1. Tooth development begins around the 6th week of gestation with the formation of the primary epithelial band, which divides into the dental lamina and vestibular lamina. 2. Teeth develop through a series of stages from bud to bell shaped to advanced bell stage when mineralization begins and root formation commences. 3. The dental lamina gives rise to the tooth buds and plays a role in shaping tooth development through later stages. The enamel organ and dental papilla are structures that form within the developing tooth bud.

1. DEVELOPMENTOFTOOTH
Dr. Yumna
Lecturer
Dental Hygiene and Technology

2. CONTENTS
1. Introduction
2. Dental Lamina
3. Vestibular Lamina
4. Tooth development
5. Developmental stages
• Budstage
• Capstage
• Bell stage
• Advanced bell stage
6. Hertwig’s epithelial root sheath and root
formation
7. Conclusion
8. References

3. INTRODUCTION

4. • Tooth formation occurs in the 6th week of
intrauterine life with the formation of primary
epithelial band.
• At about 7th week the primary epithelial band
divides into a lingual process called dental lamina &
abuccal process called vestibular lamina.
INTRODUCTION

5. INTRODUCTION
• All deciduous teeth arises from
dental lamina
• Later the permanent successors
arise from its lingual & distal
extensions

6. DENTAL
LAMINA

7. Dental Lamina
• The dental lamina is a band of epithelial
tissue seen in histologic sections of a
developing tooth.
• The dental lamina is first evidence of
tooth development and begins (in humans)
at the sixth week in utero

8. •At about 7th week the primary epithelial band
divides into an inner (lingual) process called Dental
Lamina & an outer ( buccal) process called Vestibular
Lamina

9. Dental Lamina
• The dental lamina serves as the primordium
for the ectodermal portionof the deciduous
teeth
• Later during the development ofjaws,
permanent molars arise directly from the
distal extension of thedental lamina

10. •The successors of the deciduous teeth develop from a
lingual extension of the free end of the dental lamina
opposite to the enamel organ of each deciduous
teeth.

11. Enamel Organ
• The enamel organ, also
known as dental organ, is
a cellular aggregation
seen in histologic sections
of a developing tooth. It
lies above a condensation
of cells called the dental
papilla.

12. FATEOF DENTAL LAMINA
•It is evident that total activity of dental lamina
exceeds over a period of atleast 5 years
•As the teeth continue to develop, they loose their
connection with the dental lamina

13. •Fragmentation of the
dental lamina progresses
toward the developing
enamel
organ
•However the dental
lamina may still be active
in the third molar region
after it has disappeared
elsewhere, except for
occasional epithelial
remnants

14. CLINICAL
CONSIDERATIONS

15. ANODONTIA
•Anodontia, also called anodontia
vera,is arare genetic disorder
characterized by the congenital
absenceof
all primary or permanentteeth
• It is of followingtypes
1. Complete anodontia/ total
anodontia
2. Partial anodontia/ sub-Total
anodontia
COMPLETE
PARTIAL

16. SUPERNUMERARY TEETH
• Hyperdontia is the condition of
• having supernumerary
teeth, or teeth which
appear in addition to the
regular number of teeth
• When classified by position, a
supernumerary tooth may be
referred to as
• Amesiodens
• Aparamolar, or
• A distomolar.

17. VESTIBULARLAMINA
•Labial and buccal to the dental lamina in each
dental arch, another epithelial thickening
develops independently
•It is Vestibular Lamina also termed as lip furrow
band

18. VESTIBULAR LAMINA
• Subsequently hollows and form the oral
vestibule between the alveolar portion of
the jaws and the lips and cheeks.

19. TOOTH
DEVELOPMENT

20. •At certain points along the
dental lamina, representing
the 10 mandibular & 10
maxillary teeth, ectodermal
cells multiply rapidly & little
knobs grow
•Each of these growths
from the dental lamina
represents the beginning
of the enamel organ of
the toothbud

21. DENTAL PAPILLA
On the inside of the cap like structure, the
ectomesenchymal cells increase in number. The
tissue appears more dense than the surrounding
mesenchyme and represents the beginning of the
dental papilla
B =DentalPapilla

22. DENTAL SAC/
DENTAL FOLLICLE
• Surrounding the combined
enamel organ or dental
papilla, the third part of the
tooth bud forms.
• It is known as dental
sac/follicle and it consists of
ectomesenchymal cells and
fibres that surrounds the
dental papilla and the
enamel organ.
C=Dental sac

23. DEVELOPMENTAL
STAGES

24. MORPHOLOGICAL
1. Dental lamina
2. Bud stage
3. Capstage
4. Earlybell stage
5. Advancedbellstage
6. Formationof enamelanddentin matrix
PHYSIOLOGICAL
Initiation
Proliferation
Histodifferentiation
Morphodifferentiation
Apposition

25. BUD STAGE

26. BUD STAGE
•Initial stage of tooth formation
•Enamel organ resembles a small
bud
•The enamel organ consists of
peripherally located low columnar
cells & centrally located polygonal
cells
•The area of condensation
immediately below the enamel
organ is the dentalpapilla

27. •The ectomesenchymal condensation that
surrounds the tooth bud & the dental
papilla is the tooth sac
•The dental papilla aswell asthe dental
sacare not well defined during the bud
stage
•The cells of the dental papilla form the
dentin and pulp while the dental sac
forms cementum & periodontal ligament
BUD STAGE

28. CAP STAGE

29. CAP STAGE
•As the tooth bud continues
to proliferate, it does not
expand uniformly into a large
sphere
•Unequal growth in different
parts of the tooth bud leads
to the cap stage

30. CAP STAGE
• Characterized by a shallow invagination on
the deep surface of the bud

31. OUTER & INNER
ENAMEL
EPITHELIUM

32. OUTER & INNER
ENAMELEPITHELIUM
•The peripheral cells of the
cap stage are cuboidal ,
cover the convexity of the cap
& are called the outer
enamelepithelium
•The cells in the concavity of
the cap become tall
columnar cells & represent
the inner enamel epithelium

33. •The outer enamel epithelium is separated
from the dental sac, & the inner enamel
epithelium from the dental papilla, by a
delicate basementmembrane
OUTER & INNER
ENAMELEPITHELIUM

34. STELLATE
RETICULUM

35. STELLATERETICULUM
•Polygonal cells located between the outer and the inner
enamel epithelium, begin to separate due to water being
drawn into the enamel organ
•Asa result the polygonal cells become star shaped but
maintain contact with each other by their cytoplasmic
process

36. STELLATE RETICULUM
• As the star shaped cells
form a cellular network,
they are called the
stellate reticulum

37. ENAMEL
KNOT

38. •The cells in the center of the
enamel organ are densely
packed and form the
enamel knot
•This knot projects toward the
underlying dentalpapilla
Enamel Knot

39. •At the same time avertical extension of the
enamel knot, called the enamel cordoccurs

40. • The enamel knot act asa
signaling centers as
many important growth
factors are expressed by
the cells of the enamel
knot & thus play an
important role in
determining the shape of
the tooth
• The dentalpapilla & the
dental sacare pronounced
during this stage of dental
development

41. BELL
STAGE

42. BELL STAGE
•Due to continued growth of the
enamel organ it acquires abell
shape
•In bell stage crown shape is
determined
•The folding of enamel organ to
cause different crown shapes is
shown to be dueto different rates
of mitosis & difference in cell
differentiation time

43. INNER ENAMEL EPITHELIUM
•The inner enamel epithelium consists of a single layer
of cells that differentiate into tall columnar cells called
ameloblasts
•These elongated cells are attached to one another by
junctional complexes called desmosomes

44. INNER ENAMEL EPITHELIUM
• The cells of the inner enamel epithelium
exert a strong influence on the underlying
mesenchymal cells of the dental papilla,
which later differentiate into odontoblasts

45. STRATUM INTERMEDIUM
•Afew layers of squamous cells form the stratum
intermedium , between theinner enamel epithelium & the
stellatereticulum
•These cells are closely attached by desmosomes & gap
junctions
•This layer seems to be essential to enamelformation

46. DENTAL LAMINA
•Dental lamina seems to extend
lingually and is termed
successional dental lamina asit
gives rise to enamel organs of
permanent successors of
deciduous teeth
•The enamel organs of deciduous
teeth in the bell stage show
successional lamina &
their permanent successor teeth in
the budstage

47. DENTAL SAC
•The dental sacexhibits a
circular arrangement of
fibres & resembles a capsule
around the enamelorgan
•The fibres of the dental sac
form the periodontal
ligament fibresthat span
between the root & the bone

48. DENTAL SAC
• The junction between the inner enamel
epithelium & odontoblasts outlines the
future dentino-enamel junction

52. ADVANCED BELL STAGE
Characterized by the
commencement of
mineralization & root
formation
The boundary between
the inner enamel
epithelium &
odontoblasts outline the
future dentinoenamel
junction

53. ADVANCED BELL STAGE
 Formation of dentin occurs first asa layer along
the future dentinoenamel junction in the region of
future cusps
 After the first layer of dentin is formed, the
ameloblasts lay down enamel over the dentin in the
future incisal & cuspal areas

54. The enamel formation
then proceeds coronally &
cervically in all the regions
from the dentinoenamel
junction toward the surface
The cervical portion of
enamel organ gives rise to
Hertwig Epithelial Root
Sheath (HERS)
ADVANCED BELLSTAGE

55. HERTWIG’S EPITHELIAL ROOT
SHEATH
• This HERSoutlines the future root & thus
responsible for the size, shape , length & number
ofroots

56. CLINICAL
CONSIDERATIONS

57. HUTCHINSON’SINCISOR
MULBERRYMOLARS

58. FUSION
•The phenomenon of
tooth fusion arises
through union of two
normally separated tooth
germs
• it may be either
complete or incomplete.

59. GEMINATION
Gemination arises
when two teeth
develop from one
tooth bud and, asa
result, the patient
has an extra tooth

60. ROOT
FORMATION

61. •The development of roots begin
after enamel & dentin formation
has reached the future
cementoenamel junction
•The enamel organ plays an
important role in root
development by forming HERS,
which models the shape of theroot
•HERSconsists of outer & inner
enamel epithelium only
Hertwig Epithelial Root Sheath

62. •Its remnants
epithelial network of strands
persists as an
or
clumps near the external surface of
the root
•These epithelial remnants are
found in the periodontal ligament
of erupted teeth and are called as
rests ofmallasez
Root Formation

63. •Prior to the beginning of root
formation, the root sheath
forms the epithelial
diaphragm
•The outer & the inner enamel
epithelium bend at the future
cementoenamel junction into
a horizontal plane, narrowing
the wide cervical opening
Root Formation

64. Root Formation
• The proliferation of the cells of
the epithelial diaphragm is
accompanied by the proliferation
of the cells of the connective
tissues of the pulp

65. • Last stages of the root
development
•The wide apical foramen is
reduced by opposition of dentin
& cementum to the apex of the
root
Root Formation

66. •Onthe pulpal surfaceof
the dividing epithelial
bridges, dentin formation
starts
•Onthe periphery of each
opening, root development
follows in the sameway as
described for single rooted
teeth

67. CLINICAL
CONSIDERATIONS

68. DILACERATION
•Dilaceration refers to an
angulation or a sharp bend or
curve anywhere along the root
portion ofatooth
•Caneasily be detected by
radiographs
•Careshould be taken during
extraction since these teeth are
more prone tofracture

69. CONCRESCENCE
Concrescence is a condition
Of teeth where the
cementum overlying the
roots join together.
The cause can sometimes be
trauma or crowding of teeth.
Radiographic diagnosis is
mandatory before
attemptingtooth extraction

70. CONCLUSION
Since development of tooth forms
thorough understanding
the base of
and a sounddentistry, a
knowledge is required by a dentist regarding the
development stages of tooth & the anomalies related
to it, so asto identify & treat them in aproper fashion.