Craniofacial Growth Flashcards
What does somatic mean?
Body!
How long do patients wear the twin block functional appliance for?
> 16h wear per day for 11-12 months
What are important features of the twin block and what are their purposes?
- Bite ramp of 45 degrees on both sides - used to guide the mandible forward
- Lower incisor acrylic capping - used to prevent lower incisor proclination
Skeletal changes observed in CRANIAL BASE superimposed Lat Cephs after use of Twin block
Mandible moved downwards and forwards.
(Seen at the symphysis and the lower border of the mandibular body)
Slight increase in MMA
Dental and Skeletal changes observed in REGIONAL superimposed Lat Cephs after use of Twin block
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
Does the twin block treatment result in a change in facial profile
There is some change but the not substantial contribution to facial profile
What stages of somatic maturation are important to know!
- Timing of onset, peak and end of growth
- Physiological indicators eg. menarche (girls), voice change (boys)
- Vertebral maturation
What is the timing of onset, peak height velocity (PHV) and end of growth for boys and girls?
Onset: 10 (G), 12 (B)
PHV: 12 (G), 14 (B)
End: 17.5 (G), 19 (B)
What is the growth velocity at onset and peak for girls and boys?
Onset: 5.5cm/year (G), 4.6cm/year (B)
Peak: 8.5cm/year (G), 9.5cm/year (B)
What are physiological indicators of females and males
Female: Menarche (occurs average 12 months after PHV)
Males: Voice change (begins during pubertal growth spurt), male voice = growth rate is decelerating
What are the differences in the vertebral maturation? CS 1-6
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
What are the clinical implications of the cervical vertebral maturation stages?
CS1,2: Prepubertal
CS3,4: Circumpubertal
CS5,6: Postpubertal
At which point does PHV occur in CVMS?
between CS3 and 4
Why is it important to know somatic growth for ortho?
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
Why is it bad to start treatment too early? (at onset of growth)
This is because the patient will burn out
When is the ideal window of treatment opportunity?
From late acceleration, to peak, to mid deceleration
What if its too late to start of treatment?
Just wait for the patient to stop growing completely
What is facial growth demonstrated by?
- Change in size
- Change in shape
- Change in spatial position of the maxilla and mandible
What is the direction which the maxilla grows
Downwards and forwards
Where is the origin/growth centre of maxillary growth
Nasal cartilage
Where are the growth sites/periphery of the maxilla to allow its growth
Sutural growth and Surface remodelling
Why must there be equal amounts and rates or right/left and posterior/anterior facial growth?
To allow balanced faces - prevent occlusal cant and AOB/POB
At what age are the maxillary and nasal processes supposed to fuse
8-9 weeks in utero
How does the maxilla grow in cleft patients
The growth is redirected vertically (not anteriorly)
What is the direction that the mandible grows
Downwards and forwards
How does the mandible grow?
- Condylar growth (growth site NOT centre)
- Mandibular body elongation
- Surface remodelling
What is the Goldenhar Syndrome? What does it cause?
Hemifacial Microsomia.
Severe cant of the occlusal plane
What is mandibular growth rotation?
Constitutes of resorption and deposition
- 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) - Leads to change in direction of mandibular growth
What studies show the growth of the mandible
Bolton-Brush Study
What are the structural signs in a forwards growth rotation
(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
What are the structural signs in a backwards growth rotation
(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
What is the definition of Dentoalveolar Compensation (DAC)
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
What is an example of DAC in the vertical plane
Varying the man alveolar bone thickness and hence LAFH according to the max alveolar bone thickness
What is an example of DAC in the AP(sagittal) plane
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
What is an example of DAC in the transverse plane
Patients with high palatal vaults and narrow palatal walls have buccally inclined maxillary teeth and lingually included mandibular teeth
What happens when there is still inadequate DAC
malocclusion eg. crossbite
What are the two factors influencing the DAC mechanism?
- A healthy eruptive system is required for continuous eruption of teeth during growth
- 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
What angle determines the proclination of the incisors if the interincisal angle is normal
ANB
-ve = Class III
+ve past ideal of 2 = Class II
What problems can adequate DAC result in
Crowding :(
BUT good occlusal r/s :D
What does inadequate or inoperative DAC result in
Abnormal occlusal relationships +/- crowding
If the sagittal skeletal discrepancy is mild, how will orthodontic treatment correct it.
DAC - Orthodontic camouflage
If the sagittal skeletal discrepancy is severe, and there is inadequate DAC, what is the treatment option
Orthognathic Surgery - Mandibular setback
Is there pre-orthognathic surgery treatment required?
Decompensation
