Growth Flashcards
Three stages of development
- Ovum
- Embryonic period
- Foetal period
Ovum
0 - 8 days in utero
-Fertilised ovum- Rapid mitosis- Morula- blastocyst- implantation
Embryonic period
- 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)
Foetal period
- from 3 - 9 month IU
- Head developed exceeds rest of body
- Re- proportining of body components occur
- Organogenesis/ tissue differentiate not features.
Cranial anatomy
- Two part
- Cranium ( Neurocranium)
- Face ( Vicerocranium)
Changes in shape of head with growth?
- 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
How do we measure AP skeletal pattern?
- By angle of ANB
- SNA- SNB= ANB
ANB angle changes?
- On average ANB angle gets smaller by 1 degree between age 11-20.
- 5% population - alter ANB 6 degree
Which important factor aetiology of malocclusion?
- Anterior posterior
- On average lower jaw grown little more in AP- direction than upper jaw.
How does face grow?
- 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
Define Growth rotation
- Indivisual facial bones and part of others bones grow differentially and these referred as Growth Rotations.
Mandibular growth rotation
- Reflection of differential growth in anterior part of the face compared to posterior part of face .
- Growth rotations usually refer to mand.
Maxilla growth rotation
- Maxilla also show growth rotation but lesser extent than mandible .
Define True rotation of mandible
- 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
Angular remodelling of lower border
- angular change of mandibular line when mand is registered on stable mandibular structure.
Centre of rotation - Anterior or forward rotation and percentage ?
- 80%
-Condylar head - Lower premolars
- lower incisal edge
- distal occluding molars
Mandible forward / anterior rotation cause
- 80% of people
- Increase Over bite
- Condylar head
- Lower premolars
- Lower incisal edges
- Distal occluding molar
Posterior or backward rotation sites and cause? Percentage ?
- Condyler head
- Distal occluding molars
Cause - AOB and decrease OB
- 20 %
Types of Bone growth in jaws
-All are formed through Intramembraneous ossification ( bone forms in membranes).
- All begin ossification - Endochondral.
Calcification of bones.
- 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
Endochondral which part ?
- Cranial base synchindrosses
- Mandibular condyle
Intra membranous calcification occur
- All other cranial and facial growth apart from cranial base
1 Degree Lip / palate fusion
- 6 week IU
2nd degree palate
- 7-8 week IU
Where does craniofacial growth occur?
Synchindorses - Cranial base
What is growth site?
- Where growth occurs
Growth centre
4 sites?
- 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
Cranial Vault
- Intramembranous ossification
- 8th week IU
- Functional matrix expands brain
Cranial Base
- Endochondral ossification / cartilaginous synchondroses.
- AP and vertical relationship of jaws
Naso maxillary complex
- Intra membranous ossification expect for nasal cartilage
- 7week IU
Mandible
- Intramembranous ossification but cartilage on condyler cartilage
-6week IU - Later growth and remodelling due to periosteal activity.
Growth patterns and post natal Growth?
-Neural
- Somatic
- Genital
- Lymphoid
Examples of bone growth.
-Surface remodelling - Mandible
-Cartilaginous - Mandibular condyle
- Synchonddosis- Cranial base
Periosteal activity
- 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
Control of growth
- Mainly genetic
- Partly environmental
Possible local environmental factors affecting growth? May be?
- 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
Pubertal growth spurt average and cessation of growth
Girl - 12 yrs +/-last 2 years
Boys- 14 yrs +/- last 2 year14 yrs old
Can we predict growth / change in skeletal pattern ?
- No not possible to predict Indivisual growth , we can only predict average age of growth spurt
Predict growth or changes in skeletal pattern ?
- Chronological age
- Dental age
- Secondary - sexual characteristics
- Standing height
- Growth velocity
- Cervical vertebral maturation
- Hand wrist radiographs
Can orthodontic treatment influence growth?
- A little
- short term yes
- long term no
Example of orthodontic growth change?
- Functional appliances
How functional appliance helps in growth?
- Restrain maxillary growth (short term)
- Enhanced mandible growth 1-2 mm
Can orthodontic treatment influence growth?
- 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.
Clinical significance of growth in orthodontic
- 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.
Clinical significance of growth rotations
- 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.
Influence of growth on treatment
- OB reduction
- Distal movement of posterior teeth
- space closure
- occlusal settling
- Functional appliance treatment
- Use of RME.
Relevance of growth to orthodontic treatment
- 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.
Clinical relevance of growth rotation
- 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.
Temporary posterior rotation caused by?
- Inter maxillary elastics
- Anchorage bends
- anterior bite plane
How much percentage of space closure is due to jaw rotation ?
50%
