Post natal growth and development

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Post Natal Growth and
Development

Contents
Introduction
Terminologies
Conceptsof growth
Osteogenesis
Regional development
Cranium
Nasomaxillary complex
Mandible

Contents
Clinical implications
Conclusion
References

What is post natal growth??
Post natal growth isthefirst 20 yearsof growth after
birth.
It comprises of 3periods;
How does it differfrom prenatal growth??
Prenatal growth is characterized by a rapid increasein cell
numbersand fast growth rates
Postnatal growth is characterized by declining growth
ratesand increasing maturation of tissues.

Terminologies
Primary cartilage
Secondary cartilage
Growth centre – location at which independent growth
occurs
Growth site– merelocation at which growth occurs

Terminologies
Deposition –
addition of new bone to the bony surface by osteoblastic
activity
Resorption – removal of bonedueto osteoclastic activity
+++
----

Terminologies
Cortical drift –
relocation of bone by simultaneous deposition and
resorption processes on the opposing periosteal and
endosteal surfaces
Displacement –
movement away from acertain position or place
Primary displacement- occurring in conjunction with bone’s
own growth
Secondary displacement – caused by enlargement of
adjacent or remote bones or soft tissues; but not of the bone
itself

Remodeling –
reshaping of the outline of the bone by selective
resorption of bone in some areas and deposition in other
areas
Relocation –
relative movement in space of a bony structure, due to
bone deposition on one side and resorption on the other
side

Concepts of growth
Enlow’sgrowth concepts
Concept 0ne
facial growth and development isamorphogenic process
In-depth understanding of facial morphogenesis
Normal Vs range of abnormal
Biologic reasons for these variations
Diagnosis, treatment planning and selection of
appropriate procedures
Biologic factors underlying the problems of retention,
rebound and relapse

Concept two
Bonesgrow by adding new bonetissue
Surfacefacing towardsdirection of growth– deposition
Surfacefacing away--- resorption

Concept three
Mosaic-likepattern of growth fields
Example- outer periosteal has resorptive field then the
corresponding endosteal isdepository and viceversa
Thesecombinationsproducecharacteristic growth++++++++
+++
---------
----

Concept four
Periosteal bonecovers50% of thecortical bone
Endosteal bone theremaining.

Concept five
Operation of growth fields – carried out by osteogenic
membraneand other surrounding tissues
Growth not programmed within the calcified part of bone
itself, rather the blue print lies in the surrounding soft
tissues

Concept six
All various depository and resorptive growth fields do not
havesamerateof thegrowth activity
Fields with special significance play crucial role in the
growth process--- growth sites

Example:- mandibular condyle
During remodeling bonedeposition exceedsresorption

Concept seven
Remodeling isthebasic part of bonegrowth process
Why thebonemust remodel ???
Its regional parts are moved from one location to another as
theboneenlarges
Example: ramus progressively moves posteriorly by a
combination of deposition and resorption.

Progressive, sequential movement of components as a bone
enlarges--- relocation
Relocation isthebasisfor remodeling
If we consider the previous example, ramus as a whole
relocates posteriorly and the posterior part of the corpus by
lengthening also gets relocated and occupies the same area,
oncetheramusoccupied earlier.
Growth and remodeling are in effect, inseparable parts of the
sameactual process

Palate grows downwards by periosteal resorption on nasal
sideand deposition on oral side

Why about half of any given bone can and must have a
resorptive external surface as the bone increases in overall
size???
Bone does not enlarge symmetrically by uniform deposition
of new bone.
Rather each regional part becomes relocated in a sequential
manner.
Someoutsidesurfacesarethusnecessarily resorptive

To summarize,
The process of growth remodeling accelerated by the
compositeof soft tissueareto
Progressively enlargeeach wholebone
Sequentially relocate each of the component parts of the
wholeboneto allow for overall enlargement
Shape the bone to accommodate its various functions in
accordance with the physiologic actions exerted on that
bone
Provide progressive fine-tune fitting of all the separate
bones to each other and to their contiguous, growing,
functioning soft tissues

Carry out continuous regional structural adjustments of all
parts
Note
Bonesremodel throught out life
Rebound and relapse is a normal expression of the same
remodeling functions

Concept eight
As bone enlarges, simultaneously carried away from other
bonesin direct contact with it.
The space, thus created is utilized for the bony enlargement
and theprocess--- primary displacement / translation.

Example1:
Nasomaxillary complex is in contact with the floor of the
cranium.
Whole maxillary region displaced, downward and forward
in toto away from cranium by expansive growth of the soft
tissuesin themid-facial region

Example2
The whole mandible is displaced away from its
articulation in each glenoid fossa
Condyleand ramus, grow upward and backward

Note
Theramusremodelsand becomeswider longer
Theincreasing massof masticatory muscles
Enlarged breadth of pharyngeal space
Vertical lengthening of the nasomaxillary part of the
growing face

Concept nine
Secondary displacement
Example : increase in the size of middle cranial fossa result
in a marked displacement movement of the whole maxillary
complex anteriorly and inferiorly.
This is quite independent of the growth and enlargement of
maxillaitself.

To summarize,
Overall skeletal growth processhastwo functions:
Positioning each bone
Designing and constructing each bone and all of its regional
parts so that they can carry out that bone’s multifunctional
role
The functional input to the osteogenic tissues of bone
from the soft tissues------bone develop into its definitive
morphologic structureand to occupy thelocation it does.

Concept ten
Facial growth:
Requires intimate morphogenic interrelationship among all
of its component growing, changing and functioning soft
and hard tissueparts.
No part is developmentally independent and self-
contained
Growth process works towards an ongoing state of
compositefunctional and structural equilibrium.

Other concepts
Cephalocaudal growth
Scammon’sgrowth curve
Enlow’scounterpart principle

Cephalocaudal gradient of growth

Cephalocaudal gradient
It representsthechangesin overall body proportion
during normal growth and development
In third month of IUD head takesalmost 50%of total
body length.
At birth;head -39%of total body length
In adults;head-12%of total body length.
Trunk and limbsgrow faster than head and face

Differential growth[scammon’s growth
curve]

scammon’s growth curve
Different tissuein body grow at different timesand different rates.
Neural tissues-complete90% of growth at 6yearsand 98% by 10
yearsof age.
Lymphoid tissues-proliferatesrapidly in latechildhood and reaches
allmost 200%of adult size.by about 18 yearsof agethetissues
undergoesinvolution to reach adult size.
General tissues-it hasmusclebonean organ exhibit aSshaped curve
with rapid growth upto 2-3 yearsof agefollowsby slow phaseof
growth between 3-10years.after 10 yearsarapid phaseof growth
occursterminating by 18-20 years.
Genital tissue;grow rapidly at puberty leading adult sizeafter which
growth ceases.

Enlow’s counterpart principle
Growth of any given facial or cranial part relates specially
to other structural and geometric counterparts in the face
or cranium
Regional relationshipsexist ---craniofacial region
Balanced growth = Regional and corresponding
counterparts
enlargeto sameextent
Imbalancein regional relationship isdueto differencesin
Amount of growth
Direction
Time

Different parts and theircounterparts
Part Counterpart
Palate Anterior cranial fossa
Middlecranial fossa Ramusof themandible
Maxillary arch Mandibular arch
Maxillary tubeosity Lingual tuberosity
Bony maxilla Corpusof themandible

Osteogenesis
Mechanism of boneformation
Endochondral
Intramembranous

Five steps to Endochondral bone
formation
Hypertrophy of chondrocytesand matrix calcifies
Invasion of blood vesselsand theconnectivetissue
Osteoblastsdifferentiateand produceosteoid tissue
Osteoid tissuecalcifies
Membranecoversboneand isessential

Five steps to Intramembranous bone
formation
Osteoblastsproduceosteoid tissue
Cellsand blood vesslesareencased
Osteoid tissueisproduced by membranecells
Osteoid calcifies
Essential membranecoversthebone

Comparison of selected physiologic
properties of bone and primary cartilage
important during growth
Characteristic
s
Cartilage Bone
Calcification Non-calcified Calcified
Vascularity Non-vascular Vascular
Surface
membrane
Non-essential Essential
Rigidity Flexible Inflexible
Pressure
resistance
Tolerant to
pressure
Sensitiveto
pressure

Regional development
Functions
Growth
Mechanismsand sites
Timing
Compensatory mechanisms
Theoretical and Clinical issues

Cranium
Cranial vault
Basicranium

Cranial vault
Functions: protection of brain- primary function
Growth
1)Mechanismsand sites
Cranium grows---asbrain grows
Accelerated during infancy, 90% of it iscompleteby 5th
year

As brain expands, bones of calvaria are displaced
correspondingly outwards
Primary displacement causes tension in the sutural
membranes– immediateresponse– sutural edges
At same time new bone is also formed on the flat
surfaces– both, ecto- &endocranial

Arc of curvatureof thewholebonedecreasesand thebone
becomesflatter and remodeling not extensive.
Note: Endosteal surface is in contact with the dura, that
functionsasperiosteum, isnot aresorptivesurface. Thisis
an error in the older literature, sometime still encountered.

To summarise,
Increasein cranial width
Primarily through “fill-in” ossification of proliferating
connective
tissue in the coronal.lamboidal.interparital.paritosphenoidal
and paritotemporal sutures.
Increasein cranial length
Growth of the cranial base– active response at the coronal
suture
Increasein cranial height
Activity of parietal sutures along with occipital, temporal and
sphenoidal contiguousossiousstructureswww.indiandentalacademy.com

According to Davenport
Length of brain caseat different agesisasfollows:
Age Growth in %
Birth 63
6 months 76
1 year 82
2 year 87
3 years 89
5 years 91
10 years 95
15 years 98

Timing
Growth under theinfluenceof theexpansion of the
enclosed brain
Brain growth largely completed by early childhood
Cranial vault --- oneof thefirst regionsto attain full size
Sutural system provideextensiveadaptivecapabilitiesin
pathological conditionslikehydrocephalus
Cultural practiceslikehead binding

Theoretical and clinical issues
General agreement on themechanism of growth
Littleunderstading about control of cessation of sutural
growth
Clinical issues---- abnormal and anomalousgrowth
Hydrocephalus, cranial stenosis
Surgical intervention isthetreatment of choice

Basicranium
Functions
Adapted to upright thebody posture
Development of largecerebral hemispheres
Articulates the skull with vertebral column, mandible and
maxillary region
Buffer zonebetween brain, faceand pharyngeal region
Templatefor facial growth

Theneural sideof cranial floor different from calvaria
The endocranial surface of basicranium is resorptive in
most areas
Further, fossa enlargement is accomplished by direct
remodeling involving on the outside with resorption
inside.
Variouscranial fossae
Anterior
Middle
Posterior www.indiandentalacademy.com

Middle and posterior fossae divided by the petrous
elevation
Olfactory fossaeseparated by cristagalli
The right and left middle cranial fossae--- longitudinal
midlinesphenoidal elevation
Right and left anterior and posterior cranial fossae----
longitudinal midlinebony ridge
Note
all theseelevationsdepository in nature

Mechanism and Sites
Elongation at synchondroses
Cortical drift and remodeling
Sutural growth
Thiscombination provides
Differential growth enlargement between the cranial floor
and calvaria
Expansion of confined contours in the various endo
cranial fossae
Maintenance of passages and housing for vessels and
nerves

Midventral segment of cranial floor grows much slowly
than thefloor of thelaterally located fossae.
Expansion of hemispheres--- sutural growth and cortical
drift

Midlinepart ---- synchondroses
Retention left from primary cartilgesof chondrocranium

Synchondroses
Spheno-ethmoidal
Cartilaginousband between thesphenoid and ethmoid
bones.
Ossifiesby 5-25 years
Intersphenoidal
Cartilaginousband between 2 partsof sphenoid; ossifiesby
birth

Intra-occipital
Ossifiesby 3-5 years
Spheno-occipital
Principal growth cartilageduring childhood period
Providesapressureadapted bonegrowth mechanism

Bone remodeling seen in cranial base
1- resorption on the
anterior wall of middle
cranial fossa
2- deposition on the
orbital faceof sphenoid
3-anterior displacement of
ant. cranial fossa
4-Elevation of petrous
temporal bone
Lowering of the foramen
magnum
Perimeter of the foramen
enlarges www.indiandentalacademy.com

Timing
Show reduced rateof remodeling with thecompletion of
brain growth
Cranial synchondrosesarepaced differently
Compensatory mechanism
Basicranium considered oneof themost stablesturctures
of craniofacial skeleton
Hencediplayslesscompensatory growth copmared to
other structures

Theoretical and clinical issues
Various hypotheses proposed but the concept is still not
clear
How much of the basicranial changes are under the
influenceof functioning growth fields??
How much of it due to inherent growth potential of the
cartilages???
Skeletal basedysplasia---
affectsthegrowth of craniofacial structures
Neither surgical nor orthodontic means of treatment are
successful in eliminating theunderlying defect
Treatment rendered is only compensatory --- growth of
maxillaand mandiblealtered

Functions
Important rolein mastication (attachmentsof teeth and
muscles)
Providessignificant portion of airway
Housesolfactory nerveendings
Encloseseyes
Addsresonanceto thevoicethrough thesinusescontained
within theregion

Mechanismsand Sites
Growth observed at
Sutures
Nasal septum
Periosteal and endosteal surface
Alveolar process
According to Mills “maxilla increases in size by
subperiosteal activity postnatally

Maxilla
Thegrowth mechanism isproduced by
Displacement
Growth at sutures
Surfaceremodelling

Primary displacement
Active, downward and forward
Maxillary tuberosity lengthening posteriorly
Secondary displacement-
Passive, downward and forward direction
Cranial base– middlecranial fossagrowsanteriorly

Which is the biomechanical force underlying
the maxillary displacement??
Primary displacement- anterior and inferior asit growsand
lengthensposteriorly
Natureof thisdisplacement--- reviewed historically

Controversiesregarding maxillary displacement
Maxillary tuberosity

Bone growth within the various maxillary sutures
produces pushing-apart of the bones, with resultant thrust
of whole maxilla being displaced anteriorly and inferiorly
aswell.

Nasal septum theory – Scott
Pressure accomodating expansion of nasal septal
cartilage– sourceof physical force
Drawbacks
Sourceof displacement ismultifactorial
Experimental studies– surgical deletion affected the growth
process; not that they control growth process

Functional matrix concept
Facial bones grow in a sub-ordinate growth control
relationship with all surrounding, pace-making soft tissues
Note
Concept five
Operation of growth fields – carried out by osteogenic
membraneand other surrounding tissues

Growth at sutures
Fronto-nasal
Fronto- maxillary
Zygomatic-temporal
Zygomatico-maxillary
Pterygo-palatine
All areoblique; moreor lessparallel to each other
Downward and forward growth

Surfaceremodelling
Increasein size
Changein shape
Changein functional relationship

Resorption occurs on the lateral surface of orbital rim
leading to lateral movement of theeyeball
Floor of orbit-deposition in superior, lateral and anterior
direction

Bonedeposition along posterior margin of maxillary
tuberosity
Boneresorption occurson lateral wall of nose

Also on thefloor of thenasal cavity
Increasein height of maxilla

Faceenlargesby width
Asteeth upright alveolar height increases
Except mesial wall othersresorb – increasein sizeof
maxillary sinus

Zygomatic bonemovesin posterior direction.
Anterior nasal spine prominence increases due to bone
deposition

Maxillary height
Sutural growth toward thefrontal and zygomatic bones
Appositional growth towardsthealveolar process
Maxillary width
Growth in median sutures
Vertical drift of posterior teeth with lateral expansion---- alveolar
divergence
Mutual transverserotationsof maxillae--- separation of thehalves
moreposteriorly than anteriorlyMaxillary length
Apposition on themaxillary tuberosity
Sutural growth towardsthepalatinebonewww.indiandentalacademy.com

Well designed for adaptiveand compensatory growth
Most of it seen in alveolar process
In narrow palate, alveolar processcompensatesin height
and width
Skeletal classII still wefind Angle’sClassI molar relation

Mandible
Mandibleundergoesthelargest amount of growth post-
natally and also exhibitsthelargest variability
Thefunctional partsinclude-
Ramus
Corpus
Angleof mandible
Lingual tuberosity
Thealveolar process
Thechin

Functions
Mastication
Maintenanceof airway
Speech
Facial expression

Ramus
Function
Providesan attachment basefor masticatory muscles
Plays key role in placing the corpus and dental arch into
ever-changing fit with the growing maxilla and the
limitlessstructural variationsof face

Mechanismsand sites
Movesposteriorly ; combination of resorption and
deposition
Resorption –anterior ramuswhiledeposition posteriorly---
drift posteriorly
Functionsof remodel—
Accommodatetheincreasing massof masticatory
Enlarged breadth of pharyngeal space
Lengthening of corpus

Corpus
Asanterior border of ramusresorbs– posterior drift
Conversion of earlier ramusinto posterior part of the
body.
Thusbody of themandiblelengthens

Ramusto corpusremodeling conversion
Ramusrelocated in aposterior direction; Bony arch length
increased
Resorption of anterior border of ramus---- making room
for thelast molar
This is evident from tiny mandible of fetus till attainment
of adult size
Bicondylar dimension established much earlier in
childhood; bilateral growth separation between condyles
isminimal beyond early childhood years

Coronoid process
FollowsV principle
Lingual surfacefaces- 3 directions—posterior, superior
and medial
Lengthensvertically- V oriented vertically

Deposition occurson lingual surface
Also posterior movement seen – V oriented horizontally

Angleof themandible
Lingual side- resorption antero-inferiorly whiledeposition
postero-superiorly
Buccal sideviceversa
Thisresultsin flaring of mandible

Thelingual tuberosity
Direct equivalent of maxillary tuberosity
Boundary between ramusand body
Yet not included in thebasic vocabulary of
cephalometrics
Movesposteriorly by deposition on itsposteriorly facing
surface
Ideally max. tuberosity closely overlieslingual tuberosity

Protrudesnoticeably in alingual direction
A largeresorption field below it– lingual fossa
Tuberosity relocates posteriorly with only relatively slight
lateral shift
At the same time that part of the ramus just behind
remodels medially----- becomes part of corpus, thereby
lenghtening it.

Alveolar process
Developsin responseto tooth buds
Asteeth erupt thealveolar processerupt
Addsheight and thicknessto body of mandible

Chin
A specific human characteristic; recent man only
Asageadvancesthegrowth of chin becomessignificant
Sexual and genetic factors

Mechanism
Cartilageisspecial non-vascular tissue
Secondary typeof cartilage
Endochondral mechanism of bone formation—due to
variablelevelsof compression
Proliferative process – upward and backward growth of
condyle

Height
Ramusheight increasescorrelatewith corpuslength
Anterior mandibular height is related to dental
development and overall downward and forward growth
of mandible
Width
Bigonial and bicondylar diameter increase– divergence of
mandible
Most width increases as it grows longer (Enlow’s V
principle) www.indiandentalacademy.com

Length
By combination of resorption and deposition at theramus-
corpusinterface

Clinical implications

Facial form and anatomic basis for
malocclusions
Dolicocephalic facial form
Brain inhorizontally long and relatively narrow
Basicranium moreflat and horizontally longer
Nasomaxillary complex in aprotrusiveposition relativeto
mandible
Mandible– downward and backward rotation of entire
mandible
Occlusal plane rotated to adownward-inclined plane
Retrognathic profile--- ClassII molar relation

Brachycephalic
Brain – rounder and wider
Basicranium moreupright and short
Nasomaxillary complex isshort horizontally
Retrusivemaxillaand amorerelatively prognathic
mandible
Prognathic profile, ClassIII molar relarionship

Condyle
Anatomic part of special significance
Evolutionary changes
Earlier thought to bethemaster center; now aregional
field of gowth– regional adaptivegrowth

Interrelationship among brain form, facial profile&
occlusal typepredisposes--- facial form and malocclusion
Examples
Caucasian groups-dolichocephalic headform, ClassII
malocclusionsand retrognathic profile
Far-eastern population- brachycephalic headform, Class
III malocclusion and prognathic profile

Clinical implications of growth in 3
dimensions
Sequenceof growth cessation
Growth in width --- transverseplane
Growth in length ---- antero-posterior plane
Growth in height----- vertical plane

Transverseplane
Growth completed beforeadolescent growth spurt
Minimally affected by adolescent growth changes
Example 1: 13 year old girl with cross bite; transverse
growth ceased. Interceptiveproceduresruled out.
Role of midpalatal suture in lateral displacement of palatal
shelvesisminimal
Maxillary expansion even after suture closure should be
possible

Antero-posterior plane,
Jawsto continuethroughout puberty
For example,
13 yearold girl- orthognathic maxillaand retrognathic
mandible; myofunctional appliancescan begiven
In caseof retrognathic maxilla, protraction of maxillanot
indicated beyond 14 years

Vertical plane
Growth occursupto 18-19 years
Most common discrepancies
Open bite--- Skeletal / Dental
Deep bite--- Skeletal / Dental

Conclusion

CONCLUSION
It isimportant beforeunderstanding theabnormal to have
aclear ideaof thenormal way in which thefaceand its
component partsdevelop.
Sincethedentist and orthodontist aredeeply involved in
thedevelopment of not just thedentition but theentire
dentofacial complex, it isimportant to haveathorough
understanding of growth of dentofacial complex based on
which thepractitioner may ableto manipulatethefacial
growth to hisadvantageso asto achieveasuccessful
treatment outcome.

References
Craniofacial Development ------ Sperber
Contemporary Orthodontics---- Proffit
Essentialsof facial growth --- Enlow- Hans
Facial growth---- Enlow – Poston
Glossary of Orthodontic terms----John Daskalogiannakis
OrthodonticsPracticeand Principles– TM Graber
Scientific foundationsof Dentistry----Cohen
Text book of Orthodontics---- Bishara
Text book of Orthodontics---- Moyers

Post natal growth and development

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