Components of periodontal ligament.pptx
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The periodontal ligament is a complex connective tissue that surrounds the tooth root and attaches the tooth to the alveolar bone. It is composed of collagen fibers, ground substance, blood vessels, nerves and cells. The principal collagen fibers resist various forces on the tooth and help transmit these forces to the bone. The periodontal ligament provides nutrition to surrounding structures, allows for remodeling and repair, and has proprioceptive functions through its nerve endings.
Components of periodontal ligament.pptx
- 3. PERIODONTIUM Cementum Periodontal ligament Alveolar bone Apical foramen Pulp cavity Enamel Dentin Gingiva Root canal Alveolar vessels & nerves
- 4. DEFINITION Periodontal ligament is composed of soft complex vascular and highly cellular connective tissue that surrounds the tooth roots and connects it to the inner wall of the alveolar bone.
- 5. Other terms which were previously used for periodontal ligament are:- 1. Desmondont 2. Gomphosis 3. Pericementum 4. Dental Periosteum 5. Alveolodental ligament 6. Periodontal membrane
- 6. STRUCTURE In the coronal direction it is continuous with lamina propria of gingiva & is demarcated by the alveolar crest fibers. PDL has the shape of an hour glass and is narrowest at the mid root level. It ranges in width from 0.15-0.38mm.-beertsen etal 1997
- 7. RADIOGRAPHICAPPEARANCE The interdental septum normally present as a thin radiopaque border that is adjacent to the PDL & at alveolar crest is termed as Lamina dura. Radiographic evaluation of bone changes in periodontal disease is mainly based on its appearance. Discontinuity of lamina dura indicates pathological changes.
- 8. DEVELOPMENT
- 9. cells COMPONENTS The periodontal ligament is formed of : Fibers Extracellular substances Synthetic Resorptive Progenitor Defensive Ground substances Blood Vessels, Nerves & Lymphatics. ECRM
- 13. EPITHELIALCELLRESTS OF MALASSEZ These cells are the remnants of the epithelium of Hertwigs Epithelial Root Sheath and are found close to cementum. These cells exhibit monofilaments and are attached to each other by desmosomes. The epithelia cells are isolated from connective tissue by a basal lamina. 13
- 14. cells COMPONENTS The periodontal ligament is formed of : Fibers Extracellular substances Synthetic Resorptive Progenitor Defensive Ground substances Blood Vessels, Nerves & Lymphatics. ECRM
- 15. FIBERS Principal fibers Elastic-oxytalan Indifferent fiber plexus
- 16. COLLAGEN Synthesized by fibroblasts, chondroblasts, osteoblasts & other cells Contain 2 unique amino acid hydroxy proline and hydroxy lysine along with glycine & proline (Carneiro J, Fava de Moraes F , 1955) The amount of collagen in a tissue is determined by its hydroxy proline content. There are at least 19 recognized collagen species encoded by at least 25 separate genes, dispersed among 12 chromosomes (Embery et al 2000) Collagen classes a. Principal fibers ---- Type I b. Basement membrane ---- Type IV c. Reticular fibers ---- Type III d. Tooth development ---- Type XII
- 17. PRINCIPAL FIBERS OF PDL Alveolar crest group Horizontal Oblique Apical Transeptal Inter radicular
- 18. Alveolar crest group: radiate from the cementum over the alveolar crest & to the fibrous layer of periosteum covering the alveolar bone. Function prevents extrusion of the tooth & resist lateral tooth movement Horizontal group: The fiber bundles run from the cementum to the bone at right angle to the long axis of the tooth. Function - resists horizontal and tipping forces Bone Dentin
- 19. Oblique group: The fiber bundles run obliquely. Their attachment in the bone is somewhat coronal than the attachment in the cementum. The greatest number of fiber bundles are found in this group. Function Resists vertical and intrusive forces bone dentin
- 20. Apical group The bundles radiate from the apical region of the root to the surrounding bone Function resists vertical force Interradicular group The bundles radiate from the interradicular septum to the furcation of the multirooted tooth. Function resists vertical and lateral forces. Transeptal fibers It extends interproximally Reconstructed even after destruction of bone due to periodontal disease dentin bone dentin bone
- 21. ELASTIN FIBERS PDL fibers do not contain mature elastin but two immature forms are found oxytalan and eulanin Run in apico-coronal direction to bend and attach at cervical third of root (Fulmer et al. 1974) Function - regulate vascular flow - play a role in tooth support - guides cell migration
- 22. GROUND SUBSTANCE Fills the space between the fibers and cells Composition Consists of a biochemically complex, highly hydrated, semisolid gel. Water content of 70% Glycosaminoglycan's hyaluronic acid, proteoglycans( versican , decorin ) Glycoproteins -- fibronectin , laminin , vibronectin , tenascin cementicles
- 23. FUNCTIONS PHYSICAL FORMATIVE AND REMODELING NUTRITIVE SENSORY PDL HOMEOSTASIS
- 24. PHYSICAL 1. Provision for 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 teeth to bone. 4. Maintenance of gingival tissues in their proper relationship to the teeth. 5. Resistance to impact of occlusal forces SHOCK ABSORPTION : Tensional theory & Viscoelastic theory
- 27. TRANSMISSION OF OCCLUSAL FORCES TO BONE Arrangement is like suspension bridge or hammock. Axial force The oblique fibers alter their wavy pattern and attain full length,sustain the major part of the axial force Horizontal force: Confines within pdl displacement Axis of rotation Single rooted tooth at junction of middle and apical 3rd of the root. Multirooted tooth in the bone between the roots below furcation.
- 28. 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
- 30. FORMATIVEAND REMODELING Cells have the capacity to resorb & synthesize the extracellular substance of the CT ligament, alveolar bone & cementum. Participate in physiologic tooth movement & in repair of injuries. PDL is constantly undergoing remodeling old cells and fibers are broken down and replaced by new ones. Radio autographic studies indicate a very high turnover rate of collagen in PDL. A rapid turnover of sulfated GAGs in the cells and amorphous ground substances also occur. Sodek (1977), Muhlemann; 1954)
- 31. NUTRITIVE PDL supplies nutrients to the cementum , bone, and gingiva by way of blood vessels and provides lymphatic drainage. Rich vascular plexus at apex & in the cervical part of the ligament Rich network of arcades are more evident in the PDL space adjacent to the bone than to cementum
- 32. SENSORY Periodontal ligament provides the most efficient proprioceptive mechanism 4 types of neural terminations are seen 1. Free nerve endings -pain 2. Ruffini like mechanoreceptors (apical area) 3. Meissners corpuscles - mechanoreceptors (middle 3rd) 4. Spindle like pressure and vibration endings (apex)
- 33. BLOOD SUPPLY Main blood supply is from superior and inferior alveolar arteries. The blood vessels are derived from the following:
- 34. NERVE SUPPLY Nerves found in ligament pass through foramina in alveolar bone. The nerves are the branches of second and third division of fifth cranial nerve (trigeminal nerve) and follow same path as blood vessels. These nerve fibers provide sense of touch, pressure, pain and proprioception during mastication.
- 36. Replantation, transplantation Orthodontic tooth movement trauma from occlusion Regeneration
- 37. PICK UP THE ODD ONE OUT Cementum, bone, gingiva, pulp, periodontal ligament Apical fibers, horizontal fibers, circular fibers,oblique fi Fibroblast, osteoblast, osteoclast, ameloblast Physical, chemical, nutritive, sensory,
- 38. WHO AM I I am the largest group of fibers I resist extrusion of tooth I have 19 family members I connect cell and cell, cell and matrix I am present between mid third & apical third of root