Explore the fascinating journey of oral structure development and its real-world applications. From early growth stages to its impact on speech, eating, and more, uncover the practical implications in dentistry. Join us for a concise yet insightful exploration of oral structure evolution and its applied aspects!

1. Good
morning…
Dr. TARUNI VOORA
I MDS
PUBLIC HEALTH
DENTISTRY

5. Embryonic
Fetal
Neonatal
period
Infancy
Childhood
Adolescen
ce
Adulthood
Postnatal
Prenatal
Different
periods of
human
embryology

8. o Zygote undergoes a series of mitotic divisions
known as cleavage and the daughter cells
formed are known as blastomers
o The 16celled stage is known as morula and it
is formed on 4th day after fertilization

11. Cells of inner mass
differentiate become
flattened to form the
first germ layer,
ENDODERM
Remaining cells
become columnar.
These cells form the
second germ layer,
ECTODERM

12. Space between the
epiblast and
trophoblast is called
AMNIOTIC CAVITY
Flattened cells arising from
the hypoblast spread and
line inside the blastocystic
cavity called HEUSER’S
MEMBRANE
In this way, a cavity lined on
all sides by cells of
endodermal origin is formed
called PRIMARY YOLK SAC.

13. The extra embryonic coelom
does not extend into the
cranial part of the primary
mesoderm, this part is
known as the connecting
stalk.
Inside – TROPHOBLAST
Outside – AMNIOTIC CAVITY
Outside of the YOLK
SAC
A number of small cavities
develop in the primary
mesoderm which coalesce to
form the EXTRA EMBRYONIC
COELOM.
The cells of trophoblast give
origin to mass of cells called
EXTRAEMBRYONIC MESODERM

14. At one circular area near the
margin of the disc, the cubical
cells of the hypoblast become
columnar. This area is called the
PROCHORDAL PLATE.
The appearance of the
prochordal plate determines
the central axis of the
embryo which helps
distinguish the future head
and tail.

15. Ectoderm Mesoderm Endoderm
DERIVATIVES OF
GERM LAYERS

17. Cells in the primitive knot
multiply and pass cranially in the
middle line, between ectoderm
and endoderm, reaching up to
the caudal margin of the
prochordal plate.
A depression appears
in the Centre of the
primitive knot called
blastopore.
The cranial end of the
primitive streak becomes
thickened called primitive
knot/primitive node
These cells form a
solid cord called the
notochord process or
head process

18. • Extent : from the prochordal plate to the primitive knot
• Neurulation marks the beginning of formation of the
central nervous system
• Neural tube is divided into
A cranial enlarged part that forms the
brain
A caudal tubular part that forms the
spinal cord
• The neural tube gives rise to the brain and
spinal cord.

19. As the two neural folds fuse to
form the neural tube,
the neural plate gets separated
from the overlying
surface ectoderm
They approach each other, a
cluster of cells at the edge of
the neural folds gets
separated from neighboring
cells neural crest cells
They migrate and
differentiate into many cell
types within embryo

20. Pharyngeal
apparatus

21. Majority of the structures of head and neck are derived from pharyngeal apparatus
which develop in the neck region of the embryo
At the beginning of the 4th week, a pair of curved
elevation is seen in the neck region of the embryo
They are present on the anterolateral aspect of the
neck
Pharyngeal arches are number 1,2,3,4 and 6.
The 5th arch does not develop in humans

23. Arch Nerve Muscle Skeletal
Derivatives
Artery
1 Trigeminal Muscles of
mastication
Mandible
Maxilla
Malleus
Incus
Maxillary
artery
2 Facial Muscles of
facial
expression
Lesser horn and
upper half of the body
of the hyoid bone
Stapes
Styloid process
Stylohyoid ligament
Stapedial
artery (
embryo)
Corticotymph
anic ( adult )
3 Glossopha
ryngeal
Stylopharynge
us
Greater horn and lower
half of the body of hyoid
bone
Common
carotid artery

24. Arch Nerve Muscle Skeletal
derivative
Artery
4 Vagus
superior
laryngeal
nerve
Constrictors of
pharynx
Cricothyroid
Levator veli
palatini
All the cartilages
of larynx expect
epiglottis
( thyroid ,
cricoid,
arytenoid,
corniculate and
cuneiform)
Right
subclavian
artery
6 Vagus
recurrent
laryngeal
nerve
All intrinsic
muscles of
larynx except
cricothyroid
Same as arch 4 Pulmonary
artery

25. PHARYNGEAL
CLEFTS
PHARYNGEAL
POUCHES

26. •Treacher Collins
syndrome
•Pierre Robin
syndrome
•DiGeorge syndrome
Defective
development
of
pharyngeal
arches result
in
Syndromes

27. Hypoplasia of mandible and maxilla.
Microstomia, high palate, open bite.
Malformed external ear.
Bird or Fish like appearance.
Coloboma of lower eyelid
Treacher Collins
syndrome

28. Pierre Robin syndrome
• Mandibular hypoplasia
• Prevents normal
descent of tongue
between palatal
shelves
• Micrognathia leading
to fall back of tongue
and respiratory
obstruction

29. DiGeorge
syndrome
Infants are without thymus
and parathyroid glands
•Fish mouth deformity
•Low set notched ears
•Increased susceptibility
to infection

31. ECTODERMAL
• Lips
• Cheeks
• Palate
• Teeth
• Gums
• Salivary gland
ENDODERMA
LL
• Tongue

32. Development of
nose and cheek

33. Development
of lip

35. Palate is formed
by 3
components

36. – Each palatal
process fuses with
the posterior
margin of the
primitive palate
– Two palatal process fuse
with each other in midline
– Fusion begins anteriorly
and proceeds backward
– Medial edge of palatal
processes fuse with free
lower edge of nasal
septum
6th week 7th – 12th
week
12th week

37. The part of the palate derived
from frontonasal process forms
the premaxilla, carries the
incisors teeth
Mesoderm in the palate
undergoes intramembranous
ossification to form hard
palate

39. Unilateral complete
cleft palate
Bilateral complete
cleft palate
• Occurs when
maxillary process on
one side does not
fuse with the
premaxilla.
• Always associated
with cleft lip on the
Both the maxillary
processes fail to
fuse with the
premaxilla.

40. Bifid uvula Cleft of the soft palate
• Cleft
involving only
uvula.
• No clinical
importance.
• Involving the uvula
and the whole of
the soft palate
extending into the
hard palate.

42. • Mandible is the strongest bone
of the face
• It develops from 1st pharyngeal
arch
• It development begins in the 6th
week of the embryonic life

43. Meckle’s cartilage plays no role
In development of mandible instead
It provides a framework and delimits the
region where ossification takes place
In the 6th week, a single ossification center
for each half arises in the bifurcation of
Inferior alveolar nerve into mental and
In 7th week bone begins
to develop lateral to
Meckle’s cartilage and
continues until the
posterior aspect
Between 8-12th week, mandibular
growth accelerates, as a result
mandibular length increases
Mesenchymal condensation
Is considered the initial site
Of osteogenesis

44. • Rare, Congenital
condition
• Absence of
Maxilla/Mandible
• Commonly a portion of
jaw is missing
• Small jaw
• Congenital/ Acquired
• Abnormally large
jaw
• Hereditary
DEVELOPMENTAL ANOMALIES OF JAW
AGNATHIA MICROGNATHIA MACROGNATHIA

46. During 4th week
5 swellings develop in the pharyngeal arches
Among these 5 all contribute to the development of tongue
except copula
A pair of lingual
swellings
A single
tuberculum impar
In 1st arch
Copula
In 2nd arch
Hypobranchial
eminence
In 3rd and 4th arch

47. Muscles :
Developed from
occipital myotomes
Connective tissues :
Develops from local
mesenchyme.
From 2 lingual
swellings which
arise from 1st
branchial arch
Cranial part of
Hypobranchial
eminence
Hypoglossal nerve
Lingual nerve
Glossopharyngeal
nerve

48. ANKYLOGLOSSIA
AGLOSSIA
MICROGLOSSIA
MACROGLOSSI
A

49. BIFID TONGUE MEDIAN RHOMBOID GLOSSITIS
FISSURED
TONGUE
HAIRY
TONGUE
GEOGRAPHIC
TONGUE

51. 6TH week of IU
7-8th week of
IU
6th week of
IU
3rd month of IU
Minor salivary
glands

52. Bud
stage
Development
of the gland
with
dichromatic
branches
ducts
Further
differentiation of
gland and early
formation of
lobules and
canalization of
ducts
7th month of IU
Begins at 8th
embryonal month
and leads to
further maturation
of gland with
acinar and
intercalated duct

57. The tooth develops
from two sources
Oral
epithelium
Underlying
Mesenchyme
The epithelium over the
Lower and upper jaw thickens to form
U-shaped dental lamina
The dental lamina proliferates
Into the underlying mesenchyme to form
Tooth bud
The tooth bud is
invaginated
By underlying
mesenchyme
which forms the
Dental papilla

58. Dental papilla gives rise to
Odontoblast and dental pulp
Enamel
organ
Tooth bud develops into
A bilayered cap over the
Dental papilla called
The mesenchymal
cells
Around the developing
tooth
Forms dental sac
The cells of dental sac
Differentiate into
Cementoblast

60. Microdonti
a
Macrodonti
a

62. AMELOGENESIS
IMPERFECTA – Hereditary Enamel Dysplasia,
Hereditary Brown Enamel, Hereditary
Brown opalescent Teeth.
– Defects in:
i. Formative stage  hypo plastic type
 defective formation of matrix.
ii. Calcification stage  hypo calcified
stage  defective mineralization of
formed matrix.
iii. Maturation stage  hypo
maturation  enamel crystallites

63. DENTINOGENESIS
IMPERFECTA
– Autosomal dominant
– Grey to yellowish brown
discoloration
– Tulip shaped teeth
– 2 types
– Type 1- without
osteogenesis imperfect
– Type 2- Brandywine type of
DI