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D2: 623 Ortho > 01: Craniofacial Growth > Flashcards

01: Craniofacial Growth Flashcards

1
Q

In early 20th century, what was believed about Craniofacial Growth?

A

That genetics controlled all aspects of craniofacial growth (Bone, Cartilage, Soft Tissue, Muscle)

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2
Q

Who was the forefather of the genetic growth model

A

Sicher

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3
Q

In the 50’s research noticed that environment had an effect on CF growth…what was this theory called?

A

Epigenetics

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4
Q

Under epigenetic theory, it was believed that genetics had the heaviest direct effect on which tissue?

A

Cartilage

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5
Q

Who proposed the Cartilaginous growth theory?

A

Scott, 1953

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6
Q

What happened when Scott removed the cartilage from the face of rabbits?

A

It severely stunted the growth of the rabbits facial bones

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7
Q

What particular piece of human cartilage was Scott focused on?

A

Cartilage of the Nasal Septum

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8
Q

According to epigenetics how does the cartilage of the nasal septum influence the direction the facial bones grow in?

A

Down and forward

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9
Q

After genetics and epigenetics, what is the 3rd theory of CF growth?

A

Environmental

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10
Q

Who promoted the environmental theory

A

Moss (Functional Matrix Theory)

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11
Q

What was the basic tenet of the Func. Matrix Theory

A

The environment provides the stimulation, and the bones respond in form so that their shape meets the functional requirements demanded by the environment

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12
Q

Which theory is correct?

A

None and All. Individually none of the theories explain it all, but they all have described a portion of the process

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13
Q

Which bones are influenced primarily through genetics?

A

Endochondral bones of the skull

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14
Q

Are the cranial bones intramembranous

A

Yes

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15
Q

How do the skull bones respond to the growth of the brain?

A

As the brain volume increases, the bones are pushed apart at the sutures and then they respond by getting bigger to fill the gaps

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16
Q

What force at the suture causes the cranial bones to grow

A

Tension

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17
Q

Where are the endochondral bones of the head located

A

The base of the brain

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18
Q

What are the endochondral bones of the head

A

Sphenoid
Ethmoid
Occipital

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19
Q

What are the “epiphyseal plates” of endochondral bones

A

Synchondroses

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20
Q

How does the growth of the synchondroses differ from the epiphyseal plate?

A

A synchondroses will grow in both directions

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21
Q

What are the three synchondroses of the cranial base

A

Sphenoethmoid
Spheno-occipital
Intersphenoid (between greater and lesser wings)

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22
Q

At what age does the sphenoethmoid sychondroses ossify

A

7

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23
Q

At what age does the intersphenoid sychondroses ossify

A

3

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24
Q

When does the spheno-occiptal synchondroses ossify

A

~18 (16-25 range)

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25
Q

What kind of bone is the maxilla

A

Intramembranous

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26
Q

If the maxilla is intramembranous how might a dentist be able to affect its growth?

A

Intramembranous = Environmentally Influenced

Dentist can affect the bone’s environment by altering the maxillary teeth

27
Q

What does the maxilla migrate away from

A

The Cranial Base by appositional growth at the sutures

28
Q

What two types of remodeling are happening during the maxilla’s “migration”

A

Resorption on the anterior side
Deposition on the posterior side
(Resulting from a tension force maybe supplied by the cartilage of the nasal septum)

29
Q

Who studied the bone remodeling process

A

Enlow

30
Q

How is remodeling performed on the palatal vault?

A

Resorption on the Nasal side

Deposition on the palatal side

31
Q

What is the name of the principle that describes the remodeling of the maxilla

A

the V principle

32
Q

The mandible also migrates away from the cranial base, but where does the appositional growth occur?

A

At the Condyle

33
Q

What part of the mandible is subject to extensive apposition and resorption?

A

Ramus

34
Q

How does apposition effect the ramus of the mandible

A

Resorption on Anterior of Ramus

Deposition on Posterior of Ramus

35
Q

Why can’t you look at a 10 year old and know if he will have room for his third molars

A

because you cannot tell how much of the ramus will be resorbed

36
Q

How does the growth pattern negatively affect kids that don’t have enough room in their jaw for their teeth?

A

The way the mandible grows, there will never be spontaneous growth in the middle of the mandible, where the teeth would benefit from the extra space

37
Q

What is the name of Bjork’s Theory?

A

Bjork’s Mandibular Growth Rotation Theory

38
Q

How did Bjork’s work suprise researchers?

A

His research revealed that rotational growth occurs as the mandible grows

39
Q

What is the most common growth/rotational patter in people

A

Moderate Growth
Moderate Eruption
w/Small Closing Rotation

40
Q

What part of the the mandibular growth pattern contributes to an “adult looking” face

A

The mandibular rotational growth creates a thicker jawline and a more prominent chin region

41
Q

Besides the common model, what model is still seen often

A

???

42
Q

Extreme growth model

A

Moderate Growth
Little Eruption
Lots of Closed Rotation
(Small crowded mouths with anterior overbites)

43
Q

Extreme growth model 2

A

Little growth
Lots of Eruption
Backwards rotation
(Longer lower face with an open anterior bite)

44
Q

What are Scammon’s Growth

A

Curves that track growth rates where 100 on the scale = 100% of normal adult size

45
Q

According to the Scammon’s Curve how does the brain grow

A

Brain size grows rapidly from birth and crests in the teenage years. Brains start “shrinking” in the early 20s

46
Q

According to Scammons what tissue grows to 2x normal size by the age of 12 before shrinking during puberty and reaching “normal” size by 20

A

Lymphoid (Adenoids, Tonsils)

47
Q

If you believe that the bones closer to the brain, grow like the brain. which bone grows more like the brain (Maxilla/Mandible)

A

Maxilla

48
Q

If we need to impact the growth of the maxilla, at what age must it be done?

A

Around 7-8 because the maxilla grows like the brain, ie early and reaching full size by 10-12

49
Q

Which bone is “easier” to influence the growth of? Maxilla or Mandible

A

Maxilla

50
Q

Why is the mandible harder to control the growth of?

A

Because the condyle is cartilagenous

51
Q

But, why is there hope that the mandible might be able to be manipulated more than other bone growing appositionally from cartilage?

A

Because the condyle is fibrous cartilage, not hyaline

52
Q

How does head gear help fix a class 2 malocclusion

A

It retards the growth of the maxilla and allows the mandible to “catch up”

53
Q

If nothing is done to retard the maxilla, why will the mandible never fix itself?

A

Because the maxillary teeth will respond via feedback mechanism and migrate forward along with the mandibular growth

54
Q

Could you treat Class II by forcing disclusion during the growth period?

A

Yes, because the feedback mechanism is based on the intercuspal relationship between the maxillary and mandibular teeth

55
Q

Rank Stature, Mandible, Maxilla in Growth in Size

A

Stature>Mandible>Maxilla

56
Q

What is the Cranial-Caudal Gradient of Growth

A

Structures further from the brain grow later and greater

Structure close to the brain grow early and less overall

57
Q

Out of Height, Length, and Width which stops growing first

A

Width

Length and Height are 2nd and 3rd

58
Q

To take advantage of the mandibular growth curve, when is the optimal time for ortho treatment

A 
Girls = 12 
Boys = 14

Girls = 2 years earlier on average with lots of individual variation for both boys and girls

59
Q

How can Cephalometric Radiographs help predict peak growth windows

A

Superimpose sequential films and create a growth curve

Start looking for curvature in the cervical vertebrae

60
Q

How can hand-wrist x-rays predict growth windows

A

By looking at the epiphyseal plates in the fingers, you can predict peak growth to an accuracy of 6 months

61
Q

What are the three ways to measure age

A

Chronological
Skeletal
Dental Age

62
Q

What are accuracy rates of the different ways to measure age

A

Asking age and comparing to averages (70%)
Skeletal = Direct (100%)
Dental = Looking at teeth to see which is erupted (60%)

63
Q

Best indicator for maturation for girls

A

Onset of menstruation is past peak of growth by 12 months

64
Q

What is the best maturation indicator for boys

A

Less clear then girls
Mustache hair is pre-peak
Chin hear is post-peak

D2: 623 Ortho (3 decks)

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