Terminologies and basic concepts of growth and development /certified fixed orthodontic courses by Indian dental academy

TERMINOLOGIES AND BASIC
CONCEPTS OF GROWTH AND
DEVELOPMENT.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


1

“Growth was conceived by an anatomist,
born to a biologist, delivered by a
physician, left on a chemist’s door step
and adopted by a physiologist. At an early
age she eloped with a statistician,
divorced him for a psychologist and is now
being wooed, alternately and concurrently,
by an endocrinologist, a pediatrician, a
physical anthropologist, an educationalist,
a biochemist, a physicist, a
mathematician, an orthodontist, a
eugenicist and the children’s bureau!”

2

INTRODUCTION
Knowledge about normal growth and how it
occurs is essential so that one can distinguish
any deviation.
To know about the timing of growth so that one
can “Work with growth”.


3

Growth and development are closely related but
not synonymous.
What is growth?
“Growth” is a general term implying simply that
something changes in magnitude.
How and what actually happens is explained by a
more descriptive term development.


4



“Growth refers to increase in size” Todd



“Growth may be defined as the normal
change in the amount of living substance”Moyers



“Growth usually refers to an increase in
size and number” – Proffit

5







“Change in any morphological parameter
which is measurable”- Moss.
“Size development , progressive
development (i.e, evolution, emergence,
increase or expansion)”- Webster’s
dictionary.
“Self multiplication of living substance”J.S.Huxley.

6

Development
Development=
Growth
+
Differentiation: change from generalized cells/tissues
+
to more specialized kind
Translocation: change in position


7

Development is a progress towards maturity” –
Todd
“Development refers to all naturally occurring
progressive, unidirectional, sequential
changes in the life of an individual from it’s
existence as a single cell to it’s elaboration as
a multifunctional unit terminating in death” –
Moyers
“Development connotes a maturational process
involving progressive differentiation at the
cellular and tissue levels” – Enlow

8

Major themes of development





Changing complexity
Shifts from competent to fixation
Shifts from dependent to independent
Ubiquity of genetic control modulated by
environment


9

Changing complexity






Takes place at all level of organization from the
sub-cellular to the whole organism
Normally complexity increases with
development .
Most complex period of developing dentition is
transition of dentitions.

10

Shifts from competent to fixation


Undifferentiated cells once differentiated
become fixed.

Shifts from dependent to
independent


Development brings greater independence at
most levels of organization.

11

Ubiquity of genetic control
modulated by environment


Genetic control of development is
constantly being modified by
environmental interactions


12

Correlation between growth and
development
Growth is largely an anatomic phenomenon and
quantitative in nature.
Development is a physiologic and behavioral
phenomenon and qualitative in nature.
The two processes rely on each other and under
the influence of the morphogenetic pattern, “the
three fold process”- self multiplication,
differentiation, organization growth and
development occurs, time being the fourth
13
dimension.

Morphogenesis – “A biologic process having
an underlying control at the cellular and tissue
levels.”

Control process intervened at the right time and
stage-augments, overpowers, replaces
activities .
Rate, timing, direction and magnitude are altered.
Morphogenesis works towards a state of balance
among all growing parts.


14


15

Important concepts in growth and
development






Pattern
-Differential growth
-Predictability
Variability
-Concept of normality
-Age equivalence
Timing


16

PATTERN




Pattern represents proportionality-not just
proportional relationships at a point in time
but change in these relationships over
time.
Can be defined as-a set of constraints
operating to preserve the integration of
parts under varying conditions or through
time.
17

Cephalocaudal gradient of growth


18





The accomplishment of normal human proportions is
not merely due to a general slowing down. Different
tissues grow at different rates at different times.
The overall pattern of growth is a reflection of the
growth of the various tissues making up the
organism.

19

Differential growth



Scammon’s curves for growth.
Gave a graph for four major tissues of the
body.
-lymphoid
-neural
-general
-genital


20

Body Composition Changes with Age
STRUCTURE

FETUS

NEW BORN

ADULT

Skin & fat

16 %

26 %

25 %

Viscera

16 %

16 %

11 %

Nervous
system
Muscle

21 %

15 %

03 %

25 %

25 %

43 %

Skeleton

22 %

18 %

18 %


21

Predictability




Predictability of growth pattern is a specific
kind of proportionality that exists at a particular
time and progresses towards another, at the
next time frame with slight variations.
Any change in growth pattern would indicate
some alterations in the expected changes in
body proportions.


22

Variability


No two individuals with the exception of
monozygotic twins are alike.



Clinically important to identify if an individual is
at the extreme of normal variation or is outside
the range.



What is normal?

23

Normality




Normality refers to that which is usually
expected, is ordinarily seen or typical – Moyers

Normality may not necessarily be ideal so rather
than categorizing as normal or abnormal one
can think of deviations from the normal pattern.


24



One way to evaluate normality is using growth
charts.



Used to determine if growth is normal in 2 ways-

-

location of the individual relative to the group.

- follow a child’s growth to evaluate any
unexpected changes.


25


26

Age equivalence


Because of variability all individual at a given
chronological age are neither of the same size
or same stage of maturation.



It is better to compare biologic development.



“Developmental ages” –skeletal age and dental
age are used.

27

Timing






One of the factors for variability in growth.
Timing variations arise because biologic clock of
different individuals is set differently.
Timing-largely genetically controlled.
-sex related differences
-physical differences
-environmental

28



Variation in growth and
development because of
timing are evident in
human adolescence.



Plotting change in weight
or height shows the
pattern of growth.



The distance and velocity
graphs can be plotted and
compared.

29





Growth effects
due to timing
variation
demonstrated
using growth
velocity curves.

Time variability is
reduced if graph
plotted using
developmental
age.


30

Growth spurts





Periods of sudden acceleration of growth.
Due to physiological alteration in hormonal
secretion.
Timing-sex linked.
Normal spurts are
 Infantile

spurt – at 3 years age

 Juvenile

spurt – 7-8 years (females); 8-10

years (males)
 Pubertal

spurt – 10-11 years(females); 15-

18 years (males)

31


32



Pubertal growth spurt:



Important period for orthodontic treatment.



Initiated in the brain-secretion of releasing
factors, pituitary gonadotropins.



Sex hormones released-physiological changes
occur-classic growth cure pattern.



Timing -2 years earlier in girls.



Affected by genetic and environmental factors.


33

GIRLS
Total development of adolescent growth- 3½yrs
Stage 1
Beginning of adolescent
growth

Appearance of breast buds,
initial pubic hair

Stage 2

Noticeable breast
development, axillary hair,
dark/more abundant pubic
hair.

(12 months later)
Peak velocity in height.
Stage 3
(12-18 months later)
Growth spurt ending.

Menses, broadening of hips
with adult fat distribution,
breasts completed


34

BOYS
Total development of adolescent growth- 5 yrs
Stage 1
Beginning of adolescent growth
Stage 2
(12 months later)

Fat spurt, weight gain, feminine fat
distribution
Redistribution or reduction in fat,
pubic hair, growth of penis

Height spurt beginning
Stage 3
(8-12 months later)
Peak velocity of height.
Stage 4
(15-24 months later)
Growth spurt ending

Facial hair appears on upper lip
only, axillary hair, muscular
growth with, harder/more angular
body form
Facial hair on chin and lip, adult
distribution/colour of pubic and
axillary hair, adult body form.

35

Velocity curves in for growth at adolescence
shows difference in timing between boys and
girls.


36



Growth of the jaws correlates with physiologic
events of puberty –same as height.


37







But correlation is not perfect –juvenile
acceleration of jaw growth occurs.
Sex hormones are produced in adrenals by 6
years- ‘adrenarche’.
More prominent in girls due to greater adrenal
component.


38



Important clinically-careful assessment of
physiologic age-plan orthodontic treatment.



Treatment must begin during



mixed dentition-for girls.



Near completion of permanent dentition-for
boys-Proffit.



But according to Graber, boys have a greater
tendency for 3 peaks than girls-very few girls
show the mixed dentition growth spurt.

39

Nature of skeletal growth


At cellular level there are three
mechanisms for growth.
–Hyperplasia
–Hypertrophy
–Secretion of extracellular matter


40

Mechanism of growth in
soft tissues


In soft tissues growth occurs mainly by a
combination of two mechanisms namely:

Hyperplasia-increase in the number of
parenchymal cells.
Hypertrophy-increase in size of parenchymal cells.
Secretion of extracellular material also contributes
to growth-but different from hard tissue growth
as it does not mineralize.

41







Hyperplasia is the main mechanism hypertrophy
occurring secondarily.
Interstitial growth-growth occurring at all points
in a tissue.
Also occurs in uncalcified cartilage.



Abnormalities in soft tissue growth-



Metaplasia



Dysplasia -disordered cellular development.

42

Mechanism of hard tissue growth






Two mechanisms

Endochondral bone formation: Process of
converting cartilage into bone
Intramembranous bone formation: Process of
bone formation from undifferentiated
mesenchymal tissue.

43

Endochondral bone growth


Chondrogenesis- starts around 2-18 weeks.

-Thin plate of cartilage extends from nasal cavity to
foramen magnum.
-4th month in-utero ingrowth of vascular elementscenters of ossification appear.
-occurs till the rate of mineralization exceeds the
rate of proliferation
-Growth cartilages appear where linear growth of
bone towards the force area occurs.

44


45

Primary cartilage-local factors do not influence as
there is a cartilagenous matrix-spheno-occipital
synchondrosis, nasal septal cartilage.
Secondary cartilage-local factors modulate growthcondylar and coronoid cartilage.


46

Comparison of physiologic
properties of bone and cartilage









Characteristic

cartilage

Calcification
Non calcified
Vascularity
Avascular
Surface membrane
Nonessential
Pressure resistance Tolerant
Rigidity
Flexible
Modes of growth
Interstitial
and appositional


bone
Calcified
Vascular
Essential
Sensitive
Inflexible
Appositional

47
















Endochondral bone growth occurs in areas of
increased compression
It does not form directly from cartilage but
replaces it.
Steps in bone formation:
Hypertrophy of chondrocytes and matrix calcifies
Cells degenerate
Invasion of blood vessels and connective tissue
cells.
Osteoblasts differentiate and produce osteoid
tissue.
Osteogenic tissues replace degenerating
cartilage.
osteoblastic tissue calcifies.

48


49


50


51

Intramembranous bone growth







Occurs in areas of tension.
The membranes have their own internal
deposition and remodeling mechanism.
Formed entirely by apposition of new bone to
free surfaces.
Any change is through resorption and
apposition.
Seen in areas like
 Cranial vault
 Maxilla
 Mandible except condylar cartilage

52

Steps in intramembraneous bone
growth










Undifferentiated connective tissue
undergoes series of changes.
Some cells develop into
osteoblasts.
Osteoblasts produce osteoid tissue.
Cells and blood vessels are
encased.
Osteocytes are formed
Osteoid tissue continues to be
produced by membrane cells.
Osteoid calcifies.
Essential membrane covers bone.

53


54

Bone metabolism








Biomechanical response to altered function and
applied loads depends on the metabolic status
of the patient.
Biomechanical manipulation of bone is the
physiologic basis of orthodontics.
99% of calcium is stored in the skeleton.
Endocrine, biomechanical and cell level control
factors maintain serum calcium at 10mg/dl

55

Calcium homeostasis


Orthodontics is bone manipulative
therapy-favorable calcium metabolism is
important.


56



Calcium homeostasis is supported by 3
mechanisms :



Rapid instantaneous flux of calcium from
bonefluid (seconds) by selective transfer of
calcium ions into and out of bone fluid-PTH
and vit D



Short term control of serum calcium levels
affects rates of bone formation and resorptionPTH,1,25 DHCC and calcitonin.

57



Long term regulation of metabolism have effects
on skeleton.

Clinical correlation is the high bone remodeling rate seen
at the interface of a titanium implant used for anchorage in
adults.
58

Types of Bones







Woven bone – The first bone formed in response
to orthodontic loading usually is the woven type.
It is weak, disorganized, and poorly mineralized
Lamellar bone – a strong, highly organized, wellmineralized tissue.
Makes up 99% of adult human skeleton.
secondary mineralization takes 1 year.
Full strength of bone not achieved till a year
after orthodontic treatment.

59









Composite bone – is an osseous tissue formed
by the deposition of lamellar bone within a
woven bone lattice, a process called Cancellous
compaction. This is the quickest means of
producing relatively strong bone.
Important type in physiologic response to
orthodontic loading.
Bundle bone - is a functional adaptation of
lamellar structure to allow attachment of tendons
and ligaments’
Sharpey’s fibers.

60


61

TERMINOLOGIES AND BASIC
CONCEPTS OF GROWTH
AND DEVELOPMENT.

DR.MEENAKSHI VISHWANATH

62

Mechanisms of Bone Growth and
Growth Movements.








Remodeling.
-Cortical drift.
Displacement .
Combination of remodeling and
displacement.
Modeling.
Rotation.

63

Remodeling




It is a differential growth
activity involving
deposition at one end
and resorption at the
other.
It is a basic part of
growth process.


64

Functions of Remodeling
1.

2.

3.

Sequentially relocate each component of the
whole bone
Progressively change the shape of the bone to
accommodate its various functions
Progressively change the size of whole bone


65

4. Progressive fine tune fitting of all the separate
bones to each other and to their contiguous
growing, functioning soft tissues .
5. Carry out continuous structural adjustments to
adapt to the intrinsic and extrinsic changes in
conditions.


66



Natural perception of growth-

 But a generalized

growth does not occurRemodeling in specific
areas causes change in
shape and size.

67

Deposition and Resorption
•Bone produced by covering
membrane-periosteal bone
comprises about half of the
cortical bone tissue. Bone laid
down by the lining membraneendosteal bone makes up the
other half.
•Rotations occur if the rates of
deposition and resorptions are
unequal.

68



Cortical drift.

Drift

•It occurs during remodeling, resulting in
movement of bone towards the depository
surface.

Vertical drift-

- Helps to anatomically place teeth as maxilla
and mandible enlarge.
- This vertical positioning of teeth is in addition
to eruption and not part of it.

69

Enlow’s “V” principle




Most useful and basic concept in facial growth
as many facial and cranial bones have a Vshaped configuration.
Bone deposition(+) occurs on the inner side and
resorption (-) occurs on the outer surface.


70

The direction of
movement is towards
the wide end of ‘v’.
Simultaneous growth
movement and
enlargement occurs.
Conversion of a more
wider part to a narrower
one.

71

Example with V oriented vertically and
horizontally


When bone added on lingual
side of coronoid process,
growth proceeds and this part of
the ramus increases in vertical
dimension.

Same deposits of bone also
bring about a posterior direction
of growth movement.
This produces a backward
movement of coronoid processes
even though deposit is on the
lingual side.

72

‘V’ principle applied
to the mandible
causes increase in
both posterior and
superior directions.

Causes an increase
in the transverse
dimension of the
maxilla .Increases
the airway space.


73

Transverse
histologic section
of bone:
A. Periosteal surface reorptive,
endosteal surface depository.
B. New endosteal bone added
on inner surface.
C. Endosteal layer produced
covered by periosteal layer
following outward reversal.
D. Cortex made entirely of
periosteal bone. outer surface
depository and inner surface
resorptive.

74

Types of remodeling.
4 types1.Biochemical remodeling-molecular levelmaintains calcium levels.
2.Secondary reconstruction of bone-by Haversian
systems and rebuilding of cancellous bone.
3.Pathologic remodeling-occurs after disease or
trauma.
4.Growth remodeling



75

Displacement








Displacement is a physical movement of the
whole bone as it remodels.
Occurs in conjunction with remodeling where
joints are present.
Articulations are areas ‘away’ from which the
displacement movements occur as the bone
enlarges.
Amount of enlargement equals extent of
displacement.

76


77







There are 2 types of displacement.
Primary displacement-the process of physical
carry takes place in conjunction with bone’s own
enlargement.
The amount of displacement exactly equals
amount of new bone deposition.


78





Secondary displacement-movement of bone
occurring due to growth elsewhere.
E.g.-growth of the middle cranial fossa and the
temporal lobes secondarily displaces the
nasomaxillary complex anteriorly and inferiorly.


79



“Domino effect”growth changes can
be passed on from
region to region
having effect at a
distant site.


80

Combination of remodeling and
displacement.




Multidirectional growth movements involve
remodeling ,primary and secondary
displacement.
Comparable results can be produced by different
combinations.


81

As the bone remodels, though the outer surface is
resorptive it is being carried forward by primary and
secondary displacement.


82

Principle of ‘Area relocation’
Both remodeling and
displacement together
cause a shift in the
existing position of a
particular structures with
reference to another.


83

Translation and Transformation


84

Modeling






According to Roberts et almodeling and remodeling are 2
distinct phenomena.
In bone modeling independent
sites of resorption and
formation change the form
(shape, size or both) of a
bone.
Bone remodeling is a specific,
coupled sequence of
resorption and formation
occurring to replace previously
existing bone.

85









Bone modeling is the dominant process of facial
growth and adaptation to applied loads such as
headgears, rapid palatal expansion, and
functional appliances.
Modeling changes can be seen on
cephalometric tracings.
Remodeling changes are apparent only at
microscopic level.
The mechanism for internal remodeling of dense
compact bone is through axially oriented cutting
and filling cones.

86

Cutting and filling cones


87

Frost’s Mechanostat Theory.


This concept is based on a idea that bone
adaptive response is modulated by mechanical
environment with several different mechanical
usage windows.


88

Controlling factors for modeling


Mechanical
Peak load in µE
1. Disuse atrophy
<200.
2. Bone Maintenance
200—2500.
3. Physiological Hypertrophy
2500—4000.
4. Pathological Overload
>4000.
Endocrine.
1.Bone metabolic hormones-PTH,Vit D,Calcitonin.
2.Growth Hormones-Somatotropin,IGF -1,IGF -2.
3.Sex steroids-Testosterone, Estrogen.

89



Paracrine and Autocrine-wide varity of local
agents.

Control factors for bone remodeling.
 Metabolic
a. PTH-increases activation frequency.
b. Estrogen- decreases activation frequency.
 Mechnical
a.<1000 µE, more remodeling
b. >2000 µE, less remodeling



90

Counter part principle


Growth of any given facial or cranial part relates
specifically to other structural and geometric
counterparts in the face and cranium” - Enlow


91

Growth equivalent principle
This principle proposed by Hunter & Enlow
relates the effects of cranial base growth on
the facial bone Growth.


92


93

Growth rotation





Phrase introduced by Bjork in
1955.

2 basic categories of rotations-Remodeling rotations. -


94

Displacement rotations.
Whole nasomaxillary complex
rotates clockwise or
counterclockwise depending
on the activities of the
overlying basicranium.
 Mandible also rotates in
accordance to the
nasomaxillary positions.
 Adjustive remodeling rotations
is simultaneously occurring.



95

Growth Fields






Inside and outside of every
bone are covered by an
mosaic like pattern of ‘growth
fields’.
Both depository and
resorptive surfaces are
present-if a given periosteal
area is resorptive then the
opposite endosteal surface
will be depository.
These combinations produce
the characteristic drift.

96







The irregularity is a
response to the varied
functions imposed on the
bone by various
attachments.
The operation of the
growth fields is carried
out by membranes
surrounding the hard
tissue.
The various depository
and resorptive fields do
not have the same rate of
activity.

97





The growth movement
of the bone follows the
pace setting movement
of the overall growth
field.
Important to understand
the plan of distribution of
the major growth fields
as these patterns can
show us if we are
working with or against
growth.

98





Ex. Distalization of maxillary molars putting them
into a depository field or labial placement of
lower anteriors into a resorptive field.
Variations in the facial structure can be due to a
change in-Pattern of the fields.
-Placement of the boundaries.
-Rates and amounts of deposition and
resorption.
-Timing of growth activity among different fields.


99

Growth Site and Growth Center






A site of growth is merely a location where
growth occurs.
Center is a location where independent
growth occurs.
All centers of growth are also sites, but the
reverse is not true.


100

Growth sites


Growth fields having special role in the
growth of the particular bone are called
growth sites .


101

E.g. mandibular condyle, maxillary tuberosity,

synchondrosis of the basicranium, sutures and the
alveolar process.




Such special sites do not carry out the entire growth
process for the particular bone associated with them.
All other surfaces also actively participate.


102

Growth Center
 Force, energy or motor for a

bone resides primarily within its
growth centre.



According to Baume it can be
described as ‘Places of
endochondral ossification with
tissue separation force’.


103





This concept especially when applied to
the craniofacial region is not completely
accepted.
Mandibular condyle and synchondroses of
the cranial base are still controversial.


104

GROWTH STUDIES AND
METHODS OF STUDYING
GROWTH.


Types of growth data.



Methods of gathering growth data.



Longitudinal growth studies.



Methods of studying bone growth.

105

Types of growth data.
 Opinion
 Observations.
 Ratings

and rankings.
 Quantitative measurements.

direct data.

indirect data.

derived data.


106





Opinion .
Not based on no quantitative data.
They are the crudest form of scientific
knowledge.

 Observations:

They are useful for studying all or none
phenomenon .They are used in a limited way when
more quantitative data is available. E.g. congenital
absence of teeth.


107








Ratings and rankings:
Certain data is difficult to quantify and thus
may be compared to conventional rating scale .
Ratings make use of comparisons with such
scales.
Rankings array data in ordered sequence
according to value.


108










Quantitative measurements:
Includes expressing an idea or fact as a
meaningful quantity or numbers.
Direct data: Derived from measurements taken on
living persons or cadaver with a measuring device.
Indirect data: Derived from measurements taken
from images or reproductions of the actual person.
Derived data: Obtained by comparing at least two
other measurements.

109

Methods of gathering growth data.


Longitudinal studies .



Cross sectional studies.



Overlapping or semi longitudinal studies.


110

Longitudinal studies












These are measurements made of the same
person or group at regular intervals through
time.
Advantages :
Variability in development within a group is put
in proper perspective
Serial comparison makes study of specific
developmental pattern of individual possible.
Temporary temporal problems in sampling are
smoothed with time.
Disadvantages :
Time consuming, expensive, sample loss or
attrition, averaging.
111

Cross sectional studies.











These are measurements made of different
samples or different individuals and studied at
different periods.
Advantages: Quicker, less expensive, statistical
treatment of data is easier.
Studies can be readily repeated.
Method can be used in archeological data.
Disadvantages :It must be assumed that groups
being measured and compared are similar.
Cross sectional group averages tend to obscure
112
individual variations-Esp. timing variation.

Semi longitudinal studies
 Longitudinal and cross sectional studies can be
combined to seek the advantages of both.

 In this way one might compress 15 years of
study into 3 years of gathering growth data.

 Each sub sample including children studied for
same number of years but started at different
ages.

113

Evaluation of growth data.




Working knowledge of statistics is very
important.
Cephalometrics -Developed and used in
order to study growth-day to day use in
research and practice best way to
evaluate growth.

114

LONGITUDINAL GROWTH
STUDIES.

Bolton brush growth study.
Burlington growth study.
Michigan growth study.
Denver child growth study.
Iowa child welfare study.
Forsyth twin study.

Meharry growth study.

115









Montreal growth study
Krogman Philadelphia growth study
Fels growth study
Implant studies
The Mathews implant collection
The Hixon Oregon implant study
Cleft palate study


116

Bolton Brush growth study.







The Brush enquiry was initiated in 1926 by Prof.
T. Wingate Todd with a aim of studying skeletal
development .
The Bolton study was initiated concurrently by
Dr. Holly Broadbent Sr. in 1929,which focused
on normal development of facial skeleton and
dentition.
Sample size:5000 normal healthy children.
Records: Series of x-rays, casts, dental and
medical examination and psychological tests.

117







The two collections merged officially in 1970.
In 1975 the Bolton standards of dentofacial
developmental growth were published by Dr
Holly Broadbent jr.
These standards are a series of averages that
represent optimum facial and developmental
growth and form a baseline for understanding
and assessing craniofacial growth.


118

Burlington growth study






The aim of the study was to learn more about
malocclusion, evaluate preventive and
interceptive orthodontic treatment, and obtain a
set of growth records as a database for future
studies.
Sample Size:1632 subjects followed
longitudinally.
Records :Series of x-rays, casts, photographs,
height and weight records and medical
examination.

119









The original concept for the study was presented
by Robert Moyers& the records were gathered
under Frank Popovich.
More than 247 investigations &322 studies are
based on this growth study.
Longitudinal studies by Thompson & Popovich to
derive cephalometric norms of a representative
sample was based on 210 children followed for 15
years at the Burlington growth center.
Age, sex and growth type specific craniofacial
templates were derived and static and dynamic
analysis were proposed on the basis of this study.
120

TWIN
STUDIES

Forsyth twin
study-414
pairs.

BASED ON
ORIGIN

CLEFT PALATE Implant
STUDIES
studies.

Denver growth Lancaster PA
The
study.
Hospital for sick Mathews
children-Toronto implant
Michigan
collectionstudy.
Center for
36
craniofacial
Iowa study.
Childrenanomalies
Fels studyBjork type.
-Chicago
European
 The Krogman population
Meharry study- The Krogman
The Hixon
Philadelphia
Philadelphia
Oregon
African
growth studygrowth study
implant
American.
mixed
study-270
subsample with
subjects,
121
410 pairs of
Bjork type

IMPORTANCE OF GROWTH
STUDIES.





Norms for normal growth.
When a new study is taken up, the results
of the previous studies can be used as
control.
Teleradiology
Universal method of storing and transporting
digital images that can be read between
locations.

122

Methods of studying bone growth
Experimental approaches
Measurement approaches
- Craniometry
- Anthropometry
-Comparitive anatomy
- Cephalometry

Microscopic

Macroscopic

-Implants
-Mineralized sections
-Polarized light
-Finite Element
-Fluorescent labels
Modeling
-Microradigraphy
-Autoradiography
-Microelctrodes
-Nuclear volume morphometry
-Natural markers

123








CRANIOMETRY.
Involves measurements of skull found among
human skeletal remains.
It was originally used to study the Neanderthal and
Cro-Magnon skull.
It can give information of extinct population and
pattern of growth .

Advantages:

Precise
measurements can be made.
Disadvantages: All growth
data is cross - sectional.

124







ANTHROPOMETRY :Includes measurements
using soft tissue points overlying bony
landmarks in living individuals.
It can also be done on dried skulls but variation
in soft tissue thickness would produce different
results.
Possible to follow the growth of an individual
directly by making the same measurements
repeatedly at different times , thus producing
longitudinal data.

125

Comparative anatomy:







Basic principles common to
growth in all species are first
recognized and defined by
studies in comparative
anatomy.
Comparisons with such species
can lend significant
contributions to our knowledge
about human facial growth.
Information about phylogeny of
the anatomic components
comprising the head has been
derived from comparative
studies of fossils and present
day species.

126

 CEPHALOMETRIC RADIOGRAPHY:



Combines the advantages of cephalometry and
craniometry.
It allows direct measurement of bony skeletal
dimensions and also allows the same individual to
be followed over time.

Disadvantages:
Depends

upon precise
orientation of head before taking
radiographs.
Requires precise control of
magnification
 Since it is a 2D representation
of 3D structure all
measurements are not possible.

127








Measurement data can be represented in different
ways
Graphs can be plotted –velocity and distance
curves.
Based on increase in number and weight.
To interpret the data the mode of mathematical
transformation should be known.


128

Mineralized sections








Fully mineralized sections are superior to
demineralized specimens as there is less
processing distortions and both organic and
inorganic matrix can be studied simultaneously.
Cellular details and resolutions can be enhanced
by reducing the thickness of the sections.
Specific stains can be used to enhance both
cellular and extra cellular details.
Thin sections can however quench more rapidly.
129

Polarized light.








The lamellar fringe pattern of the bone revealed
with polarized light indicates the orientation of
collagen fibers within the bone matrix.
Most lamellar bone has alternating layers of
collagen fibers oriented at right angles.
However 2 other configurations can also be
noted:
Longitudinally aligned-Resist tension.
Transverse / circumferential fibers supporting
compression.

130





Loading condition at
the time of bone
formation dictate the
orientation of collagen
fibers .
Thus bone formation
can adapt to different
loading conditions by
changing the internal
lamellar organization
of bone tissue.

131

Fluorescent Labels/Vital Stains.




Originated by John Hunter.
Dye marks the location where active growth is
occurring.

Administered

in vivo
calcium binding labels are
anabolic time markers of
bone formation.
Mechanism of bone growth
is determined by analysis of
label incidence and
interlabel distance.


132





Sequential use of different
colored labels can be
used to assess bone
growth, healing and
functional adaptation.
Tetracycline, calcein
green, xylenol orange,
alizarin complexone,
demeclocycline and
oxytetracycline are some
commonly used labels.

133

Microradiography.







This gives high resolution of
images of bone sections and
show differential density between
primary and secondary bone.
Strength of the bone is directly
related to the degree of
mineralization. Thus secondary
bone has more strength than
primary bone.

Secondary mineralization process
takes about 8 months to form and
hence the minimum retention
period after active orthodontic
correction should be 6-8 months.

134

Autoradiography.







In this method radioactive precursors for
structural and metabolic materials are detected
within tissue by coating histological sections with
a nuclear track emulsion.
Localization of radioactive disintegration reveals
the location of the precursors.
Specific radioactive labels for protein
carbohydrates or nucleic acids are injected at
known interval prior to tissue sampling.

135









Quantitative and
qualitative assessment
of the label uptake is a
physiologic index of cell
activity.
Commonly used
autoradiographic labels
are:
A. 3 H thymidine.
B. 3 H proline.
C. Bromodeoxyuridine.

136

Nuclear volume morphometry






It is a cytomorphometric procedure which
measures the nuclear size for assessing the
stages of differentiation of osteoblastic precursor
cells.
Pre osteoblasts have significantly larger nuclei
than their committed osteoprogenitor precursors
or their osteoblast progeny.
The method is used in determining the relative
differentiation of PDL and other bone living cells.

137







Natural markers.

The persistence of certain
developmental features has
led to their use as natural
markers by means of serial
radiography.

Eg: trabaculae,nutrient canals
and lines of arrested growth
can be used for reference to
study deposition, resorption
and remodeling.
Certain natural markers are
used as cephalometric
landmarks.


138

Implants





Bjork devised a method of
implanting tiny bits of
tantalum or biologically inert
alloys into growing bone
which served as
radiographic reference
markers for serial
cephalometric study.

The method allows precise
orientation of serial
cephalograms and
information on the amount
and sites of bone growth.

139

Finite element modeling (FEM).






It is a analytical method for calculating stresses
and strain within mechanically loaded structures
by breaking the structure down into group of
small elements of known mechanical behavior
so that the response of the entire structure to
loading is estimated.
The method requires accurate and precise
measurements of known landmarks in the
system.
It utility in analysis of growth and development
has not been tested except to compare its
findings with conventional methods.

140

Microelectrodes






Thin tungsten or glass electrodes are inserted
into the PDL.
The changes in electrical potential are measured
in the extra cellular space during initial response
to orthodontic treatment
In general widened areas have negative
electrical potential and compressed positive.

141

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142

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