The periodontal ligament is a connective tissue that connects the cementum of teeth to the alveolar bone. It contains principal collagen fibers, fibroblasts that produce the fibers, undifferentiated cells, and a ground substance of proteoglycans and glycoproteins. The principal fibers develop in stages from the cementum to bone and resist various forces on teeth. The periodontal ligament plays an important role in tooth support and is vital for tooth function.

1. PERIODONTAL LIGAMENT
IN
HEALTH AND DISEASE
PRESENTED BY –
DR SHRUTI LENDHEY

2. INDEX
 Introduction
 Definition
 Development
 Content
 Functions of pdl
 Clinical considerations
 Periodontal ligament in disease
 Regenerative potential of pdl
 Summary
 References

3. INTRODUCTION
The periodontal ligament is
situated in the space
between the roots of the
teeth and the lamina dura or
the alveolar bone proper.
 The width of PDL is
approximately 0.25mm
(range 0.2 to 0.4mm)

4. In the coronal direction, the periodontal ligament is
continuous with the lamina propria of the gingiva
and is demarcated from the gingiva by the collagen
fiber bundles which connect the alveolar bone crest
with the root.
The periodontal ligament space has the shape of an
hourglass and is narrowest at the mid root level

5. DEFINITION
 The periodontal ligament is a complex cellular and highly
vascular connective tissue structure that surrounds the tooth
root and connects it to the inner wall of the alveolar bone. It is
continuous with the connective tissues of the gingiva and
communicates with the marrow spaces through vascular
channels in the bone
- Carranza
The periodontal ligament is the soft, richly vascular and cellular
connective tissue which surrounds the roots of the teeth and
joins the root cementum with the socket wall.
- Lindhe

6. DEVELOPMENT
The periodontal fibroblast have
their origin in the dental follicle and
begins to differentiate during root
development.
(Ten Cate et al 1971)
 With continuing apical
development of the root, the cells of
dental follicle differentiate into
cementoblast to form cementum
lining the root surface, and this
subsequently leads to the
appearance of periodontal ligament
fibroblasts and formation of
periodontal ligament.

7.  All of these development processes occur prior to eruption of
teeth (Grant and Bernick 1972)
 Fiber formation and deposition occur sequentially from the
newly forming CEJ to the apex of the tooth root.
 The first fibers to develop ultimately become the dentogingival
and Transeptal fibers of the gingiva while those that develop
apical to CEJ ultimately form fibers of periodontal ligament.
 As the teeth begins to erupt, the orientation of the ligament
fibers changes according to the stage of eruption.
(Grant and Bernick 1972)

8. Stages of organisation of PDL

9.  Illustration of the development of the
principle fibers of the periodontal
ligament.
Development of principal fibres of PDL

10. HISTOLOGICAL STRUCTURE
CELLS
CONNECTIVE
TISSUE CELLS
EPITHELIAL REST
CELLS
CELLS ASSOC. WITH
NEUROVASCULAR
ELEMENTS
DEFENCE CELLS
EXTRACELLULAR
COMPONENTS
FIBERS
GROUND
SUBSTANCE
BLOOD SUPPLY,
NERVE SUPPLY
AND LYMPHATICS

11. Extracellular components
FIBERS:
Principal fibers
Oxytalan fibres
Indifferent fiber plexus
GROUND SUBSTANCE:
Proteoglycans
Glycoproteins

12. PERIODONTAL FIBERS
The most important element
of the periodontal ligament
are the principal fibers.
 These are collagenous in
nature and are arranged in
bundles. They follow a wavy
course.
The terminal portion of these
fibers are inserted in the
cementum and bone and
called as Sharpey’s fibers.

13. Sicher (1923) postulated the existence of an intermediate
zone, located midway between the bone and the cementum in
which fibres intermesh. It was presumed to an area of high
metabolic activity where the fibres could be sliced and
unsliced with ease.
 Sicher (1942) stated that human PDL consists of
 alveolar fibres
 dental fibres
 an intermediate plexus
Berkovitz et al(1980) demonstrated a “zone of shear” – a site
of remodeling during eruption.
However, its location is in dispute ie if it lies near the tooth
surface or in the centre.

14. COLLAGEN
Collagen is the predominant protein of the periodontal
tissues.
 Composed of different amino acids, the most important of
which are Proline, glycine,hydroxyproline, hydroxylysine .
(Carneiro J).
The amount of collagen can be determined by its
hydroxyproline content.
Collagen fibrils have transverse striation with a characteristic
periodicity of 64nm; this striation is caused by the
overlapping of tropocollagen molecules.

15. The molecular configuration of collagen give them tensile
strength greater than that of steel
Sodek (1977) found collagen synthesis in PDL of adult rat to
be
 2 fold greater than that of gingiva
 4 fold….. than skin
 6 fold …...than that of bone.

16. STAGES IN THE FORMATION OF
COLLAGEN
TROPOCOLLAG
EN
MOLECULES
MICRO
FIBRILS
COLLAGEN
FIBRILS
COLLAGEN
FIBER

17. In collagen types I and III these fibrils associate to
form fibers, and in collagen type I the fibers
associate to form bundles.
Collagen microfibrils, fibrils, fibers, and bundles

18. PRINCIPAL FIBERS
The principal fibers of the periodontal ligament are
arranged in six groups that develops sequentially .
1. TRANSSEPTAL GROUP
2. ALVEOLAR CREST GROUP
3. HORIZONTAL GROUP
4. OBLIQUE GROUP
5. APICAL GROUP
6. INTERRADICULAR FIBER

19. TRANSEPTAL GROUP
 EXTENT: Interproximally over
the alveolar bone crest and are
embedded in the cementum of
adjacent teeth.
FEATURES:
 They are reconstructed even
after the destruction of
alveolar bone.
 These fibers may be
considered as belonging to the
gingiva as they don’t have
any osseous attachment
TRANSSEPTAL FIBERS

20. ALVEOLAR CREST GROUP
EXTENT: These fibers run
obliquely from the cementum
just beneath the junctional
epithelium to the alveolar crest
FEATURES:
1. Prevent the extrusion of the
tooth and resist lateral tooth
movement
2. Incision of these fibres
during surgery does not
increase mobility unless
significant attachment loss
has occured. (Gillespie BR) (1979)

21. HORIZONTAL GROUP
EXTENT: In horizontal direction
at right angles to the long axis of
the tooth from the cementum to
the alveolar bone.
FEATURES:
Restrain lateral tooth
movements

22. OBLIQUE GROUP
EXTENT: They extend from the
cementum in a coronal direction
obliquely to the bone,
 attached superiorly to the alveolar
bone and inferiorly to cementum
FEATURES:
1. Largest group of fibres.
2. Bear the brunt of the vertical
masticatory stresses and
transform stresses into tension on
the alveolar bone.

23. APICAL GROUP
EXTENT: They radiate in a
rather irregular fashion from the
cementum to the bone at the
apical region of the socket.
FEATURES:
1. They do not occur on
incompletely formed roots
2. Prevent tipping and resist
luxation.

24. INTERRADICULAR GROUP
EXTENT:
They fan out from the
cementum to the tooth in the
furcation areas of multirooted
teeth.
FEATURES:
It resist luxation and also
tipping and torquing

25. OXYTALAN FIBERS
Describe by Fullmer (1974).
Two immature elastins are oxytalan
and eluanin are seen.
The oxytalan fibers run parallel to the
root surface in a vertical direction and
bend to attach to the cementum in the
cervical third of the root.
They are thought to regulate the
vascular flow.
OXYTALAN FIBRES

26. INDIFFERENT FIBER PLEXUS
In addition there are small collagen fibers
associated with the larger principal collagen
fibers.
These fibers run in all directions forming a
plexus- called the indifferent fiber plexus

27. CELLULAR ELEMENTS
Cells o f th e PDL is categ o rized as : -
1 ) Syn th etic cells -
Fib r o b last
O steo b last
Cemen to b last
2 ) Reso r p tive cells -
Fib r o b last
O steo clast
Cemen to clast
3 ) Pr o g en ito r cells
4 ) Ep ith elial cell r est o f Malassez
5 ) Defen ce cells - mast cells an d macro p h ag es

28. FIBROBLASTS
Periodontal fibroblasts are the most common cells in the
periodontal ligament
Responsible for metabolism of extracellular matrix components
 Appear as ovoid or elongated cells oriented along the principal
fibers and exhibit pseudopodia like processes.
These cells synthesize collagen and also possess the capacity to
phagocytose "old" collagen fibers and degrade them via
enzymes hydrolysis.

29. The collagen turnover appears to be regulated by fibroblasts in a
process of intracellular degradation of collagen not involving the
action of collagenase
The fibroblasts in the ligament are oriented more or less parallel to
the collagen fibers, whereas in cross-sections they may exhibit a
stellate appearance, with cytoplasmic processes segregating
individual bundles of collagen fibers.
FIBROBLAST

30. The fibroblasts of the periodontal ligament are
interconnected by numerous junctions which can be
categorized as gap and adherence type junctions.
(Beertsen)
Adherence type of junctionGap junction

31. FUNCTION OF FIBROBLASTS
 The main function of fibroblast is the production of various type of
fibers and synthesis of connective tissue matrix.
They produce;
Collagen fibers
Reticulin fibers
Oxytalan fibers
Elastin fibers

32. The periodontal ligament is known to have two main lineages
of fibroblasts-the common connective tissue fibroblast and the
osteoblast-like fibroblasts, rich in alkaline phosphatase.
 These cells have the capacity to give rise to bone cells and
cementoblasts. They are also responsible for the production of
acellular extrinsic fiber cementum in the mature periodontal
ligament.
Periodontal ligament fibroblasts are also needed to maintain
the normal width of the periodontal ligament by preventing the
encroachment of bone and cementum into the periodontal
ligament space.

33. CEMENTOBLAST
Cementoblast are cementum forming cells
lining the surface of cementum.
Cementoblast are not as elongated as the
fibroblast, being cuboidal cells. They are
rich in cytoplasm and contain large nuclei.
They have all the intercellular substance
necessary for protein synthesis and
secretion.
CEMENTOBLAST

34. OSTEOCLAST
The surface of alveolar bone shows a
number of resorption concavities
termed as howship’s lacunae in
which osteoclast lies.
Osteoclast shows considerable
change in size and shape ranging
from small mononuclear to large
multinucleated.
 The cell which lie close to the bone
often has brush border.
OSTEOCLAST

35. CEMENTOCLAST
Cementoclast are the cells which are found close to
the cementum being desorbed.
These cells are actively involved in the resorption
process of the cementum.
Cementoclast has the same cytoplasmic feature as that
of osteoclast, and they are supposed to be derived
from the blood cell of the macrophage type.

36. PROGENITOR CELLS
An important constituent of the periodontal
ligament is undifferentiated mesechymal cells or
progenitor cells.
These have a location of within 5 micron of the
blood vessels.
However it has been demonstrated that these cells
are the source of cells in the periodontal ligament

37. EPITHELIAL REST CELLS
 The cell rests of Malassez form a
latticework in the periodontal
ligament and appear as either
isolated clusters of cells or
interlacing strands.
The epithelial rests are considered
remnants of Hertwig's root sheath
which disintegrates during root
development.
The epithelial cell rests are situated
in the periodontal ligament at a
distance of 15–75 μm from the
cementum(C) on the root surface. EPITHELIAL REST
CELL OF MALASSEZ

38. During the 1st and 2nd decade of life
they are most numerous near the
apical end of root and in the last
decade they are more prevalent in the
cervical area.
They diminish in number with age by
degenerating and disappearing or
undergoing calcification to become
cementicles.
Play a role in tissue homeostasis as
well as tissue regeneration.
EPITHELIAL REST
CELL OF MALASSEZ

39. DEFENCE CELLS
NEUTROPHILS
LYMPHOCYTES
MACROPHAGES
MAST CELLS
EOSINOPHILS

40. MAST CELLS
Mast cells are often associated with blood vessels. They
show a large number of intracytoplasmic granules.
When the cell is stimulated it degranulates and is also
involved in production of histamine, heparin and other
factors associated with anaphylaxis
MAST CELLS

41. MACROPHAGES
Macrophages are responsible for
phagocytosing particulate matter
and invading the microorganisms
They also synthesize a range of
molecules with important
function such as interferon,
prostaglandin and factors that
stimulates the fibroblast and
endothelial cells.
MACROPHAGES

42. GROUND SUBSTANCE
The periodontal ligament also contains a large
proportion of ground substance filling the spaces
between fibers and cells. It consists of two main
components:
Glycosaminoglycans such as hyaluronic acid
proteoglycans
 Glycoproteins such as fibronectin and laminin.

43. PROTEOGLYCANS
The Proteoglycans are compounds containing anionic
polysaccharides (glycosoaminoglycans) which are
covalently attached to protein coat.
Two proteoglycans have been isolated (Gibson 1992)
Dermatan sulphate
Chondroitin sulphate
The chondroitin sulfate rich proteoglycans play a role in
absorbing compressive shocks and thereby protect the cells
of the ligament from damage during occlusal contact

44. GLYCOPROTEIN
The complex glycoprotein are called as fibronectin. The
fibronectin is widely distributed between cross striated
collagen fibrils, surrounding these fibrils in the microfibrillar
network.
These proteins are thought to promote attachment of cells
specially to collagen fibrils.
As cells preferentially attach to fibronectin they are also
helpful in the orientation and migration of cells.

45. Like fibronectin, PDL also contain tenascin that is
more like a fetal connective tissue. Tenascin is not
present uniformly in the PDL but it is more
concentrated near the alveolar bone and
cementum.
In addition PDL also contain osteonectin,
vitronectin and osteopoetin. The osteopoetin is
produced during alveolar bone regeneration.
(Lekic et al 1996)

46. CEMENTICLES
These are calcified masses which are
adherent to or detached from the root
surfaces.
 They may develop from :
Calcified epithelial rests
Around small spicules of cementum
or alveolar bone traumatically
displaced into the PDL.
From calcified Sharpey’s fibers
From calcified thrombosed vessels in
the ligament

47. BLOOD SUPPLY
Derived from the inferior and superior
alveolar arteries to the mandible and
maxilla and reaches the PDL from 3
main sources :-
 Apical group of arteries: These are
branches of vessels supplying the tooth
pulp.
 Alveolar group of arteries: These arteries
enter the PDL space from the alveolar
bone. These are also referred to as
perforating arteries..
 Gingival group of arteries: These are
derived from the gingival blood supply.
These enter the PDL from the crestal
region and anastomoses with the
vascular network of PDL.

48. NERVE SUPPLY
 The nerve supply of the PDL comes from either the
inferior or superior dental nerves.
1. Bundles of nerve fibers run from the apical region of
the tooth to the gingival margin.
2. Nerves enter the ligament horizontally through
multiple foramina in the bone.
 The periodontal ligament is capable of transmitting
tactile ,pressure and pain sensations by trigeminal
pathways.

49. FUNCTIONS OF
PERIODONTAL LIGAMENT

50. PHYSICAL
FUNCTIONS
FORMATIVE AND
REMODELLING
FUNCTION
NUTRITIONAL AND
SENSORY FUNCTIONS
REGULATION OF
PERIODONTAL
LIGAMENT WIDTH
FUNCTIONS

51. PHYSICAL FUNCTIONS
 The physical functions entail the following:
1. Provision of a soft tissue "casing" to protect the vessels
and nerves from injury by mechanical forces
2. Transmission of occlusal forces to the bone
3. Attachment of the teeth to the bone
4. Maintenance of the gingival tissues in their proper
relationship to the teeth
5. Resistance to the impact of occlusal forces (shock
absorption)

52. Resistance To Impact to occlusal forces :-
Acts as shock absorber to the occlusal forces, there are
two theories have been considered ;
1. Tensional theory
2. Viscoelastic theory (Bien SM 1966)
Transmission of occlusal forces to bone:-
-The arrangement of principle fiber is like a suspension
bridge.
-The apical portion of root moves in a direction opposite
to the coronal portion.
(Picton DC)

53. In areas of tension, the principal fiber bundles are
taut rather than wavy. In areas of pressure, the fibers
are compressed, the tooth is displaced, and a
corresponding distortion of bone exists in the
direction of root movement.
In single-rooted teeth, the axis of rotation is located
in the area between the apical third and the middle
third of the root.
In multi-rooted teeth, the axis of rotation is located in
the bone between the roots.

54. The periodontal ligament has an hourglass shape, and is
narrowest at the axis of rotation.
(Coolidge ED)
The PDL is thinner at the mesial root surface than on the
distal surface.
Distribution of faciolingual forces
(arrow) around the axis of
rotation (black circle on root) in a
mandibular premolar. The
periodontal ligament fibers are
compressed in areas of pressure
and distension in areas of
tension.
Left, The same tooth in a resting
state.

55. PROPRIOCEPTION
One of the main functions of the PDL in the masticatory cycle
is to provide sensory feedback during chewing.
Humans are capable of detecting the presence of very small
particles between the occlusal surfaces of teeth. The teeth also
can serve as an excellent judge of material properties.
There are proprioceptive sensors in the PDL that provide
sensory information about how fast and how hard to bite
(Hannam 1982).
Lund and Lamarre (1973) anesthetized patient’s teeth and
found a 40% reduction in bite force applied, indicating that
PDL proprioceptors are important in the control of bite force

56. FORMATIVE AND REMODELING
FUNCTION
Cells of the PDL participate in the formation and remodeling
of the cementum and the bone, which occurs during the tooth
movement.
Variation in the cellular enzyme activity is related with the
remodeling.
(Gibson W)
Cartilage formation in the periodontal ligament is a
metaplastic phenomenon which may be due to the repair from
injury. (Bauer WH)

57. The PDL is constantly undergoing remodeling.
(Muhlemann)
Studies by the use of radioactive element
suggest that the turnover rate of collagen is
twice as that of gingiva and four times as that
of skin ,as established in rat molar
(Sodek J)

58. NUTRITIONAL FUNCTIONS
The periodontal ligament supplies nutrients to the
cementum, bone and gingiva by way of the blood vessels
and also provides lymphatic drainage.
PDL is highly vascularized tissue and this may provide
hydrodynamic damping to applied forces, as well as high
perfusion rates to the periodontal ligament.

59. SENSORY FUNCTIONS
NEURAL TERMINATIONS
FREE
ENDINGS
-pain
sensation
RUFFINI
MECHANO
RECEPTORS
-primarily in
apical areas
COILED
MEISSNER’S
CORPUSCLE
-primarily
in midroot
region
SPINDLE
LIKE
ENDINGS
-pressure and
vibration
mainly in apex

61. REGULATION OF PERIODONTAL LIGAMENT
WIDTH
The cells, vascular elements and extracellular matrix
proteins of the periodontal ligament function
collectively to enable the teeth to adjust their position
while remaining firmly attached to the bony socket.
Cytokines and growth factors are important locally
acting regulators of cell function and periodontal
ligament cells are capable of synthesizing and secreting
some of these factors.

62. Protein S100A4- a member of the S100 calcium
binding protein family, suppresses the expression of
osteoblastic genes in the PDL cells and thus inhibit
mineralization in PDL .
( Kato et al 2005)
Prostaglandins PGE2 & PGF2 which are also
produced by periodontal ligament cells, can inhibit
mineralized bone nodule formation and prevent
mineralization by periodontal ligament cells in vitro.

63. As prostaglandins and interleukin-1 can strongly induce
matrix degradation, there is evidently an important
relationship between mechanical forces, cytokine
production and regulation of the periodontal ligament space
The appropriate regulation of these signaling systems is
clinically important since the failure of homeostatic
mechanisms to regulate periodontal ligament width may
lead to tooth ankylosis and/or root resorption.

64. CLINICAL
CONSIDERATIONS

65. AGING AND ITS EFFECT ON PDL
Aging of the periodontal ligament fiber:
Qualitative studies of the aged human periodontal ligament
have suggested that the main change with age is increased
collagen fibrosis and decreased cellularity.
(Grant and Bernick 1972)
Aging results in greater number of elastic fibres, decrease
in vascularity, mitotic activity ,collagen fibres and
mucopolysaccharides .

66. Both an increase and a decrease in the width of the
ligament is seen with aging.
A reduction in width may be accounted for by a lower
functional demand owing to decrease in strength of the
masticatory musculature..
Decreased width may also result from encroachment of the
ligament by continuous deposition of cementum and bone.
An increase in width may be due to availability of fewer
teeth to support the entire functional load

67. Periodontal Ligament becomes thinner as age advances
11 – 16 years - 0.21 mm,
32 – 52 yrs - 0.18mm,
51 – 67 yrs - 0.15mm.
PDL is thinner in functionless teeth or teeth without
antagonists and thick and wide in teeth subjected to excessive
occlusal stress.

68. PHYSIOLOGIC DRIFT
Tooth movement does not end when active eruption is
completed and the tooth is in functional occlusion. With time
and wear, the proximal contact areas of the teeth are flattened
and the teeth tend to move mesially.This is referred to as
“Physiologic mesial migration”.
 The width of periodontal ligament is greater on mesial than
on the distal side owing to physiologic mesial migration. By
the age 40 it results in reduction of about 0.5cm in the length
of the dental arch from the midline to the third molars.

69. ORTHODONTIC CONSIDERATIONS
During orthodontic correction, due to force applied in a labio-
lingual direction, the principal fibres lose their wavy nature , are
stretched on the labial side and are compressed on the lingual
aspect and hence, teeth are brought into the desired position.
Once the treatment is completed, it is advisable to give a
retentive appliance. This is because, the teeth have a tendency
to move back to its original position due to the rheologic
property of the periodontal fibres (elastic memory)
Supracrestal fibrotomy is usually done after derotation to
prevent relapse.

70. RECESSION
Some of the inter-radicular fibres
may be lost if age related gingival
recession exposes the furcation
area.
 Total loss of the fibres occurs in
case of inflammatory periodontal
disease involving the furcation
area.

71. ANKYLOSIS
Ankylosis of a tooth is defined as an anatomical fusion
of alveolar bone with cementum and can occur either
before or after the tooth erupts into the oral cavity.
Essentially, the periodontal ligament is obliterated by a
'bony bridge' and the root becomes fused to the alveolar
bone.
The most common theory that is known to cause
ankylosis is traumatic injury of the periodontal
ligament
(Kracke: 1975,Andreasen: 1981).

72. Risk of ankylosis is
highest for teeth
with subluxation or
avulsion injuries
because of the
nature and severity
of damage to the
periodontal
ligament

73. PERIODONTAL LIGAMENT
IN DISEASE

74. LOCALIZED AGGRESSIVE PERIODONTITIS
The alveolar attachment of
the periodontal ligament
fibers is lost initially.
This is followed by
widening of periodontal
ligament space owing to
bone resorption.
Remaining Periodontal
ligament fibers run parallel
to the root surface.

75. PAPILLON –LEFEVRE SYNDROME
Reduced density of Periodontal
ligament fiber attachment
produced by defective
Periodontal ligament
With advancing disease, there is
deep penetration of
inflammatory cells into
periodontal ligament resulting
in deep periodontal pockets.
Early loss of both deciduous
and permanent teeth .

76. NON- SUPPURATIVE PERIODONTITIS
The granuloma itself constitutes
mainly of chronic inflammatory
granulation tissue composed mainly
of plasma cells, lymphocytes,
fibroblasts and a varying density of
collagen bundles
Widening of Periodontal ligament
space, with breaks in continuity of
the lamina dura.
The ligament seems to be more
resistant to the spread of periapical
inflammation than the adjacent
marrow spaces.

77. SUPPURATIVE APICAL PERIODONTITIS
The periapical suppurative
lesions are composed of a focus
of infection around the apical
foramen, which with the
accumulation of
Polymorphonuclear neutrophils,
results in pus formation.
Pus may accumulate in the
adjacent marrow spaces as well
as the periodontal ligament
space.

78. NECROTIZING ULCERATIVE
PERIODONTITIS
Spread to involve the
periodontal ligament.
There is loss of crestal bone,
and the ligament is affected
by marked vasodilatation
and thrombosis, resulting in
localized ischaemic
necrosis.

79. TUBERCULOSIS
The oral lesion is crateriform,
painless ulcer with a caseated
base, which may rarely extend
to the Periodontal Ligament and
cause tooth loss.
In general, periodontal lesions
are secondary to pulmonary
tuberculosis.

80. LEPROSY
Gingival ulceration in
lepromatous leprosy may
spread to cause severe
periodontal ligament
destruction.
It causes both, widening
of lamina dura and
periodontal ligament
space.

81. SCLERODERMA
 Systemic Connective tissue
disease characterized by
vasomotor disturbances,
fibrosis, subsequent atrophy
of the skin, subcutaneous
tissue ,muscles and assoc
immunologic disturbances.
Extreme generalised
widening of the periodontal
ligament two to three times
the normal thickness.

82. OSTEOSARCOMA
Localized symmetric
widening of the PDL space
The medullary bone adjacent
to widened ligament space
shows a ragged moth eaten
pattern.
Male prediliction.

83. PAGET’S DISEASE
Enlargement of jaws may cause
spaces to appear between teeth
or dentures to lose their proper
fit; serum alkaline phosphatase
levels are elevated in active
disease
Classic finding is a patchy
mixed radiolucency/radiopacity
with a cotton wool appearance,
may see hypercemntosis of
tooth roots, loss of lamina dura,
obliteration of PDL space, or
resorption of roots

84. REGENERATIVE POTENTIAL
The objective of regenerative potential is to restore the
destroyed connective tissue, form new cementum and bone and
induce attachment of new connective tissue fibers.
(Egelberg J)
Many reports indicate that restoration of destroyed periodontal
ligament is at least possible, although their effectiveness is
unclear and success is unpredictable.
(Lynch SE)
In regenerating periodontal ligament, the fibroblast population
must first produce oriented collagen bundles and then maintain
the orientation of these fibers during the development of normal
function.

85. Cell kinetic experiments in mice and rats have shown that
periodontal ligament fibroblast populations are a renewal cell
system in steady state: the number of new cells generated by
mitosis is equal to the number of cells lost through apoptosis and
migration. (Mc Culloch CAG)
In other renewal systems, the most primitive cell is classified as a
stem cell, characterized by extensive self-renewal, responsiveness
to regulatory factors, generation of multiple types of different
specialized cells. Consequently, periodontal ligament fibroblast
populations are renewal cell systems like stem cells.
Short-term application of platelet-derived and insulin-like growth
factors can enhance new attachment procedures in dogs.
(Lynch SE)

86. CONCLUSION
Over the past decade, insight into the physiology of the
periodontal ligament and the properties of its cells has
increased. This insight has come from the synthesis of
research results from sources as varied as in vivo rodent
models, in vitro studies of cells and tissues and protein
biochemistry. Based on these studies, we conclude that the
periodontal ligament is a unique connective tissue: it cannot
be readily replaced by cell populations other than those that
have their origin in the ligament itself.

87. REFERENCES
CLINICAL PERIODONTOLOGY
CARRANZA 10TH EDITION
ORBANS TEXTBOOK OFORAL HISTOLOGY
PERIODONTICS MEDICINE, SURGERY, IMPLANT
LOUIS.F.ROSE
CLINICAL PERIODONTOLOGY AND IMPLANT
DENTISTRY
JAN LINDHE 5TH EDITION
 PERIODONOLOGY 2000
VOLUME 13, 1997

88. THANK YOU