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Orthodontics > Craniofacial Growth > Flashcards

Craniofacial Growth Flashcards

1
Q

What does somatic mean?

A

Body!

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2
Q

How long do patients wear the twin block functional appliance for?

A

> 16h wear per day for 11-12 months

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3
Q

What are important features of the twin block and what are their purposes?

A
  1. Bite ramp of 45 degrees on both sides - used to guide the mandible forward
  2. Lower incisor acrylic capping - used to prevent lower incisor proclination
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4
Q

Skeletal changes observed in CRANIAL BASE superimposed Lat Cephs after use of Twin block

A

Mandible moved downwards and forwards.
(Seen at the symphysis and the lower border of the mandibular body)
Slight increase in MMA

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5
Q

Dental and Skeletal changes observed in REGIONAL superimposed Lat Cephs after use of Twin block

A

Dental (max):
U1 tipped palatally
U6 extruded
Skeletal (max):
NIL

Dental (man):
L1 no change
L6 extruded and mesialised
Skeletal (man):
Condyle grew upwards and backwards

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6
Q

Does the twin block treatment result in a change in facial profile

A

There is some change but the not substantial contribution to facial profile

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7
Q

What stages of somatic maturation are important to know!

A
  1. Timing of onset, peak and end of growth
  2. Physiological indicators eg. menarche (girls), voice change (boys)
  3. Vertebral maturation
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8
Q

What is the timing of onset, peak height velocity (PHV) and end of growth for boys and girls?

A

Onset: 10 (G), 12 (B)
PHV: 12 (G), 14 (B)
End: 17.5 (G), 19 (B)

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9
Q

What is the growth velocity at onset and peak for girls and boys?

A

Onset: 5.5cm/year (G), 4.6cm/year (B)
Peak: 8.5cm/year (G), 9.5cm/year (B)

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10
Q

What are physiological indicators of females and males

A

Female: Menarche (occurs average 12 months after PHV)
Males: Voice change (begins during pubertal growth spurt), male voice = growth rate is decelerating

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11
Q

What are the differences in the vertebral maturation? CS 1-6

A

CS1: F,F,F
CS2: C(C2),F,F
CS3: C,C,F
CS4: C,C,C + Rectangular horizontal morphology (C3, C4)
CS5: C,C,C + Squarish/RH
CS6: C,C,C + Rectangular vertical/RH

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12
Q

What are the clinical implications of the cervical vertebral maturation stages?

A

CS1,2: Prepubertal
CS3,4: Circumpubertal
CS5,6: Postpubertal

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13
Q

At which point does PHV occur in CVMS?

A

between CS3 and 4

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14
Q

Why is it important to know somatic growth for ortho?

A

It shines light onto the patient’s growth stage based on growth rate - onset, pre-pubertal, PHV, post-pubertal, little/no more growth

And it also guides clinicians on:
1. When to start treatment
2. How long to delay the start of treatment
3. The duration of treatment
4. The window of treatment opportunity

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15
Q

Why is it bad to start treatment too early? (at onset of growth)

A

This is because the patient will burn out

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16
Q

When is the ideal window of treatment opportunity?

A

From late acceleration, to peak, to mid deceleration

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17
Q

What if its too late to start of treatment?

A

Just wait for the patient to stop growing completely

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18
Q

What is facial growth demonstrated by?

A
  1. Change in size
  2. Change in shape
  3. Change in spatial position of the maxilla and mandible
19
Q

What is the direction which the maxilla grows

A

Downwards and forwards

20
Q

Where is the origin/growth centre of maxillary growth

A

Nasal cartilage

21
Q

Where are the growth sites/periphery of the maxilla to allow its growth

A

Sutural growth and Surface remodelling

22
Q

Why must there be equal amounts and rates or right/left and posterior/anterior facial growth?

A

To allow balanced faces - prevent occlusal cant and AOB/POB

23
Q

At what age are the maxillary and nasal processes supposed to fuse

A

8-9 weeks in utero

24
Q

How does the maxilla grow in cleft patients

A

The growth is redirected vertically (not anteriorly)

25
Q

What is the direction that the mandible grows

A

Downwards and forwards

26
Q

How does the mandible grow?

A
  1. Condylar growth (growth site NOT centre)
  2. Mandibular body elongation
  3. Surface remodelling
27
Q

What is the Goldenhar Syndrome? What does it cause?

A

Hemifacial Microsomia.
Severe cant of the occlusal plane

28
Q

What is mandibular growth rotation?

A

Constitutes of resorption and deposition

  1. The surface remodeling or “Molding” of the shape of the mandible during facial growth
    2 Remodeling of the mandible is influenced by the facial and oral soft tissue muscle environment. (MOFE, MOM)
  2. Leads to change in direction of mandibular growth
29
Q

What studies show the growth of the mandible

A

Bolton-Brush Study

30
Q

What are the structural signs in a forwards growth rotation

A

(Bjork AJO 1969)
1. Condyle Inclination: Forward/Vertical
2. Mandibular Canal (IDN): More curvature
3. Shape of Mandible Border: Convex
4. Symphysis inclination: Forward, strong chin
5. Inter-incisal angle: Obtuse (retrocline lower incisors)
6. Inter-molar/inter-PM angle: obtuse
7. LAFH: Decreased

31
Q

What are the structural signs in a backwards growth rotation

A

(Bjork AJO 1969)
1. Condyle Inclination: Backwards
2. Mandibular Canal (IDN): Less curvature
3. Shape of Mandible Border: Antegonial notch
4. Symphysis inclination: Backwards, weaker chin
5. Inter-incisal angle: More acute (proclined lower incisors)
6. Inter-molar/inter-PM angle: more acute
7. LAFH: increased

32
Q

What is the definition of Dentoalveolar Compensation (DAC)

A

The physiological process or mechanism by which the development of the dental and alveolar arches is controlled so as to secure occlusion of the teeth and adaptation to the basal parts of the jaws

OR

System which attempts to maintain normal inter-arch relationships under varying jaw relationships

33
Q

What is an example of DAC in the vertical plane

A

Varying the man alveolar bone thickness and hence LAFH according to the max alveolar bone thickness

34
Q

What is an example of DAC in the AP(sagittal) plane

A

Proclined max incisors and retroclined man incisors in a Class III skeletal base.

Retroclined max incisors and proclined man incisors in a Class II skeletal base

35
Q

What is an example of DAC in the transverse plane

A

Patients with high palatal vaults and narrow palatal walls have buccally inclined maxillary teeth and lingually included mandibular teeth

36
Q

What happens when there is still inadequate DAC

A

malocclusion eg. crossbite

37
Q

What are the two factors influencing the DAC mechanism?

A
  1. A healthy eruptive system is required for continuous eruption of teeth during growth
  2. Forces acting on teeth by soft tissues - tongue cheeks lips eg. mentalis muscle is important for retroclining the lower man incisors in Class III pts
38
Q

What angle determines the proclination of the incisors if the interincisal angle is normal

A

ANB
-ve = Class III
+ve past ideal of 2 = Class II

39
Q

What problems can adequate DAC result in

A

Crowding :(
BUT good occlusal r/s :D

40
Q

What does inadequate or inoperative DAC result in

A

Abnormal occlusal relationships +/- crowding

41
Q

If the sagittal skeletal discrepancy is mild, how will orthodontic treatment correct it.

A

DAC - Orthodontic camouflage

42
Q

If the sagittal skeletal discrepancy is severe, and there is inadequate DAC, what is the treatment option

A

Orthognathic Surgery - Mandibular setback

43
Q

Is there pre-orthognathic surgery treatment required?

A

Decompensation

Orthodontics (18 decks)

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