Periodontal Ligament PDF

PERIODONTAL LIGAMENT MALINAO, DMD  DEFINITION AND LOCATION Soft connective tissue that surrounds the root of a tooth occupying the space between the root of a tooth and the walls of the alveolar bone and that of gingiva Acts as suspensory ligament for the tooth ...

PERIODONTAL LIGAMENT MALINAO, DMD  DEFINITION AND LOCATION Soft connective tissue that surrounds the root of a tooth occupying the space between the root of a tooth and the walls of the alveolar bone and that of gingiva Acts as suspensory ligament for the tooth  FUNCTIONS 1. Supportive function (suspension and securance) - sustain the tooth against the forces of occlusion and mastication 2. Homeostatic function (formative or developmental resorptive functions) - cells of the PDL have the capacity to synthesize and resorb the extracellular substance of the connective tissue of the ligament, alveolar bone, and cementum 3. Nutritive function - blood transport nutrients and other substances and bring waste and other products away from the periodontal tissues 4. Sensory (innervation)  STRUCTURAL ELEMENTS I. Extracellular substance (collagen and oxytalan fibers) A. Fibrous elements a. Interstitial or indefinite fibers b. Principal fibers 1. Free gingival ligament 2. Transseptal or interdental ligament 3. Alveolo-dental ligament a. Alveolar crest group b. Horizontal group c. Oblique group d. Apical group e. Interradicular group B. Ground substance a. Proteoglycans b. Glycoproteins  STRUCTURAL ELEMENTS II. Cellular Elements III. Blood vessels A. Synthetic cells Sources of blood supply a. Fibroblast A. Branch from dental artery b. Cementoblast B. Branch of interdental artery B. Resorptive cells a. Osteoclasts C. Branch from interradicular artery b. Fibroclasts c. Cementoclasts IV. Nerves C. Progenitor cells Form of nerve endings a. Undifferentiated cells A. Knob-like swellings D. Epithelial cells B. Loop or rings a. Epithelial rest of Malassez C. Free nerve endings E. Other types of connective tissue cells a. Mast cells b. Macrophages V. Lymphatic vessels  FIBROUS ELEMENTS 1. Reticular fibers – limited to capillaries 2. Elastic fibers – limited to bigger arterioles and big arteries 3. Oxytalan fibers – normally present in the PDL but these fibers do not span from cementum to bone 4. Collagen fibers – collagen is a high molecular weight protein to which a small number of sugar is attached  PRINCIPAL FIBER BUNDLES 1. Free gingival ligament – group of fibers running from cementum at the neck of the tooth to the connective tissue supporting the gingival epithelium 2. Transseptal or interdental fibers – group of fibers attached from the cementum of the mesial of one tooth to the cementum on the distal of the adjacent tooth 3. Alveolar crest group – fibers attach from cementum at the neck to the crest of the alveolar bone 4. Horizontal group – fibers running horizontally from cementum to the alveolar bone 5. Oblique group – fibers running from cementum to the alveolar bone in coronal direction 6. Apical group – fibers attached from cementum of the root apex to the wall of the fundus of the alveolus 7. Interradicular group – found in between roots of multirooted tooth  SUMMARY OF ATTACHEMNT AND FUNCTIONS OF PRINCIPAL GROUPS PRINCIPLE FIBER PROXIMAL DISTAL ATTACHMENT FUNCTION ATTACHEMENT GINGIVAL LIGAMENT CEMENTUM GINGIVA (CONNECTIVE HOLDS VESTIBULAR AND (CERVICAL) TISSUE) ORAL GINGIVA FIRMLY ATTACHED TO THE TOOTH SURFACE TRANSSEPTAL CEMENTUM CEMEMENTUM SUPPORT INTERPROXIMAL LIGAMENT (ADJOINING TEETH) GINGIVA. MAINTAIN MESIO- DISTAL RELATIONSHIP OF TEETH ALVEIOLAR CREST CEMENTUM ALVEOLAR BONE ANCHOR TOOTH TO ALVEOLUS GROUP (CREST) AND OPPOSE LATERAL STRESS  SUMMARY OF ATTACHEMNT AND FUNCTIONS OF PRINCIPAL GROUPS PRINCIPLE FIBER PROXIMAL DISTAL ATTACHMENT FUNCTION ATTACHMENT HORIZONTAL CEMENTUM ALVEOLAR BONE RESIST TOOTH GROUP (OCCLUSAL 3RD) DISPLACEMENT BY LATERAL PRESSURE OBLIQUE GROUP CEMENTUM ALVEOLAR BONE SUSTAIN OCCLUSAL STRESS; (APICAL 2/3RDS) SUSPEND AND ANCHOR TOOTH SOCKET APICAL GROUP CEMENTUM ALVEOLAR BONE PREVENT VESTIBULO-ORAL (FUNDUS) TIPPING INTERRADICULAR CEMENTUM INTERRADICULAR RESIST TIPPING AND GROUP SEPTUM (CREST) TORQUE  CELLULAR ELEMENTS A. SYNTHETIC CELLS FIBROBLAST – long slender-shaped cells with a large oval nuclei and granular cytoplasm, found everywhere CEMENTOBLASTS – flat cells with flat nuclei found on the surface of cementum OSTEOBLASTS – cells for bone formation found on the surface of the bone  CELLULAR ELEMENTS B. RESOPRTIVE CELLS OSTEOCLASTS – found on the surface of the bone usually along the shallow depressions FIBROCLASTS – recent evidence shows that collagen fibrils of PDL cane be resorbed under physiologic conditions by mononuclear cells resembling fibroblast CEMENTOCLASTS – used to identify a mononuclear cell or multinuclear cell that resorbs the cementum or root portion C. PROGENITOR CELLS UNDIFFERENTIATED CELLS  CELLULAR ELEMENTS D. EPITHELIAL CELLS EPITHELIAL REST OF MALASSEZ – groups, cord, or rows of cells surrounded by a delicate membrane (basal lamina) found near and parallel to the root surface E. OTHER CELLS MAST CELLS – large cells with centrally located round nuclei found abundant in connective tissue usually near small blood vessels MACROPHAGES – scavenger cells of the body chiefly concerned with ingesting and digesting dead cells, foreign bodies, and other debris  BLOOD VESSELS, NERVES, & LYMPHATIC VESSELS The vascular supply of the periodontal ligament is abundant. The afferent arteries come from 3 sources 1. BRANCH FROM DENTAL ARTERY 2. BRANCHES FROM INTERDENTAL OR INTERALVEOLAR ARTERIES 3. BRANCHES FROM INTERRADICULAR ARTERY The nerves of the periodontal ligament follow the path of the blood vessels and come from dental, interdental, and interradicular nerves. The lymphatic capillaries follow the course of veins. The flow of lymph follows the venous flow  DEVELOPMENT OF PERIODONTAL LIGAMENT PDL was derived from dental sac This consists of thick layer of cells termed as dental follicle Inner loose layer or cemental fibers – seen partly inserted into the developing cementum Outer layer or alveolar fiber – partly inserted into the forming alveolar bone During tooth eruption, the 3 groups form a lattice or plexus (intermediate plexus), which later rearrange into functional groups called principal fibers, as the tooth emerges out