parietal bones

Question 14

What does the cranial vault grow in response to and till what age?

Answer 14

Expands in response to the growing brain until age 7

Question 15

When is the rate of growth of the cranial vault the greatest?

Answer 15

In the first 3 years of life

Question 16

What are the 2 ways that the bone grows in the cranial vault?

Answer 16

• bone growth at sutures
• external and internal surfaces are remodelled through surface deposition and resorption to displace the bones radially (resorption on internal surface of calvarian

Question 17

After neural (brain) growth ceases the forehead continues to enlarge in response to what?

Answer 17

In response to the expanding air sinuses (pneumatisation)

Note: generally more pronounced in males

Question 18

Where do fontanelles exist? How many are present at birth and when do they close by?

Answer 18

Where more than 2 bones meet together.

6 present at birth and close by 18months

Question 19

What are the 2 ways that bone grows in the cranial base

Question 20

After neural growth ceases, what happens to the cranial vault in terms in growth?

Answer 20

The forehead continues to enlarge in response to accommodate expanding air sinuses (pneumatisation)

Note: is generally more pronounced in males

Question 21

Where do fontanelles exist?

Answer 21

Where more than 2 bones meet

Question 22

How many fontanelles are present at birth and at what age do they close?

Answer 22

18

-close by 18 months

Question 23

Growth in the cranial base occurs in what 2 ways?

Answer 23

Endochondral ossification

Surface remodelling

Question 24

Half of the growth of the cranial vault is completed by what age?

Answer 24

3 years

Question 25

What is the spheno-ethmoidal synchondrosis and when does it fuse?

Answer 25

• cartilaginous joint between the sphenoid and the ethmoid bones
• fuses at 7 years

Question 26

What bones form the cranial base?

Answer 26

• frontal
• etmoid
• sphenoid
• temporal
• occipital

Question 27

When does the spheno-occipital synchondrosis close and when does it fuse?

Answer 27

13-15 in females

15-17 in males

Fuses at around 20

Question 28

The anterior cranial bases growth is realtively stable after what age and why is this imortant?

Answer 28

After 4 years

Has been used for superimposition in cephalometric analysis. This allows the orthodontist to asses skeletal changes due to growth and/or treatment

Question 29

How does the cranial base relate to the mandible and maxilla?

Answer 29

The cranial base detemines how the maxilla and mandible relate to each other

The shape or angle of the cranial base affects the jaw relationship

Question 30

How does the shape/angle of the cranial base affect jaw relationships?

Answer 30

• a small angle is more likely to be associated with a class III skeletal relationsip
• a large angle is more likely to be associated with a class II skeletal pattern

Question 31

The maxilla/nasomaxillary complex includes what? (bones/structures)

Answer 31

• orbits
• nasal cavity
• upper jaw (maxilla)
• zygomatic processes

Question 32

When do all of the sutures close?

Answer 32

When facial growth is complete

Question 33

In what direction does the maxilla/nasomaxillary complex grow?

Answer 33

It is displaced downwards and forwards relative to the anterior cranial base

Displaced is when a mass of bone is moved relative to its neighbours. ITs brought about by forces exerted by soft tissues and by intrinsic growth of the bone itself

Question 35

The growth of the maxilla/nasomaxillary complex tends to follow what?

Answer 35

Follows neural growth early on and so slows down towards age 7

Question 36

Forwards displacement of the maxillary complex creates space for what?

Answer 36

It creates space posteriorally for the development of the maxillary tuberosities and space for eruption of molar teeth

Question 37

Describe how the maxillary complex grows

Answer 37

• Sutural growth takes place at the zygomatic ad frontal bones and mid palatine suture
• Suface deposition and resorption e.g. deposition on lower border of hard palate and the alveolar process and resorption on the floor of the nasal cavity and floor or the orbits

Question 38

Describe how the mandible grows.

Answer 38

• grows downwards and forwards
• Growth occurs at the condylar cartilage (secondary cartilage)
• Growth occurs by surface remodelling (resorption and deposition of bone)
• resorption is mainly anteriorally and lingually
• deposition is mainly posteriorally and laterally
• this results in the increase of the height of the ramus and increase in the length of the dental arch to accomodate the permanent teeth

Question 39

What are the differences between the growth of the maxilla and the mandible?

Answer 39

• Mandible increases more in length
• mandible = growth accelerated significantly during pubertal growth spurt whereas maxilla = after 7 growth is very slow
• Mandible growth slows to adult level between 17 and 19 whereas maxilla is around 12

Question 40

Orthodontic treatment which utilitses the growth of the mandible is best carries out when?

Answer 40

During the pubertal growth spurt (note this is earlier in girls than in boys)

Question 41

Treatment which utilises the growth of the maxilla is best carried out when?

Answer 41

Before the circumaxilary sutures and palates have fused (early teenage years)

Question 42

What are growth rotations?

Answer 42

A growth rotation is due to an imbalance in the growth of the anterior and posterior face height and can lead to a ‘short’ or ‘long’ face

Question 43

Forward/backwards growth rotations lead to what?

Answer 43

Forward roation = ‘short face’

Backwards rotation = ‘long face’

Question 44

Forwards growth rotation can lead to what?

Answer 44

Development of a deep bite

(reduces Frankford Mandibular Plane)

Question 45

A backwards growth rotation can lead to what?

Answer 45

The development of an anterior open bite