Dr.Jaffar Raza Syed Page 1

Periodontal Ligament

width of periodontal ligament 0.15 to 0.38 mm

shape Hour-glass shape: Periodontal ligament is thinnest at the axis of

rotation in the middle and widens coronally and apically

constituents of periodontal ligament space

A. Periodontal ligament fibres

B. Cellular elements

C. Ground substances

(i) Glycosaminoglycans

(ii) Glycoproteins.

Dr.Jaffar Raza Syed

Principal Fibres of

1. Transseptal group

Functions:

(i) Reconstructed even after destruction of the

alveolar bone has occurred in the periodontal disease.

(ii) Responsible for returning teeth to their

original state after orthodontic therapy.

Position:

They may be considered

gingiva because they do not have osseous

attachment.

Principal Fibres of periodontal ligament fibres.

(i) Reconstructed even after destruction of the

occurred in the periodontal disease.

(ii) Responsible for returning teeth to their

orthodontic therapy.

may be considered to belong to the

gingiva because they do not have osseous

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Dr.Jaffar Raza Syed

2. Alveolar crest group

Functions:

(i) Prevent extrusion

(ii) Prevent lateral tooth movements

Position:

Extends obliquely from the cementum

just beneath the junctional epithelium

to the alveolar crest.

3. Horizontal group

Position:

Extends at right angles to the long axis

of the tooth from cementum to alveolar bone.

(ii) Prevent lateral tooth movements

om the cementum

junctional epithelium

Extends at right angles to the long axis

cementum to alveolar bone.

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Dr.Jaffar Raza Syed

4. Oblique group

Functions:

(i) Bear vertical masticatory stress

(ii) Transform vertical stress into tension

on the alveolar bone.

Position:

Extends from the cementum in a coronal

Direction obliquely to the bone.

(i) Bear vertical masticatory stresses

(ii) Transform vertical stress into tension

cementum in a coronal

to the bone.

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Dr.Jaffar Raza Syed Page 5

5. Apical group

Functions:

(i) Prevents tooth tipping

(ii) Resists luxation

(iii) Protects neurovascular supply to the tooth.

Position:

It radiates in irregular fashion

from cementum to bone at apical

region of socket.

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6. Interradicular group

Functions:

(i) Prevents luxation

(ii) Prevents tooth tipping and torquing.

Position:

Found only between roots of multirooted tooth running from

cementum into bone, forming crest of interradicular septum

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various cells of periodontal ligament

(i) Connective tissue cells:

(a) Synthetic cells

• Osteoblasts

• Fibroblasts

• Cementoblasts

(b) Resorptive cells

• Osteoclasts

• Fibroblasts

• Cementoclasts

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(ii) Epithelial cells: Epithelial rests of malassez

(iii) Immune system cells:

(a) Neutrophils

(b) Lymphocytes

(c) Macrophages

(d) Mast cells

(e) Eosinophils

(iv) Cells associated with neurovascular elements

(v) Progenitor cells.

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Blood supply of periodontal ligament.

The blood supply is derived from the inferior and superior alveolar

arteries and reaches the periodontal ligament from 3 sources:

(i) Apical vessels

(ii) Penetrating vessels from the alveolar bone

(iii) Anastomosing vessels from the gingival

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Functions Of Periodontal Ligament

(i) Supportive:

• Attaches the teeth to the bone.

• Transmit occlusal forces to the bone.

• Maintain gingival tissues in their proper relationship to the teeth.

• Resist the impact of occlusal forces acting as a shock absorber.

• Protect the blood vessels and nerves from injury by mechanical

forces.

(ii) Sensory: Capable of transmitting

• Tactile

• Pressure

• Pain sensations by trigeminal pathways.

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(iii) Nutritive: Supply nutrients to

• Cementum

• Bone

• Gingiva through blood vessels and lymphatics.

(iv) Homeostatic/formative: Helps in the formation and resorption of

• Cementum

• Bone during physiologic tooth movement and repair of injuries.