290926982-Theories-of-Growth- orthodontic department .pdf

290926982-Theories-of-Growth.pdf

1. Therories
of Growth
Guided by:
Dr.
Basanta
K.
Shrestha
,
Assoc. Prof and Head,
Presented by:

Dr.
Rajesh Gyawali,

Resident
Orthodontics and
Dentofacial
Orthopedics Unit
Faculty of Dentistry,
Institute of Medicine(IOM), Kathmandu
[email protected]

2. Introduction
Theories with changing paradigm
•Genetic Theory
•SuturalTheory
•CartilageneousTheory
•Functional Matrix Theory
•ServosystemTherory

3. •Enlow’sexpanding ‘V’ principle
•Enlow’scounterpart principle
•Neurotrophicprocess in oro-facial
growth
•Revolution in develpmentalmolecular
biology

4. •Growth in orthodontics ?
•How does growth occur ?
Many theories are proposed.

5. Paradigm 1 Paradigm 2
Paradigm 1
Paradigm 2
Paradigm 1
Paradigm 2
Normal science Scientific revolution Normal science

6. Genes determine all.
Growth is controlled by genetic influences
and is pre programmed.
More assumed than proven.
"perhaps this part is genetically controlled
while that is not"

7. •Brashin 1930.
•Bone grows by deposition
at one surface and
resorptionat another.
•Exclusively by bone remodelling.
•Sutures and cartilage –no role.

8. By Weinmannand Sicher.
Intrinsic, genetically regulated, primary
growth of bone occurs in suture.

9. Expansive proliferative growth
at suturalconnective tissue
Forces the bones away
from each other
Increase in volume
of skull

10. Evidence against suturaltheory
Area of the suture transplanted to another
location no growth.
Growth at sutures will respond to outside
influence-
•Facial bones mechanically pulled apart at
the sutures, new bone will fill in,
•If a suture is compressed, growth at that
site will be impeded.

11. James H. Scott in 1950.
Nasal septum is most active and important for
craniofacial skeletal growth late prenatally and
early postnatally
Nasal septum is most active and important for
craniofacial skeletal growth late prenatally and
early postnatally

13. Transplantation of cartilage to other site –
•Nasal septalcartilage,
•Epiphysealcartilage
•Cartilage from spheno-occipital synchondrosis
grew at another site.
Except the
Condylarcartilage

14. Effect on growth on removing cartilage at early age:
Experiments
on animals
Reduced
growth of
midface
Arguments:- Effects of surgery
Interference with blood supply

15. Removal of nasal septum after injury at age 8

16. Genomic
paradigm
Functional
paradigm
Melvin Moss-
Functional Matrix Theory
Growth is immutable
and predetermined
Growth can be
modified by function
Orthodontic treatment
limited to tooth
movements only
Use of functional
orthopedic appliances
to modify growth

17. ByMelvinMossin1960.
“Origin,form,position,growthandmaintenance
ofallskeletaltissuesandorgansarealways
secondary,compensatoryandnecessaryresponses
tochronologicallyandmorphologicallyprior
eventsorprocessesthatoccurinspecifically
relatednon-skeletaltissues,organsorfunctional
spaces.”

18. Bone grows in direct response to its extrinsic
environment
“Bones do not grow, bones are grown”
Skeletal Unit Functional Matrix
Functional cranial component
Macro-
skeletal
unit
Micro-
skeletal
unit
Periosteal
Matrix
Capsular
Matrix

19. Functional matrix hypothesis
of craniofacial growth.

20. By AlexandrePetrovic.
The hormonally regulated growth of the
midfaceand anterior cranial base, which
provides a constantly changing reference
input via the occlusion,
The rate-limiting effect of this midfacial
growth on the growth of the mandible.

21. Maxillary
growth
Condylar
growth
Hormonal
factor
Muscle
functions
CNS
Propioceptors:
Periodontium-TMJ
Occlusal
deviation

22. Multifactorialtheory
Combined -
Functional Matrix Theory
SuturalTheory
Genetic Theory

23. 5Factors-
Intrinsic genetic factor
Local epigenetic factor
General epigenetic factor
Local environmental factor
General environmental factor

24. V shaped pattern of growth
Deposition occurs on the inner side of
the wide ends of the V
Resorptionon the outer
surface

28. Growth of one part relates specifically to other
structural and geometric counterparts in the face
and cranium.
Regional part and its particular counterpart
enlarge to the same extent, balanced growth
occurs.

29. The different parts and their counterparts are :
Nasomaxillarycomplex –anterior cranial fossa.
Horizontal dimension of the pharyngeal
space -middle cranial fossa.
Middle cranial fossa-breadth of the ramus.
Maxillary -mandibulardental arch.
Bony maxilla -corpus of the mandible.
Maxillary tuberosity-lingual tuberosity.

30. Network of nerves (all kinds, motor as well as
sensory) as links for feedback interrelationships
Pathways for stimuli that can trigger certain bone
and soft tissue remodeling responses
Transport of neurosecretorymaterial along nerve
tracts or by an exoplasmicstreaming within the
neuron

31. New discoveries relating to the role of neural
crest cells and regulatory genetic factors
Homeoboxgene (conserved sequence of DNA)
Encodes for transciptionfactors
and signaling molecules
Regulates expression of other
genes during development

32. Neural crest cells
•highly pluripotent
•important role in the development of head
•migrate extensively throughout the embryo
•forms of craniofacial bones, cartilages and
connective tissues.
Lateral border of the
crest of neuroectoderm
Neural crest
cells

33. THANK YOU