Periodontium

1. PERIODONTIUM
By: Maryam Bahrami
PhD Student of Anatomical Sciences ,
March 2018

2. Definition:
Periodontium refers to the
specialized tissues that both
surround and support the teeth,
maintaining them in the
maxillary and mandibular bones.
2

3. Components of Periodontium
It consists of four principal
components namely:
 Gingiva
 Periodontal ligament (PDL)
 Cementum
 Alveolar bone
3

4.  Avulsed teeth
The periodontal ligament will regenerate and revascularize a tooth that is
replaced within half an hour has a 90% chance of successful re-implantation.
4

5.  Tooth germ implant
 Tooth extraction
 Removal of neural crest cells
5

6. Development of Periodontium Components
Cementum
DEFINITION:
CEMENTUM IS A HARD, AVASCULAR
CONNECTIVE TISSUE THAT COVERS
THE ROOTS OF THE TEETH.
Cementogenesis
Cementum formation occurs along the entire
tooth.
Ectomesenchymal cells from the inner portion
of the dental follicle come in with predentin
by differentiating into cementoblasts and
they lay down cementum.
6

7. TYPES OF CEMENTUM
CEMENTUM is classified according to
the presence or absence of cells within its
Matrix:
CELLULAR CEMENTUM, which has
an adaptive role in response to tooth
wear and movement and is associated
with repair of periodontal disease.
ACELLULAR CEMENTUM, which
provides attachment for the tooth.
A- CELLULAR CEMENTUM
B-ACELLULAR CEMENTUM
7

8. ACELLULAR CEMENTUM
Hyaline layer of Hopewell-Smith
 0.5-0.8 µm thick.
 First layer of cementum is actually
induced by the inner cells of the
HERS and is deposited on the root’s
surface is called primary acellular
cementum or primary acellular
intrinsic fiber cementum.
 It is situated between the granular
dentin layer of Tomes and the
secondary cementum.
 Approximately 15 µm thick.
8

9. Secondary (cellular) cementum
which has an adaptive role in response to tooth wear and movement and
is associated with repair of periodontal disease.
9

10. Epithelial rests of Malassez
originate from the degeneration
of Hertwig's epithelial root sheath
to form quiescent cell rests that
persist as the sole epithelial cells
in the periodontium.
10

11. 11

12. Formation of periodontal ligament
Definition:
The periodontal ligament is the soft specialized connective tissue situated
between the cementum covering the root of the tooth and the bone forming
the socket wall.
12

13. Development of lamina dura
The alveolar process contains a region
of compact bone adjacent to the
periodontal ligament called Lamina
dura.
Lamina dura producing osteoblasts
have a specific phenotype that
differentiates from dental follicle cells.
13

14. PHYSICAL CHARACTERSTICS AND
COMPOSITION
 COLOR: YELLOW.
 HARDNESS: LESS THAN DENTIN.
 COMPOSITION: ORGANIC MATRIX
(50%) AND INORGANIC ELEMENT
(45-50%).
 ORGANIC MATRIX: COLLAGENOUS
AND NONCOLLAGENOUS
PROTEINS.
Histology of periodontium
14

15. Collagenous component
 Type I Collagen is predominant in cementum, constitutes 90% of
organic component of cellular cementum.
 Type III, Type XII, are also present.
 Type XII is found in high concentration in PDL.
 Traces of Type V, VI and XIV are also found in cementum.
15

16. CEMENTOENAMEL JUNCTION
Relation of Cementum to Enamel at the Cementoenamel Junction (CEJ)
"OMG rule"
• In 60% of the teeth cementum OVERLAPS enamel.
• In 30% of the teeth cementum just MEETS enamel forming a butt joint.
• In 10% of the teeth there is a small GAP between cementum and enamel.
16

17.  Varies in thickness: thickest in the
apex and In the inter-radicular areas of
multirooted teeth, and thinnest in the
cervical area
 20 to 50 µm in the cervical areas to
 150 to 300 µm apically
17

18. Cementoblast and cementocyte
 CEMENTUM is excreted by cells called CEMENTOBLASTS within the root of the
tooth.
 CEMENTOBLASTS are the formative cells of cementum and derive from dental
follicle.
18

19.  Cementoid: Young matrix that becomes secondarily mineralized.
 Cementum is deposited in increments similar to bone and dentin
19

20. Presence or absence of cells
 Cellular Cementum
 Acellular Cementum
Origin of collagenous fibers of the
matrix
 Extrinsic fiber cementum
 Intrinsic fiber cementum
 Mixed fiber cementum
Prefunctional and functional
 PREFUNCTIONAL, which occurs
through out root formation.
 FUNCTIONAL, which starts when
the tooth is in occlusion and
continues through out life.
Classification of Cementum
20

21. Classification of cementum
1. Primary Acellular Intrinsic Fiber Cementum (AIFC-Primary
Cementum)
2. Primary Acellular Extrinsic Fiber Cementum (AEFC-Primary
Cementum)
3. Secondary Cellular Intrinsic Fiber Cementum (CIFC-Secondary
Cementum)
4. Secondary Cellular Mixed Fiber Cementum
5. Acellular Afribrillar Cementum(AAC)
6. Intermediate Cementum
7. Mixed Stratified Cementum
21

22. 1. Primary acellular intrinsic fiber
cementum:
 Containing intrinsic fiber
 Cementoblasts
 Before PDL forms
 First cementum
 Acellular
 15-20μm
22

23. 2. Primary Acellular Extrinsic
Fiber Cementum:
 Located in cervical half of the root
and constitutes the bulk of cementum.
 The collagen fibers derived from
Sharpey’s fibers and ground
substance from cementoblasts.
 Covers 2/3rds of root corresponding
with the distribution of primary
 acellular cementum
 Principal tissue of attachment
 Function in anchoring of tooth
 Fibers are well mineralized
23

24. 24

25. 3. Secondary Cellular intrinsic fiber
cementum
 Starts forming after the tooth is in
occlusion
 Incorporated cells with majority of
fibers organized
 Cells have phenotype of bone forming
cells
 Very minor role in attachment
(virtually absent in incisors and canine
teeth)
 Corresponds to cellular cementum and
is seen in middle to apical of root.
25

26. 4. Secondary cellular mixed fiber
cementum
 Adaptation
 Both intrinsic and extrinsic fibers
[Extrinsic (5 – 7 µm) and Intrinsic (1 –
2 µm)]
 Bulk of secondary cementum
 Cementocytes
 Laminated structure
 Cementoid on the surface
 Apical portion
 Intrinsic fibers are uniformly
mineralized but the extrinsic fibers are
variably mineralized with some central
unmineralized cores
26

27. 5. Acellular afibrillar cementum:
 Limited to enamel surface
 Close to the CE junction
 Lacks collagen so plays no role in
attachment
 Developmental anomaly vs. true
product of epithelial cells
27

28. 6. intermediate cementum
7. Cellular Mixed Stratified
Cementum
 Contains cells.
 Composed of Extrinsic (Sharpey’s)
and intrinsic fibers.
 It includes cementocytes within
lacunae with processes in
canaliculi directed towards the
PDL.
 Its laminated structure.
 The presence of cementoid on its
surface.
28

29. ‫فققیط‬
 The periodontal ligament is the dense
fibrous connective tissue that occupies
the periodontal space between the root
of the tooth and the alveolus.
 It ranges from 0.15-0.38 mm.
Histology of periodontal memberane
29

30. FUNCTIONS OF PDL
SUPPORT: PDL supports teeth in their socket. It prevents loosening of
teeth.
MASTICATORY LOAD: PDL permits teeth to withstand the considerable
forces of mastication.
SENSORY: PDL is supplied by abundant receptors and nerves that sense the
movement when teeth are in function. Helps in the proper positioning of the
jaws during normal function.
NUTRITIVE: Blood vessels of ligament provide essential nutrients for the
ligament’s vitality and hard tissue of cementum and alveolar bone.
30

31. Components of the Periodontal ligament
The PDL consists:
 CELLS
 AN EXTRACELLULAR
COMPARTMENT
Consists of well defined collagenous
fibres embedded in a non collagenous
extra cellular matrix of glycoproteins and
glycolipids.
31

32. Cellular Elements
Five types of cells have been identified in the PDL:
 Synthetic cells
Fibroblasts,Osteoblasts, cementoblasts
 Resorportive cells
Fibroblasts, Osteoclasts, cementoclasts
 Progenitor cells
Undifferentiated stem cells
 Epithelial cells
Epithelial cell rests of malassez
 Defense cells
Mast cells, Macrophages, eiosinophils
32

33. PDL Fibroblasts
 Assembles procollagen molecules
 Oriented parallel to collagen fibers
 Fibronexus
 Are motile due to contractile properties
 Perform fibroclastic function
 Show numerous microtubules &
microfilaments
 Contains lysosomal system
33

34. Fibronexus
34

35. 35

36. 36

37. Undifferentiated stem cells
 Can differentiate to different types of
cells
 Can undergo mitotic devision
 Have small, closed face nucleus
 Little amount of cytoplasm
 Found close to blood vessels
37

38. Cementoblasts
Situated within the PDL, cementum
cells are associated properly with the
hard tissues.
38

39. Osteoblasts
 Situated within the PDL, and are associated
properly with the hard tissues.
 Both are rich in alkaline phosphatase
activity.
39

40. Osteoclasts
Cementoclasts or odontoclasts
Both are rich in acid phosphatase
activity.
40

41. 41

42. EPITHELIAL CELLS
 remnants of the epithelial root
sheath of Hertwig
42

43. Fibers
 The connective tissue fibers are
mainly collagenous, but there
may be small amounts of
oxytalan and reticulin fibers,
and in some species, elastin
fibers.
43

44. Collagens fiber
 The predominant collagens of PDL are
types I, III and XII.
 Individual fibrils having a smaller average
diameter than tendon collagen fibrils.
PRINCIPAL FIBERS
ASSOCIATED (GINGIVAL) FIBERS
44

45.  alveolar crest group
 the horizontal group
 the oblique group
 the apical group
 the interradicular group
All these principal fibres are
embedded as sharpeys fibres in
the cementum or bone.
45
PRINCIPAL FIBER BUNDLES OF PDL

46. THE ALVEOLAR CREST GROUP
These are attached to the cementum
just below the cementoenamel
junction and running downward and
outward to insert into the rim of the
alveolus.
46

47. The Horizontal fibres
extend at right angles to the long
axis of the tooth from the
cementum to the alveolar bone.
47

48. THE OBLIQUE GROUP
They are the most numerous in the
PDL and running from the
cementum in an oblique direction to
insert into the bone coronally
48

49. THE APICAL GROUP
These are radiating from the
cementum around the apex of
the root to the bone forming the
base of the socket.
49

50. Found only in the multi-rooted
teeth and running from the
cementum into the bone forming
the crest of the Interradicular
septum.
50
THE INTERADICULAR GROUP

51. 51

52. Gingival ligament
 These groups are found in the
lamina propria of the gingiva
and collectively form the
gingival ligament.
1. Dentogingival group
2. Alveologingival group
3. Circular group
4. Dentoperiosteal group
5. Transseptal fiber system
52

53. 1. Dentogingival group
2. Alveologingival group
3. Circular group
4. Dentoperiosteal group
53

54. 54
5. Transseptal fiber system

55. 55

56. Oxytalan fibers
 These are immature elastic fibers.
 They need special stains to be
demonstrated.
 They tend to run in an axial
direction, one end being embedded in
bone or cementum and the other in
the wall of blood vessels.
 At the apical region they form a
complex network.
56

57. 57

58. The functions of oxytalan fibers:
1-Support nerves.
2- Support blood vessels.
3- Help fibroblasts migration.
58

59. Elaunin fibers
They are seen as bundles of
microfibrils embedded in a
relatively small amount of
amorphous elastin. These fibers
may be found within the fibers
of the gingival ligament.
 Interstitial space
59

60. Ground Substance
Fills the space between the fibers and cells
Overlooked possibly because difficult to investigate and not recognized in
routine methods
COMPOSITION
Consists of a biochemically complex, highly hydrated, semisolid gel.
 Water content of 70%
 Glycosaminoglycan's – hyaluronic acid, proteoglycans( versican , decorin )
 Glycoproteins -- fibronectin , laminin , vibronectin , tenascin
60

61. BLOOD SUPPLY
 PDL is exceptionally well
vascularized
Superior and inferior alveolar
arteries
Perforating arteries
 Abundant in the PDL of posterior
teeth than in that of anterior teeth
and are in greater numbers in
mandibular than in maxillary teeth
 Arteriovenous anastomoses occur
within the PDL
61

62. 62

63. NERVE SUPPLY
 Nerve fibers running from the apical
region toward the gingival margin
 Two branches, one extending apically
and the other gingivally
 Four types of neural terminations now
have been described
1. Free nerve endings (most frequent)
2. Around the root apex and resembles
Ruffini’s corpuscles
3. Coiled form found in the midregion
of the PDL
4. Associated with the root apex and
consists of spindlelike endings
surrounded by a fibrous capsule.
Sympathetic supply
63

64. 64

65. Age changes in PDL
 The cell number and cell activity decreases with aging.
 One of the prominent changes seen in the calcified tissues of
periodontium
 This remarkable changes affect the supporting structures of the teeth.
 With aging the activity of the PDL tissue decreases because of
restricted diets and therefore normal functional stimulation of the
tissue is diminished
 Any loss of gingival height and periodontal disease promotes
destructive changes in the PDL
65

66. ALVEOLAR PROCESS
The alveolar process is the portion of the maxilla and mandible that
forms and supports the tooth sockets (alveoli).
66

67. Functions of alveolar bone are:
 Houses the roots of teeth.
 Anchors the roots of teeth to the alveoli, which is achieved by the insertion of
Sharpey’s fibers into the alveolar bone proper.
 Helps to move the teeth for better occlusion.
 Helps to absorb and distribute occlusal forces generated during tooth contact.
 Supplies vessels to periodontal ligament.
 Houses and protects developing permanent teeth, while supporting primary
teeth.
 Organizes eruption of primary and permanent teeth.
67

68.  Near the end of the 2nd month of
fetal life, mandible and maxilla form
a groove that is opened toward the
surface of the oral cavity
 As tooth germs start to develop,
bony septa form gradually. The
alveolar process starts developing
strictly during tooth eruption.
68
DEVELOPMENT OF ALVEOLAR PROCESS

69. Newborn infant. Symphysis wide open. Mental ossicle (radiograph). (B) Child
9 months of age. Symphysis partly closed. Mental ossicles fused to mandible
and bony septa between developing teeth seen (radiograph).
69

70. The alveolar process consists of:
 Alveolar bone proper
 INNER & OUTER (BUCCAL &
LINGUAL) CORTICAL PLATE.
 Central bone is SPONGIOSA.
70

71. 71

72. Alveolar bone proper:
Bundle Bone
• The compact or dense bone that lines
the tooth. Contains either perforating
fibers from periodontal ligament
(Sharpey’s fibers) or just compact bone
72

73.  Radiographically, the bundle bone is
the lamina dura. The lining of the
alveolus is fairly smooth in the
young but rougher in the adults.
73

74.  It is perforated by many
foramina that transmit
nerves and vessels
(cribriform plate).
74

75. INNER & OUTER (BUCCAL & LINGUAL) CORTICAL PLATE.
Alveolar process is continuous with basal bone of maxilla and mandible
Arbitrarily the root apices delineate the alveolar bone from basal bone
75

76. 76

77. SPONGY BONE
 Spongy bone (anatomic term)/ Trabecular bone (radiographic term)/ Cancellous
bone (histologic term)
 Presence of trabeculae enclosing irregular marrow spaces lined with a layer of
thin, flattened endosteal cells
 Matrix consists of irregularly arranged lamellae separated by incremental and
resorption lines
 Type 1: The interdental and interradicular trabeculae are regular and
horizontal in a ladder like arrangement.
 Type2: Shows irregularly arranged numerous delicate interdental and
interradicular trabeculae
77

78. 78

79. 79

80. INTERNAL
RECONSTRUCTIO
NOF
ALVEOLARBONE
80
INTERNAL RECONSTRUCTION OF ALVEOLAR BONE

81. AGE CHANGES
In older individuals:
 Alveolar sockets appear jagged and uneven.
 The marrow spaces have fatty infiltration.
 The alveolar process in edentulous jaws decreases in size.
 Loss of maxillary bone is accompanied by increase in size of the maxillary
sinus.
 Internal trabecular arrangement is more open, which indicates bone loss.
 The distance between the crest of the alveolar bone and CEJ increases with
age—approximately by 2.81 mm.
81