Growth and development /fixed orthodontic courses

GROWTH
AND
DEVELOPMENT
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INDIAN DENTAL ACADEMY
Leader in continuing dental education
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HISTORICAL REMARKS

The first important publications about
growth of the face appeared in England
in the second half of the 18th century.
The greatest contribution came from
‘John Hunter’, who gathered his
information primarily from human
skeletal material . Hunter suggested,
among other things, that the corpus of
the mandible became longer by
resoption of the bone on the anterior
surface of the ramus and bone
apposition on the posterior border.
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In addition, he sought to support his concepts with
animal experiments. He made use of the phenomenon
noticed by ‘Belchier’ that, in living animals, ‘Alizarin’
stains the areas where new bone is formed. ‘Humphry’
studied the growth of the mandible by inserting metal
wires in the mandibles of young pigs.
This approach previously had been used by ‘Duhamel’ in
long bones. Both vital staining and insertion of metal
implants are techniques which are still used in the study
of the growth of the facial skeleton.
A special method for the study of bone growth has been
developed by ‘Enlow’. He indicated the possibility of
distinguishing the areas of bone where either endosteal
or periosteal apposition has occurred
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In this manner, Enlow and his co workers could give a
detailed account of the remodeling processes in the
mandible, the maxilla, and other bones. By working back
to establish the succession in which histological changes
had occurred, they were able to come to conclusions
similar to those reached by other researchers such as
‘Hunter and later Brash’ from the results of experiments
with vital staining in animals.
The combination of radiographic
cephalometry with the use of metal implants such as
‘Bjork’ introduced using human material, has augmented
still further the possibilities for interpretation of
longitudinal growth www.indiandentalacademy.
research.
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INTRODUCTION
Facial balance is of great concern to health
specialists not only because many vital organs are
concentrated in that circumscribed area, but also
because of social value of the face.
Artists , Dentists , Physicians
and Anthropologists have studied the face from
different angles.Probably no discipline in
medicine and certainly none in dentistry devotes
so much time to growth research than
‘Orthodontics’. www.indiandentalacademy.
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Orthodontists in increasing numbers believe that a
recognition of facial variation forms a part of modern
orthodontic treatment planning. They have investigated
the relationship between dental occlusion and skeletal
balance of the face.
In recent years clinical experience and
research by Ricketts, Sassouni, Bjork etc all have
brought to light the close interdependence of facial
proportions in three dimensions of space and vertical
proportion is one of them.
Vertical malocclusion results from
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the interplay of many different etiological factors
during the growth period. These factors include growth
of maxilla and mandible, function of lips and tongue,
and dentoalveolar development with eruption of teeth.
The key to success of any
orthodontic treatment is ‘correct diagnosis and
treatment planning’.
Finally, our treatment must be
aimed at restoration of normal jaw function or
improved function, optimal facial esthetics, and long
term dental and skeletal stability.
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CONTENTS
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DEFINITIONS
DIFFERENT KINDS OF GROWTH
VARIABLES AFFECTING GROWTH
GROWTH PATTERN AND
VARIABLITY.
FACIAL GROWTH
GROWTH SPURTS
GROWTH TRENDS
METHODS OF STUDYING
GROWTH
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Growth is the physiochemical process by which an
organism becomes longer. Growth may result in increase
or decrease in size, change in form or proportion,
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complexity and texture.
Development is the sequence of the changes from
fertilization to maturity consisting of histologic,
morphologic, functional and maturative changes.
According to Moyers, development refers to all the
natural occurring un directional changes in the life of an
individual from its existence as a single cell to its
elaboration as a multifunctional unit terminating in
death.
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DEFINITIONS
According to Meridith : Growth is the entire series of
sequential anatomic and physiological changes taking
place from the beginning of prenatal life to the close of
senility
According to Huxley : Growth is the self multiplication of
living substances.
Krogman : It’s the increase in size, change in proportion
and progressive complexity.
Todd : Growth is an increase in size.
Scott’s definition : Growth is a three fold process in
which all multiplication, differentiation and organization
takes place
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According to Salzmann : Growth is the
physiochemical process found in living organisms
which manifesto itself in structure, composition,
size and shape of the organism.
According to Moss : Growth is the increase or
decrease of the size of living organisms.
According to Moyers : Quantitative aspect of
biologic development per unit time.
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DIFFERENT KINDS OF GROWTH
1. Size change : Changes in size during growth are easily
recognized and measured.
2. Positional change : Tissues and organs may migrate from
one area to another during growth.
3. Proportional change : Parts of the body change in
relationship with one another during growth.
4. Functional change : The goal of growth is mature
function in each tissue and organ. Tissues and organs undergo
changes in functional capabilities during growth process.
5. Maturational change : Growth of the body as a whole is
directed towards the achievement of the period of stability and
adulthood.
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6. Compositional change: Growth involves
changes in composition of parts of the body
7. Timing and Sequential change :
a. Prenatal growth
b. Postnatal growth
c. Maturity
d. Old age.
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FACTORS AFFECTING PHYSICAL
GROWTH

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 GENETIC FACTORS
 ENVIRONMENTAL FACTORS
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 NUTRITION
 EXTRA CRANIAL AND INTRA CRANIAL
PRESSURE.
 ILLNESS
 RACE
 CLIMATE AND SEASONAL AFFECTS
 ADULT PHYSIQUE
 SOCIO ECONOMIC FACTORS
 EXERCISE
 SECULAR TRENDS
 FAMILY SIZE AND BIRTH ORDER
 PSYCHOLOGICAL FACTORS
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 MATERNAL FACTORS.

GENETIC FACTORS:
Genetic control influences the size of the
organism to a great extent and the rate of the onset of growth
event. Not all genes are active at birth.
It is believed that size at birth relates to about
18% to the genome of the fetus, 20% to the maternal genome, 32%
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maternal environmental factors, and the remaining 20% to
unknown factors.
After birth infants growth rate is no longer dependent on
maternal factors but increasingly related to his own genetic
makeup.
In 1-2 yrs, post natal shift has a significant
relationship to the genetic background of the child, reflective of
mid parental height.
During adolescence, growth correlates with the prenatal
size more strongly. Hence the size of the parents can be
considered as a best indicator of the eventual predicted size of a
newborn baby.
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ENVIRONMENTAL FACTORS
Environmental factors influence the growth process to an
important extent. During excessively unfavourable circumstances,
such as serious chronic illness, prolonged starvation, and
situations of great stress, the growth rate is reduced and even can
come to a stand still. An eloquent example of this is the
displacement of the adolescent growth spurt to a later age when
living conditions are extremely poor. This phenomenon has been
documented in certain German towns during world war II.
When a period of extra ordinarily bad conditions is
followed by a favorable one, the growth is resumed and the
unattained growth is achieved through acceleration.
When circumstances are continually very bad
as in Netherlands in the middle of previous century, the
adolescent growth spurt is then displaced so far that there is no
possibility of catching up sufficiently before growth ceases.
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The retardation of body growth through
starvation is clearly demonstrated by animal
experiments too. ‘McCance’ was able to restrain
the growth of a pig to such a degree that after
one year, it weighed only 5kgs.

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 NUTRITION :
Malnutrition may affect all aspects of growth
including size of parts, body proportion, quality and texture of tissues and onset
of growth events.
It may delay growth and the adolescent growth spurts. For eg, iodine deficient
diet affects the cranio facial growth in relation to all the dimensions.
Malnutrition involves deficiency in calories and required
food elements. When adequate calories are added to the diet, they began to
grow again.
A sufficient diet includes an adequate
supply of protein. Ca, Ph, Mg, and Fl are essential for proper bone and tooth
growth.
Iron is needed for Hemoglobin production.
Vitamin A controls activities of both osteoblasts and osteoclasts.
Vitamin C is necessary for proper bone and connective tissue growth.
Vitamin D is required for normal bone growth.
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HORMONES
Probably all endocrine glands influence growth.
Growth hormone can be detected at the end of second
fetal month, soon after the pituitary has formed.
Production of growth hormone is thought to be
controlled by hypothalamus. Excess of growth
hormone produces Gigantism and deficiency causes
dwarfism.
Insulin is important in protein synthesis, and
growth hormone is incapable of causing the
formation of normal amounts of ribonucleic acid
without the help of insulin.
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The anterior lobe of the pituitary
also secretes thyrotrophic hormone, which
affects the growth by stimulating the thyroid
gland.
The changes seen at adolescence are
caused by the secretion of Androgens and
Gonadal hormones.
The Gonadotrophic hormone of the pituitary
gland stimulates the production of testosterone
in males and progesterone is females.
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• Hormones responsible for growth are•
Group -1
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Growth hormone
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Insulin
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Thyrotropic hormone
• Group- 2
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Parathormone
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Group-3
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Androgens
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Progestrone and Oestrogen
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Group-4
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Prolactin hormone
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EXTRA CRANIAL AND INTRA CRANIAL PRESSURE:
Any factor affecting the physical growth is
expected to be associated with a profound and
wide spread effect on the size and shape of the
cranial vault.
Artificially induced reshaping of the
cranial vault has been practiced in many
cultures. The baby’s skull is molded by
wrapping it in a bondage by using a cradle
board. Extra cranial mechanical forces exerted
during the period of growth can effect on the
size and shape of the part.
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ILLNESS : Usual childhood illness ordinarily cannot be shown to have

much effect on growth. Prolonged and debilitating illness, how ever can have
marked effect on all aspects of growth.
 RACE : Although the differences in growth among different races can be
attributed to other nutritional and environmental factors, there is some
evidence that race does play a role in growth process.
‘Gene pool differences’ accounts for the fact that the North
American Blacks are ahead of Whites in skeletal maturity at birth and for at
least 2yrs of life. They also calcify and erupt their teeth about 1yr earlier than
whites.
The black American children who were analyzed have
significantly larger arch dimensions than their white counterparts.
Studies were also conducted among the Mexican-Americans to
white and blacks. Skeletally Mexican-American men had longer maxillary and
mandibular lengths than black or white men. Mexican-American were slightly
more maxillary protrusive than white women.
Dentally both Mexican-Americans sexes had more protrusive and proclined
lower incisors than their white counterparts.
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CLIMATE AND SEASONAL EFFECTS:
There is a general tendency for those living in
cold climates to have a greater proportion of adipose tissue. There are
seasonal variations in the growth rates of children and weight of new
born children. Boys and girls grow ore in the spring and summer than
in autumn and winter. But climatic changes seems to have no direct
effect on rate of growth.
SOCIO ECONOMIC FACTORS :
Children brought up in affluent and favorable
socio-economic conditions show earlier onset of growth events. They
also tend to grow larger in size than children living in unfavorable
socio-economic conditions.
EXERCISE :
Although exercise may be essential for healthy body,
strenuous and regular exercises have not
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been associated with more favorable growth. Certain aspects of growth such as
development of some motor skills and increase in muscle mass is found to be
influenced by exercise.
FAMILY SIZE AND BIRTH ORDER :
There are differences in the size of individuals, in their
maturational levels of achievement and in their intelligence that can be correlated
with the size of the family which they came from.
Studies have shown that first born babies tend to weigh less at birth and have
small stature but higher I.Q. The smaller the family size, the better would be
nutrition and other favorable conditions.
SECULAR TRENDS :
This refers to the phenomenon that people have grown larger
over the last century. This has principally came into light from ‘Swedish data but
also has definitely been established in the Netherlands. It is assumed that better
nutrition and the elimination of most infantile diseases are the most important
causes of the appearance of a secular displacement of the course of growth.
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It seems likely that during a critical
period – the last part of the prenatal period and the first 2
or 3 yrs after birth – environmental factors can influence
the rate of growth, and the development of the nervous
system. When children from the middle of the 20th century
had ceased growing, they displayed larger facial
measurements than their parents.

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ADULT PHYSIQUE:
Certain correlation between adult physique
and earlier developmental events present, eg- tall women tend to
mature later. Variations in the rate of growth are associated with
differing somatotypes.
PSYCHOLOGICAL DISTURBANCE:
Can lead to inhibition of growth by various methods. Children
experiencing stressful conditions display an inhibition of growth
hormone. These may also happen under less extreme conditions and
thus amount for lesser variations in individual growth.
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MATERNAL FACTORS:
Size of a full term infant is
related to the size of the mother. With adipose tissue
development at 7 months, there is an increase weight gain
and the fetus fills the uterine cavity where the uterine size
constraint is a factor for the fetal growth. The placenta
grows by cell numbering till 35 weeks.

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GROWTH PATTERN AND
VARIABILITY
 GROWTH PATTERN :
Growth pattern represents proportionality which
refers not just to a set of proportional relationships at a point in
time, but to the change in these proportional relationships over time.
In another words, the physical arrangement of the body at any one
time is a pattern of spatially proportioned parts.

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SCAMMON’S GROWTH CURVE:
Body tissues can be classified into 4
types .Lymphoid tissue, Neural tissue, General
tissue, General tissue and Genital tissue.
LYMPHOID TISSUE: Proliferates rapidly in late
childhood and reaches almost 200% of adult size.
This is an adaptation to protect children from
infection as they are more prone to it.

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NEURAL TISSUE:
Grows very rapidly and almost adult size by 6-7 yrs of age.
GENERAL TISSUE:
Consists of muscles, bones and other organs. These tissues
exhibit an ‘S’ shaped curve with a rapid growth upto 2-3 yrs of age
followed by a slow phase of growth between 3-10 yrs. After the
10th yr, a rapid phase of growth occurs terminating by 18th-20th
yr.
GENITAL TISSUE:
Consists of reproductive organs. They show negligible
growth until puberty. However they grow rapidly at puberty
reaching adult size after which growth ceases
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Cephalo Caudal
Gradient of Growth:
Means that
there is an axis of increased growth
extending from head towards the
feet. The concept is as follows.
At about 3rd
month of intrauterine development,
the head takes 50% of the total body
length. In contrast, the limbs are
rudimentary and the neck under
developed.
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By the time of birth, the trunk and limbs has grown faster
than the head and face ; so the proportion of entire body devoted to
head has decreased to about 30%, with a progressive reduction of the
relative size to about 12% further.
All of these changes, which are a part of the
normal growth pattern, reflects the ‘Cephalo Caudal Gradient of
Growth’.
All tissues do not grow at same rate :
The muscular and skeletal elements grow
faster than the brain, C.N.S etc. Reason for the gradients of growth
is that different tissues grow at different rates and are concentrated
in various parts of the body. For eg, Scammon’s curves for growth of
four tissue systems of the body.
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 Predictability :
The proportional relationships within a pattern can be
specified mathematically and the only difference between a growth
pattern and a geometric one is the addition of time dimension.
Therefore, a change in the growth
pattern would indicate an alteration in the expected and predictable
sequence of changes in proportions expected for that individual.
 Growth Variability :
Every one is not alike in the way they grow. 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 on a standard growth chart. The normal variability is derived
from large scale studies of groups of children, which is shown by the
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solid lines on the graph.

TIMING
The timing of developmental events is largely
under genetic control .
There are sex – related differences
in the timing of many growth phenomena.
Usually girls precede boys, for eg – in pubescence, dental
calcification, and ossification of carpal bones.
Timing is more critical in the fusion of facial
parts in early prenatal growth. Cleft lip and/ or Cleft
palate is a well known example of a gross craniofacial
deformity resulting from a failure of facial parts to fuse at
a critical time. www.indiandentalacademy.
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GROWTH SPURTS
 Growth does not take place in a
steady manner. There are certain
periods where there is sudden increase
in growth which is called ‘GROWTH
SPRUTS’ which are sex linked.
 PRENATAL
 POSTNATAL
PRENATAL:
Growth spurts just before
birth.
POSTNATAL :
1.First Peak- Greatest increment of
growth during 3yr age level.
2.Second Peak – Pre-pubertal which is
6-7 yrs in females and 7-9yrs in males.
3.Third Peak - Pubertal whichcom
is

1.

2.

3.
4.
5.

CLINICAL IMPLICATION OF GROWTH
SPURTS
These are obvious for orthopedic correction of maxillo mandibular
relationships. Very few girls seems to show the mixed dentition
growth spurts; all show the pubertal growth spurt.
Pubertal increments still offer the best time for a large number of
cases, as far as predictability, growth direction, patient
management and total treatment time are concerned.
Malocclusion requiring surgical correction can be undertaken after
the growth spurt is completed.
Malocclusion of dental arches can be treated taking advantage of
growth spurts during the active growth period.
Arch expansion and Rapid expansions can be undertaken during
periods of maximum growth.
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( CHARLES TWEED)

GROWTH TRENDS

Tweed employed 4 angles namely
FMA, IMPA, FMIA, and ANB.
Type A :
Tracing made from pre-orthodontic lateral
cephalograms taken 18 months apart are superimposed on SN
with ‘S’.
It will be observed that the middle and lower face are
growing forward and downward in union, with no change in
size of the ANB angle. If the case is class-1 in nature with an
ANB angle that does not exceed 4-5°, no treatment is
indicated until the full eruption of all four permanent cuspid
teeth.
Type A Subdivision:
The ANB angle difference is greater than
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4.5°. So greater tooth movement is required during correction.

Type B :
ANB readings ranges from 6-12°, and only 15% of the
patients are with this type of growth trend. If the pre-orthodontic
tracings reveal that growth is downward and forward with the
middle face growing forward more rapidly than the lower as
designated by an increase in size of ANB.
If ANB is less than 4°, prognosis is fair.
If ANB ranges from 7°- 12°, prognosis is poor.
Type –B subdivision :
The ANB is large and seriel examination is found to be
increasing during the observation period. Treatment may be long and
difficult and extraction is required as a rule.
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Type C :
Mandible grows rather downward and
forward at a faster rate than middle third of face. This
shows lessening or decrease on the ANB angles. These
constitutes 60% of patients.
Type C subdivisions :
The mandible is found to be growing
forward more than maxilla but only slightly downwards.

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METHODS OF STUDYING
GROWTH

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METHODS OF GATHERING GROWTH DATA
1. Longitudinal studies :
Measurement of a particular person or group
of persons made at a regular interval through the passage of time is
considered as longitudinal method of gathering data.
Advantages
1. Specific pattern of an individual as he develops can be
studied , permitting serial comparison with himself.
2. While studying a group, variability in development
among individual within the group is thrown into perspective.
3. Any mistakes in measuring at a given time are seen more
easily and corrections made more properly.
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Disadvantages
1. Time
2. Expenses
3. Attrition

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2. Cross Sectional Studies
A different individual or a different sample is
studied at different periods at a particular time to derive at a data.
Advantages
1. Data required for the study can be collected immediately.
2. Less expensive
3. Sample size
4. Allows repeating of studies more easily.
Disadvantages
1. It must be assumed that groups being measured and
compared are similar.
2. Tends to obscure individual variations.
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3 Semi longitudinal Data
Two methods are combined to seek advantages of
each. For eg, each sub sample including children studied for
same number of years, but started at different ages.
eg. Sub sample A may go from 3-6 yrs
Sub sample B may go from 4-7 yrs
Sub sample C may go from 5-8 yrs

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MEASUREMENT APPROACHES
-CRANIOMETRY
-ANTHROPOMETRY
-CEPHALOMETRIC
RADIOLOGY
EXPERIMENTAL APPROACHES
-VITAL STAINING
-RADIOISOTOPES
-IMPLANTS
-COMPARATIVE
ANATOMY
GENETIC STUDIES
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CRANIOMETRY
Study based on measurement of skull
found among human skeletal remains.
Originally used to study the
Neanderthal and Cro-Magnon peoples.
From such skeletal
materials, it has been possible to piece
together a great deal of knowledge
about extinct populations and to get
some idea of their pattern of growth by
comparing one skull with another.
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Craniometry has the advantage that rather
precise measurements can be made on dry skulls.
But has the disadvantage for growth
studies that, by necessity, all these growth data
must be cross-sectional.
Means that, although different ages are
represented in the population, the same
individual can be measured at only one point in
time.
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ANTHROPOMETRY
‘Orthodontists are functioning

ANTHROPOLOGISTS . We measure the
bones of the face, skull and teeth and study the
relationship of these structures’

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anthropos ~ human

logia ~ study

it is the study of humankind, from its
beginnings millions of years ago to
the present
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ANTHROPOMETRY
Is defined as the systemized
art of measuring and taking observations on
man, his skeleton, his brain or other organs, by
the most reliable means and methods & for
scientific purposes

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~The fundamental rule in anthropometry. is
to measure only those parts which
are needed to throw light upon the
problem being investigated

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Methods of measurement
~Measuring tape
~Sliding calipers
~Other instruments

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These details are added on with
~Casts of upper & lower teeth
~Photographs
~Radiographs

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In this method, various landmarks established in
studies of dry skulls are measured in living individuals
simply by using soft tissue points overlying these bony
landmarks.
Although soft tissue introduces variation,
anthropometry does make it possible to follow the growth
of an individual directly , making the same measurements
repeatedly at different times.
In recent years , ‘Farkas’
anthropometric studies have provided valuable new data
for human facial proportions and their changes over time.
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CEPHALOMETRIC RADIOLOGY
Has considerable importance not only in the study of growth,
but also in the clinical evaluation of orthodontic patients.
The technique depends on precisely orienting the head before
making a radiograph with equally precise control of
magnification.
This approach can combine the advantages
of both Craniometry and Anthropometry.

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Given by ‘Boardbent’ in 1931.
1. Lateral cephalogram
2. Frontal cephalogram
. Helps in orthodontic diagnosis by enabling the study of
skeletal, dental and soft tissue structures of cranio-facial
region.
. Helps in classification of skeletal and dental abnormalities
and also helps in establishing facial type.
. Helps in planning treatment for an individual.
. Helps in evaluation of the treatment results by quantifying
the changes brought about by the treatment.
. Helps in predicting the growth related changes and changes
associated with surgical treatment.
. As a valuable aid in the research work involving the craniodento- facial region.
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EQUIPMENT
Cephalometric radiographs are taken using an
apparatus that consists of an X- ray source and a head
holding device called the Cephalostat.
Cephalostat consists of two ear rods, that prevent the
movement of the head in the horizontal plane. Vertical
stabilization of the head is brought about by an Orbital
pointer that contacts the lower border of the left orbit.
The upper part of the face is supported by
the forehead clamp positioned above the region of the nasal
bridge. The distance between the X- ray source and the midsagital plane of the patient is fixed at 5 feet.
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ADVANTAGES
. This Approach can combine the advantages of
Craniometry and Anthropometry.
. It allows a direct measurement of bony
skeletal dimensions, since bone is seen through the soft
tissue covering in the radiograph and it also allows the same
individual to be followed over time.
DISADVANTAGS
.It produces a two dimensional representation
of a three dimensional structure, so even with precise head
positioning, not all measurements are possible.
But this can be overcome by making more than one
radiograph at different orientation and using different
angulations to calculate oblique distances.
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CEPHALOMETRIC TEMPLATES
Proportionate templates have been shown
to be useful in orthodontic diagnosis for comparing
cephalometric tracings to established norms.
In 1952, ‘Baum’ devised a set of four templates
to be overlaid directly on the x-ray films, using the Downs
Analysis.
‘Popovich and Grainger’, studied a population in
Burlington, Ontario, devised templates for ages 3-6 and 1012 that could be used to assess anteroposterior, vertical and
lateral facial development.
‘Johnston’ introduced a simplified method
of long term growth forecasting in which the tracing is
superimposed on a printed grid.
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The templates are drawn on millimeter graph
paper, so that the vertical lines of the paper will correspond to the
vertical – to – ground reference plane. Ranges of one standard
deviation from the norm are indicated for the SN, Palatal, and
Mandibular planes and for points N, Pg, A, and B.
The choice of patients template should be based
on the patient’s age, and more specifically, on the length of the
anterior cranial base (SN).
Next step is to superimpose the patient’s tracing on the ideal
template. Its recommended that superimposing at nasion, which is
more prominent point on the anterior cranial base, from which the
maxillary and mandibular protrution or retrution can be measured.

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. It provides an immediate picture of the patient’s
dentoskeletal structures without any measurements or
calculations.
. It makes it easier to judge the outlines of the hard
and soft tissue components than by merely using points and
planes.
. It allows comparison of the patient’s tracing with an
age- appropriate ideal templates.
. It allows any anomalies of the common intra cranial
reference planes, thus reducing diagnostic errors.
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VITAL STAINING
Dyes that stain mineralizing tissues are injected to
an animal. These dyes remain in the bones and teeth and can
be detected later after sacrifice of the animal. This method
was originated by ‘John Hunter’ in the 18th century. He
observed that the bones of pigs that occasionally were fed
textile waste were often stained in an interesting way. He
discovered that the active agent was a dye called
‘ALIZARIN’, which is still used for vital staining studies.
Alizarin reacts strongly with ‘Calcium’ at sites where bone
calcification is occurring . Since these sites are active
skeletal growth, the dye marks the locations at which active
growth was occurring when it was injected.
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Tetracycline is an excellent vital stain that binds to calcium at growth sites in
the same way as ‘Alizarin’.
But disadvantage is that it causes discoloration of teeth.
Lines formed by vital dyes become colored as a subsequent bone growth occurs.
Vital dyes stains only that bone which is actively being laid down during the
period in which the dye is in the blood stream.
Thus the thin colored line on the bone is seen and subsequently formed bones are
not colored.
Advantages
.Revels the manner in which bone is laid down, the sites of growth, the
direction of growth and relative duration at different sites and timings of
growth.
Disadvantage
It does not provide direct evidence of bone resoption.
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RADIOISOTOPES
Radioisotopes of certain elements or compounds often
are used as markers for studying bone growth.
Such labeled material is injected and then after a time,
located within the growing bone by means of ‘Greger
counters’, by the use of ‘Auto radiographic’ techniques.
In auto radiographic techniques, the bones or sections of
bones are placed against photographic emulsions that are
exposed by emission of radioactive substance.
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The gamma- emitting isotope 99m Tc, can be
used to detect areas of rapid bone growth in humans.
Radioactive isotopes used are
Calcium 45
Phosphorus 32
Technitium 33

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IMPLANTS
Metal pins are placed in bones anywhere in the
skeleton including face and jaws.
These metal pins are well tolerated by the skeleton and
become permanently incorporated into the bone without
causing any problems.
Developed by ‘BJORK’ and coworkers at the Royal Dental
College in Copenhagen has provided important new
information about the growth pattern of the jaws.

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Superimposing cephalometric radiographs on the
implanted pins allows precise observation of both changes in
the position of one bone relative to another and changes in
the external counters of individual bones.

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NATURAL MARKERS
Certain persistent developmental features of
bone are used as natural markers. By means of Serial
Radiography, trabculae, nutrient canals and lines or
arrested growths are used for reference to study bone
deposition, resoption and remodelling changes.
COMPARATIVE ANATOMY
Growth of human beings is compared with growth
of other species. It is carried out for experiments of growth
and development, which cannot be done using human
subjects.
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HAND-WRIST RADIOGRAPHS
It is specially indicated for children in
whom discrepancy between chronologic and maturational
age exists and it is not clear where child should be placed on
developmental scale.
Hand-wrist radiograph examination can give accurate
bone age picture.
The Carpals and distal end of Radius and Ulna are used in
assessing skeletal or bone age.
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Interpretation of Hand-wrist radiograph gives
a general idea of amount of growth but not the direction of
growth.
Bjork used the Ulna Sesamoid centre as an
indicator of growth completion.
It is also a valuable aid in research aimed at studying role
of heridity, nutrition etc on the skeletal maturity pattern.

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Thank you
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