Post Natal Growth and Development

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Post Natal Growth and
Development
INDIAN DENTAL ACADEMY
Leader in continuing dental education

Contents
Introduction
Terminologies
Concepts of growth
Osteogenesis
Regional development
Cranium
Nasomaxillary complex
Mandible


Contents
Clinical implications
Conclusion
References


What is post natal growth??
Post natal growth is the first 20 years of growth after
birth.
It compressed of 3periods;
How does it defer from prenatal growth??
Prenatal growth is characterized by a rapid increase
in cell numbers and fast growth rates
Postnatal growth is characterized by declining
growth rates and increasing maturation of tissues.

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


Terminologies
Deposition –
addition of new bone to the bony surface by
osteoblastic activity

Resorption – removal of bone due to 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 a certain 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’s growth concepts
Concept 0ne
facial growth and development is a morphogenic
process
In-depth understanding of facial morphogenesis
Normal Vs range of abnormal
Biologic reasons for these variations
Diagnosis, treatment planning
appropriate procedures

and

selection

of

Biologic factors underlying the problems of retention,
rebound and relapse

Concept two
Bones grow by adding new bone tissue
Surface facing towards direction of growth– deposition
Surface facing away--- resorption


Concept three
Mosaic-like pattern of growth fields
Example- outer periosteal has resorptive field then the
corresponding endosteal is depository and vice versa
These combinations produce characteristic growth


Concept four
Periosteal bone covers 50% of the cortical bone
Endosteal bone the remaining.


Concept five
Operation of growth fields – carried out by osteogenic
membrane and 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 have same rate of the growth activity
Fields with special significance play crucial role in the
growth process--- growth sites


Example:- mandibular condyle
During remodeling
resorption

bone

deposition


exceeds

Concept seven
Remodeling is the basic part of bone growth process

Why the bone must remodel ???
Its regional parts are moved from one location to
another as the bone enlarges
Example: ramus progressively moves posteriorly by a
combination of deposition and resorption.


Progressive, sequential movement of components as
a bone enlarges--- relocation
Relocation is the basis for 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, once the ramus occupied
earlier.
Growth and remodeling are in effect, inseparable parts
of the same actual process

Palate grows downwards by periosteal resorption on
nasal side and 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.
Some outside surfaces are thus necessarily resorptive


To summarize,
The process of growth remodeling accelerated by
the composite of soft tissue are to
Progressively enlarge each whole bone
Sequentially relocate each of the component parts of
the whole bone to 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
Bones remodel 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 bones in direct contact with it.
The space, thus created is utilized for the bony
enlargement and the process--- primary displacement
/ translation.


Example 1:
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 tissues in the mid-facial region


Example 2
The whole mandible is displaced away from its
articulation in each glenoid fossa
Condyle and ramus, grow upward and backward


Note
The ramus remodels and becomes wider
longer
The increasing mass of 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

enlargement of maxilla itself.


growth

and

To summarize,
Overall skeletal growth process has two 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 structure and to occupy the
location it does.

Concept ten
Facial growth:
Requires intimate morphogenic interrelationship
among all of its component growing, changing and
functioning soft and hard tissue parts.

No part is developmentally independent and selfcontained
Growth process works towards an ongoing state of
composite functional and structural equilibrium.


Other concepts
Cephalocaudal growth
Scammon’s growth curve

Enlow’s counterpart principle


Cephalocaudal gradient of growth


Cephalocaudal gradient
It represents the changes in overall body proportion
during normal growth and development
In third month of IUD head takes almost 50%of total
body length.
At birth;head -39%of total body length
In adults;head-12%of total body length.
Trunk and limbs grow faster than head and face


Differential growth[scammon’s growth
curve]


scammon’s growth curve
Different tissue in body grow at different times and different
rates.
Neural tissues-complete 90% of growth at 6years and 98% by
10 years of age.
Lymphoid tissues-proliferates rapidly in late childhood and
reaches allmost 200%of adult size.by about 18 years of age the
tissues undergoes involution to reach adult size.
General tissues-it has muscle bone an organ exhibit a S
shaped curve with rapid growth upto 2-3 years of age follows by
slow phase of growth between 3-10years .after 10 years a
rapid phase of growth occurs terminating by 18-20 years.
Genital tissue;grow rapidly at puberty leading adult size after
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 relationships exist ---craniofacial region
Balanced growth = Regional and corresponding
counterparts
enlarge to same extent

Imbalance in
differences in

regional

relationship

Amount of growth
Direction


is

due

to

Different parts and their counterparts
Part

Counterpart

Palate

Anterior cranial fossa

Middle cranial fossa

Ramus of the mandible

Maxillary arch

Mandibular arch

Maxillary tubeosity

Lingual tuberosity

Bony maxilla

Corpus of the mandible


Osteogenesis
Mechanism of bone formation
Endochondral
Intramembranous


Five steps to Endochondral bone
formation
Hypertrophy of chondrocytes and matrix calcifies
Invasion of blood vessels and the connective tissue
Osteoblasts differentiate and produce osteoid tissue
Osteoid tissue calcifies

Membrane covers bone and is essential


Five steps to Intramembranous bone
formation
Osteoblasts produce osteoid tissue
Cells and blood vessles are encased
Osteoid tissue is produced by membrane cells
Osteoid calcifies

Essential membrane covers the bone


Comparison of selected physiologic
properties of bone and primary cartilage
important during growth
Characteristic Cartilage
s
Calcification Non-calcified

Bone

Vascularity

Non-vascular

Vascular

Surface
membrane
Rigidity

Non-essential

Essential

Flexible

Inflexible

Pressure
resistance

Tolerant to
Sensitive to
pressure
pressure

Calcified

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


Cranium
Cranial vault

Basicranium


Cranial vault
Functions: protection of brain- primary function
Growth
1)Mechanisms and sites
Cranium grows ---as brain grows
Accelerated during infancy, 90% of it is complete by
5th year


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


Arc of curvature of the whole bone decreases and
the bone becomes flatter and remodeling not
extensive.
Note: Endosteal surface is in contact with the dura,
that functions as periosteum, is not a resorptive
surface. This is an error in the older literature,
sometime still encountered.


To summarise,

Increase in cranial width
Primarily through “fill-in” ossification of proliferating
connective
tissue
in
coronal.lamboidal.interparital.paritosphenoidal
paritotemporal sutures.

the
and

Increase in cranial length
Growth of the cranial base– active response at the
coronal suture

Increase in cranial height
Activity of parietal sutures along with occipital, temporal

According to Davenport
Length of brain case at different ages is as follows:
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


Growth of the braincase
in
width
(no.
of
mm/year)

Age

Cranial
width

First 9
months
(prenatal)
6 months
(postnatal)
6-12

100 mm

1-2 years

+9mm

2-3 years

+1.5mm


+50mm
+20mm

Timing
Growth under the influence of the expansion of the
enclosed brain
Brain growth largely completed by early childhood
Cranial vault --- one of the first regions to attain full
size
Sutural system provide extensive adaptive
capabilities in
pathological conditions like hydrocephalus
Cultural practiceswww.indiandentalacademy.com
like head binding

Theoretical and clinical issues
General agreement on the mechanism of growth
Little understading about control of cessation of
sutural growth
Clinical issues ---- abnormal and anomalous growth
Hydrocephalus, cranial stenosis
Surgical intervention is the treatment of choice


Basicranium
Functions
Adapted to upright the body posture
Development of large cerebral hemispheres

Articulates the skull with vertebral column, mandible
and maxillary region
Buffer zone between brain, face and pharyngeal

region
Template for facial growth

The neural side of 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.
Various cranial fossae
Anterior
Middle
Posterior


Middle and posterior fossae divided by the petrous
elevation
Olfactory fossae separated by crista galli
The right and left middle cranial
longitudinal midline sphenoidal elevation

fossae---

Right and left anterior and posterior cranial fossae---longitudinal midline bony ridge

Note
all these elevations depository in nature

Mechanism and Sites
Elongation at synchondroses
Cortical drift and remodeling
Sutural growth
This combination 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 the floor of the laterally located fossae.
Expansion of hemispheres--- sutural growth and
cortical drift


Midline part ---- synchondroses
Retention
left
chondrocranium

from

primary


cartilges

of

Synchondroses
Spheno-ethmoidal
Cartilaginous band between the sphenoid and ethmoid
bones.
Ossifies by 5-25 years

Intersphenoidal
Cartilaginous band between 2 parts of sphenoid;
ossifies by birth


Intra-occipital
Ossifies by 3-5 years

Spheno-occipital
Principal growth cartilage during childhood period
Provides a pressure adapted bone growth mechanism


Bone remodeling seen in cranial base
1- resorption on the
anterior wall of middle
cranial fossa
2- deposition on the
orbital face of 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 rate of remodeling with the
completion of brain growth
Cranial synchondroses are paced differently
Compensatory mechanism
Basicranium considered one of the most stable
sturctures of craniofacial skeleton
Hence diplays less compensatory 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
influence of functioning growth fields??
How much of it due to inherent growth potential of the
cartilages???

Skeletal base dysplasia--affects the growth of craniofacial structures
Neither surgical nor orthodontic means of treatment
are successful in eliminating the underlying defect
Treatment rendered is only compensatory --- growth of
maxilla and mandible altered

Functions
Important role in mastication (attachments of teeth
and muscles)
Provides significant portion of airway
Houses olfactory nerve endings
Encloses eyes
Adds resonance to the voice through the sinuses
contained within the region


Mechanisms and 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
The growth mechanism is produced by
Displacement
Growth at sutures
Surface remodelling


Primary displacement
Active, downward and forward
Maxillary tuberosity lengthening posteriorly

Secondary displacementPassive, downward and forward direction
Cranial base– middle cranial fossa grows anteriorly
Important during primary dentition periods


Which is the biomechanical force
underlying the maxillary displacement??
Primary displacement- anterior and inferior as it grows
and lengthens posteriorly
Nature of this displacement--- reviewed historically


Controversies regarding 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 as well.


Nasal septum theory – Scott
Pressure accomodating expansion of nasal septal
cartilage– source of physical force
Drawbacks
Source of displacement is multifactorial

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
membrane and other surrounding tissues


Growth at sutures
Fronto-nasal
Fronto- maxillary
Zygomatic-temporal
Zygomatico-maxillary
Pterygo-palatine

All are oblique; more or less parallel to each
other
Downward and forward growth

Surface remodelling
Increase in size
Change in shape
Change in functional relationship


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


Bone deposition along posterior margin of maxillary
tuberosity
Bone resorption occurs on lateral wall of nose


Also on the floor of the nasal cavity
Increase in height of maxilla


Face enlarges by width
As teeth upright alveolar height increases
Except mesial wall others resorb – increase in size
of maxillary sinus


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


Maxillary height
Sutural growth toward the frontal and zygomatic bones
Appositional growth towards the alveolar process
Maxillary width
Growth in median sutures
Vertical drift of posterior teeth with lateral expansion---- alveolar
divergence
Mutual transverse rotations of maxillae--- separation of the
halves more posteriorly than anteriorlyMaxillary length
Apposition on the maxillary tuberosity
Sutural growth towards the palatine bone

Well designed for adaptive and compensatory
growth
Most of it seen in alveolar process
In narrow palate , alveolar process compensates in
height and width
Skeletal class II still we find Angle’s Class I molar
relation


Mandible
Mandible undergoes the largest amount of growth
post-natally and also exhibits the largest variability
The functional parts includeRamus
Corpus
Angle of mandible
Lingual tuberosity
The alveolar process
The chin


Functions
Mastication
Maintenance of airway
Speech
Facial expression


Ramus
Function
Provides an attachment base for masticatory
muscles
Plays key role in placing the corpus and dental arch
into ever-changing fit with the growing maxilla and
the limitless structural variations of face


Mechanisms and sites
Moves posteriorly ; combination of resorption and
deposition
Resorption –anterior ramus while deposition
posteriorly---drift posteriorly

Functions of remodel—
Accommodate the increasing mass of masticatory
Enlarged breadth of pharyngeal space
Lengthening of corpus


Corpus
As anterior border of ramus resorbs – posterior drift
Conversion of earlier ramus into posterior part of the
body.
Thus body of the mandible lengthens


Ramus to corpus remodeling conversion
Ramus relocated in a posterior direction; Bony arch
length increased
Resorption of anterior border of ramus---- making
room for the last 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 is minimal beyond early childhood years

Coronoid process
Follows V principle
Lingual surface faces- 3 directions—posterior,
superior and medial
Lengthens vertically- V oriented vertically


Deposition occurs on lingual surface
Also posterior movement seen – V oriented
horizontally


Angle of the mandible
Lingual side- resorption antero-inferiorly while
deposition postero-superiorly
Buccal side vice versa
This results in flaring of mandible


The lingual tuberosity
Direct equivalent of maxillary tuberosity
Boundary between ramus and body
Yet not included in the basic vocabulary of
cephalometrics
Moves posteriorly by deposition on its posteriorly
facing surface
Ideally max. tuberosity closely overlies lingual
tuberosity


Protrudes noticeably in a lingual direction
A large resorption 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
Develops in response to tooth buds
As teeth erupt the alveolar process erupt
Adds height and thickness to body of mandible


Chin
A specific human characteristic; recent man only
As age advances the growth of chin becomes
significant
Sexual and genetic factors


Condyle
Anatomic part of special significance
Evolutionary changes
Earlier thought to be the master center; now a
regional field of gowth– regional adaptive growth


Mechanism
Cartilage is special non-vascular tissue
Secondary type of cartilage
Endochondral mechanism of bone formation—due to
variable levels of compression
Proliferative process – upward and backward growth
of condyle


Height
Ramus height increases correlate with corpus length
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)

Length
By combination of resorption and deposition at the
ramus-corpus interface


Clinical implications


Facial form and anatomic basis for
malocclusions
Dolicocephalic facial form
Brain inhorizontally long and relatively narrow
Basicranium more flat and horizontally longer
Nasomaxillary complex in a protrusive position
relative to mandible
Mandible – downward and backward rotation of
entire mandible
Occlusal plane rotated to a downward-inclined plane
Retrognathic profile--- Class II molar relation

Brachycephalic
Brain – rounder and wider
Basicranium more upright and short
Nasomaxillary complex is short horizontally
Retrusive maxilla and a more relatively prognathic
mandible
Prognathic profile, Class III molar relarionship


Interrelationship among brain form, facial profile &
occlusal type predisposes --- facial form and
malocclusion
Examples
Caucasian groups-dolichocephalic headform, Class
II malocclusions and retrognathic profile
Far-eastern population- brachycephalic headform,
Class III malocclusion and prognathic profile

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


Transverse plane
Growth completed before adolescent growth spurt
Minimally affected by adolescent growth changes
Example 1: 13 year old girl with cross bite; transverse
growth ceased. Interceptive procedures ruled out.
Role of midpalatal suture in lateral displacement of
palatal shelves is minimal
Maxillary expansion even after suture closure should be
possible


Antero-posterior plane,
Jaws to continue throughout puberty
For example,
13 yearold girl- orthognathic maxilla and retrognathic
mandible; myofunctional appliances can be given
In case of retrognathic maxilla, protraction of maxilla
not indicated beyond 14 years


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

Skeletal

Dental

Open bite

FMP angle
>250

Deep bite

<250

Infra erupted
incisors, supra
erupted molars
Vice versa


Conclusion


CONCLUSION
It is important before understanding the abnormal to
have a clear idea of the way the face and its
component part develop.since the dentist and
orthodontist are heavily involved in the development
of not just the dentition but the entire dentofacial
complex,practitioner may able to manipulate the
facial growth for the benefit of the patient,
We do not fully understand the factors which control
the amount and direction of growth.


References
Craniofacial Development ------ Sperber

Contemporary Orthodontics---- Proffit
Essentials of facial growth --- Enlow- Hans
Facial growth---- Enlow – Poston

Glossary of Orthodontic terms----John
Daskalogiannakis
Orthodontics Practice and Principles– TM Graber

Scientific foundations of Dentistry----Cohen
Text book of Orthodontics---- Bishara
Text book of Orthodontics---- Moyers

Thank you
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