This document summarizes the development of the periodontium. It describes the stages of tooth development from the primary epithelial band to root formation overseen by Hertwig's epithelial root sheath. Cementum formation and the role of cementoblasts are discussed. The periodontal ligament develops from the dental follicle and maintains homeostasis through various molecules. Alveolar bone formation occurs concurrently to provide support. The junctional epithelium proliferates during passive eruption. Clinical significance and conclusions emphasize repairing lost periodontal tissues through understanding periodontium development.

2. Dr. SONI BISTA
1ST YEAR PG STUDENT
PERIODONTOLOGY AND ORA
IMPLANTOLOGY
UNDER THE GUIDANCE:
Assoc.Prof.Dr.MANDEEP SINGH
DINGRA
Asst.Prof.Dr.BIKASH KUMAR

4. DEFINITION
OVERVIEW OF DEVELOPMENT OF
TOOTH
ROOT FORMATION
STAGES IN TOOTH GROWTH
SIGNALING IN TOOTH DEVELOPMENT
CEMENTOGENESIS
PDL FORMATION
ALVEOLAR BONE FORMATION
DENTINOGINGIVAL JUNCTION
FORMATION
CLINICAL CONSIDERATION
CONCLUSION
REFERENCES

6. PERIODONTIUM
GREEK MEANING: “PERI”_AROUND
“ODONT”_TOOTH
“Tissue investing and supporting the
teeth consists of Cementum, PDL, bone
lining the alveolus and that part of the
gingiva facing the tooth”_Tencate 5th edi.
“Tissue supporting the tooth are developmentally derived from the
dental follicle proper, whereas those investing the tooth, that is
gingiva, are an adaptation of oral mucosa”
_Richard ten Cate

7. OVERVIEWOF DEVELOPMENT OF
TOOTH

8. NEURAL CREST DEVELOPMENT
3 germ layer..
Neural plate within ectoderm..
Neural tubes…
Neural crest cells…

9. D
E
R
I
V
A
T
I
V
E
S

10. PRIMARY EPITHELIAL BAND
After 37 days of development
A continuous band of thickened epithelium forms around the
mouth in upper and lower jaws
This band are roughly horseshoe shaped
Corresponds in position to the future dental arches of upper and
lower jaws
Each band of epithelium called as primary epithelial band
(Gives rise to)
DENTAL LAMINA VESTIBULAR LAMINA
(At about 7th
week)

13. • First evidence of tooth development.
• Continued and localized proliferative activity lead to formation of a
series of epithelial ingrowth into the ectomesenchyme at the sites
corresponding to the position of the future deciduous teeth.
FATE: Total activity is about 5 years
Eventually, the dental lamina disintegrates into small clusters of epithelium and is
resorbed. In situations when the clusters are not resorbed, (this remnant of
the dental lamina is sometimes known as the cell rest of Serres) eruption
cysts are formed over the developing tooth and delay its eruption into the oral
cavity.
• From this, tooth development proceeds
in 3 stages: bud stage,
cap stage,
bell stage.
DENTAL LAMINA
VESTIBULAR LAMINA:
The vestibule forms as a
result of proliferation of
vestibular lamina into the
ectomesenchyme

14. BUD STAGE
8TH
WEEK
Represented by 1st
epithelial incursion into the
ectomesenchyme of the
jaw.
Supporting
ectomesenchymal cells are
closely packed beneath and
around the epithelial bud…

15. CAP STAGE
9-10
WEEKS
CONDENSATION
OF
ECTOMESENCHYM
E
DENTAL ORGAN
DENTAL PAPILLA
DENTAL FOLLICLE
Proliferative
stage
Epithelial bud_proliferate into
ectomesenchyme

16. BELL
STAGE
11-12TH
WEEK
OUTER
DENTAL
EPITHEL
IUM
STRATU
M
RECTIC
ULUM
STRATU
M
INTERM
EDIUM
INNER
DENTAL
EPITHELI
UM
Histodifferentiati
on and
morphodifferent
ion
glycosaminog
lycans
CERVI
CAL
LOOP

17. ADVANCED
BELL
STAGE
Two important events:
1.Dental lamina joining
the tooth germ to the
oral epithelium
breaks up into
discrete islands of
epithelial cells…
Separating the
developing tooth from
the oral epithelium.
2. Inner dental
epithelium__folds__
making it possible to
recognize the shape
INNERVATION:
Clusters of blood vessels
and pioneer nerve fibers
are found ramifying around
the tooth germ in dental
follicle .

19. ROOT
FORMATION
Major function of HERS(Schour and Massler)
Induce and regulate root formation including
the size, shape, number of root.
HERS characters:
1. Consists of inner and outer enamel epithelium
only.
Inner
cells(short in size) cells in coronal
root
region
Differentiation of radicular differentiation of
Papilla cells dental follicle
Odontoblasts cementoblasts
First layer of acellular
cementum
radicular dentin.
Hertwig’ epithelial
root sheath

23.  Cementum is the calcified, avascular
mesenchymal tissue that forms
the outer covering of the anatomic root.
 Latin: “Caementum”:quarried stone[i.e. Chips
of stone used in making mortar]
 It was first demonstrated microscopically in
1835 by two pupils of purkinje.
 It is a specialized connective tissue that
shares some physical, chemical & structural
characteristics with compact bone.
cEmEnTum

24. CEMENTOGENESIS
 Cementum is deposited on the surface of root dentin
 HERS Hyaline layer of Hopewell-Smith/Intermediate Cementum
(after basement supporting root sheath breaks up)
• Secrete distinct class of enamel protein in the gap between collagen
fibers(from mantle dentin) and basement membrane.
This layer contains product of epithelial cell activity/form of enameloid
Thus the dentin of the root surface is covered by an epithelial product
of the root sheath cells that is more mineralized than other dentin.
+
Functions to “cement” cementum into dentin as well as
provide the initial attachment of ligament fibrils to the tooth.

26. [Hertwig’s epithelial root sheath is broken up &
separated from root, and differentiation of
cementoblasts lead to formation of cementum]

27. Cementogenesis….
• Root sheath fragments into network that allows:
follicular cells to pass through it + it comes into
apposition with newly formed root surface.
differentiate into cememtoblasts
deposit
organic matrix against root surface and around forming
ligament fiber bundles/extrinsic fibers.
mineralization of this matrix is called cementoid

occurs with deposition of apatite crystals
initially is matrix vesicles
followed by mineralization of collagen fibrils.

28. Growth factor families involved in the differentiation
of cemetoblasts from dental follicle....
TGFβ 1-5
BMP2-8
EGF & IGF
PGE2 & PGF2α enhance
differentiation by activating
protein kinase cell signalling
pathway
Fibroblast growth factor
promotes proliferation, migration
& angiogenesis
CAP, BSP and osteopontine helps
in attachment of differentiated
cells to newly forming tissue

29. PRIMARY CEMENTUM
 First formed cementum is acellular
 Develops slowly as tooth is erupting
 Covers coronal two third of the root
 Highly calcified.
 Its collagenous component may be derived entirely
from extrinsic fibers of the PDL(Sharpey’ fiber)
 Also contain intrinsic fibers that are calcified and
irregularly arranged or parallel to the surface.

30. SECONDARY CEMENTUM
 Develops after tooth is in occlusion.
 Rapidly formed and less mineralized
 Deposited around apical two third of the root.
 Cellular as cementoblasts gets trapped in lacunae within
matrix they form.
 Its Organic matrix contains collagen fibers derived from
2 sources extrinsic fibers of PDL_are arranged obliquely
as
they enter cementum.
intinsic fibers(formed as a result of
cementoblastic activity)__are parallel to root.
 Secondary cementum formation is a continuous process
Thus thickness of cementum on root surface increases with
age.

31. FATE OF HERS…
Fragmentation of root sheath
disruption of its basal lamina
some cell are lost Most cells persists as
strands/clusters
(transform into mesenchymal cells) (where collagen are
trapped)
called as epithelial
rests of malassez
-dark staining nuclei and little

33. PDL formation
• After root formation_dental follicle PDL
• In front of forming PDL increase rate of cell division
fibroblasts
collagen fibrils of PDL
(oblique orientation)
+
ground substancesof PDL

35. •Rearrangement of fiber ends in the
plexus is supposed to accommodate tooth
eruption without necessitating the
embedding of new fibers into tooth and
the bone.

36. BEFORE TOOTH
ERUPTION:
•Crests of alveolar bone
is above CEJ
•Developing fiber
bundles of PDL are all
directed obliquely.
•More apical orientation
DURING TOOTH ERUPTION:
•Level of alveolar crest comes to
coincide with CEJ
•Oblique fibers below the free
gingival fibers becomes horizontally
aligned called as alveolar crest
fibers.
•More coronal orientation.
TEETH IN
FUNCTION:
•Fiber bundles of
PDL thickens and
are constantly
remodeled by
fibroblasts

37. PDL homeostasis
 A remarkable capacity of PDL is that it maintains its width more or less,
despite the fact, it is squeezed in between two hard tissues.
 Various molecules have been proposed, which play a role in maintaining
an unmineralized PDL.
Msx2
Bone sialoprotein
Matrix Gla protein
(Inhibitors of
mineralization)
• Inhibit mineralized bone tissue
• Prevents osteogening
differentiation of PDL fibroblasts
by repressing cbfa1 activity
• osteopontin
Prostaglandins

39. ALVEOLAR PROCESS
 It is the portion of maxilla and mandible that forms and
support the tooth socket(alveoli)
 It develops and undergoes remodeling with tooth
formation and eruption; they are dependent bony
structure.
 It forms when the tooth erupts to provide the osseous
attachment to the forming PDL & it disappears
gradually after the tooth is lost.

40. As PDL is
forming;
new bone
deposition
takes place
around developing
Ligament fiber
bundles against
crypt walls
Cells migrate into PDL from bone
marrow
(by way of vascular channels)
Occupy perivascular location
within PDL
Reinforce the resident
perivascular cells
To provide daughter cells
Migrate to bone and cementum
Differentiate into osteoblast and
cementoblast and also PDL
fibroblast.

41. Intramembranous
ossification
Formation of
bone matrix
Formation of
woven bone
Appositional growth
& formation of
harvesian system
(osteon)
Endochondral
bone formation
Formation of
cartiagenous
model

42. Stages of Intramembranous Ossification

43. Stages of Intramembranous Ossification

44. Stages of Intramembranous Ossification

45. Stages of Intramembranous Ossification

46. Formation
of bone
collar
around
hyaline
cartilage
model.
1
2
3
4
Invasion of
internal cavities
by the
periosteal bud
and spongy
bone formation.
5Formation of the
medullary cavity as
ossification continues;
appearance of
secondary ossification
centers in the epiphyses
in preparation for stage
5.
Hyaline
cartilage
Primary
ossification
center
Bone
collar
Deteriorating
cartilage matrix
Spongy
bone
formation
Blood
vessel of
periosteal
bud
Secondary
ossification
center
Epiphyseal
blood vessel
Medullary
cavity
Epiphyseal
plate
cartilage
Spongy bone
Articular
cartilage
Stages of Endochondral Ossification
Cavitation
of the
hyaline
cartilage
within the
cartilage
model.
Ossification of the
epiphyses; when
completed, hyaline
cartilage remains only
in the epiphyseal plates
and articular cartilages

48. GINGIVA
Gingiva is the part of the oral
mucosa that covers the alveolar
processes of the jaws and tooth root
to a level just coronal to CEJ_McCall

49. DENTOGINGIVAL
JUNCTION
• The epithelium of the gingiva which gets attached
to the tooth is called as junctional or attachment
epithelium.
• Consists of collarlike band of stratified squamous
nonkeratinizing epithelium.
• Forms an epithelial barrier against bacteria.
JUNCTIONAL EPITHELIUM

50. DEVELOPMENT OF JUNCTIONAL
EPITHELIUM AND GINGIVAL
SULCUS

52. STAGES OF PASSIVE
ERUPTION
The teeth reach the
line of occlusion.
J.E and base of
gingival sulcus are on
the enamel
Stage 1

53. STAGES OF PASSIVE
ERUPTION
J.E proliferates so that
part is on cementum
and part is on enamel.
Stage 2

54. STAGES OF PASSIVE
ERUPTION
 Entire J.E is on
cementum and base of
the sulcus is at CEJ.
As J.E proliferates
from the crown into the
root,it doesnot remain
at CEJ any longer than
at any other area of the
tooth.
Stage 3

55. STAGES OF PASSIVE
ERUPTION
 J.E has
proliferated farther
on the cementum.
the base of the sulcus is on
the cementum, a portion of
which is exposed.
Proliferation of the J.E onto
the root is accompained by
degeneration of gingival and
PDL fibers and their
detachment from the tooth.
Stage 4

57. DURINGINITIATION

58. DURINGMORPHODIFFERENTIATION

59. CLINICAL
SIGNIFICANCE

60. CONCLUSION
The widespread occurrence of
periodontal disease and the realization
that periodontal tissue lost to the
disease can be repaired has resulted
in considerable effort to understand the
factors and cells regulating the
formation,maintenance and

61. REFERENCES
• Carranza’s clinical
periodontology,11th edition
• Orban’s oral histology and
embryology,12th edition.
• Oral
histology:development,structure
and function,A.R Tencate,4th
edition.
• Oral development and