Periodontal Ligament & Development presentation

The periodontal ligament is composed of a complex vascular and
highly cellular connective tissue that surrounds the tooth root and
connects it to the inner wall of the alveolar bone.179 It is continuous
with the connective tissue of the gingiva, and it communicates with
the marrow spaces through vascular channels in the bone. Although
the average width of the periodontal ligament space is about 0.2
mm, considerable variation exists. The periodontal space is dimin
ished around teeth that are not in function and in unerupted teeth,
but it is increased in teeth that have been subjected to hyperfunction.
Periodontal Fibers
The most important elements of the periodontal ligament are the
principal ¿bers, which are collagenous and arranged in bundles and
which follow a wavy course when viewed in a longitudinal sec
tion (Fig. 4.35). The terminal portions of the principal ¿bers that
are inserted into cementum and bone are termed Sharpey ¿bers
(Fig. 4.36). The principal ¿ber bundles consist of individual ¿bers
that form a continuous anastomosing network between tooth and
bone.2659 Once embedded in the wall of the alveolus or in the tooth,
Sharpey ¿bers calcify to a signi¿cant degree. They are associated
with abundant noncollagenous proteins that are typically found in
bone, and they have also been identi¿ed in tooth cementum.33137179
Notable among these proteins are osteopontin and bone sialopro
tein.167 262 These proteins are thought to contribute to the regulation
of mineralization and to tissue cohesion at sites of increased biome
chanical strain.179196
Type I collagen is a protein that is composed of three chains
twisted into a triple helix. The amino acid sequence contains charac
teristic repeats of Gly-X-Y, with proline occupying the X or Y posi
tion, and hydroxylysine and hydroxyproline in the Y position.51 The
amount of collagen in a tissue can be determined by its hydroxy
proline content. Collagen is responsible for the maintenance of the The principal ¿bers of the periodontal ligament are arranged
in six groups that develop sequentially in the developing root: the
transseptal, alveolar crest, horizontal, oblique, apical, and interra
dicular ¿bers (Fig. 4.38).
Transseptal ¿bers extend interproximally over the alveolar bone
crest and are embedded in the cementum of adjacent teeth (Fig.
4.39). They are reconstructed even after the destruction of the alve
olar bone that results from periodontal disease. These ¿bers may
be considered as belonging to the gingiva because they do not have
osseous attachment.
Alveolar crest ¿bers extend obliquely from the cementum just
beneath the junctional epithelium to the alveolar crest (Fig. 4.40).
Fibers also run from the cementum over the alveolar crest and to
the ¿brous layer of the periosteum that covers the alveolar bone.
The alveolar crest ¿bers prevent the extrusion of the tooth53 and
resist lateral tooth movements. The incision of these ¿bers during
47
periodontal surg

1. Periodontal LigamentPeriodontal Ligament

Synonyms:Synonyms:
 Periodontal membranePeriodontal membrane
 PericementumPericementum
 Dental periosteum Dental periosteum
 Alveolodental membraneAlveolodental membrane

2. PeriodontiumPeriodontium
The word Periodontium refers to the The word Periodontium refers to the
attachment apparatus of teeth and consists :attachment apparatus of teeth and consists :
– CementumCementum
– Alveolar bone Alveolar bone
– Periodontal ligament Periodontal ligament
– Part of GingivaPart of Gingiva

3. Periodontal LigamentPeriodontal Ligament

Is the connective tissue which surrounds the Is the connective tissue which surrounds the
roots of the teeth. roots of the teeth.
Attaches it to the bony alveolus. Attaches it to the bony alveolus.
Is continuous with the connective tissue of Is continuous with the connective tissue of
Gingiva. Gingiva.
In the apical region - it is continuous with the In the apical region - it is continuous with the
pulp.pulp.
The average width of the periodontal ligament isThe average width of the periodontal ligament is
0.20.2μμm.m.

4. 280 – Relationships of Periodontal Ligament280 – Relationships of Periodontal Ligament

5. Reduced in nonfunctional and Reduced in nonfunctional and
unerupted teeth.unerupted teeth.
Increased in teeth subjected to heavy Increased in teeth subjected to heavy
functional stresses. functional stresses.
Thicker in deciduous teeth than Thicker in deciduous teeth than
permanent teeth. In cervical region permanent teeth. In cervical region
and apical regions and lesser in and apical regions and lesser in
middle portion of the root.middle portion of the root.
The principal fibers run a wavy course The principal fibers run a wavy course
from Cementum to alveolar bone. from Cementum to alveolar bone.

6. 292 – 292 – Branching Principal FibersBranching Principal Fibers

7. 293 – 293 – Sharpey’s FibersSharpey’s Fibers
A – Alveolar Bone B - CementumA – Alveolar Bone B - Cementum

8. Sharpey's Fibers:Sharpey's Fibers: The collagen fibers are The collagen fibers are
embedded into the cementum on one side of the embedded into the cementum on one side of the
periodontal space and into alveolar bone on the periodontal space and into alveolar bone on the
other.other.
Inter Mediate Plexus:Inter Mediate Plexus:
 When examined under light microscope theWhen examined under light microscope the
fibers appear to be joined in the mid region of thefibers appear to be joined in the mid region of the
periodontal space giving rise to a zone of distinctperiodontal space giving rise to a zone of distinct
appearance, so called "appearance, so called "Inter Mediate PlexusInter Mediate Plexus" –" –
believed to be site for rapid remodeling of fibers. believed to be site for rapid remodeling of fibers.

9. 289 – 289 – Intermediate PlexusIntermediate Plexus

10. FunctionsFunctions
1.1.FormativeFormative
2.2.SupportiveSupportive
3.3.SensorySensory
4.4.Nutritive.Nutritive.
5.5.OcclusionOcclusion
6.6.ReparativeReparative
7.7.Protective.Protective.

11.  Periodontal Ligament consists of:Periodontal Ligament consists of:
– Cells Cells
– Extracellular substance:Extracellular substance:
 Fibers Fibers
 Ground substance Ground substance
Structure and CompositionStructure and Composition

12. Cells Cells
of of
Periodontal LigamentPeriodontal Ligament

13. 296 – 296 – Cells in Periodontal LigamentCells in Periodontal Ligament
A – Alveolar Bone B - CementumA – Alveolar Bone B - Cementum

14. The cells of Periodontal Ligament:The cells of Periodontal Ligament:
1. Synthetic cells:1. Synthetic cells:
OsteoblastsOsteoblasts
FibroblastsFibroblasts
CementoblastsCementoblasts
2. Resorptive cells:2. Resorptive cells:
OsteoclastsOsteoclasts
FibroblastsFibroblasts
CementoclastsCementoclasts
3. Progenitor cells.3. Progenitor cells.
Epithelial cells:Epithelial cells: Cell rests of Malassez. Cell rests of Malassez.
Other Connective tissue cells: Other Connective tissue cells:
Mast cellsMast cells
MacrophagesMacrophages

15. Synthetic cellsSynthetic cells

16. OsteoblastsOsteoblasts

 Bone forming cells lining the tooth socketBone forming cells lining the tooth socket
closely resembling cementoblasts. closely resembling cementoblasts.
 Alveolus constantly resorbed and rebuilt. Alveolus constantly resorbed and rebuilt.
 Irregularly cuboid in shape with large singleIrregularly cuboid in shape with large single
nucleus - containing large nucleoli and finenucleus - containing large nucleoli and fine
chromatin particles.chromatin particles.

17. 302 - 302 - OsteoblastsOsteoblasts

18. FibroblastsFibroblasts
 Predominant cells. Predominant cells.
 Capable of secretion and degeneration of Capable of secretion and degeneration of
collagen.collagen.
 Fibroblasts are of various shapes: Fibroblasts are of various shapes:
– Fusiform Fusiform
– Tripolar Tripolar
– StellateStellate
 With cytoplasmic processes of various lengths.With cytoplasmic processes of various lengths.
 When active they have a low nuclear toWhen active they have a low nuclear to
cytoplasmic ratio.cytoplasmic ratio.
 The nucleus is Large and oval and contains oneThe nucleus is Large and oval and contains one
or two nucleoli and rich in cytoplasmic organelles.or two nucleoli and rich in cytoplasmic organelles.

19. 297 - 297 - FibroblastsFibroblasts
A – Alveolar BoneA – Alveolar Bone
B – FibroblastsB – Fibroblasts
C - CementumC - Cementum

20. CementoblastsCementoblasts
 Plump cuboidal cells with large nucleus spheroidPlump cuboidal cells with large nucleus spheroid
or oval in shape.or oval in shape.
 Active in cementum formation found adjacent toActive in cementum formation found adjacent to
the surface with irregular finger like projectionsthe surface with irregular finger like projections
which fit around the fibers and with intracellularwhich fit around the fibers and with intracellular
organelles.organelles.
 Cells depositing cellular cementum Cells depositing cellular cementum
 Show abundant basophilic cytoplasm andShow abundant basophilic cytoplasm and
cytoplasmic processes. cytoplasmic processes.
 Cells depositing - a cellular cementum - shows noCells depositing - a cellular cementum - shows no
prominent cytoplasmic processes.prominent cytoplasmic processes.

21. 300 - 300 - CementoblstsCementoblsts

22. Resorptive cellsResorptive cells
Osteoclasts & Cementoclasts:Osteoclasts & Cementoclasts:
 Found in areas of resorption.Found in areas of resorption.
 MultinucleatedMultinucleated
 Originate from undifferentiated mesenchymal Originate from undifferentiated mesenchymal
cells in periodontal ligament.cells in periodontal ligament.

23. 303 – Osteoclasts in Howship’s Lacunae303 – Osteoclasts in Howship’s Lacunae

24.  Cytoplasm of the cells produce a substanceCytoplasm of the cells produce a substance
which dissolves the organic components of bonewhich dissolves the organic components of bone
and a chelating agent capable of bringingand a chelating agent capable of bringing
calcium salts into solution.calcium salts into solution.
 Where ever their cytoplasm comes into contactWhere ever their cytoplasm comes into contact
with bone - hollows or grooves called 'Howship'swith bone - hollows or grooves called 'Howship's
Lacunae' are formed.Lacunae' are formed.
 When bone resorption ceases - they disappear.When bone resorption ceases - they disappear.

25. Progenitor cellsProgenitor cells
 These cells have the capacity to undergoThese cells have the capacity to undergo
mitotic division. mitotic division.
 They give rise to all of the specializedThey give rise to all of the specialized
synthetic cells.synthetic cells.
Epithelial cell rests of Malassez:Epithelial cell rests of Malassez:
 Remains of Hertwig’s Epithelial RootRemains of Hertwig’s Epithelial Root
Sheath.Sheath.
 Epithelial double strands and islands Epithelial double strands and islands
limitedlimited
by basement membrane of reticulin.by basement membrane of reticulin.

26. 304a,304b -304a,304b - Cell Rests of MalassezCell Rests of Malassez

27. Mast cellsMast cells
 These are small round or oval cells.These are small round or oval cells.
 12 - 1512 - 15μμm. m.
 Characterized by numerous cytoplasmicCharacterized by numerous cytoplasmic
granules. granules.
 These granules contain heparin and histamine.These granules contain heparin and histamine.
 Histamine plays and important role inHistamine plays and important role in
inflammatory reactions and also in antigeninflammatory reactions and also in antigen
antibody reaction.antibody reaction.

28. MacrophagesMacrophages
 These can be visualized by the presence ofThese can be visualized by the presence of
phagocytosed material in their cytoplasm. phagocytosed material in their cytoplasm.
 They are derived from blood monocytes.They are derived from blood monocytes.

29. Extracellular SubstanceExtracellular Substance
Comprises of:Comprises of:
–Fibers:Fibers:
Collagen Collagen
Oxytalan.Oxytalan.
–Ground substance:Ground substance:
ProteoglycansProteoglycans
Glycoproteins.Glycoproteins.

30. Fibers Fibers
of of
Periodontal LigamentPeriodontal Ligament

31. FibersFibers
 Made up of collagen and Oxytalan. Made up of collagen and Oxytalan.
 Elastic fibers are restricted to the walls of bloodElastic fibers are restricted to the walls of blood
vessels.vessels.
 The majority of fibers are collagen. The majority of fibers are collagen.
 Mostly made up of type I collagen and someMostly made up of type I collagen and some
amount of type III collagen.amount of type III collagen.
 The collagen fibers are gathered in bundlesThe collagen fibers are gathered in bundles
having a clear orientation relative to thehaving a clear orientation relative to the
periodontal space - Principal fibers.periodontal space - Principal fibers.

32. 281 – T.S – thro Bone – Tooth - Ligament281 – T.S – thro Bone – Tooth - Ligament
A – Root B – Alveolar BoneA – Root B – Alveolar Bone

33. Principal FibersPrincipal Fibers
Arranged in five groups:Arranged in five groups:
1. Alveolar crest group.1. Alveolar crest group.
2. Horizontal group.2. Horizontal group.
3. Oblique group.3. Oblique group.
4. Apical group.4. Apical group.
5. Interradicular group. 5. Interradicular group.

34. 284 – 284 – Principal FibersPrincipal Fibers
1.1.Alveolo DentalAlveolo Dental
2.2.HorizontalHorizontal
3.3.ObliqueOblique
4.4.ApicalApical
5.5.InterradicularInterradicular

35. Principal FibersPrincipal Fibers
Alveolar Crest group:Alveolar Crest group:
They radiate from the crest of the alveolarThey radiate from the crest of the alveolar
process and attach themselves to the cervicalprocess and attach themselves to the cervical
part of the Cementum.part of the Cementum.
Horizontal group:Horizontal group:
They run at right angles to long axis of toothThey run at right angles to long axis of tooth
from Cementum to Bone.from Cementum to Bone.

36. 285- Dento Alveolar & Horizontal285- Dento Alveolar & Horizontal
A – Dento-alveolarA – Dento-alveolar
B - HorizontalB - Horizontal

37. Principal Fibers – contd…Principal Fibers – contd…
Oblique group:Oblique group:
They run obliquely. They run obliquely.
They are attached to cementum apically fromThey are attached to cementum apically from
their attachment to the bone. their attachment to the bone.
These fibers constitute the main attachment.These fibers constitute the main attachment.
Apical group:Apical group:
They radiate from the apical region of the rootThey radiate from the apical region of the root
to the surrounding bone.to the surrounding bone.
Interradicular Group:Interradicular Group:
From the crest of interradicular septum,From the crest of interradicular septum,
bundles extend to furcation of multirooted teeth.bundles extend to furcation of multirooted teeth.

38. 286 – 286 – Oblique setOblique set

39. 287 – 287 – Apical setApical set

40. 288 – 288 – Inter-radicularInter-radicular

41. Gingival FibersGingival Fibers

42. Fiber Bundles in the GingivaFiber Bundles in the Gingiva
1. Dento Gingival1. Dento Gingival
2. Alveo Gingival2. Alveo Gingival
3. Circular3. Circular
4. Dento Periosteal4. Dento Periosteal
5. Inter dental ligament.5. Inter dental ligament.

43. Oxytalan FibersOxytalan Fibers
 These are immature elastic fibers. These are immature elastic fibers.
 Found in the periodontal ligament. Found in the periodontal ligament.
 Largely restricted to the walls of blood vessels.Largely restricted to the walls of blood vessels.
 The orientation of these fibers is quite different.The orientation of these fibers is quite different.
 They tend to run axially - one end beingThey tend to run axially - one end being
embedded into cementum or possibly in boneembedded into cementum or possibly in bone
and the other - into the wall of a blood vessel. and the other - into the wall of a blood vessel.
 In the vicinity of apex they form a complexIn the vicinity of apex they form a complex
network.network.

44. 294a,295b,295 –294a,295b,295 – Oxytalan FibersOxytalan Fibers

45. Ground SubstanceGround Substance
in in
Periodontal LigamentPeriodontal Ligament

46. Ground SubstanceGround Substance
 Glycosaminoglycans:Glycosaminoglycans:
– Hyaluronic acidHyaluronic acid
– Dermatan sulfateDermatan sulfate
– Chondroitin sulfate.Chondroitin sulfate.
 Carbohydrates, proteins, lipids and Glycoproteins.Carbohydrates, proteins, lipids and Glycoproteins.
 Other Structures Present in connectinve tissue: Other Structures Present in connectinve tissue:
– Blood vesselsBlood vessels
– LymphaticsLymphatics
– Nerves and Cementicles.Nerves and Cementicles.

47. Blood Supply Blood Supply
& &
Lymphatic DrainageLymphatic Drainage

48. Blood Supply:Blood Supply:
From three sources -From three sources -
1. From the apical vessels supplying the dental1. From the apical vessels supplying the dental
pulp.pulp.
2. Branches from intra-alveolar vessels.2. Branches from intra-alveolar vessels.
3. Branches form gingival vessels.3. Branches form gingival vessels.
Lymphatics:Lymphatics:
Net work of lymphatic vessels following the path Net work of lymphatic vessels following the path
of blood vessels.of blood vessels.
The flow is iron the ligament toward and into the The flow is iron the ligament toward and into the
adjacent alveolar bone.adjacent alveolar bone.

49. 306a – 306a – Blood VesselsBlood Vessels

50. Nerve SupplyNerve Supply

51. Nerves are usually associated with blood vessels Nerves are usually associated with blood vessels
 Pass through foramina in the alveolar bone toPass through foramina in the alveolar bone to
enter the periodontal ligament. enter the periodontal ligament.
 Myelinated or non myelinated. Myelinated or non myelinated.
 Either large or small in diameter:Either large or small in diameter:
- larger diameter - concerned with touch.- larger diameter - concerned with touch.
- smaller diameter - concerned with pain.- smaller diameter - concerned with pain.
Cementicles:Cementicles:
 Calcified bodies.Calcified bodies.
 Origin is probably from degenerated epithelialOrigin is probably from degenerated epithelial
cells – forming a nidus for calcification.cells – forming a nidus for calcification.

52. 306b - 306b - Nerve BundlesNerve Bundles
A – Alveolar boneA – Alveolar bone
B - DentinB - Dentin

53. Development Development
of of
Periodontal LigamentPeriodontal Ligament

54. DevelopmentDevelopment
Derived from dental sac or follicle around theDerived from dental sac or follicle around the
tooth germ.tooth germ.
Around the tooth germ 3 zones can be seen:Around the tooth germ 3 zones can be seen:
–Outer zone - fibers related to bone.Outer zone - fibers related to bone.
– Inter mediate zone - unoriented fibers.Inter mediate zone - unoriented fibers.
–Inner zone - fibers adjacent to tooth.Inner zone - fibers adjacent to tooth.

55. 404 – 404 –
Dental Follicle & Development of Periodontal Dental Follicle & Development of Periodontal
LigamentLigament
A – HERSA – HERS
B – Dental PapillaB – Dental Papilla
C – OdontoblastsC – Odontoblasts
D – Root DentinD – Root Dentin
E – Predentin E – Predentin
F – CementoblastsF – Cementoblasts
G – CementumG – Cementum
H – Alveolar BoneH – Alveolar Bone

56.  During formation of cementum - inner zone ofDuring formation of cementum - inner zone of
fibers are attached to tooth root.fibers are attached to tooth root.
 As the tooth moves - functional orientation ofAs the tooth moves - functional orientation of
fibers takes place.fibers takes place.
 As the tooth reaches the plane of occlusion –As the tooth reaches the plane of occlusion –
functional orientation is completed.functional orientation is completed.
 Due to functional stresses - some changes takeDue to functional stresses - some changes take
place in the structural arrangement of periodontalplace in the structural arrangement of periodontal
ligament - which occurs throughout out the life.ligament - which occurs throughout out the life.