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Orthodontics > Growth > Flashcards

Growth Flashcards

1
Q

Three stages of development

A
  • Ovum
  • Embryonic period
  • Foetal period
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2
Q

Ovum

A

0 - 8 days in utero

-Fertilised ovum- Rapid mitosis- Morula- blastocyst- implantation

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3
Q

Embryonic period

A
  • from 2nd to 12th week IU
  • Divided into -
    Pre somite period - 8-20,days (Endoderm Ectoderm)
    Somite period - 21-31 days IU (Body system/organs)
    Post- Somite period 4-10 weeks IU ( external feature/ head growth)
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4
Q

Foetal period

A
  • from 3 - 9 month IU
  • Head developed exceeds rest of body
  • Re- proportining of body components occur
  • Organogenesis/ tissue differentiate not features.
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5
Q

Cranial anatomy

A
  • Two part
  • Cranium ( Neurocranium)
  • Face ( Vicerocranium)
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6
Q

Changes in shape of head with growth?

A
  • Face gets relatively larger within the head
  • The face grows most in height (Vertical), then Depth (Anterior posterior), then Width (transverse)
  • V>A>T
  • Face continue grow througout life
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7
Q

How do we measure AP skeletal pattern?

A
  • By angle of ANB
  • SNA- SNB= ANB
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8
Q

ANB angle changes?

A
  • On average ANB angle gets smaller by 1 degree between age 11-20.
  • 5% population - alter ANB 6 degree
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9
Q

Which important factor aetiology of malocclusion?

A
  • Anterior posterior
  • On average lower jaw grown little more in AP- direction than upper jaw.
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10
Q

How does face grow?

A
  • Face grow down and forward relatively to cranial base
  • Face cont to grow until 6th decade of life and beyond
  • Indivisual facial growth is different called Growth rotation
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11
Q

Define Growth rotation

A
  • Indivisual facial bones and part of others bones grow differentially and these referred as Growth Rotations.
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12
Q

Mandibular growth rotation

A
  • Reflection of differential growth in anterior part of the face compared to posterior part of face .
  • Growth rotations usually refer to mand.
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13
Q

Maxilla growth rotation

A
  • Maxilla also show growth rotation but lesser extent than mandible .
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14
Q

Define True rotation of mandible

A
  • Rotation of mandibular body relative to the anterior cranial base as its stable structure in mandible.
  • 50% of true rotation of lower border
  • 50% of true rotation masked by remodelling
  • 20% rotation - more efficient counter remodelling process
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15
Q

Angular remodelling of lower border

A
  • angular change of mandibular line when mand is registered on stable mandibular structure.
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16
Q

Centre of rotation - Anterior or forward rotation and percentage ?

A
  • 80%
    -Condylar head
  • Lower premolars
  • lower incisal edge
  • distal occluding molars
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17
Q

Mandible forward / anterior rotation cause

A
  • 80% of people
  • Increase Over bite
  • Condylar head
  • Lower premolars
  • Lower incisal edges
  • Distal occluding molar
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18
Q

Posterior or backward rotation sites and cause? Percentage ?

A
  • Condyler head
  • Distal occluding molars

Cause - AOB and decrease OB
- 20 %

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19
Q

Types of Bone growth in jaws

A

-All are formed through Intramembraneous ossification ( bone forms in membranes).
- All begin ossification - Endochondral.

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20
Q

Calcification of bones.

A
  • Endochondral - Replacement of cartilage - 3rd month IU
  • Intra- membranous - Periosteal remodelling
    at suture and surface. All other cranial and facial growth - 6-4 weeks IU appart from cranial base
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21
Q

Endochondral which part ?

A
  • Cranial base synchindrosses
  • Mandibular condyle
22
Q

Intra membranous calcification occur

A
  • All other cranial and facial growth apart from cranial base
23
Q

1 Degree Lip / palate fusion

A
  • 6 week IU
24
Q

2nd degree palate

A
  • 7-8 week IU
25
Q

Where does craniofacial growth occur?

A

Synchindorses - Cranial base

26
Q

What is growth site?

A
  • Where growth occurs
27
Q

Growth centre
4 sites?

A
  • Location at which independent, genetically controlled growth occurs. Growth centre can be growth site but growth site cannot be growth centre.
  • spheno - occipital synchondrosis - active until puberty
    -Fronto- ethmoidal syncchondrosis- active Until puberty
    -Spheno - ethmoidal synchondrosis - active until age of 7yrs
  • Nasal septum cartilage
28
Q

Cranial Vault

A
  • Intramembranous ossification
  • 8th week IU
  • Functional matrix expands brain
29
Q

Cranial Base

A
  • Endochondral ossification / cartilaginous synchondroses.
  • AP and vertical relationship of jaws
30
Q

Naso maxillary complex

A
  • Intra membranous ossification expect for nasal cartilage
  • 7week IU
31
Q

Mandible

A
  • Intramembranous ossification but cartilage on condyler cartilage
    -6week IU
  • Later growth and remodelling due to periosteal activity.
32
Q

Growth patterns and post natal Growth?

A

-Neural
- Somatic
- Genital
- Lymphoid

33
Q

Examples of bone growth.

A

-Surface remodelling - Mandible
-Cartilaginous - Mandibular condyle
- Synchonddosis- Cranial base

34
Q

Periosteal activity

A
  • Formation of new bone due to injury or other stimuli Periosteum surronding bone
  • Periosteal/ sutural can be influenced by pressure and tension e.g orthdontic forces
35
Q

Control of growth

A
  • Mainly genetic
  • Partly environmental
36
Q

Possible local environmental factors affecting growth? May be?

A
  • Nutrition- Softer food to gradually smaller jaws over the centuries.
  • Mouth breathing - Small effect on jaw
  • Bottle feeding - no effect
  • Jaw/ tongue/ lip exercises/ cranial massage- no evidence
37
Q

Pubertal growth spurt average and cessation of growth

A

Girl - 12 yrs +/-last 2 years
Boys- 14 yrs +/- last 2 year14 yrs old

38
Q

Can we predict growth / change in skeletal pattern ?

A
  • No not possible to predict Indivisual growth , we can only predict average age of growth spurt
39
Q

Predict growth or changes in skeletal pattern ?

A
  • Chronological age
  • Dental age
  • Secondary - sexual characteristics
  • Standing height
  • Growth velocity
  • Cervical vertebral maturation
  • Hand wrist radiographs
40
Q

Can orthodontic treatment influence growth?

A
  • A little
  • short term yes
  • long term no
41
Q

Example of orthodontic growth change?

A
  • Functional appliances
42
Q

How functional appliance helps in growth?

A
  • Restrain maxillary growth (short term)
  • Enhanced mandible growth 1-2 mm
43
Q

Can orthodontic treatment influence growth?

A
  • A little
  • Head gear and functional can both slightly restrain forward growth of maxilla
  • Functionals can slightly increase growth of mandible 1-2mm
  • Nothing can restrain forward growth of mandible
    -Reverse headgear can slightly increase anterior maxillary growth.
44
Q

Clinical significance of growth in orthodontic

A
  • The unpredictable variation in change of skeletal pattern can have large effect on treatment
  • Remember that success or failure may be due to unusual growth not appliances
  • Excessive vertical growth can cause anterior open bites to develop.
  • Treat class 3 cases a little later- Remember average trend to more class 3
  • Treat class 2 cases a little earlier- Growth helps to reduce overbite - Bite planes work poorly in adults.
  • Growth is essential for spontaneous alignment and space closure following extractions
  • Remember the ages when growth -on average- and stops
  • Orthognathic surgery and implant should be after growth stops.
45
Q

Clinical significance of growth rotations

A
  • Not much
  • Incisor crowding may result from the dental compensations to growth rotation
  • Growth rotation is academically very interesting as insight to mechanism of growth in the face.
46
Q

Influence of growth on treatment

A
  • OB reduction
  • Distal movement of posterior teeth
  • space closure
  • occlusal settling
  • Functional appliance treatment
  • Use of RME.
47
Q

Relevance of growth to orthodontic treatment

A
  • Orthdontic treatment is quicker if growth is present
  • Orthodontic tx has very little influence over SK pattern, using orthodontic alone there are more options available for treating SK class 2 cases than SK class 3. I.e HG is less frequently used on CL 3 cases and chin cups produce only temporary correction of sk discrepancy.
48
Q

Clinical relevance of growth rotation

A
  • OB deepens- with anterior growth rotation and it is difficult to decrease so consider a bite plane to prevent the OB deepening.
  • Posterior rotation- Pts have increased anterior vertical face height and long face appearance possibly with high MMP angle.
49
Q

Temporary posterior rotation caused by?

A
  • Inter maxillary elastics
  • Anchorage bends
  • anterior bite plane
50
Q

How much percentage of space closure is due to jaw rotation ?

A

50%

Orthodontics (53 decks)

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