Details about the growth of the bone and development of the body in orthodontic

1. GROWTH AND DEVELOPMENT
GENERAL PRINCIPLES AND CONCEPTS
PRESENTED BY
DHANANJAY SINGH

2.  CONTENTS
1.Definition related to growth
2.Factors affecting physical growth
3.Some concepts of growth
4.Methods gathering growth data
5.Types of growth data
6.Methods of studying growth
7.Mechanisms of bone growth
8.Osteogenesis
9.Theories of growth
10.Other theories related to craniofacial growth

3. 1.DEFINITIONS RELATED TO GROWTH
• GROWTH
“The self multiplication of living substances”.(J.S.
Huxley)
“Increase in size , change in proportion and
progressive complexity.” (Krogman)
“An increase in size.” (Todd)

4. “Entire series of sequential anatomic and physiological
changes taking place from the beginning of prenatal life to
senility.” (Meridith)
“Quantitative aspects of biologic development per unit of
time”.(Moyers)
“Change in any morphological parameter which is
measurable.”(Moss)

5. DEVELOPMENT
*According to Todd, “is progress towards maturity”.
*According to Mayers, “all the naturally occurring
unidirectional changes in the life of an individual
from its existence as a single cell to its elaboration as
a multifunctional unit terminating in death.”

7. DIFFERENTIATION
Differentiation is the change from a generalized cell
or tissue to one that is more specialized.
Thus differentiation is change in quality or kind.

8. 2.FACTORS AFFECTING PHYSICAL GROWTH
1.Heredity
2.Nutrition
3.Illness
4.Race
5.Socio-economical factors
6.family size and birth order
7.Climatic and seasonal effects
8.Pscycological disturbance
9.Exercise

9. Heredity:-
There seems to be a considerable genetics influence in the size of
parts, rate of growth and onset of growth.
Nutrition:-
Malnutrition may affect size of parts, body proportions, quality &
texture of tissues, & onsets of growth events.
Race:-
Although the differences in growth among different races can
attributed to other nutritional and environmental factors.
Example- American blacks, calcification & eruption of teeth occurs
almost a year earlier than their white counterparts

10. Illness:-
Prolonged and debilitating illness however can have a marked
effect on all aspects of growth.
Family size and birth order:-
*The smaller the family size, the better would be the nutrition and
other favourable conditions.
*Studies have shown that the first born babies tent weight less at
birth have smaller stature but higher I.Q.
Psychological disturbances:-
It is seen that children experiencing stressful conditions display an
inhibition of growth hormone secretion.

11. 3.Some concepts of growth
Concepts of normality:-
The concept of normality must not be equated with that of
the ideal.
Another aspect of cranio-facial growth is that normality
changes with age.

12. Rhythm of growth
*According to Hooton, ‘Human growth is not a steady and
uniform process wherein all parts of the body enlarge at the
same rate and the increments of one year are equal to that
of the preceding or succeeding year.
*This growth rhythm is most clearly seen in stature or body
weight.

13. GROWTH SPURTS
*Growth does not take place uniformly at all times .
*There seems to be periods when a sudden
acceleration of growth occurs.
*This sudden increase in growth is termed ‘growth
spurt’.
*The timing of the growth spurts differ in boys and
girls.

14. The following are the timings of growth spurts.
a. Just before birth
b. One year after birth
c. Mixed dentition growth spurt
Boys:8-11 yrs
Girls:-7-9 yrs
d. Pre-pubertal growth spurt
Boys: 14-16 yrs
Girls:11-13 yrs
*Growth modification by means of functional and
orthodontic appliances elicit better response during growth
spurts.

15. DIFFERENTIAL GROWTH
The human body does not grow at the same rate throughout
life.
Different organs growth, different rates, to a different
amount and at different times.
Two important aspects of growth-
1.Scammon’s curve of growth
2.Cephalo-caudal gradient of growth

16. Scammon’s curve of growth:-
The body tissues can be broadly classified in to four types.
1.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.
By about 18 years of age, lymphoid tissues undergoes involution to
reach adult size.
2.Neural tissue grows very rapidly and almost reaches adult size by
6-7 years of age.
3.General tissue or Visceral tissue consist of the muscles, bones &
other organs .
These tissues exhibit an “S” shaped curve with rapid growth up to 2-3
years of age followed by a slow phase of growth b/w 3-10 yrs.

17. 4.Genital tissue consists of the reproductive organs.
They show negligible growth until puberty.
However they grow rapidly at puberty reaching adult size after which
growth ceases

18. Cephalo-caudal gradient of growth:-
Cephalo-caudal gradient of growth simply means there is an
axis of increased growth extending from head towards the
feet.
This growth concept can be illustrated as followss:
a.The head takes up about 50% of the total body length
around the third month of intra uterine life.
At the time of birth, the trunk and the limbs have grown
more than the head, there by reducing the head to about
30% of body length.
b. The lower limbs are rudimentary around the 2nd months
of IUL.
They later grow and represent almost 50% of the body
length at adulthood

19. c. At birth, the cranium is proportionally larger than the face.
Post-natally the face grows more than the cranium.

20. METHODS OF GATHERING GROWTH DATA
*The various growth studies can be broadly grouped as:
a. Longitudinal studies
b. Cross sectional studies
c. Semi- longitudinal studies.
Longitudinal studies
*This is a type of study where the observation and
measurements pertaining to growth are made on a person
or a group of persons at a regular intervals over a prolonged
period of time.
*Thus, longitudinal studies are long-term studies where the
same samples are studied by means of follow-up
examination.

21. Advantages :-
*The specific developmental pattern of an individual can be
studied and compared.
*Variation in development among individuals within the same
sample can be studied.
Disadvantages :-
*Longitudinal studies are carried out over long periods of
time. It often takes years or decades to complete a study.
*Longitudinal studies require maintenance of laboratory
research personnel and data storage systems. Thus, they can
be expensive.

22. *There is a risk of the sample size reducing due to change of
place or other unforeseen events.
Cross-sectional studies :-
*Cross- sectional studies are carried out by observation and
measurement made of different samples and studied at
different periods.
Advantages :-
*These studies are of short duration.
*They are less expensive .
*It is possible to get a large sample .
*It is possible to repeat the study in case of any flaw.

23. Semi- longitudinal studies:-
It is possible to combine the cross- sectional and
longitudinal methods so as to derive the advantages of both
the systems of gathering growth data.

24. TYPES OF GROWTH DATA
The physical growth can be studied by a number of ways:
Opinion:-
Opinion is the crudest means of studying growth.
This method of studying growth is not very scientific and should be
avoided when better methods are available.
Observations :-
They are useful in studying all or none phenomena such as presence
or absence of caries , class II molar relation etc.
Ratings and rankings:-
Rating makes use of standard, conventionally accepted
scales for classification.
It involves the arrangement of data in an orderly sequence
based on the value.

25. Quantitative measurements :-
The measurements made can be of three types:-
Direct Data: Direct Data are obtained from measurements
that are taken on living persons or cadavers by means of
scales , measuring tapes or capillers.
Indirect Data: The growth measurements can also be had
from images or reproduction of the person such as
photographs , radiographs or dental casts.
Derived Data: They are data that are derived after
comparing two measurements. These two sets of
measurements can be of different time frames or of two
different samples.

26. METHODS OF STUDYING GROWTH
According to profitt there are two main approaches to
studying physical Growth.
Measurement approaches:
They comprise of measurement techniques that are carried
out on living individuals. These methods do not harm the
animal.
Experimental approaches:
These are destructive techniques where the animal that is
studied is sacrificed.
Experimental approaches are usually not carried out on
humans.

27. Bimetric tests
They are tests in which physical characteristics such as
weight, height, skeletal maturation and ossification are
measured and compared with standards .
Vital staining
This technique involves administration of certain dyes to the
experimental animal that get incorporated in the bones.
It is possible to study the manner in which bone is laid
down, the site of growth , the direction , duration , and
amount of growth at different sites in the bone.
Radioisotopes
Radioisotopes of certain elements or compounds , when
injected into tissue get incorporated in the developing bone
and act as in vivo markers.

28. Implants
It involves the implanting of small bits of biologically inert
alloys into growing bone. These serve as radiographic
reference points for serial radiographic analysis.
These implants are embedded in certain areas of maxilla
and mandible in order to study the growth of the skull.
*The areas where the implants are placed in the maxilla
are:
1.Hard palate behind the deciduous canines (prior to
eruption of maxillary permanent incisors).
2.Below the anterior nasal spine( after eruption of maxillary
incisors).

29. 3.Two implants on either side of the zygomatic process of
maxilla.
4. Border between hard palate and alveolar process medial
to the first molar.

30. *The areas where implants are used in mandible are:-
1.Anterior aspect of symphysis ,in the midline below the
root tips.
2.Two pins on the right side of the mandibular.
One pin under the first premolar and the other below the
second premolar or first molar.
3.One pin on the external aspect of the right ramus at the
level of occlusal surface of molars.

32. Radiographic techniques
The most commonly used radiographic techniques are
cephalometry and hand-wrist radiographs.
Cephalometry:-
It is standardized radiographic technique of the cranio-facial
region.
Cephalometry makes it possible to take serial radiographs of
a patient skull in order to study the growth changes taking
place.
It is valuable aid in orthodontic diagnosis, treatment
planning, evaluation of treatment results and for growth
prediction.

34. Hand-wrist X-rays
Radiographs of the hand-wrist region are used to study the
biological or skeletal age of a person.
The hand-wrist area has a number of small spongy bones
called carpels that have a definite schedule of appearance
and ossification.

36. Natural markers
*Normal bone has certain histological features such as
nutrient canals, lines of arrested growth and certain
prominent trabeculae.
*These develop mental features of a bone can be used as
natural markers to study growth by means of serial
radiographs.
*Natural markers can be used to study bone deposition,
resorption and bone remodelling.

37. Mechanisms of bone growth
Bone is a specialized tissue of mesodermal origin . It forms the
structural framework of the body.
Bone is calcified tissue that supports the body and gives points of
attachment to musculature.
Bone deposition and resorption
Bone changes in shape and size by two basic mechanisms,bone
deposition and bone resorption. The process of bone deposition and
resorption together is called bone remodelling.
The changes that bone deposition and resorption can produce are:
a. Change in size
b. Change in shape
c. Change in proportion
d. Change in relationship of the bone with adjacent structures.

38. Cortical drift
*A combination of bone deposition and resorption resulting
in a growth movement towards the depositing surface is
called cortical drift.
*If bone deposition and resorption on either side of bone
are equal then the thickness of the bone remains constant.
*If in case more bone is deposited on one side and less bone
is resorbed on the opposite side then the thickness of the
bone increases.

39. Displacement
It is the movement of the whole bone as a unit.
Displacement can be of two types.
Primary displacement: If a bone gets displaced as a result
of its own growth ,it is called primary displacement. For ex.
Growth of the maxilla at the tuberosity region results in
pushing of the maxilla against the cranial base which results
in the displacement of the maxilla in a forward and
downward direction.

40. Primary displacement of maxilla due to its own
growth

41. Secondary Displacement
If the bone gets displaced as a result of growth and
enlargement of an adjacent bone, it is called secondary
displacement.
For ex- the growth of the cranial base causes the forward
and downward displacement of the maxilla.

42. Osteogenesis
The process of bone formation is called osteogenesis.
Bone formation takes place in two ways.
1.Endochondral bone formation
2.Intra-chondral bone formation

43. Endochondral bone formation
*In this type of osteogenesis the bone formation of a cartilaginous
model that is subsequently replaced by bone.
*Mesenchymal cells become condensed at the site of bone formation.
*Some mesenchymal cells differentiate into chondroblasts and lay
down hyaline cartilage.
*The cartilage is surrounded by a membrane called perichondrium.
This is highly vascular and contains osteogenic cells.
*The intra-cellular substance surrounding the cartilage cells becomes
calcified due to the influence of enzyme alkaline phosphatase
secreting by the cartilage cells.
*Thus the nutrition to the cartilage cells is cut off leading to their
death. This results in formation of empty spaces called primary
areolae.

44. *The blood vessels and osteogenic cells from the perichondrium
invade the calcified cartilaginous matrix that is now reduced to bars or
walls due to eating away of the calcified matrix. This leaves large
spaces between the walls called secondary areolae.
*The osteogenic cells from the perichondrium become osteoblasts and
arrange along the surface of these bars of calcified matrix.
*The osteoblasts lay down osteoid , which later becomes calcified to
form a lamellae of bone. Now another layer of osteoid is secreted and
this goes on and on. Thus, the calcified matrix of cartilage acts as a
support for bone formation.

46. Intra-membranous bone formation
*In this type of ossification , the formation of bone is not
preceded by formation of a cartilaginous model.
*At the site of bone formation , mesenchymal cells become
aggregated.
*Some mesenchymal cells lay down bundles of collagen
fibre.
*Some mesenchymal cells enlarge and acquire a basophilic
cytoplasm and form osteoblasts.

47. *These osteoblasts secrete a gelatinous matrix called
osteoid around the collagen fibres.
*They deposit calcium salts into the osteoid leading to
conversion of osteoid into bone lamellae.
*Now the osteoblasts move away from the lamellae and a
new layer of osteoid is secreted which also gets calcified.
*Some of the osteoblasts gets entrapped between the two
lamellae. They are called osteocytes.

49. Theories of growth
genetic theory:-
This theory simply states that all growth is controlled by
genetic influence and is preplanned.
This is one of the earliest theories put forward

50. Sutural theory:-
Sicher believed that cranio-facial growth occurs at the
sutures.
According to him paired parallel sutures that attach facial
areas to the skull and the cranial base region push the naso-
maxillary complex forwards to pace its growth with that of
the mandible.
This theory also acknowledges the genetic influence of
growth.

51. Cartilaginous theory
This theory put forward by James Scott.
According to him intrinsic growth controlling factors are
present in cartilage and periosteum with sutures being only
secondary.
He viewed the cartilaginous sites throughout the skull as
primary centres of growth.
According to Scott, the nasal septal cartilage is the
pacemaker for growth of the entire naso-maxillary complex.

52. The functional matrix concept
According to Melvin Moss the functional matrix concept
attempts to comprehend the relationship between form &
function.
The functional matrix hypothesis claims that the origin,
form, position, growth and maintenance of all skeletal tissue
and organ.
The functional cranial component is divided in to:
1.functional matrix
2.skeletal unit

53. 1.Functional Matrix
It consist of muscles, glands, nerves, vessels, fat,
teeth and the functioning spaces.
The functional matrices is divided in to two:
a. Periosteal matrices
b. Capsular matrices

54. a.Periosteal matrices:-
The periosteal matrices act directly and actively upon their
related skeletal units.
Their functional demands produce a secondary
compansatory transformation of the size and shape of their
skeletal units.
This transformation due to the action of periosteal matrices
is brought about by bone deposition and resorption.

55. b. Capsular matrices:-
The capsular matrices act indirectly and passively on their
related skeletal units producing a secondarey compensatory
translation in space.
The neuro-cranial capsule and the oro-facial capsule are
examples of capsular matrices.
Each of these capsules is an envelop which contains a series
of functional cranial components .

56. The neuro-cranial capsule surrounds and protects the neuro-
cranial capsular functional matrix , which is the brain,
leptomeninges and C.S.F.
The neurocranial capsule is made up of skin, connective
tissue, aponeurotic layer, periosteum, base of skull and 2
layers of duramater.
The oro-facial capsules surrounds and protects the oro-naso-
pharyngeal spaces that constitute the oro-facial capsular
matrix.

57. The skeletal unit :-
All skeletal tissues associated with a single function are
called “the skeletal unit”.
The skeletal unit may be comprised of bone, cartilage and
tendinous tissue.
When a bone is comprised of several contigous skeletal
units, they termed “micro skeletal unit”
Example- In the mandible it is made up of alveolar, angular,
condylar, gonial, mental, coronoid and basal micro skeletal
units.

58. In the maxilla it is made up of orbital, pneumatic, palatal &
basal micro-skeletal unit.
When adjoining portions of a number of neighjbouring bones
are united to function as a single cranial component, we term
this a “macro-skeletal unit”.
Example:-The entire endocranial surface of the calavarium.

59. Van Limborgh’s theory
A multi-factorial theory was put forward by Van Limborgh in
1970.
Van Limborgh explains the process of growth and
development in a view that combines all three exisiting
theories.
Van Limborgh suggested the following five factors that he
believed controles growth:
intrinsic genetic factors:-
they are the genetic control of the skeletal units themselves.

60. Local epigenetic factors:-
Bone growth is determined by genetic control originating
from adjacent structures like brain, eyes etc.
General epigenetic factors:-
they are genetic factors determining growth from distant
structures, Eg- sex hormones, growth hormones etc.
Local environmental factors:-
they are non genetic factors from local external
environment. Eg- habits, muscles force etc.
General environmental factors:-
they are general non genetic influences such as nutrition,
oxygen etc.

61. Other theories related to cranio-facial
growth
Enlow’s expanding ‘V’ principle:-
*Many facial bones or parts of bone have a ‘V’ shaped
pattern of growth.
*The growth movements and enlargement of these bones
occurs towards the wide ends of the ‘V’ as a result of
differential deposition & selective resorption of bone.
*Bone depostion occurs on the inner side of the wide end
of the ‘V’ and bone resorption on the outer surface.

62. *Deposition is also take place at the ends of the 2 arms of
the ‘V’ resulting in growth movement towards the ends.
*The ‘V’ pattern of the growth occurs in a number of regions
such as-
The base of the mandible, Ends of long bones, Mandibular
body, Palate,etc.

64. Enlow’s counterpart principle
The counterpart principle of craniofacial growth of any given
facial or cranial part relates specifically to other structural
geometric counterparts in the face & cranium.
Imbalances in the regional relationships are produced by
differences in:-
a. Amounts of growth b/w the counterparts.
b. Directions of growth b/w the counterparts.
c. Time of growth b/w the counterparts.

65. The different parts & their counterparts are:-
1.Nasomaxillary complex relates to the anterior cranial
fossa.
2.Horizontal dimension of the pharyngeal space relates to
the middle cranial fossa.
3.middle cranial fossa & breadth of ramus are counterparts.
4.maxillary & mandibular arches are mutual counterparts.
5.Bony maxilla & corpus of mandible are mutual
counterparts.
6.Maxillary tuberosity & lingual tuberosity are counterparts.

66. Neurotrophic process in oro-facial-growth:-
Neutrophism is a non-impulse transmitting neural function
that involves axoplasmic transport & provides for long term
interaction & innervated tissues that homeostatically
regulates the morphological, compositional & functional
integrity of those tissues.
The difference types of neurotrophic mechanisms are:-
1.Neuro-epithelial trophism
2.Neuro-visceral trophism
3.Neuro-muscular trophism

67. 1.Neuro-epithelial trophism:-
*Epithelial mitosis & synthesis are neurotrophically
controlled.
*The normal epithelial growth is controlled by release of
certain neurotrophic substances by the nerve synapses.
*If this neurotrophic process is lacking or is deficient,
abnormal epithelial growth, oro-facial hypoplasia &
malformation etc., occur.

68. 2.Neuro-muscular trophism:-
*Embryonic myogenesis is independent of neural is
innervation and trophic control.
*Approximately at the myoblast stage of differentiation,
neural innervation is estalished without whiuch further
myogenesis usually cannot continue.

69. 3.Neuro-muscular trophism
The salivary glands, fat tissue and other organs are
trophically regulated, at least in part.

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