-Dr.Mary Joseph PERIODONTAL LIGAMENT

2.  Introduction
 Definition
 Shape
 Cellular and Extracellular components
 Principal fibers
 Functions
 Neurovascular supply and Lymphatic drainage
 Theories of tooth support
 Age changes
 Clinical considerations
 Science Transfer.

3.  The normal periodontium provides the
support necessary to maintain teeth in
function.
 It consists of three principal supporting
components: periodontal ligament,
cementum , and alveolar bone.

4.  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.

5.  The periodontal
ligament space has
the shape of an hour
glass and is narrowest
at the mid root level
axis of rotation.
 The width of the
periodontal ligament
is approximately 0.25
mm (range 0.2–0.4
mm)
 Progressive decrease
in thickness with age

6. ◦ ABP-Alveolar Bone Proper
◦ PL-Periodontal Ligament
◦ RC-Root Cementum

7.  Immediately after tooth erruption, fibroblasts
alligned obliquely along the long axis of the
tooth, form alveolar crestal fibers[at coronal
third]
 At first occlusal contact-horizontal group form
at coronal third.
 At defnite occlusion, maturation of oblique fiber
bundles occur.
 This later develops into the apical fiber group
with completion of root formation.
 Thus, the defnitive PDL architecture is
established.

8. Principal fibers of
the periodontal
ligament follow a
wavy course when
sectioned
longitudinally
y
ALV. BONE
PDL
PDL
ROOT
BONE

10. Formative cells Resorptive cells Progenitor cells
Epithelial cells
Immune system
cells
Cells associated
with neurovascular
elements

11. Fibers
Collagen
Principal group
Secondary group
Elastic
Oxytalan
Elaunin
Ground substance
Glycosamino glycans
Proteoglycans
Glycoproteins-fibronectin,laminin.
70%water

12.  Fibroblasts
 Osteoblasts
 Cementoblasts

13. • Fibroblasts
• Osteoclasts
• Cementoclasts

14.  Remanents of
Hertwig
Epithelial
Root Sheath

15.  1.PDL cells found close to cementum (Malassez
in 1884).
 2.Remanents of Hertwig’s epithelial root sheath.
 3. Abundant in furcation area and apical and
cervical area.
 4. Appear cluster-like ducts with cells separated
from surrounding connective tissue by basal
lamina.
 5. Cuboidal cells with prominent nuclei.
 6 .These cells may undergo calcification to
become CEMENTICLES.

16.  1. Undergo mitotic division when stimulated
by orthodontic movement or wounds.
 2. Located in vicinity of blood vessels.
 3. Capable of sustained renewal and tissue
regeneration; repair and differentiation.

17.  Neutrophils
 Lymphocytes
 Macrophages
 Mast cells
 Eosinophils

18. Synthesized by fibroblasts, osteoblasts,
odontoblasts.
 5µm diameter bundles form principle fibers .
 Subunits are called collagen fibrils have
transverse striations with periodicity of 64 nm.
 Mainly composed of type I-70% .
 Second most common type III-20%
 Type V and type VI- small amounts.
 Type IV maintains integrity and elasticity of
extracellular matrix
 both type IV and type VII associated with
epithelial rests and blood vessels.
 Type XII collagen occurs only when ligament is
fully functional.

20. Transseptal
Alveolar
crestal
Horizontal Oblique
Apical Interradicular

21.  Transseptal fibers extend interproximally
over the alveolar bone crest and are
embedded in the cementum of adjacent
teeth

22.  extend obliquely from cementum just
beneath junctional epithelium to alveolar
crest .
 run from cementum over alveolar crest
to fibrous layer of periosteum covering
alveolar bone.
 Prevents extrusion of tooth
 Resists lateral tooth movement

23.  Horizontal fibers extend at right angles to
the long axis of the tooth from cementum
to alveolar bone.
 Resists tipping forces.
 Prevents lateral movements

24.  largest group, extend from cementum in a
coronal direction obliquely to bone .
 bear brunt of vertical masticatory stresses
and transform them into tension on alveolar
bone.

25.  radiate in a irregular manner from
cementum to bone at apical region of
socket.
 do not occur on incompletely formed roots.
 Resists tipping forces and luxation.
 Protects blood vessels and nerves.

26.  fan out from cementum to tooth in
furcation areas of multirooted teeth.
 Resists tipping, torquing and luxation.

27.  Located between Principal fibers
 located coronoapically.
 Elastin fibers
Oxytalan
Elaunin
 Indifferent fiber plexus-small collagen fibers
associated with principal fibers

28. 1. Physical
2. Formative and Remodelling
3. Nutritional and Sensory
4. Regulation of periodontal ligament width

29.  The periodontal ligament supplies nutrients
to the cementum, bone, and gingiva by way
of the blood vessels and also provides
lymphatic drainage.

30. • blood supply derived from the inferior and superior alveolar arteries
to mandible and maxilla, and reaches periodontal ligament from
three sources
• apical vessels
• penetrating vessels from the alveolar bone
• anastomosing vessels from the gingiva
Blood supply of the periodontium

31.  The palatal gingiva of
maxilla drains to deep
cervical lymph nodes
 Except for third molars
and mandibular
incisors, all teeth with
their adjacent
periodontal tissues are
drain to submandibular
lymph nodes
 The third molars drain
to the jugulodigastric
lymph nodes and
mandibular incisors to
submental lymph nodes.

32.  Superior and Inferior
alveolar nerves-branches
of Trigeminal nerve.
 Nerves pass through the
apical foramen to enter
PDL
 Finer branches enter
middle and cervical
portions through alveolar
bone.
 They provide sense of
touch, pressure, pain and
proprioception during
mastication.

33.  adaptability to rapidly changing applied force
and capacity to maintain its width at constant
dimensions lifetime.
 ability of periodontal ligament cells to
synthesize and secrete a wide range of
regulatory molecules

34. Tensional theory
 force applied to crown cause principal
fibres first unfold and straighten and then
transmit forces to the alveolar bone →an
elastic deformation of bony socket.

35. Visco elastic theory
Proposed by Bien.S.M.,1966 and Birn.H.1966.
displacement of the tooth is largely controlled
by fluid movements with fibres have only a
secondary role.
forces →extracellular fluid passes from pdl into
marrow spaces of bone through foramina in
cribriform plate→fibre bundles absorb shock
and tighten→blood vessel stenosis .
Arterial back pressure causes ballooning of
vessels and passage of blood ultra filtrate into
tissues replenishing tissue fluids.

36. Thixotrophic theory
Pdl behaves like a thixotrophic material -
a collagenous gel and that fibres are only
artefacts.

37. Age changes in Periodontal ligament
• With aging activity of PDL tissue decreases→
restricted diets and therefore normal functional
stimulation of tissue is diminished.
• In non functional teeth PDL width starts to
decrease.
• loss of gingival height related to gingival and
periodontal disease promotes destructive changes
in PDL.

38.  primary role support the tooth in the bony socket.
 thickness varies .
 thinnest in middle region of root →fulcrum of
physiological movement.
 thin in functionless and embedded teeth
 wide in teeth under excessive occlussal stresses.

39.  The supporting tissues of a tooth long out of function
require time to become adapted to new functional demands
.
 In acute trauma, accidental blows, rapid mechanical
seperations may produce fractures or resorption of
cementum, tears of fibre bundles, haemorrhage, and
necrosis →adjacent alveolar bone is resorbed, periodontal
ligament is widened and tooth becomes loose.

40.  In orthodontic tooth movement within physiological limits
◦ initial compression on pressure side is compensated by bone
resorption,
◦ on tension side bone apposition occurs,
◦ large forces results in necrosis of periodontal ligament and
alveolar bone.
 The periodontal ligament in periapical area is often site of
periapical granuloma which proliferates to produce a cyst-
common pathological lesion.

41.  The commonest pathology is chronic inflammatory
periodontal disease. The toxins released from bacteria in
dental plaque and metabolites of the host’s defence
mechanism destroy the PDL and adjacent bone leading to
tooth mobility and loss.
 Surgical techniques like Guided Tissue Regeneration are
being used for correction for PDL destruction.
 More recently tissue engineering principles used with
biological principles like gene therapy, use of bio-
compatible scaffolds (with growth factors) offer an
alternative to existing therapy.

42.  The use of progenitors cells or the mesenchymal stem
cells to regenerate the PDL is being thought of by the
activation of the mesenchymal stem cells towards
terminal differentiation, tissue repair and degeneration.

44. References
1. CARANZA’S CLINICAL PERIODONTOLOGY 11th EDITION
2. CLINICAL PERIODONTOLOGY AND IMPLANT DENTISTRY 5TH EDITION ,
JAN LINDHE
3. Orban’s Oral Histology And Embryology 12th edition
4. William Giannobile ,Pamela Robey Periodontal Disease: Engineering the
Future of Care (National Institute for Craniofacial Research).
5. Dangaria SJ, Ito Y, Luan X, Diekwisch TG. Stem Cells Dev. Successful
Periodontal Ligament Regeneration by Periodontal Progenitor
Preseeding on Natural Tooth Root Surfaces.2011 Oct;20(10):1659-68.
doi: 10.1089/scd.2010.0431. Epub 2011 Mar 9.
6. J Han,D Menicanin,S Gronthos,PM Bartold Stem cells, tissue
engineering and periodontal regenerationJun;59 Suppl . 2011 Oct;
20(10): 1659–1668. Aust Dent J. 2014