Growth and development basic concepts /certified fixed orthodontic courses by Indian dental academy

GROWTH AND
DEVELOPMENT
Basic concepts

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


DEFINITIONS
 GROWTH

According to J.X.HUXLEY
“The self multiplication of living substance”
According to KROGMAN
“Increase in size, change in proportion and
progressive complexity”
According to MOYER`S
“Quantitative aspect of biologic development per
unit time”

DEFINITIONS
According to TODD
“ An inrease in size”
According to MERIDITH
“Entire series of sequential anatomic and
physiologic changes taking place from the beginning of
prenatal life to senility”
According to MOSS
“Change in any morphological parameter
which is measurable”

DEVELOPMENT
 According to TODD

“Progress towards maturity”


DIFFERENTIATION
“Differentiation is the change
from a generalized cell or tissue to one that is more
specialised.”

 According to MOYER`S


Developmental Sciences
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Physical Growth


 Molecular biology

It includes molecular genetics, biophysics, and genetic
engineering.
 Developmental biology
It includes cellular biology ,embryology, teratology,
reproductive biology and perinatal biology.
 Developmental oral biology
concerned with craniofacial growth and development.
 Physical Growth
The field of physical growth is the study of organ and
body growth.

It includes analysis of such morphogenesis, height and
weight, growth rates, retarded growth, metabolic
disturbances in growth, developmental physical fitness,
pubescence and morphometrics.
 Behavioral development
As the child grows physically,pattern of interactions
develop with the environment. (i.e. Behavior)
Behavior appears in typical sequences during
development just as the physical attributes of the body
appear in an expected pattern.

 Scientists studying behavioral development include

embryologists, developmental psychologists,
psychiatrists, physiologists, physiologic psychologists,
and geneticists.


GROWTH PATTERN, VARIABILITY AND TIMING
(A)PATTERN
 Pattern reflects proportionality, usually of a complex
set of proportions rather than just a single proportional
relationship.
 The physical arrangement of body at one time is a
pattern of spatially proportioned parts.


SCAMMONS GROWTH CURVE


 Not all body systems grows at the same rate.
 The muscular and skeletal elements grows faster than

the brain and central nervous system as reflected in
relative decrease of head size.


Cephalocaudal growth gradient- Body
•In Fetal life at about third
month of intra uterine
development, head takes up
50% of total body length.
•By time of birth, trunk and
limbs grown faster than head & face. Head decreased to about
30%.
•Over all pattern of growth thereafter follows this course, with
a progressive reduction of size of head to about 12% of adult.

Cephalocaudal growth gradient- Face
•Infant has much larger cranium
and a much smaller face.
•This change in proportionality, with
an emphasis on growth of the face
relative to cranium is an important aspect of pattern of facial
growth.
•When facial growth pattern viewed against perspective of the
cephalocaudal gradient, it is not surprising that the mandible,
being further away from the brain, tends to grown more than
later than maxilla which is closer.

(B)VARIABILITY
 The second important concept in the study of growth
and development is variability
 It is very important clinically, to decide whether an
individual is merely at the extreme of the normal
variation or falls from outside.
 Rather than categorizing people as normal or
abnormal, it is more useful to think in terms of
deviations from the usual pattern and to express
variability quantitatively.
 one way to do this is to evaluate a given child relative
to peers on a standard growth chart.

GROWTH CHARTS


(C) TIMING
 A Final major concept in physical growth and
development is that of timing.
 There are sex related timing differences in the timing of
many growth phenomena.
 Usually girls precede boys, for eg. in pubescence, dental
calcification, and ossification of carpal bones.


•Growth plotted either in height or
weight at any age or amount of
change in any given interval.
•A curve like black line is called a
“distance curve” where the red line is
a “ velocity curve”.
•Plotting velocity rather than distance makes it easier to see
when accelerations and decelerations in the rate of growth
occurred.

Growth spurt
 Growth does not take place uniformly at all times. These

seems to be periods when sudden increase in growth
termed “growth spurt”
 The timing of growth spurt differ in boys and girls.
 The following are timing of growth spurts.
One year after birth


Mixed dentition growth spurt.

Boys :8-11 years

Girls -7-9 years
pre-pubertal growth spurt

Boys -14-16 years

Girls - 11-13years


 Growth modification procedures using functional and

orthopedic appliance are carried out during growth
period. Surgical resective procedures are best carried
out period after the cassation of

data analyzation

Types of growth
a. opinion

gathering
growth data

b. observations
c. Rating and rankings
d. Quantitative
measurements
(i).Direct data
(ii)Indirect growth
measurements

a.

Longitudinal

b.

cross sectional

c.

overlapping or
semilongitudinal data

(iii).derived data

Evaluation of growth data

Types of growth data
(A) OPINION
 Opinion is at best a clever guess based on experience.
 crudest form of scientific knowledge and are not

accepted wherever data is not available.


(B) OBSERVATIONS
 Observations are useful for studying all-or-none
phenomena.
eg. congenital absence of teeth


 (C) RATINGS AND RANKINGS

Ratings make use of comparisons with conventional
accepted or scales or classification.
Ranking may array data in ordered sequences
according to value.
This method used for evaluation of ear shape, eye
colour and fingerprints.

 (D) QUANTITATIVE MEASUREMENTS

Quantitation minimizes misunderstanding and permits
the testing of hypotheses by other workers.
1)Direct data- data derived from measurements
taken on the living person or cadaver by means of
calipers, scales, measuring tapes and other measuring
devices.
Measuring of teeth with a boley gauge in the mouth of a
patient produces direct data.


Indirect growth measurements measurements taken from sources other than the actual
person.
e.g. photographs, dental casts or cephalograms.

Derived data- obtained by comparing at least two or
more measurements.
e.g. In a person, mandible grew 2mm between ages 7
and 8, the 2mm have actually been measured; rather
the mandibular length at 7 years has been substracted
from the mandibular length at 8years and the
increment thus derived is assumed to represent growth.

METHODS OF GATHERING GROWTH DATA
 (A) Longitudinal
Measurement made of the same person or group at regular

intervals through time are longitudinal measurements.

1)Advantages of the longitudinal method.
variability in development among individuals within the

group is put in proper perspective.
The specific developmental pattern of an individual can be
studied, permitting serial comparisons.
Temporary temporal problems in sampling are smoothed out
with time, and an unusual event or a mistake in measuring is
more easily seen and corrections made.

 DISADVANTAGE OF THE LONGITUDINAL METHOD.
TIME- If one wish to study the growth of the human face from the

birth to adulthood by means of longitudinal data, it will take a life
time to gather the data.
EXPENSE- Longitudinal studies necessitate the maintenance of
laboratories, research personnel, and data storage for a long time
and thus are costly.
ATTRITION-The parents of children in longitudinal studies change
their places of residence or lose interest in the study and some
children die. The result is a gradual diminution in sample size.
AVERAGING- The changes in average size of a group of individuals
do not adequately indicate the sequence of events that is follewed
by any single individual.

 (b) Cross sectional
Measurement made of different individuals or different

samples and studied at different periods are cross-sectional
measurements.

Advantages of the cross-sectional method.
It is quicker.
It is less costly
Because it is simpler to get large samples by the cross-

sectional method, statistical treatment of the data sometimes
is made easier.
The method allows repeating of studies more readily.
The method is used for cadavers, skeletons and aracheologic
data.

Disadvantages of the cross-sectional method
It must always be assumed that the groups being measured

and compared are similar. Cross sectional group averages
tend to obscure individual variations. This is particularly
obfuscating when studying the timing of developmental
events, for example, the onset of pubescence or the
adolescent growth spurt.

 Craniomeric, anthropometric and cephalometric data

can be expressed as cross sectionally.


 (c) Overlapping or semi longitudinal data
 Longitudinal and cross sectional methods are combined by

some workers to seek the advantages of each.
 In this way one might compress 15 years of study into
3years of gathering data, each sub sample including
children studied for the same number of years but started
at different ages.
 e.g.subsample A-3 TO 6 YEARS
subsample B-4 TO 7 YEARS
subsample C- 5 TO 8 YEARS

ANTHROPOMETRY

 The technque of measuring skeletal dimensions on living

individuals is called anthropometry.
 Various landmarks are established in studies of dry skull
are measured in living individuals simply by using soft
tissue points overlying these bony landmarks.


CEPHALOMETRY
 Cephalometrics is used for study of growth and

development.
 This approach can combine the advantages of
craniometry and anthropometry.
 It allows a direct measurement of bony skeletal
dimensions, since the bone can be seen through the soft
tissue covering in a radiograph.
 It also allows the same individual to be followed over
time.

EVALUATION OF GROWTH AND DATA
 Evaluation of growth data is one the most complicated

and fascinating branches of statistics.
 Many facts of growth lie hidden in ‘clinicians’ or
‘scientists’ crude hunches and can be bared for further
study only by careful and imaginative statistical
dissection.


VARIABLES AFFECTING PHYSICAL GROWTH
 HEREDITY
 NUTRITION
 ILLNESS
 RACE
 CLIMATE AND SEASONAL EFFECTS ON GROWTH
 ADULT PHYSIQUE
 SOCIOECNOMIC FACTORS
 EXERCISE
 FAMILY SIZE AND BIRTH ORDER
 SECULAR TRENDS



HEREDITY
 There is genetic control of the size of the parts to a

great extend, of the rate of the growth, and of the onset
of the growth events.
eg. dental classification, the eruption of

teeth, ossification of bones,
and the start of the adolescent growth spurt.

 There is considerable degree of independence between

growth before and growth during adolescence.


NUTRITION
 Malnutrition delay the growth and the

adolescent growth spurt.
 Children have fine recuperative powers
provided the adverse conditions have not
seen too extreme.
 With the return of good nutrition growth
takes place unusually fast until the
genetically determined curve neared
once more and subsequently followed.

ILLNESS
 The usually minor childhood illness does not have much

effect on physical growth.
 Serious prolonged and debilitating illness have a
marked effect on growth


RACE
 Racial differences show differences in growth

pattern.
 It is due to genetic, climatic, nutritional or
socioecnomic differences.
eg. north american blacks are ahead of whites in
skeletal maturity at birth and for at least first 2years
of life.

CLIMATIC AND SEASONAL EFFECTS OF GROWTH
 There is a general tendency for those living in cold

climates to have greater proportion of adipose tissue
and much has been made of the skeletal variations
associated with variations in climate.
 There is seasonal variations in the growth rate of
children and in the weight of newborn babies.
 Contray to popular belief, climate has little direct effect
on the rate of growth.


ADULT PHYSIQUE
 There are correlations between the adult

physique and earlier development events.
eg. tall women tends to mature later and there are

variations in the rate of growth associated with
differing somatotypes.


SOCIO ECONOMIC FACTORS
 Children living in favorable socioeconomic conditions

tend to be larger, display different types of growth and
show variation timing of growth when compared with
disadvantaged children.
eg. height and weight ratios.


EXERCISE
 A strong case for the effects of exercise

on linear growth has not been made in a
quantitative fashion.
 children who exercise strenuously and
regularly have not been shown to grow
more favorably.


FAMILY SIZE AND BIRTH ORDER
 There are differences in the sizes of the

individuals. in their maturational level of
achievement, and in their intelligence
that can be correlated with the size of the
family from which they came.
 First born children tend to weight less at
birth and ultimately achieve less stature
and a higher I.Q.

SECULAR TRENDS
 Size and maturational changes in large populations can

be shown to be occuring with time that, as yet have not
been well explained.
e.g. Fifteen year old boys are approximately 5 inches
taller than 15 year old boys were 50 years ago.


Psychological disturbance
 It has been shown that children experiencing stressful

conditions display an inhibition of growth hormone.
 When the emotional stress is removed they begin again
to secrete growth hormone normally, and ‘catch up’
growth is seen.


The evaluation of physical growth
 WHY ASSESS……?
For the identification of grossly abnormal pathologic growth.
For the recognition and diagnosis of significant deviation from

normal growth.
For the planning of therapy.
For the determination of efficacy of therapy.


 Questions to be asked…
1. What is the status of the patient at the moment…?
2. What is progress of grow to date…?
3. How does he/she compare with others…?
4. How does he/she fit family pattern…?
5. What will he/she do in the future…?


Rudiments of bone growth
1.OSTEOGENESIS.
a) Endochondral bone formation.

Mesenchymal tissue
Cartilage
Cartilage cells hypertrophy, calcification of matrix,
degeneration of cells.
Osteogenic tissues invade the dying and disintegrating
cartilage and replace it.

Endochondrial bone formation
ZONE A, reserve cartilage feeds new
cells into b, zone of cell division.
ZONE B, cells undergo rapid division
forms column of flattened
chondrocytes. It is responsible for
elongation of bone.
ZONE C, the daugther cells undergo hypertrophy.
ZONE D, the matrix calcifies
ZONE E, the calcified matrix becomes partially resorbed and
invaded by vessels.

 ZONE F, undifferentiated cells carried in by

sprouts
provide osteoblasts, which in turn deposit a thin crust of
bone on the remnants of the calcified cartilage matrix.
 Entire process is continuous and repetitive, one zone
transferring into next.
 ZONE B changed directly to ZONE C ( arrow1).
 ZONE D INTO ZONE E (arrow2).
 ZONE E INTO ZONE F(arrow3).
 As entire cartilage grows in a linear direction toward
top of illustration bone replacement follows.

Endochondrial bone formation (conti)
•Growth of cranial synchondrosis is
schematized. Note that proliferation in bone
formation occurs on both sides of plate, in
contrast to epiphyseal plate pictured in D.
•A typical long-bone epiphysis showing a
secondary center, articular cartilage,
epiphysial plate and medullary
endochondral bone is represented D.


Endochondral bone formation (conti.)
•It represents growth cartilage of
mandbular condyle. A zone of
prechondrocytes occur
proliferation occurs just beneath a
covering layer of fibrous capsule.


b) Intramembranous Bone formation
Undifferentiated mesenchymal cells
Osteoblasts
Elaborate osteoid matrix
Calcification of matrix
Formation of bone

Intramembranous bone formation
•In a center of ossification (A)
cells and matrix of the matrix
undifferentiated connective
tissue undergo series of
changes that produce small
spicules of bone.
•Some cells remain relatively
undifferentiated(1), but others develop into osteoblasts(2) that
lay down first fibrous bone matrix (osteoid), which subsequently

become mineralized as in stage B.
 Original blood vessels are retained in close proximity to
the formative bony trabeculae(3).
 As bone deposition by osteoblasts continues, some of
these cells are enclosed by their own deposits and
become osteocytes(4).
 Some undifferentiated cells develop into new
osteoblasts(6) and other remaining osteoblasts undergo
cell division to accommodate enlargement of
trabeculae.
 Outline of an early bone spicule(5) is shown in enlarged
trabeculae for reference.

 Blood vessels have now become enclosed in the fine,

cancellous spaces (c) .
 This spaces also contain scattering fibers ,
undifferentiated connective tissue cells, and osteoblasts.


Intramembranous bone formation(conti.)
•At lower magnification (D)
characterstic fine, cancellous
nature of cortex is seen.
•This bone tissue is widely
distributed in prenatal as well
as young postnatal skeleton.
•It is a particularly fast growing variety of bone tissue.
•Note that periosteum has become arranged into (cellular)
and outer (fibrous) layers.

Vital staining

Radioisotopes

Implants

Methods of studying bone growth

Comparative anatomy

Roentgenographic
Cephalometry

Natural Markers

Vital staining
 Procion and Tetracycline are used extensively in bone

research.
 The primary value of vital dyes lies depicting the
pattern of post natal bone deposition over an extended
period in one animal.


Radioisotopes
 Radioisotope material is injected and after a time,

located within the growing bones by means of Geiger
counters or autoradiographic techniques.
 In latter method , bones or sections of bones are placed
against photographic emulsions that are exposed by
emission of radiation from the radioactive substance.


Implants
 These serve as radiographic reference markers for

serial cephalometric analysis.
 The method allows precise orientation of serial
cephalograms and information on the amount and sites
of bone growth.
 This method is useful because bone does not grow
interstitially and therefore implants inside a bone are
stable

Comparative Anatomy
 Significant contributions to our knowledge of human

facial growth have been provided through
comparisions with other species.
 Not only can experimental work done more readily on
animals but often basic principles common to growth in
all species are first recognized and defined by studies in
comparative anatomy.


Roentegenographic cephalometry
 Cephaometry has contributed significantly to our

knowledge of human craniofacial skeletal growth, and
cephalometric methods are used rountinely, not only
for the study of facial growth but also for orthodontic
diagnosis, treatment planning and the assessment of
therapeutic results.


Natural markers
 The persistance of certain developmental features has

led to their use as natural markers.
 By means of serial radiography trabeculae, nutrient
canals and lines of arrested growth can be used for
reference to study deposition, resorption and
remodeling.
e.g. Trabeculae, Nutrient canals.


Example Natural markers-Mandibular canal


Mechanisms of bone growth

Deposition
Growth field
and Resorption

Remodeling


Growth
movements

Deposition and Resorption
 On one side of the bony cortex new bone is added, on

the other side, bone is taken away.
 Deposition occurs on the surface of facing the direction
of growth.
 Resorption occurs on the surface facing away.
 The result is a process termed cortical drift, a gradual
moment of growing area of the bone.


Deposition and resorption (cont..)
•According to enlow V principle many
facial bones or parts have v shape.
•Note deposition(+) occurs on inner side
and resorption(-) occurs on outer.
•The “V” moves from A to B as overall
dimension increases ie.movement toward
wide end of V.
•Simultaneous growth movement and
enlargement occur.


GROWTH FIELDS
 All surfaces, inside and outside of every bone are

covered by an irregular pattern of “growth fields”
comprised of various soft tissue osteogenic membrane
or cartilages.
 Hard bone tissue does not contain genetic program for
growth ,rather the determinants of bone growth reside
in the bone’s investing soft tissue- muscle, integument,
mucosa, blood vessels, nerves etc..
 Varying activities and rates of growth of these fields
are basis for differential growth processes that produce
bone of irregular shapes.

REMODELLING
 The required differential growth activity necessary for

bone shaping termed remodelling.
 It involves simultaneous deposition and resorption on
all inner and outer surface of entire bone.
 Remodelling a basic part of growth process, not only
provides regional changes in shape, dimensions, and
proportions. It also produces regional adjustments that
adapt to the developing function of bone and its various
growing soft tissues.

GROWTH MOVEMENTS
CORTICAL DRIFT
DISPLACEMENT
CORTICAL DRIFT
 Drift is combination of resorption and deposition
resulting in growth movement toward the depository
surface.
 Drift is seen with remodeling enlargement and is
produced by deposition of new bone on one side of
cortical plate while resorption occurs on the opposite
side.

DISPLACEMENT
 It is on the other hand is movement of whole bone as a
unit.
 As a bone is carried away from its articulation with
other bones, growth remodeling simultaneously
maintains relationship of bone to each other.
e.g. as entire mandible is displaced from its articulation
in the glenoid fossa , it is necessary for condyle and
ramus to move upward and backward to maintain
relationships.

Displacement


OVER ALL PATTERN OF CRANIOFACIAL GROWTH
•The additive result of displacement,
growth, and remodeling appears to be
downward an forward despite local
change in many directions.
•There are sexual differences in
overall growth (men grow more, grow
actively over a longer time span, display more “spurts”. and
so forth). But such differences are better understood by
regional dimorphism.
•Most significant overall sexual differences are seen in the
achievement of facial height.

RACIAL AND ETHNIC DIFFERENCES
 The literature on racial morphologic craniofacial

diversity is detailed and extensive but there are few
studies on growth differences among racial, ethnic, and
national groups.
 Most extensively reported on are north american whites
and Europeans. Serial cephalometric data of north
american blacks exist but not fully analyzed.
 International orthodontic clinical literature suggests
different distribution of malocclusions among to name
obvious examples Japanese, Italians,swedes,British,and
north american whites.

“ADULT” CRANIOFACIAL GROWTH
BEHRENTS STUDY RESULTS
 Craniofacial size and shape changes continue past 17
years to oldest age studied.
 Significant sexual dimorphism exists: men are larger at
all ages, they grow more and their adult growth is
more apt to persist along the same vectors of
adolescent growth .
 Women showed periods of increased rates of
craniofacial growth, apparently related to time of
pregnancies.
(conti…)

 Skeletal changes resulted from continuous localized

remodeling, producing differential alterations in size
and shape.
 The amount of growth were not sufficient to serve as a
basis for practical adult orthopedic or functional
appliance therapy.
 The amount of growth were sufficient however, to
cause significant adaptations in mandibular orientation
and occlusal relations.


Prediction of Growth

 A number of methods are available for this. These cannot

go into details concerning certain aspects such as:
Age related individual peculiarites.
Growth

changes in untreated cases, compared with those in
treated cases, taking into account treatment mechanism and the
age of the patient at the beginning of treatment.
Growth changes occurring after conclusion of treatment.


Johnston method
 LE JOHNSTON has produced a diagram on the assumption

of regular annual changes and an average direction of
growth. He states that accurate prediction can be made
in 65% of cases.
 Johnston simplified method of generating a long-term
forecast by use of a printed ‘forecast grid’. Each point
was advanced one grid unit per year, using a standard
S-N orientation registered at S.

Johnston diagram


Growth in S-N Line
 A number methods are based on average increase in S-N

line using this for differentiated prediction of vertical
and sagittal growth changes.
 The reliability of this method is said to be 70%.


Ricketts short term prediction
 This makes distinction between vertical and horizontal

growth.
 The method is said to be 80% reliable.


Ricketts Computer Analysis


 Basic materials are cephalometric data relating to

structural synthesis stored in the computer, with a
structural analysis done in the individual case.
 Individual assessment again based on statistical mean
values.
 This computer diagnosis requires patient to be a certain
age and is also limited to specific treatment techniques.


CONCLUSION
 To the biologist growth and development are the

normal changes from birth to death in an individual
organism. The evaluation of the growth and
development of the individual patient is an important
part of orthodontics as a basis of comparison with the
normal as a means of discovering and diagnosing mal
development (malocclusion), and as the foundation for
planning orthodontic treatment.


Thank you
Leader in continuing dental
education


Growth and development basic concepts /certified fixed orthodontic courses by Indian dental academy

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