This ppt provides an overall knowledge of various stages of tooth development.

1. ODONTOGENESIS
P.S KAAVIYA THARSINI
I Year MDS

2. ODONTOGENESIS
• Odontogenesis is the processof toothdevelopment whichis
continuousin nature thatinvolves interactionsbetweenthe
epithelialand ectomesenchymal tissuesmediatedby multiple
signalingmolecules.

3. • It takes place in sequential stagesfor both dentitions.
# Primary dentition(embryonicperiodand fetal period)
# Permanent dentition( mostly fetal periodand after
birth)

4. • Teeth are ectodermal organs formed by oral epithelium and underlying
connective tissue.
Epithelium
First brachial arch
( Stratified squamous
epithelium)
Connective tissue
Ectomesenchyme
neural crest cells

5. PHYSIOLOGIC
PROCESSES
INITIATION
PROLIFERATION
HISTODIFFERENTIATION
MORPHODIFFERENTIATION
APPOSITION

6. ODONTOGENESIS
INITIATION
PROLIFERATION
MORPHODIFFERENTIATION
HISTODIFFERENTIATION
APPOSITION
MATURATION & ERUPTION

7. PRIMARY EPITHELIAL BAND
• About 6 weeks of IU life, a continuous band
of odontogenic epithelium forms in upper and
lower jaws.
• in the position of future dental arches -
roughly horseshoe-shaped
• gives rise to two subdivisions
that ingrow into the underlying
ectomesenchyme
INITIATION

8. DENTAL AND
VESTIBULAR
LAMINA BUCCALLY - VESTIBULAR LAMINA ( vestibule)
LINGUALLY - DENTAL LAMINA ( teeth)

10. In dental lamina, 10 little knobs grow into the
underlying mesenchyme
represents the tooth bud of a deciduous tooth.
Not all of these start to develop at the same time
first to appear are those of the anterior mandibular
region.
DENTAL PLACODE

11. Identifiable morphological stages in tooth development are as follows
BUD STAGE
CAP STAGE
BELL STAGE
MORPHOGENESIS

12. BUD STAGE

13. • Around 11th week of IU life, the tooth bud
grows larger
• shallow invagination of deep surface of bud
• The epithelial outgrowth, which superficially
resembles a cap sitting on a ball of condensed
ectomesenchyme is referred as enamel
organ.

14. The area
of ectomesenchymal condensation
immediately subjacent to the
enamel organ is the dental papilla.
The condensed
ectomesenchyme
that surrounds the tooth
bud and the dental papilla
is the dental sac / follicle.

15. OUTER AND INNER ENAMEL EPITHELIUM
• The peripheral cells are cuboidal, cover the
convexity of the ‘cap,’ and are called the outer
enamel epithelium (OEE)
• The cells in the concavity of the ‘cap’ become
columnar cells and represent the inner enamel
epithelium (IEE).
• The OEE is separated from the dental sac, and the
IEE from the dental papilla, by a delicate basement
membrane.

16. STELLATE RETICULUM
• The cells in the center are polygonal in
shape which synthesize and secrete
glycosaminoglycans into the
extracellular compartment between
the epithelial cells.
• SR gives cushion like consistency and
acts as shock absorber

17. TRANSITORY
STRUCTURES
ENAMEL KNOT
ENAMEL CORD
ENAMEL SEPTUM
ENAMEL NAVEL

18. Enamel niche
• The enamel niche is an apparent structure in histologic
sections, created because the dental lamina is a sheet
rather than a single strand and often contains a concavity
filled with connective tissue

20. BELL
STAGE

21. EARLY BELL STAGE
• At around 14th week of IU Life, the
enamel organ assumes a bell
shape as the invagination of the
epithelium deepens
• During this stage, the cells that will
be making the hard tissues of the
crown (ameloblasts and
odontoblasts) acquire their
distinctive characteristics
(histodifferentiation)
• the crown assumes its final shape
(morphodifferentiation).

22. INNER ENAMEL
EPITHELIUM
• The inner enamel epithelium consists of a single layer of cells that
differentiate prior to amelogenesis into tall columnar cells called
ameloblasts .
• These cells are 4 to 5 micrometers (µm) in diameter and about 40
µm high

23. STRATUM INTERMEDIUM
• A few layers of squamous cells between
the inner enamel epithelium and the
stellate reticulum
• It work synergistically with inner enamel
epithelium as a single functional unit and
form enamel.
• It is absent in the outlines of root
portions

24. Stellate
reticulum
• The stellate reticulum expands
further, mainly by an increase in
the amount of intercellular fluid.
• Before enamel formation begins,
it collapses, reducing the distance
thus making it nearer to the
nutrient capillaries in dental sac.

25. OUTER ENAMEL EPITHELIUM
• The cells become flatten to a low cuboidal form.
• At the end of this stage, preparatory to and during
the formation of enamel, the formerly smooth
surface is laid in folds.
• Between the folds, the adjacent mesenchyme
forms papillae that contain capillary loops
that provides a rich nutritional supply

26. Dental papilla
• An acellular zone is present between the basal
lamina and dental papilla
• peripheral cells of ectomesenchyme differentiate
into odontoblasts under the influence of the IEE.
• First- cuboidal form; later - columnar form
• acquires the specific potential to produce dentin.
• The basement membrane that separates the enamel
organ and the dental papilla just prior to dentin
formation is called the membrana preformativa

27. Dental sac
Before formation of dental tissues
begins, the dental sac shows a
circular arrangement of its fibers
and resembles a capsular structure.
these fibers differentiate to
form periodontal fibers

28. CERVICAL LOOP
• region where the inner and outer enamel
epithelia meet is known as the zone of
reflexion or cervical loop
• This point is where the cells continue to
divide until the tooth crown attains its full
size and after which it gives rise to
epithelial component of root
formation.

29. Dental lamina
• The dental lamina is seen to
extend lingually and is termed
successional dental lamina
• The enamel organs of deciduous
teeth in the bell stage show
successional lamina and their
permanent successor teeth in the
bud stage

30. 2 Main events
Breakdown of dental
lamina (primary teeth)
• Fragments
• Formation of clusters of
epithelial cells
• epithelial pearls
(Cell rests of Serre)
Crown pattern
Determination​​
• By differential rates of
mitotic division and
their cessation within
IEE.

31. BELL STAGE (outer to inner)

32. ADAVANCED
BELL STAGE
• commencement of mineralization and root formation.
• formation of dentin occurs along the future dentinoenamel junction
• After the first layer of dentin, the ameloblast which has already differentiated lay
down enamel over the dentin in the future incisal and cuspal areas.
• then proceeds, in all regions from the dentinoenamel junction (DEJ) towards the
surface.

33. TIMELINE OF HUMAN TOOTH DEVELOPMENT

34. ROOT FORMATION
• prior to the beginning of root formation, it
bends to form epithelial diaphragm
narrowing the wide apical foramen
• The plane of the diaphragm remains
relatively fixed.

35. • The free end of the diaphragm does
not grow into the connective tissue,
but the epithelium proliferates
coronal to the epithelial diaphragm.
root
sheath (HERS)
• The function of HERs is to shape the
root(s) by inducing dentin
formation

36. • Root dentin forms when the outer cells of the dental
papilla undergo induction and then differentiates to
become odontoblasts
• these cells undergo dentinogenesis and begin to
secrete predentin.
• When dentin formation is completed in one
part, HERs is disintegrated there.
• These epithelial remnants are called as CELL RESTS
OF MALASSEZ
ROOT FORMATION

37. CEMENTOGENESIS
• starts when the HERS get disintegrated
• contact of dental sac cells with the dentin surface induces
these cells to become immature cementoblast
• The cementoblasts move to cover the root dentin and lays
down cementum matrix
• Thus, Dentinocemental junction (DCJ) is formed

38. •
In the last stages, proliferation of the epithelium lags behind that of the
pulpal connective tissue.
Then, the apical foramen gets narrowed by apposition of dentin and cementum
to the apex of the root

39. MULTIROOT FORMATION
• Like anterior teeth, multirooted teeth also originate as a single root on the base of the
crown. This part is considered the root trunk.
• To produce multiple roots, there is differential growth of HERS
• elongation of Cervical loop occurs, which allows the development of long, tongue-like
horizontal extensions or flaps within it.
• Two or three such extensions can be present on multirooted teeth

40. • The free ends of these extensions grow towards
each other and gets fused.
• On the pulpal surfaces of these openings,
dentin formation starts after the induction of
the odontoblasts followed by disintegration of
HERS and cementum formation.
• Root development then proceeds in the same
way as described for a single-rooted tooth

41. VASCULAR SUPPLY
• Angiogenesis, has not been studied extensively during the process of tooth development.
• Clusters of blood vessels are found around the tooth germ in the dental follicle and entering the
dental papilla during the cap stage.
• Their number in the papilla increases, reaching a maximum during the bell stage when matrix
deposition begins

42. NERVE SUPPLY
• Pioneer nerve fibers approach the developing tooth during the bud-to cap stage of development.
• nerve fibers ramify and form a rich plexus around the tooth germ.
• Penetration of nerves into the dental papilla occurs with the onset of dentinogenesis.
• initial innervation is concerned with the sensory innervation of the future periodontal ligament
and pulp.

44. Clinical considerations
• INITIATION
Disturbance: Anodontia, partial or complete
Clinical ramifications: Disruption of
occlusion and esthetic complications
treated by prosthetic replacement with
partial or full dentures, bridges, and/or implants

45. Disturbance: Supernumerary teeth
Clinical ramifications: Crowding, failure of eruption of
nearby teeth, and disruption of occlusion
treated by surgical removal if needed and/or
orthodontic therapy

46. BUD STAGE
• Disturbance: Microdontia or macrodontia
• Clinical ramifications: Esthetic and crowding or
spacing complications
• treated with full restorative crown on
microdontic tooth (lateral incisor), possibly extraction
(third molar), if crowding by orthodontic correction

47. • Disturbance: Dens in dente
• Clinical ramifications: Deep lingual pit that
may need endodontic therapy

48. CAP STAGE
• Disturbance: Gemination
• Clinical ramifications: Esthetic and spacing
complications
• treated by orthodontic therapy

49. CAP STAGE
• Disturbance: Fusion
• Clinical ramifications: Esthetic
and spacing complications
• treated by orthodontic therapy

50. CAP STAGE
• Disturbance: Tubercle
• Clinical ramifications: Occlusal
complications

51. Apposition and
Maturation
Stage
• Disturbance: Amelogenesis imperfecta
• Clinical ramifications: Esthetic and function complications

52. Apposition
and Maturation Stage
•Disturbance: Dentinogenesis imperfecta​
•Clinical ramifications: Esthetic and function
complications​

53. Root formation
• Disturbance:
• Clinical ramifications:

54. Cementogenesis
• Disturbance: Concrescence
• Clinical ramifications:
Extraction or endodontic
complications

55. Root development
• Disturbance: Dilaceration
• Clinical ramifications: resulting in either
distorted root(s) or severe associated
crown angulation in a formed tooth
can cause complications during
extraction and endodontic therapy

56. Root development
• Disturbance: Accessory roots (or
supernumerary roots).
• Clinical ramifications: These accessory roots can
present complications in extraction and
endodontic therapy;

57. REFERENCES
Ten Cate's Oral Histology: development,
structure, and function
Orban's Oral Histology & Embryology
Berkovitz - Oral anatomy, histology and
embryology
Margaret J. Fehrenbach - Illustrated Dental
Embryology, Histology, and Anatomy