INTRODUCTION TO GROWTH AND DEVELOPMENT; GROWTH THEORIES; DEVELOPMENT FROM OVUM;DEVELOPMENT OF CRANIAL BASE ; DEVELOPMENT OF MAXILLA AND MANDIBLE ; DEVELOPMENT OF PALATE ; GUM-PADS

1. GROWTH
AND
DEVELOPMENT
DR. NARENDRA PRASSATH SATHIAMOORTHY
POST GRADUATE
PEDODONTICS
THAI MOOGAMBIGAI DENTAL COLLEGE

2. 1
GROWTH AND DEVELOPMENT –
PART 1
NARENDRAPRASSATH
1ST YEARPG
DEPARTMENT OF PEDODONTICS
THAI MOOGAMBIGAO DENTAL COLLEGE
THE BASE

3. 22
CONTENTS FOR
PART -1
• Definition
• Development
• Differentiation
• Concepts Of Growth
• Methods Of Studying
Growth
• Theories Of Growth

4. 33
DEFINTIONS
• It is a dynamic process with stable pattern of changes resulting in the increase in
physical change of mass during the course of development.
• Stewart (1982): Defined as developmental increase in mass
• Proffit (1986): Growth refers to increase in size or number
• Moyer (1988): Changes in amount of living substance
• Moss: Change in any morphological parameter which is measurable
• Todd (1931): Growth refers to increase in size
• JS Huxley: Self multiplication of living substance.

5. 44
DEFINTION
• Kroggman – Increase in size , change in proportion and progressive complexity
• Meridith - entire series of sequential anatomic and physiologic changes taking
place from the beginning of prenatal life to senility
• Limitation:
• Through growth is generally associated with an increase in size , yet some conditions
involving regression are also considered to take place during growth .
• Example: atrophy of thymus gland
No definitions are universally accepted

6. 55
DEVELOPMENT
It is defined as:
• Todd (1931): Increase in complexity.
•Moyers (1988): 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.
• Pinkham (1994): Development addresses the progressive development of a tissue.
•Enlow: A maturational process involving progressive differentiation at the cellular and tissue
levels.
DIFFERENTIATION
IT IS THE CHANGE FROM A GENERALIZED CELL OR TISSUE TO ONE
THAT IS MORE SPECIALIZED.
THUS DIFFERENTIATION IS CHANGE IN QUALITY OR KIND.

7. CONCEPTS OF GROWTH
67
•CONCEPT OF NORMALITY
•RHYTHM OF GROWTH
•GROWTH SPURTS
•DIFFERENTIAL GROWTH

8. CONCEPT OF NORMALITY
68
• What is normal ??
Normal refers to that which is usually expected, is ordinally seen or is typical..
The concept of normality must not be equated with that of ideal
While ideal denotes the central tendency for the group, normal refers to A range.
The cranio-facial growth with age.
Thus what is normally seen or is expected for one age group may not be
necessarily normal for a different age group

9. 8
RHYTHM OF GROWTH
8
• According to hooton,
• Human growth is not A steady and uniform process where in all parts of the body enlarge at the same rate
and the increments off one year are equal to that of the preceding or succeeding year.
• Growth rhythm is clearly seen in stature or body weight
• 1st wave □ both sex [ birth to 5th or 6th year] + intense and rapid in first 2 years
• Terminates in boys – 10th to 12th year
• Terminates in girls □ 10th year
• 2nd wave □ accelerated growth inadolescenece
• Terminates in female ( 14TH and 16th year) / males ( 16th and 18th year)
• 3rd wave □ final period of slowgrowth
• Terminates in 18th and 20th year while in boys until 25th year

10. 99
GROWTH SPURT
• Growth does not take place uniformly at all times.
• There some periods □ sudden acceleration of growth
• Sudden growth is termed as growth spurts
• Just before birth
• One year after birth
• Mixed dentition growth spurt :
• boys□ 8 To 11 years
• Girls □ 7 to 9 years
• Pre-pubertal growth spurt
• Boys□ 14 – 16 years
• Girls □ 11 -13 years
Importance of growth
spurts:
Growth
means of
orthodontic
modification by
functional and
appliances elicit
better response.
During growth spurts
Surgical correction involving
the maxilla and ,mandible
should carry out after
cessation of the growth spurt

11. DIFFERENTIAL GROWTH
11
SCAMMON`S CURVE OF
GROWTH
10
CEPHALO-CAUDIAL
GRADIENT OF
GROWTH

12. 10
12

13. • Lymphoid tissue :
proliferates rapidly in late
childhood and reaches 200% of
adult size
Genital tissue
Negligible growth until puberty
After puberty rapid growth
10
13

14. 10
14

15. 10
15

16. 10
16

17. C.C.G.G
1710
• Head takes upto 50% of total body length around the third month
of IUL
• At time of birth , the trunk and the limbs have growth more
than the head , reducing the head size upto 30 %
• When attaining to the adult size, the size of the head is reduced
upto 12%
• Lower limbs are rudimentary around the 2nd month of life
• They later grow and represent 50% of body length
• At birth cranium is larger than the face, post natally the face grows
more than the cranium.

18. 10
18

19. TYPES OF DATA
 METHODS OF GATHERING DATA
• Longitudinal studies
Made in group of persons at regular
intervals of time on A prolonged period
• Cross – sectional studies
 Made on different samples at different
period at shoirt duration
• Semi-longitudinal studies
 Combining the two studies &
deriving the advantage 18
• Opinion □ clever guess of an experienced
person
• Observations □ phenomenal
• Rating and rankings□ using scales
• Quantiative measurements
Direct□ taking measurements from living or
cadavers
Indirect□ from past images,
photographs/radiographs
Derived data□ comparing the two
measurements at the different frames
GROWTH DATA

20. Methods Of Studying
Growth
2019
• According to profitt,
• Measurement approaches :
• comprise of measurement techniques that are carried out on living individuals
. do not harm the animal
• Experimental approaches:
• Destructive techniques , animals are sacrificed
• Not carried on humans

21. BIMETRIC TESTS
2119
•Test On Physical Characteristics:
•Weight
•Height
•Skeletal Maturation
•Ossification
•Measured And Compared With The Healthy Individuals

22. VITAL STAINING
22
• 1936□ belchier, accidentally noted that bones off animals that had eaten madder plants , their
bones stained red.
• The technique of administration of the dyes.
• Helps to study the manner of the bone , which is laid down ,site of growth, the direction, duration
and the amount of growth
• Dyes:
• Alizarin red 5
• Acid alizarin blue
• Trypon blue
• Tetracycline
• Pb(c2h3o2)2□ lead acetate
19

23. 2222
Radio-
Isotopes
• These are certain elements or
compounds, when injected into tissue get
incorporated in the developing bone and
act as in vivo markers.
• These radio-isotopes can later detected
by tracking down the radioactivity they
emit.
•The radioisotope used include:
technetium -33
calcium - 45
potassium 32

24. 2323
Radiographic
techniques
• William conhard roentgen in 1895 □ introduction of X rays
• Cephalometry:
• Standardized radiographic technique of the cranio-facial region
• Introduced by broadbent – 1931
• Helps in taking of serial radiographic of patients skull to study the growth changes
• Aids in orthodontic diagnosis, treatment planning, evaluation of the treatment
• Hand-wrist radiography:
• Radiograph of wrist
• Radiograph on the small spongy bones - carpels

25. 2424
THEORIES INVOLVING IN THE BONE GROWTH
• Genetic theory—Brodie, 1941
• Scott’s cartilaginous theory—Scott, 1953
• Sutural dominance theory—Sicher, 1955
• Functional matrix concept—Moss, 1962
• Van Limborg’s concept—Von Limborg, 1970
•Cybernetics—Petrovic, Stutzman, 1974.
Other theories related to craniofacial growth are:
• Enlow’s expanding ‘V’ principle
• Enlow’s counterpart principle
• Neurotrophic process in oro-facial growth.

26. 2525
GENETIC THEORY
• This theory was popularized by Allan G. Brodie in 1940s and it states that
craniofacial growth is controlled by genetics.
• This theory states that genes such as Homobox, Sonic hedgehog, Transcription factor
and IHH (protein) play an important role in craniofacial development.
• This theory had proposed that genes control all the functions of growth and
development.
• The role of genetic programming has long been presumed by many to have a
fundamental and perhaps overriding influence in establishing the basic facial pattern.
• Epigenetic regulation can determine the behavioral
• growth activities of certain tissues.

27. 2626
SCOTT’S HYPOTHESIS/CARTILAGINOUS THEORY/NASAL SEPTUM THEORY
(SCOTT, 1953)
James Scott, an Irish Anatomist proposed that cartilaginous nasal septum has features and occupies a strategic
position that might cause the mid-face region to displace rather than the sutures.
•Because the cartilage is more pressure tolerant it has more capacity to push the naso-maxillary complex
downward and forward, thus giving rise to the nasal septum theory.
• This theory states that determinant of craniofacial growth is by growth of cartilages.
• The fact that cartilage does not grow while bone merely replaces it makes this theory attractive.
SUPPORT:
• Although there is no cartilage in maxilla, there is a cartilage in nasal septum and this naso-maxillary
complex grows as a unit.
• Nasal septum and epiphyseal cartilages continue to grow when implanted in cultures thus showing their
innate growth potential.
• Removal of nasal septum lead to mid-facial deformities.

28. 2727
SUTURAL DOMINANCE THEORY/SICHER’S
HYPOTHESIS (SICHER, 1955)
• Sicher proposed that sutures cause most of craniofacial growth and to support his theory.
• He conducted some experiments using vital dyes.
• He said that primary event was proliferation of connective tissue between two bones leading to appositional growth.
• Sicher felt that connective tissue in sutures of vault and naso-maxillary complex produced forces that separate the
bones and cause expansion.
• SUPPORT:
• If sutures are pulled apart bone fills in and if sutures are compressed, then there is impeded growth.
• DEMERITS:
• Sutures when transplanted from face to abdominal pouch do not grow.
• Presence of forces triggers bone resorptions and not deposition.
• Growth can be seen in cases of untreated cleft palate patients even in absence of sutures.
Thus, we can conclude that sutures are not primary determinants of growth and are just the growth sites.

29. 2828
FUNCTIONAL MATRIX CONCEPT/MOSS
HYPOTHESIS (MOSS, 1962)
• This theory was introduced by Melvin Moss based on functional cranial component by
Van Der Klaaus.
• This theory claimed that the control for growth was not in cartilage or bone but in
adjacent soft tissues thus emphasizing that neither the nasal septum nor the mandibular
condyle are Determinants of growth.
• He theorizes that growth of face occurs as a response to functional needs and is mediated
by the soft tissues in which jaws are embedded.
• The functional matrix hypothesis claims that the origin, form, position, growth and
maintenance of all skeletal tissues and organs are always secondary, compensatory and
necessary response to chronologically and morphologically
• A large number of functions are carried out independently in the craniofacial region like
respiration, olfaction, hearing, chewing, etc.

30. 29
Functional Matrix
This consists of teeth, organs, glands,
muscles, nerves and vessels as well as
non-skeletal cartilages.
It is divided into periosteal and
capsular matrix.
Periosteal Matrix
•All non skeletal units adjacent to
skeletal units.
•Act directly and actively upon their
related skeletal units producing a
secondary compensatory
transformation
Capsular Matrix
•Neuro-cranial capsule:
–Sandwiched between skin and Dura mater
–Act indirectly and passively upon their
related skeletal units producing a secondary
compensatory translation.
–Expansion of capsule takes place and the
skeletal units move in the expanded capsule
thus giving translative growth without
deposition and resorptions.
•Oro-facial capsule:
–Surround and protect oro-nasopharyngeal
space
–Volumetric growth of these spaces is the
primary morphogenic event in facial growth.
FUNCTIONAL MATRIX CONCEPT

31. 3030
Skeletal Unit
This skeletal unit may be comprised of bone, cartilage or tendon. All skeletal tissues are
related to a specific functional matrix, i.e. all skeletal tissues are associated with a single
function.
Micro-skeletal Unit
• Bones consisting of number of small skeletal units
•When a combination of several bones make up this unit it is called as micro-skeletal unit
like mandible.
Macro-skeletal Unit
When there is a contribution of parts of many adjacent bones such a unit is called as
macro-skeletal unit like maxilla
LIMITATION:
In hydrocephalic patients, the size of brain is small but the cranial vault is bigger.

32. VAN LIMBORG’S CONCEPT
(VAN LIMBORG, 1970)
3231
According to him, all the previous theories were not complete and acceptable but each had
some elements of significance that cannot be denied.
This theory suggested five factors that control growth:
1.Intrinsic genetic factors: Genetic control of the skeletal units themselves
2.Local epigenetic factors: Bone growth is determined by genetic control originating from
Adjacent factors like brains, eyes, etc.
3.General epigenetic factors: Genetic factors determining growth from distant structures
like growth hormones, sex hormones, etc.
4.Local environmental factors: From External Environnent like habits, muscle forces, etc.
5.General environmental factors: Nutrition, Oxygen, etc.

33. CYBERNETICS/SERVO-SYSTEM THEORY
(PETROVIC, STUTZMAN, 1974)
•Using the language of cybernetics, Petrovic reasons that it is the
interaction of series of casual changes of feedback mechanisms which
determine the growth of craniofacial regions.
• According to this theory, control of primary cartilage takes a
cybernetics form of a command whereas control of secondary cartilage
is comprised of indirect and direct effects of cell’s multiplication.
Cybernetics
•Science dealing with comparative study of operations of complex
computers of human nervous system.
31
33

34. 33
Servo-
system
 Command: Signal established independent of feedback system. It affects the
behavior of the control system without being affected by the consequences of
the behavior,
 e.g. secretion of growth hormone or testosterone is not modulated by
variations in craniofacial growth.
 Reference input elements: Establish relation between command (growth
hormone) and reference input (Sagittal position of maxillary arch).
 They include septal cartilage, septo-premaxillary frenum and maxillary bones.
• Reference input: Signal established as a standard of comparison.
• Peripheral comparator: Compares reference input and output, e. g. position of
33
• Controlled variable: Output signal of the system

35. ENLOW’S EXPANDING ‘V’ PRINCIPLE
35
This is the most basic and useful concept of growth.
•Many facial and cranial bones have a V-shaped pattern of growth and the expansion of these occurs along
the ends of V as a result of selective bone resorptions and deposition.
•The pattern of growth is such that there is deposition along the inner side and wide ends of V and
resorptions on the outer aspect
•Some of the bones which grow according to this pattern are end of long bones, base of mandible,
mandibular body and palate.
34

36. Enlow’s Counterpart Principle
3634
•This principle states that growth of any facial or cranial part relates
specifically to other structural and geometric counterparts in face
and cranium
Body part and their geometric counterparts
• Naso-maxillary complex—anterior cranial fossa
• Maxillary arch—mandibular arch
• Bony maxilla—corpus of mandible
• Maxillary tuberosity—lingual tuberosity

37. 3636
NEUROTROPHISM (BEHRENT, MOSS, 1976)
The physiology of neurotrophism is based on the fact that nervous system apart from conducting efferent and afferents is
also concerned with the integrity of body structures.
• Nerve control of skeletal growth by transmission of a substance through its axons is called as neurotrophism.
Types of neurotrophic mechanisms
Neuro-epithelial trophism
– Epithelial mitosis and synthesis is neuro-trophically controlled
– Normal epithelial growth is controlled by release of neuro-trophic substances from nerve synapse.
– Presence of taste buds is dependent on intact innervation.
• Neuro-visceral trophism
– Salivary glands, fat tissue are partly trophically regulated.
• Neuro-muscular trophism
– Innervation is required at the myoblast stage of differentiation.

38. GROWTH AND
DEVELOPMENT PART -2

39. CONTENTS
• Factors Affecting Growth
• Hormones In Growth
• Mechanism Of Growth
• Types Of Osteogenesis
• Specific Periods
• Fertilization/ Clevage
• Formation Of Neural Crest
• Formation Of BranchialArch
• Defects In Growth

40. genetic influence on the size of parts , rate of growth & the onset of growth
FACTORS AFFECTING THE GROWTH
Nutrition
Malnutrition affects the growth , parts , the body , proportions , quality and texture of growth
prolonged minor childhood illness can cause a marked effect
Race
Due to some environmental factors growth can be affected.
E.g.: American black grows faster than American whites
Family size and birth order
First born babies tend to weight less
birth but high in IQ
HEREDITARY

41. HORMONES INVOLVING IN THE GROWTH
• Growth hormone from pituitary
• Thyroid hormone
• T3 and T4
• Sex hormones like testosterone, oestrogen,
• Sex gland stimulating hormone

42. MECHANISM OF BONE
GROWTH
• Bone is a specialized tissue of mesodermal origin.
• It forms the structural framework of the body.
• Normal bone contains between 32- 36% of organic matter.
• Bone deposition and resorptions is called bone remodelling
• Change in shape , size, proportion, relationship of bone with
adjacent structures.

43. CORTICAL DRIFT
• Most bones grow by interplay of bone deposition and resorptions
• Combination of bone deposition and resorptions resulting in a growth
movement towards the depositing surface is called cortical drift.
• Bone deposition is equal proportion is leads to normal bone growth

44. Displaceme
nt
Movement of the whole bone as a unit
Primary Displacement :
Bone gets displaced as a result of its own growth
E.g.: growth of the maxilla in the tuberosity region
Secondary Displacement
Bone gets displaced as a result of growth and enlargement of an
adjacent bone
E.g.: growth of the cranial base causes the forward and downward
displacement of the maxilla

45. TYPES OF OSTEOGENESIS
Endochondral bone formation
• Bone formation is preceded by formation of a cartilaginous model that is subsequently
replaced by bone
• Condensation of mesenchyme cells @ site of bone formation
• Formation of hyaline cartilage
• Cartilage is surrounded by membrane called perichondrium
• Invasion of blood vessels in perichondrium leads to formation of calcium matrix
• Osteogenic cells from perichondrium become osteoblasts and arrange along the surface of
these bars of calcified matrix
• Osteoblasts lay down osteoid, which later becomes calcified to form a lamella of bone .

46. Intra – Membraneous Bone
Formation
The formation of bone is not preceded by formation of a cartilaginous
model
Instead bone laid down directly in a fibrous membrane
Osteoblasts move away from the lamellae on a new layer of osteoid is
secreted which also gets calcified.
Osteoblasts get entrapped between two lamellas. These are called
osteocytes

47. SPECIFIC PERIODS
• Period of ovum:
Approximately two weeks from the time of fertilization.
During this period , the cleavage of the ovum and the
attachment of there ovum to the intra – uterine wall
• Period of embryo
Period extends from the fourteenth day to the fifty sixth day
of intra uterine life.
During this period the major part of the development of the
facial and the cranial region occurs.

48. PERIOD OF THE FETUS
This phase extends between the fifty sixth day of
IUL.
In this period , accelerated growth of the
cranio-facial structures occurs resulting in an
increase in their size.
In addition, a change in proportion between
various structures also occurs.

49. Fertilizatio
n• Male and the female germ cells are called spermatozoa and the ova
respectively.
• Unlike the general human cells which contain 46 chromosomes , the
germ cells contain only half the number of chromosomes.
• Fusion of male and female cells called fertilization.
• Fertilized egg cells undergoes a series of rapid divisions leading to
formation of ball of cells called the morula which contain approximately
16 cells.
.

50. THE CLEVAGE
• Fluid seeps into the morula which results in realigning of
the cells to form a fluid filled hollow ball called the
blastocyst.
• The cells that line the primary yolk sac are called
trophoblasts while the cluster of cells that form the inner
cell mass is called embryoblasts.
• The trophoblasts are associated with the implantation of
the embryo and the formation of the placenta.
• The inner cell mass or embryoblast forms the embryo
proper.

51. Formation ofGerm
Layers• Further development of blastocyst leads to
differentiates rapidly to form a two –
layered germ disc.
• Upper layer is the ectoderm which is
columnar and the lowest layer is the
endoderm which is flattened cells.
• Cavity which forms between the
ectodermal layer and the trophoblast is
called the amniotic cavity ,
• while the cavity that forms below the
endodermal layer is called the secondary
yolk sac and it develops by the migration
of peripheral cells of the endoderm

52. • In further progress in embryonic development , the embryo in circular disc comprising of 2
layer of cells , the columnar ectodermal layer and the cuboidal endodermal layer.
• A small enlargements of the ectodermal and endodermal cells is seen at once circular area near
the margin of this disc.
• This area is called as the prochordal plate and it helps in establishing the axis of the embryo.
• The formation iof the prochordal plate help us to distingu8ish the left halves and the right
halves of embryo as well head and tails
• Primitive streak:
• some ectodermal cells along the central axis near the tail end of the disc proliferate to form an
elevation called primitive streak.
• The cells of the ectoderm along the primitive streak start proliferating and pass laterally
between the ectodermal and endodermal; layers to form mesoderm
• This development is called as gastrulation, where bilaminar disk is converted to trilaminar
disc

53. FORMATION OF NEURAL
CREST
• A thickening is seen within the embryo at the head end of the
ectodermal layer .
• This plate is neural plate and acquires raised margins called the
neural folds.
• This neural folds encompass a midline depression called the neural
groove.
• The neural folds eventually fuse together to form the brain and the
spinal cord.

55. FOLDING OF THE
EMBRYO
• As the embryonic disc comprising the three germ layers enlarges the disc
becomes folded in the head and tail ends .
• These folds are called then head and the tail folds.
• Similar folds are seen in the lateral aspect called the lateral folds.
• Due to the formation of the head and tail folds , a part of the head and tail folds
, a part of the yolk sac becomes enclosed within the embryo.
• This enclosed tube lined by endoderm is called the primitive gut and it gives
rise to git tract

56. FORMATION OF THE PHARYNGEAL
ARCHES

57. • Formation of the fold at the head end of the embryo helps
in formation of the primitive oral cavity or stomedeum.
• Around the 4th week of iul a series of mesodermal
thickenings are seen in the wall of cranial most part of the
foregut.
• They are called branchial arches or pharyngeal arches
• These arches are seen as 6 cylindrical thickenings that
expand and pass beneath the floor of the pharynx and
approach their anatomic counter parts of the opposite side

60. Growth and
Development Part -3
Growth of Countenance

61. ●The skull is a bony structure that forms
the head in vertebrates. It supports the structures of
the face and provides a protective cavity for the brain.
●The skull is composed of two parts: the cranium and
the mandible.
●In humans, these two parts are the neuro-cranium and
the viscera-cranium or facial skeleton that includes the
mandible as its largest bone.
●The skull forms the anterior most portion of the skeleton
and is a product of cephalisation—housing the brain, and
several sensory structures such as the eyes, ears, nose,
and mouth.
●In humans these sensory structures are part of the facial
skeleton.
●

62. PARTS
OF
THE
SKULL

63. PRE-NATAL
GROWTH
OF
THE
CRANIAL
BASE
●Formation of the cranial base is seen in post or
late somitic period of 4th to 8th of intra uterine
life
●During this period mesenchymal tissue derived
from the primitive streak , neural crest and
occipital sclerotomes condense around the
developing brain
●Capsule formed around the brain called
ectomenix capsule.
●The basal portion of this capsule gives rise to
future cranial base

64. The development of the skull and the formation of the
cartilages of the cranial base is dependant upon the
presence of many other cranial structures like brain,
cranial nerves and eyes
From around the 40th day onwards , this ecto-meningeal
capsule is slowly converted into cartilage .
This forms an endo-chondrol ossification

65. FORMATIO
N OF
THE
CARTILAGE
S
CARTILAGE FORMATION TAKES
PLACE IN 4 REGIONS
●PARACHORDAL
●HYPOPHYSEAL
●NASAL
●OTIC

66. PARA-
CHOR
DAL
●Chondrification
centres forming
around the cranial
end of the
notochord are
called
para-chordal
cartilages

67. DEVELOLMENT
OF
PITUITARY GLAND,
WINGS
OF
SPHENOID,
CRISTAGALLI,
● Cranial to the termination of notochord – which at the level of the
oro-pharyngeal membrane .
● The hypophyseal pouch develops which give rise to the anterior
lobe of pituitary gland
● On either side of the hypophyseal stem two hypophyseal or post
–sphenoiod cartilages develop.
● These cartilages fuse together and form the posterior part of the
body of the sphenoid
● Cranial to the pituirary gland , two sphenoid or trabecular cartilages
develop which fuse together and form the anterior part of body of
sphenoid.
● Anteriorly , the pre-sphenoid cartilage forms a vertical cartilaginous
plae called mes-ethmoid cartilage which give rise to the
perpendicular plate of ethmoid and cristagalli
● Lateral to the pituitary gland , chondrification centres are seen in
lesser wing (orbito- sphenoid) and greater wing of sphenoid

68. NASAL
●Initially during the
development , a
capsule is seen
around the nasal
organ.
●This capsule
chondrifies and
forms the cartilages
of the nostrils , which
fuse with the
cartilages of the
cranial base

69. OTIC
● A capsule around the vestibulo-cochlear sense organs, this
capsule chondrifies and later ossifies to give rise to the
mastoid and petrous portions of the temporal bone .
● The otic cartilages also fuse with the cartilages of the cranial
base.
● The initially separates centre of cartilage formation in the
cranial base fuse together into single irregular and greatly
perforated cranial base
● The early establishment of various nerves , blood vessels ,
from and to the brain results in numerous perforations or
foramina in the developing cranial base .

70. Chodro-cra
nial
ossification

71. Occipital bone
●Occipital bone shows both 5□endochondral
and 2 intra membraneous ossification.
●Supranuchal squamous part ossifies intra-
membraneously from one pair of ossification centers
which appear in the 8th week of intra uterine life
●Infra-nuchal line squamous part ,ossifies
endochondrally from 2 centers , which appear at the
10th week of intra uterine life
●Basilar part ossifies endochondrally from a single
median ossification center appearing in the 11th week
of intra-uterinelife.
●This gives rise to the anterior portion of the occipital
condyles and the anterior boundary of foramen
magnum
●A pair of endochondral ossification centers appears in
the 12th week forming the lateral boundary of foramen
magnum and the posterior portion of the condyles

72. Temporal
bone
●Ossifies both endochondrally and intra-
memebraneously from 11 centers.
●Squamous part of the temporal bone ossifies from a
single intra-membraneous center that appaears in the
8th week of intra-uterine life.
●The tympanic ring ossifies from four intra-
membraneous centers that appear in the 12th week of
intra uterinewall
●The petrous part of temporal bone ossifies from 4
endochondral centres that appear in the 5th month
of intra uterine life.
●The styloid process ossifies from 2 endochondrol
centres

73. Ethmoid
bone ● This bone shows only endo-chondrol ossification .
● It ossifies 3 centres
● One centre locator centrally that forms the median floor of
the anterior cranial fossa.
● 2 lateral centres in the nasal capsule

74. Sphenoid bone
● Bone ossifies both intra-membraneously and endochondrally .
● There are at least 15 ossification centers.
●Lesser wing: Endochondrol ossification
occurs in the orbito-sphenoid cartilage
●Greater wing: Two Intra membraneous ossification
centres in ali-sphenoid cartilage.
●Medial pterygoid plate: Ossifies endochondrallly from
a secondary cartilage in the hamular process
●Anterior part of body of sphenoid: Ossifies
endochondrolly from 5 centres. The centre of
ossification is seen in pre-sphenoid cartilage
●Posterior part of body of sphenoid: Ossifies
endochondrolly from four centres. The centre of
ossification is the post-sphenoid cartilage.

75. Uneven
nature
of
growth
of
cranial
base
●Growth of the cranial base is highly uneven.
●Attributed to the uneven nature of growth in
different regions.
●Cranial base growth resembles the growth
resembles the growth of the ventral surface of
overlying brain.
●Anterior and posterior parts of the cranial base
grow at different rates.
●Between the 10th and 40th weeks of intra-uterine
life , the anterior cranial base increases in length
and width by 7 times while, during the same
period of posterior cranial base increases only 5
fold

76. Development of
eye
●Eye formation in the human embryo begins at
approximately three weeks into embryonic
development and continues through the tenth
week.
● Cells from both the mesodermal and the
ectodermal tissues contribute to the formation of
the eye.
● Specifically, the eye is derived from
the neuroepithelium, surface ectoderm, and the
extracellular mesenchyme which consists of both
the neural crest and mesoderm.
●Neuroepithelium forms the retina, ciliary body, iris,
and optic nerves. Surface ectoderm forms
the lens, corneal epithelium and eyelid. The
extracellular mesenchyme forms the sclera, the
corneal endothelium and stroma, blood
vessels, muscles, and vitreous.

77. Development
of
face
●The facial prominences are five swellings that appear
in the fourth week and come from the first and second
pharyngeal arch.
●They are basically made of mesenchyme that comes
from the neural crest.
●The frontonasal prominence is a single structure that
is ventral to the forebrain. It is derived from neural
crest cells, which have an ectodermal origin.
● These neural crest cells migrate from the ectoderm as
the forebrain closes, invading the space that will form
the frontonasal prominence.
●The maxillary and mandibular prominences are
derived from the first arch.
●The maxillary prominence is initially located
superior/lateral to
the stomodeum while the mandibular prominence is
located inferior to it and will fuse early on.

78. Facial
bones

79. Nasal placode
●Nasal placodes originate on the frontonasal prominence
from the ectoderm.
●They thicken and sink in to form Nasal Pits, which deepen
to form the Nasal Sacs.
● At the same time, mesodermal cells proliferate around
the placodes, and the sides of these swellings form the
medial and lateral nasal prominences.
●The lateral nasal prominence is separated from the
maxillary prominence by the nasolacrimal groove.
●As the maxillary prominences continue growing they merge
laterally with the mandibular prominences to form the
cheeks. Their growth compresses the medial nasal
prominences and causes them to fuse around the 10th week
of development.
●. The intermaxillary segment yields the portion of the
upper lip containing the philtrum, the upper jaw with 4
incisors, and the primary palate

80. Nasal
cavity

81. Development of
the
nasal
cavity
●The formation of the lateral and medial nasal
prominences makes the nasal placodes lie in the floor of
the depression, called nasal pits.
●The nasal pits deepen and develop the nasal sacs in the
sixth week. These new structures grow dorsocaudally in
front of the forming brain.
●In the beginning, the nasal sacs are separated from the
oral cavity by the oronasal membrane.
●This membrane disappears in the seventh week leaving a
connection between the nasal cavities and the oral
cavity, called the primitive choanae.
● Later, when the development of the secondary palate
occurs, the choanae changes its position and locates at
the junction of the nasal cavity and the pharynx.

82. Development
of
maxillary
sinus
●3rd month of intra uterine life
●Develops from the expansion of nasal
mucous membrane into the maxillary
bone.
●Later the sinus enlarges by resorptions of
the internal wall of maxilla.

83. GROWTH AND DEVELOPMENT
PART- 4
GROWTH OF
PILLARS
OF
ORAL CAVITY

84. THE
MAXILLA

85. INTRO TO MAXILLA
 The maxilla, also known as the upper jaw, is A vital viscera-cranium structure of the skull.
 It is involved in the formation of the orbit, nose and palate, holds the upper teeth and plays
an important role for mastication and communication.

86. borders of maxilla
 Superiorly: Frontal Bone
 Posteriorly: Sphenoid, Palatine, Lacrimal, Ethmoid Bones
 Medially: Nasal Bone, Vomer
 Inferior: Nasal Concha
 Laterally: Zygomatic Bone

87. Surfaces of maxilla
• Shape  Pyramidal
• Base- Directed Mesially At
Nasal Surface
• Apex- Directed Laterally At
Zygomatic Process
4 Surfaces
• Anterior –Facial
• Posterior- Infra-temporal
• Medial –Nasal
• Superior- Orbital
Encloses A Cavity Of Maxillary Sinus

88. pre – natal embryology of maxilla
 4th week of intra-uterine life,
 Shallow depression forms below primitive mouth which is called stomedeum
 Floor of the stomedeum is formed by the bucco-pharyngeal membrane that
separates the stomedeum from the foregut.
 Around the 4th week first branchial arch which is the mandibular arch lead to
the development of naso-maxillary region
 Mesoderm of the tri-laminar disc covers the developing brain which proliferates
and forms a downward projection that overlaps the upper part of the
stomedeum which is called the fronto-nasal process
 Fronto-nasal process lead to the development of maxillary process as a bud
from the mandibular arch .

89. POST-NATAL GROWTH OF MAXILLA
 DISPLACEMENT
 GROWTH AT SUTURES
 SURFACE REMODELLING

90. DISPLACEMENT
 Maxilla is attached to the cranial base by number of sutures
 Growth of cranial base is directly bearing on naso-maxillary growth.
 Primary displacement takes in the maxillary tuberosity region at the posterior
part.
 The whole maxilla is carried out anteriorly.
 Amount of the forward displacement equals the amount of posterior
lengthening.
 Secondary displacement take place at the naso-maxillary complex occurs in
downward and forward direction as the cranial base grows
 Naso-maxillary complex is simply moved anteriorly as the middle cranial fossa
grows in that direction.

91. Growth at sutures
 Sutures are all oblique in nature more or less
parallel to each other
 This allows the downward and forward
repositioning of maxilla grow at the suture.
 As the growth of the surrounding soft tissue
occurs the maxilla grows downwards and forward.
 This leads to opening of the space at the sutural
attachments.
 New bone is formed on either side of the suture.
 Overall size of bone increases on either side
• Fronto-nasal suture
• Fronto-maxillary
suture
• Zygomatico-
temporal suture
• Zygomatico-
maxillary suture
• Pterygo-palatine
suture

92. Surface re-modelling
It is the concept of bone deposition and the
resorptions.
Leads to :
Increase in size
Changes in shape of bone
Change in functional relationship

93. 1. Resorption occurs at the lateral surface of the orbital rim
leading to the lateral movement of the eye ball
2. Floor of the orbit faces superiorly, laterally and anteriorly;
surface deposition occurs here and results in growth in a
superior , lateral & anterior direction.
3. Bone deposition occurs along the posterior margin of the
maxillary tuberosity.
4. Cause the lengthening of the dental arch and enlargement of
the antero-posterior dimension the erupting molars
5. Bone resorptions occurs on the lateral wall; of the nose
leading to an increase in size of the nasal cavity

94. 1. The zygomatic bone moves in a posterior direction .this is
achieved by resorptions on the anterior surface and
deposition on the posterior surface.
2. The face enlarges in width by bone formation on the lateral
surface of the zygomatic arch and resorptions its medial
surface.
3. The anterior nasal spine prominence increases due to the
bone deposition
4. As the teeth erupting bone deposition occurs at the alveolar
margins. This increases the maxillary height and depth of the
palate.
5. The entire wall of the sinus except the mesial wall undergoes

95. THE
MANDIBLE

96. Intro to mandible
 The mandible, lower jaw or jawbone is the largest,
strongest and lowest bone in the human face.
 It forms the lower jaw and holds the lower teeth in place.
The mandible sits beneath the maxilla.
 It is the only movable bone of the skull
 The bone is formed in the fetus from a fusion of the left
and right mandibular prominences, and the point where
these sides join, the mandibular symphysis, is still visible as
a faint ridge in the midline.

97. Pre-natal development of mandible
 4th week of intra-uterine life ,
 The pharyngeal arches are laid down on the lateral and ventral aspects of the
cranial most part of the foregut that lies in close approximation with the
stomedeum.
 First arch is called the mandibular arch and The second arch  hyoid arch
consists of central cartilage rod that forms the skeleton arch , a muscular
component termed as branchiomere, it consist of vascular element and the
neural element.
 Formed maxillary process from the stomedeum , it gives bud at dorsal end,
which grows ventro-medially ,cranial to the main part of the arch , which is
called as mandibular process.
 The mandibular process of both sides grow towards each other and fuse in the
midline.
 They now form the lower border of the stomedeum that is the lower lip and
lower jaw.

98. Meckel`s cartilage
 Meckel`s cartilage derived from the first branchial
arch around the 41st – 45th day of intra uterine life.
 It extends from the cartilaginous otic capsule to the
midline or symphysis and provides a template for
guiding the growth of the mandible.
 Major portion of the meckel`s cartilage disappears
during growth. But remaining parts develops into,
 1)mental ossicles
 2) incus and malleus
 3)spine of sphenoid bone
 4)anterior ligament of malleus
 5) spheno-mandibular ligament

99.  Trigeminal nerve is the first formed element in mandible.
 Mesenchyme condensation of first branchial arch; neurotropic factors produced by
the nerve induce osteogenesis in the ossification centres.
 Mandible arises in 6th week of intra-uterine life in the region of the bifurcation of the
inferior alveolar nerve and incisive branches.
 As ossification continues , the meckel`s cartilage becomes surrounded and invaded by
bone.
 Later meckel`s cartilage continues into the middle ear and develops into the auditory
ossicles that is malleus and incus.
 The spheno-mandibular ligament that extends from the lingula of mandible to the
sphenoid bone also forms a remnant of the meckel`s cartilage.

100. ENDO-CHONDROL BONE FORMATION
THE CONDYLAR PROCESS
THE CORONOID PROCESS
THE MENTAL REGION

101. CONDYLAR PROCESS
 5th week of IUL
 Mesenchyme condensation seen in the ventral
part of the developing mandible .
 Later it develops into cone – shaped cartilage by
10th week and ossified by 14th week.
 Later it fuses with mandibular ramus.

102. Coronoid process
 Secondary cartilages appears in the coronoid process
in the 10-14th week of intra uterine life
 Later it develops into temporalis muscle
 Finally it is incorporated into the bone of ramus and
disappeared during birth

103. MENTAL REGION
One or two cartilages appears on the either side of the symphysis get
ossified in the 7th month of IUL to form mental ossicles
Formed ossicles become incorporated into the intra-membraneous
bone when the symphysis completely during the first year of life.

104. • While the mandible appears in
the adult as single bone, it is
developmentally and
functionally divisible into a
several skeletal sub-unit.
• Basal bone forms one unit, to
which is attached the alveolar
process, coronoid process,
condylar process, angular
process, the ramus, the lingual
tuberosity and the chin.
POST NATAL GROWTH OF MANDIBLE

105. RAMUS:
It moves progressively posterior by a
combination of deposition and resorption.
Resorption occurs on anterior part of ramus
while bone deposition occur on the posterior
region.
This result in a “drift” in posterior direction.
Functions of the remodelling of ramus are:
1. Accommodate the increasing mass of the
masticatory muscles inserted intoit.
2. To accommodate the enlarged breadth
of the pharyngeal space.
3. To facilitate the lengthening of the mandibular
body, which in turn accommodates the
erupting molars.

106. CORPUS OR THE BODYOFTHE MANDIBLE:
• Displacement of the ramus results in the conversion of the
ramal bone into the posterior part of the body of the
mandible.
• In this manner, it lengthens. Thus additional space made
available by means of resorption of the anterior border
of the ramus is made use of to accommodate the
erupting molar.

107. ANGLE OF THE MANDIBLE:
• On the lingual side of the angle of the
mandible, resorption take place on the
posterio-inferior aspect while deposition
on the anterio-superior aspect.
• On the buccal side, resorption occur on
the anterio- superior part while
deposition takes place on poserio-
superior part.
• This results in flaring of the angle of
mandible as age advances.

108. LINGUALTUBEROSITY:
• It moves posteriorly by deposition on its
posteriorly facing surface.
• It protrudes noticeably in a lingual
direction and that it lies well toward the
midline of ramus.
• The prominence of the tuberosity is
increased by the presence of the large
resorption field just below it.

109. ALVEOLAR PROCESS:
• It develops in response to the presence of tooth
buds.
• As the teeth erupt, it develops and increases in
height by bone deposition at the margins.

110. THE CHIN:
• As the age advances the
growth of chin becomes
significant.
• It is influenced by sexual
and specific genetic factors.
• Usually males are seen to
have prominent chin as
compared to females.
• Mental tuberosity forms by
bone deposition during
childhood.

111. THE CORONOID PROCESS:
• The growth follows the enlarging ‘V’principle.
• Viewing, the logitudinal section of coronoid
process from posterior aspect, it can be seen that
deposition occurs on the lingual (medial) surfaces
of the left and right coronoid process.
• Although additions take places on the lingual side,
the vertical dimension of the coronoid process also
increases. This follows the ‘V’principle.
• Viewing from the occusal aspect, the deposition
on lingual of coronoid process brings about
posterior growth movement in ‘V’pattern

112. THE CONDYLE:
• The head of the condyle is covered by the thin layer of cartilage
called the condylar cartilage.
• The presence of condylar cartilage is an adaptation to withstand
the compression that occurs at the joint.
• It is believed that the growth of the soft tissues including the
muscles and the connective tissues carries the mandible forward
away from cranial base.
• Bone growth follows secondary at the condyle to maintain
constant contact with cranial base.
• The condylar growth rate increases at puberty reaching a peak
between 121/2-14years.
• The growth ceases around20 years of age.

113. GROWTH AND
DEVELOPMENT
PART -5

114. THE
PALATE

115. PALATE
Palate separated the oral cavity from
the nasal cavity
Large- anterior –hard palate
Small – posterior – soft palate
Soft palate is attached to the
posterior margin of the hard palate

116. Development of palate
 Maxillary process ,
palatal shelves given off
by maxillary process ,
fronto-nasal process.
 Fronto-nasal process
pre-maxilla
 Palatal shelves rest of
the palate

117. Development of hard palate
 The hard palate is a thin
horizontal bony plate made up of two
bones of the facial skeleton, located in
the roof of the mouth.
 The bones are the palatine process of
the maxilla and the horizontal plate of
palatine bone.
 The hard palate spans the alveolar
arch formed by the alveolar
process that holds the upper teeth

118.  The hard palate is formed by the palatine process of
the maxilla and horizontal plate of palatine bone. It
forms a partition between the nasal passages and
the mouth.
 On the anterior portion of the hard palate are the
plicae, irregular ridges in the mucous membrane that
help facilitate the movement of food backward
towards the larynx.
 This partition is continued deeper into the mouth by a
fleshy extension called the soft palate.

119. Development of soft palate
 The soft palate also known as
the velum, palatal velum, or muscular
palate) is, in mammals, the
soft tissue constituting the back of the
roof of the mouth.
 The soft palate is part of the palate of
the mouth; the other part is the hard
palate.
 The soft palate is distinguished from
the hard palate at the front of the
mouth in that it does not

120. adjacent of soft palate
 In normal position the one surface is directed upwards & backwards ,
another surface directed towards forward and backward.
 Median part is prolonged upwards and backwards as a conical
projection is called as uvula
 The lateral margins of the palate are continuous with 2 folds of
mucous membrane
 The anterior of these connects the palate to the lateral margin of the
posterior part of the tongue and is called palato-glossal fold.
 The posterior fold connects the palate to the wall of the pharynx is
called the palato-pharyngeal fold
 Soft palate consists of two layers of mucousd membrane , between
the layer there is a fibrous basis called the palatine -aponeurosis

121. Muscles of soft palate
 Tensor Veli Palatini, Which Is Involved
In Swallowing
 Palatoglossus, Involved In Swallowing
 Palatopharyngeus, Involved In Breathing
 Levator Veli Palatini, Involved In Swallowing
 Musculus Uvulae, Which Moves The Uvula

122. Ossification of the palate
Taker place in 8th week of IUL
Intra-membraneous type of ossification
Ossification centre derived from the maxilla
Mid –palatal suture ossifies by 12-14 years
Arch expansion takes place treatment of
malocclusion

123. The Gum Pads
The alveolar arches of an infant at the time of birth
are called Gum Pads.
These are greatly thickened oral mucous membrane
of the gums, which soon become segmented, and each
segment is a developing tooth site.
They are pink in color and firm in consistency.

124. Maxillary gum pad

126. Mandibular gum pad

128. • The pads get divided into a labio/buccal and a
lingual portion which differentiates later.
• Transverse grooves separate the gum pads into 10
segments.
• The groove between the canine and the first molar
region is called the lateral sulcus, which helps to
judge the inter-arch relationship.

129. The upper gum pad is horse shoe shaped and
shows:
- Gingival groove: Separates gum pad from the
palate.
- Dental groove: Starts at the incisive papilla,
extends backward to touch the gingival groove
in the canine region and then moves laterally to
end in the molar region.
- Lateral sulcus.

130. • The lower gum pad is U- shaped and
rectangular, characterized by:
- Gingival groove: Lingual
extension of the gum pads.
- Dental groove: Joins gingival
groove in the canine region.
- Lateral sulcus.

131. • Anterior open bite is seen at rest with contact
only in the molar region.
• Tongue protrudes anteriorly through this
space.
• The intermaxillary space closure, occurs with
eruption of primary teeth, thus it is a self-
correcting anomaly of the developing
dentition.

132. • Complete overjet
• Class II pattern with the maxillary gum pad
being more prominent.
• Mandibular lateral sulci posterior to maxillary
lateral sulci.
• Mandibular functional movements are mainly
vertical and to a little extent anteroposterior.
• Lateral movements are absent.