Periodontal ligament

PERIODONTAL LIGAMENT.
Monday, November 2, 2020 2
Guided By:
Dr. Parul Aneja
Dr. Sahaya Stelin Kasper.
Dr. Mariyam Momin
I Year PG
Department of Periodontology & Oral
Implantology.

CONTENTS
 INTRODUCTION
 SYNONYMS
 DEFINITIONS
 DEVELOPMENT OF PERIODONTAL LIGAMENT
 DEVELOPMENT OF PRINCIPAL FIBERS OF PDL
 STRUCTURE OF PERIODONTAL LIGAMENT
 FACTORS MAINTAINING PDL WIDTH
 STRUCTURAL COMPONENTS OF PDL
 PRINCIPAL FIBERS OF PDL
 BLOOD SUPPLY OF PDL
 LYMPHATIC SUPPLY OF PDL
 NERVE SUPPLY OF PDL
 FUNCTIONS OF PDL
 CLINICAL SIGNIFICANCE
 CONCLUSION.

INTRODUCTION
The term periodontium
arises from the Greek word
peri meaning around and
odont meaning tooth, thus it
can be simply defined as the
“tissues investing and
supporting the teeth”. The
periodontium is composed
of the following tissues
namely alveolar bone, root
cementum, periodontal
ligament (supporting
tissues) and gingiva
(investing tissue).
Tissues of the Periodontium

PERIODONTAL LIGAMENT.
• It is a specialized fibrous connective
tissue that surrounds and attaches the
roots of the teeth to the alveolar bone.
It is also referred to as periodontal
membrane.
• The periodontal ligament is composed
of a complex vascular and highly
cellular connective tissue that
surrounds the tooth and connects it to
the inner wall of the alveolar bone.
• It is continuous with connective tissue
of gingiva & it connects with the
marrow spaces through vascular
channels in the bone.
• Although the average width of PDL
space is documented to be about
0.2mm, considerable variation exists.
• The periodontal space is diminished
around the teeth that are not in
function and in unerupted teeth, but it
is increased in teeth that have been
subjected to hyperfunction.
Periodontal ligament

SYNONYMS OF PERIODONTAL
LIGAMENT.
 Gomphosis
Desmodont
Peri-cementum
Dental periosteum
Alveo-dental ligament
Periodontal membrane.

Radiographic appearance of PDL
In radiograph it appears as a radiolucent line
between the root and alveolar bone.
Radiographic appearance of PDL space

DEFINTIONS.
 PDL is composed of complex vascular and highly cellular
connective tissue that surrounds the root and connects
it to the inner wall of alveolar bone.
- Carranza.
 ACCORDING TO BERKOVITZ:
“It is the dense fibrous connective tissue that occupies the
periodontal ligament space between the roots of teeth and
alveolus. It is derived from the dental follicle above alveolar
crest and is continuous with connective tissue of gingiva and
the apical foramen which is further continuation with dental
pulp.

 It is a narrow and highly cellular CT that forms the
interface between alveolar bone and cementum.
(Periodontol 2000,vol.3,1993)
 Soft, richly vascular and cellular connective tissue
which surrounds the roots of the teeth and joins the
root cementum with the socket wall. (Jan Lindhe 5th
ed)
 The periodontal ligament occupies the periodontal
space, which is located between the cementum and
the periodontal surface of alveolar bone and extends
coronally to the most apical part of the lamina propria
of the gingiva. (Orban’s)

DEVELOPMENT OF PDL
• The development of the periodontal
ligament begins with root formation prior to
tooth eruption.
• The continuous proliferation of the internal
and external enamel epithelium forms the
cervical loop of the tooth bud.
• This sheath of epithelial cells grows apically,
in the form of Hertwig’s epithelial root
sheath, between the dental papilla and the
dental follicle.
• At this stage, the sheath forms a
circumferential structure encompassing
dental papilla separating it externally from
dental follicle cells.
• The dental follicle cells located between the
alveolar bone and the epithelial root sheath
are composed of two subpopulations,
1. mesenchymal cells of the dental
follicle proper
2.perifollicular mesenchyme.
Development of PDL

As the root formation continues, cells in the
perifollicular mesenchyme gain their polarity,
cellular volume & become widely seperated.
Actively synthesize & deposit collagen fibrils in
developing PDL.
Type I collagen is secreted.
Assembles as collagen bundles on the bone and
cementum surface.
Establish continuity across the ligament space.
Development of PDL….

Development of Principal fibers.
The principal fibers develop in conjunction with the eruption
of the tooth. The fibroblasts surrounding the developing root
produce collagen fibers. These fibers are seen in the
periodontal space without a specific orientation. As and when
the tooth erupts, the orientation of the fibers alters.
1. First small, fine brush-like fibrils are seen arising from the
root cementum and projecting into the periodontal ligament
space.
2. Similar fibers are seen on the surface of the bone but only
in thin, small numbers.
3. Later on, the number and thickness of fibers originating
from the bone increase and elongate. They radiate towards
the loose connective tissue in the midportion of the
periodontal ligament.
4. The fibers originating from the cementum also increase in
length and thickness and fuses with the fibers originating from
the alveolar bone in the periodontal ligament space.Monday, November 2, 2020 13

5. They mature progressively towards the
root apex as the eruption progresses.
When the tooth, following eruption,
reaches contact in occlusion and starts to
function, the principle fibers become
organized in bundles and run continuously
from bone to cementum.
For long, it was believed that this middle
portion where the splicing of fibers from
cementum and bone takes place, it forms
the intermediate plexus. These plexus
were thought to play a significant role in
orientation and adjustment of fibers
during eruption and functional movement
of teeth. But recent investigations have
revealed that, in humans these plexus
disappears once the fusion of cemental
and osseous fibers are completed.
Development of periodontal
ligament fibers (principal)Monday, November 2, 2020 14

STRUCTURE OF PDL
• The periodontal ligament space has the shape of an hourglass
and is narrowest at the mid-root level. The width of
periodontal ligament is approximately 0.15-0.38mm.
Hourglass
Hourglass appearance of PDLMonday, November 2, 2020 16

Average width
• Depending on age
11-16 years – 0.21mm
32-52 years – 0.18mm
51-67 years – 0.15mm
• According to functional state of tissues
Time of eruption – 0.1 – 0.5mm
At function - 0.2 – 0.35mm
Hypofunction - 0.1 – 0.15mm

Factors maintaining PDL width
One of the important feature of PDL is
maintenance of space inspite of its constant
exposure to various mechanical forces. The
following factors thought to contribute to
maintenance of PDL space.
1. PDL fibroblasts
2. Epithelial cells of Malassez
3. Nitric oxide (NO)

1. PDL fibroblasts
- The most important mechanisms by which PDL
fibroblasts maintain their space are as follows:
Msx protein
- The greater expression of Msx homebox protein within
PDL thought to be a defense mechanism that prevents
PDL mineralization.
S100 protein
-PDL shows a greater expression of S100 which regulates
expression of osteoblast differentiation genes coding for
proteins such as osteocalcin and alkaline phosphatase
and thus, inhibits.
PDL associated protein 1 (PLAP-1)
-it is a potent inhibitor of mineralization as it can bind
with BMP and antagonize its action. This binding prevents
cyto-differentiaton and as a result expression of
osteoblast phenotype is restricted.

PDL FibroblastMonday, November 2, 2020 20

2. Epithelial cells of Malassez
- The presence of cell rests of
Malassez in PDL space thought
to be deterrent to osteoblast
differentiation and is, therefore,
important, especially in coronal
areas of tooth.
3. Nitric oxide (NO)
- On application of mechanical
stresses, increased NO production
from the PDL is thought to result
in osteoclast activity and bone
resorption thereby maintaining
the PDL space.
Epithelial cell Rest of
Malassez

STRUCTURAL COMPONENTS OF PDL.
PDL
Cellular
components
Extra cellular
components
Interstitial
tissues
Components of PDLMonday, November 2, 2020 22

Cellular components
Synthetic cells
1. Osteoblasts
2. Fibroblasts
3. Cementoblasts
Resorptive cells
1. Osteoclasts
2. Fibroblasts
3. Cementoclasts
Immune system cells/ blood cells
1. Mast cells
2. Macrophages
3. Neutrophils
4. Eosinophils
5. Lymphocytes
Cellular components of PDL
Components of PDL

Other cells
1. Undifferentiated mesenchymal cells
2. Cell rests of Malassez
Extra cellular substances
Ground substance
1. Proteoglycans
2. Glycoprotein
Fibers
1. Principal fibers
2. Secondary fibers
Interstitial tissue
1. Cementicles
2. Cells associated with neurovascular elements
(blood vessels, lymphatics and nerves)

Cellular components
Synthetic cells
1. Osteoblasts
2. Fibroblasts
3. Cementoblasts
Synthetic cells of PDLMonday, November 2, 2020 25

• Osteoblasts
1. Osteoblasts are the cells which
produce the matrix for new bone
formation.
2. Bone surface of PDL is largely lined by
osteoblasts. They may be in resting or
functional depending on the
functional state of PDL.
3. Number of osteoblasts decrease with
increase in age.
Structure
- Functional osteoblast is- plumpy,
irregularly cuboid with large nucleus
and the resting osteoblast is- flat.
Functions
- They provide matrix for new bone
formation.
Osteoblast

• Fibroblasts
Fibroblasts are the principle cells of PDL.
Phenotypically distinct and functionally
different sub-populations of fibroblasts exist
in PDL.
Structure
- Fibroblast is a stellate or spindle-shaped
cell.
Functions
1. It controls homeostasis of PDL.
2. Ingestion & degradation of foreign
bodies & cross-linked collagen.
3. Secretes collagenase enzyme which
regulates constitution and condition of
PDL.
4. Maintain PDL matrix by processing
proteins, collagen elastin &
glycosaminoglycans.
5. Helps in the eruption of teeth by their
contractile property (collagen traction
theory). FibroblastMonday, November 2, 2020 27

• Cementoblasts
Cementoblasts develop from
mesenchymal cells or fibroblasts and
align themselves along the external
border of dentin.
Structure
1.These cells have a centrally placed
nucleus and basophilic cytoplasm.
2. Cytoplasm contains many
mitochondria, golgi apparatus &
RER.
Functions
1. Cementocytes are the
connective tissue cell types
responsible for the formation of
cementum.
2. These cells aid in reattachment
Cementoblast of PDL fibers to
root by forming fresh cementum
whenever required. CementoblastMonday, November 2, 2020 28

Resorptive cells
• Osteoclasts
Osteoclasts are the cells which are responsible for bone
resorption.
Structure
1. These are the cells that resorb the bone & tend to be
large & multinucleated.
2. Osteoclasts are characterized by the presence of acid
phosphatase within its cytoplasmic vesicles and
vacuoles.
3. Acid phosphatase is an important constituent of
hydrolytic system of osteoclasts, take part in bone
resorption.
4. Cytoplasm contains numerous mitochondria, golgi
apparatus, RER, lysosome & free ribosomes.
5. The characteristic feature of osteoclasts are the
plasma membrane of the cell lying adjacent to the
bone that has been actively undergoing resorption is
raised in characteristic folds & is termed as ruffled or
striated border.
Functions
- Mitochondria produce citric acid which aids in
resorption of bone material.
Osteoclast

• Fibroblast
1. Exhibit lysosomes that contain fragments of collagen
that appear to be undergoing digestion.
2. They aid in remodeling of PDL.
3. The presence of these cells indicate resorption of
fibers occur during either disease or physiological
turnover or remodeling of PDL.
• Cementoclasts
1. Cementoclasts originate from hemopoietic tissue &
aids in resorption of cementum.
2. Resorption of cementum occurs in certain
circumstances and in these instances cementoclasts
are located in Howship’s lacunae.

Resorptive cells

Immune system cells
• Mast cells
1. These are relatively small, round
or oval cells having a diameter of
almost 12-15/um.
2. The cells contain numerous
cytoplasmic granules with small
or round nucleus.
3. The cytoplasmic granules contain
heparin & histamine. The
physiologic role of heparin in
mast cells does not appear to be
clear.
4. Mast cell histamine plays a role
in the inflammatory reaction &
they have been shown to
degranulate in response to
antigen-antibody formation on
their surface.
Mast cell histologyMonday, November 2, 2020 32

• Macrophages
- Macrophages are large, oval/
spindle shaped cells with a
darkly staining nucleus &
granular cytoplasm.
Functions
1. They participate in
inflammatory reaction.
2. They play a role in
immunological defense.
3. Engulf & digest dead cells,
foreign bodies & other
debris.
4. Secretes a growth factor
that regulates respiration
of adjacent fibroblasts.
Macrophage histology
Macrophage

1. These are the
totipotent cells,
capable of
differentiating into
odontoblasts,
fibroblasts or defense
cells depending upon
the nature of stimulus.
2. They appear as large
polyhedral cells with
large centric lightly
staining nucleus,
abundant cytoplasm &
peripheral cytoplasmic
extension.
Undifferentiated mesenchymal cells
Undifferentiated mesenchymal
cells

• Cell rests of Malassez
1. Clusters of epithelial cell
rests observed in PDL are
called as cell rests of
Malassez.
2. They are remnants of apical
extensions of HERS. They
appear as elongated
strands, duct like structures
or follicular aggregates.
Significance
- They proliferate and form
cysts (periapical cysts / lateral
root cysts) in PDL. Under
certain pathological conditions,
they undergo rapid
proliferation& can produce
variety of cysts & tumors that
are unique to jaw. Cell rests of MalassezMonday, November 2, 2020 35

EXTRACELLULAR COMPONENTS
Ground substance
1. Ground substance is
made up of
glycoprotein and
proteoglycans.
2. A special glycoprotein
called fibronectin is
seen in PDL and
attaches fibroblasts
and collagen.
3. It gives support to cells
of PDL and acts as
main transport
medium.Monday, November 2, 2020 36

Fibers of PDL
• PDL fibroblasts aids in the production of various
types of fibers as follows:
Mature fibers
- Collagen fibers
Immature fibers
1. Elastin fibers
2. Reticulin fibers
3. Oxytalan fibers
PDL fibersMonday, November 2, 2020 37

Elastin fibers
1. PDL does not contain mature
elastin but it contains two
immature forms, oxytalan &
eulanin.
2. It was found that they provide
elastic properties to PDL.
Oxytalan fibers
1. They are immature elastic fibers
found in human PDL.
2. They orient in an axial direction, &
at apex they form a complex
network.
3. Function of these fibers is
unknown; they may support the
blood vessels of PDL.
Reticular fibers
- Reticulate fibers are fine, immature
collagen fibers with a lattice like
arrangement.
Oxytalan fibers
Reticular fibers

Collagen fibers
1. Majority of fibers in PDL are
collagenous in nature. Collagen
fibers are inelastic and
undulated.
2. Most of the collagen fibers of PDL
are aggregated in bundles,
known as principle fiber group.
3. The principle fibers are
composed primarily of Type I
collagen whereas reticular fibers
are made up of Type III collagen.
Type IV collagen is seen in basal
lamina.
4. In PDL small collagen fibers
arranged in all direction, forming
a plexus have also been reported.
They are closely associated with
principle fibers & are termed as
indifferent fiber plexus.
Collagen fibers

PRINCIPAL FIBERS OF PDL
• The most important
elements of PDL are
principal fibers. These
fibers are collagenous in
nature & are arranged in
bundles. They follow a
wavy course.
• In addition to the
principal fiber groups,
PDL contains other well
formed fibers located
between the principal
fiber bundles. These
fibers are known as
secondary fibers of PDL.
Principal fiber groups in
periodontal ligamentMonday, November 2, 2020 40

Types of principal group fibers
The principal fibers of
periodontal ligament are
arranged in six groups
that develop sequentially
in the developing root.
1. Trans-septal group
2. Alveolar crest fibers
3. Horizontal group
fibers
4. Oblique fibers
5. Apical fibers
6. Inter-radicular fibers. Principal fiber groups in
periodontal ligamentMonday, November 2, 2020 41

Sharpey’s Fibers
• The terminal portion of these principle fibers that insert into
cementum & bone are termed as Sharpey’s fibers.
Sharpey’s fibersMonday, November 2, 2020 43

Intermediate plexus
1. Intermediate plexus was
described by Sicher in 1966.
2. Fibers arising from cementum
and bone are joined in the mid
region of PDL space giving rise to
a zone of distinct appearance in
light microscope is known as
intermediate plexus.
3. It was believed that intermediate
plexus provide a site where rapid
remodeling of fibers occur,
allowing adjustment in the
ligament to be made to
accommodate small movements
of the tooth.
4. However, evidence derived from
electron microscope provides no
support for this and was
believed to be an artifact.
Intermediate plexus

STRUCTURES PRESENT IN
CONNECTIVE TISSUE
Cementicles
1. Cementicles are
calcified masses
adherent to or
detached from the
root surface.
2. They may be
developed from
calcified epithelial
rests, calcified
Sharpey’s fibers and
calcified thrombosed
vessels within the
PDL.
Cementicles

Blood
vessels
Area of
supply
Dental artery Apical region of
PDL
Inter-radicular
artery
Middle &
coronal aspect
of PDL
Inter-dental
artery
Coronal portion
of PDL
Blood vessels
Periodontal ligament is supplied by branches derived
from three sources- dental, inter-radicular and inter-
dental arteries.
Periodontal blood supplyMonday, November 2, 2020 46

Lymphatics
• Lymphatic channels follow the paths of vessels &
nerves.
• They appear to originate as cull-de-sac in gingival and
palatal mucosa, spongy bone & tissues of PDL.
Lymph nodes draining PDL
1. Submandibular lymph nodes
2. Submental lymph nodes
3. Superficial cervical lymph
nodes
4. Deep cervical lymph nodes.

Nerves
1. All innervations of PDL are
mediated by dental
branches of alveolar nerves.
2. Nerve fibers are either of
large diameter or small
diameter.
3. Small fibers in fine branches
are concerned with pain.
4. Large fiber ends are
bulbous, club like or spindle
shaped & are concerned
with pressure.
Nerve supply of PDL

Nerve fibers Significance
Nociceptors Pain
Meissner’s corpuscles Tactile
Mechanoreceptors Pressure
Krause- type end bulbs Temperature
Nerve supply of PDL
Mechanoreceptors of PDLMonday, November 2, 2020 49

Neural termination
The nerve bundles are divided into single myelinated fibers, which later
on loose their myelin sheath & end in one of the 4 types of neural
termination.
1. Free nerve endings carry pain sensation.
2. Spindle like pressure & vibration endings are located mainly at apex.
3. Ruffini like mechanoreceptors carry pressure sensations located in
apical area.
4. Meissner’s corpuscles are also mechanoreceptors located primarily in
mid-root region.
Sensation Transmission
Pain Small diameter nerves
Temperature Intermediate type
Pressure Large diameter nerves
Neural terminations in PDL

FUNCTIONS OF PERIODONTAL
LIGAMENT.
PDL performs the
following functions:
1. Protective functions
2. Supportive functions
3. Sensory functions
4. Nutritive functions
5. Homeostatic
functions.

Protective functions
- PDL provides soft tissue ‘casing’ in order to
protect the vessels and nerves from injury due to
mechanical forces.
Supportive/ Tooth anchorage
1. Tooth anchorage is achieved by bundles of collagenous fibers
that attach radicular cementum to alveolar bone.
2. Collagenous fibers acts as cushion and attaches PDL to the
cementum.
3. Presence of numerous blood vessels provides hydraulic
mechanism for the support of tooth.
4. When tooth is moved in its socket as a result of forces during
mastication and orthodontic treatment, part of PDL space will be
narrowed and PDL will be compressed.
5. Compressed PDL provides support to loaded tooth and acts as a
cushion.

Sensory functions
1. PDL through its nerve supply provides most efficient
proprioceptive mechanism.
2. PDL is supplied by nerve fibers that can transmit
sensation of touch, pressure and pain to higher centres.
3. They detect most delicate force to tooth and they
detect slight displacement of tooth.
4. They follow the paths of vascular and lymphatic
channels and provide stimulation for muscular
components of blood vessel walls.
5. Pain sensation is transmitted by small diameter nerves,
temperature by intermediate type; pressure by large
myelinated fibers.
Nutritive functions
-PDL supplies nutrients to the cementum, bone &
gingiva by means of blood vessels & also provide
lymphatic drainage.Monday, November 2, 2020 53

Homeostatic functions
1. Homeostatic functions of PDL include fibrous tissue and calcified tissue
development and maintenance.
2. Cells of PDL have capacity to resorb and synthesize connective tissue of PDL,
cementum and alveolar bone.
3. Collagen of PDL has faster turnover of all connective tissues in the body.
4. Osteogenic layer of PDL lies adjacent to alveolar processes, helps in bone
formation.
5. Cementogenic layer of PDL lies adjacent to root participate in the formation of
cementum.
6. If PDL is destroyed, bone will form in PDL space and results in ankylosis between
bone and teeth.

PHYSICAL FUNCTIONS OF PDL
• The physical functions of PDL
are as follows:
1. PDL transmits occlusal forces
to the alveolar bone.
2. PDL provides resistance to
impact of occlusal forces.
3. PDL provide attachment of
teeth to the alveolar bone.
4. PDL maintains gingival tissues
in their proper relationship to
the teeth.
5. PDL provides soft tissue
casting to protect the vessels
and nerves from injury by
mechanical forces.

Formative & remodeling function
• The PDL is constantly undergoing remodeling. Old cells
& fibers are broken down and replaced by new ones, &
mitotic activity can be observed in the fibroblasts &
endothelial cells.
• Fibroblasts form the collagen fibers, and the residual
mesenchymal cells develop into osteoblasts and
cementoblasts.
Remodeling of
Periodontium

Resistance to the impact of occlusal
forces (Shock absorption)
• The proprioceptor nerve endings in the ligament form part of
the extremely refined neurological control of mastication,
and thus protect the ligament from damage.
• In addition, blood supply, ground substance and collagen
bundles all take part in the absorption of functional stresses
and their transmission to bone.

Transmission of occlusal forces to the
bone
• The arrangement of principle fibers is similar to that of a
suspension bridge or hammock.
• When an axial force is applied to the tooth, the root
displaces into the alveolus. The oblique fibers alter their
wavy, untensed pattern and assume their full length to
sustain the major part of the axial force.
• When a horizontal or tipping force is applied, two phases of
tooth movement occur. The first is within the PDL and
second produces a displacement of the facial and lingual
bony plates.
• The tooth rotates about an axis. The apical portion of the
tooth moves in a direction opposite to the coronal portion.

THEORIES OF TRANSMISSION OF
OCCLUSAL FORCES BY PDL.
Tooth support
by PDL
Tensional
theory
Visco-elastic
theory
Thixotropic
theory
Theories of tooth support by PDL.Monday, November 2, 2020 59

Tensional theory
Elastic deformation of socket.
Transmission of forces to alveolar bone
Unfolding of principal fibers
Application of force to the crown
Tensional theory of PDL.Monday, November 2, 2020 60

Tensional theory
• According to this theory, the principle fibers of
PDL play a major role in supporting the tooth
and transmitting forces to the bone.
• When the forces are applied to the tooth,
principle fibers unfold and straighten and then
transmit forces to alveolar bone, causing
elastic deformation of socket.

Visco-elastic theory
Replenishes tissue with fluids
Ballooning of vessels
Arterial back pressure
Stenosis of blood vessels
Absorption of shock & tighten by bundle fibers
Depletion of tissue fluids
Transfer of extra cellular fluid from PDL into marrow spaces
Application of force
Visco-elastic theory of PDL

• Visco-elastic theory based on the fact that, the
fluid movements largely control the displacement
of tooth, with fibers playing a secondary role.
• When the forces are transmitted to the tooth, the
extracellular fluid is pushed from PDL into the
marrow spaces through cribriform plate.
• After the depletion of tissue fluids, the bundle
fibers absorb the shock and tighten. This leads to
blood vessel stenosis, arterial back pressure,
ballooning of vessels, tissue replenishes with
fluids.
Visco-elastic theory

Thixotropic theory
• It describes the PDL to behave like a thixotropic
material. A thixotropic material is the one which
can undergo a gel/ sol/ gel transformation.
• This theory considers the PDL to be a collagenous
thixotropic gel and that fibers are only artifacts.
• This theory is very radical & completely changes
the perspective on the PDL & for now has not
been accepted.

CLINICAL SIGNIFICANCE.
1. The primary role of PDL is to support the tooth in its bony
socket.
2. The thickness of PDL varies from individual to individual & in
different teeth in same person.
3. Due to acute trauma & in accidental blows to PDL, many
pathological changes will be produced such as fracture or
resorption of cementum & alveolar bone.
4. A direct union between cementum & alveolar bone with
intervening PDL is called as ankylosis. It is also called
gomphosis when the PDL connects the root to the bone.
5. The orthodontic tooth movement depends on the
resorption & formation of both bone & PDL.
6. Localization of pain in a tooth is through the PDL. This is the
reason, a dentist ‘percuses’ a tooth.
7. In acute inflammation of PDL, the tooth is lifted in the socket
as exudate lifts the tooth in the socket.Monday, November 2, 2020 65

CONCLUSION
• Periodontal ligament is a fibrous connective tissue
forming important part of the periodontium.
• Without it tooth is support less.
• PDL is a physically small, but functionally important
tissue in tooth support, proprioception & regulation of
alveolar bone volume.
• PDL is an absolute requirement for rapid remodeling of
alveolar bone when forces are applied to the teeth.
• Cells of PDL are Pluri-potent & helps in regeneration of
all the components of periodontium lost in the
periodontal disease process.

References
• Newman & Carranza’s Clinical Periodontology-
(13th edition)
• Essentials of Clinical Periodontology &
Periodontics – (Shantipriya Reddy 3rd edition)
• Essentials of Periodontology – (Sahitya Reddy
S)
• Orban’s Oral Histology & Embryology – (4th
edition)

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