003.biology of periodontal tissues

periodontology

1. Biology of Periodontal Tissues DR Syed Jaffar raza Lecturer Periodontology

2.   Periodontium is the functional unit of tissues supporting the tooth including gingiva Periodontal ligament Cementum Alveolar process.   The tooth and periodontium are together called as the dentoperiodontal unit

3. The Gingiva Macroscopic Features The gingiva is that part of the oral mucosa (masticatory mucosa) that covers the alveolar process of the jaws and surrounds the necks of the teeth. Anatomically, the gingival is divided into marginal Attached interdental gingival

4. Gingival Sulcus It is defined as the space or shallow crevice between the tooth and the free gingiva, which extends apical to the junctional epithelium. It is V-shaped and barely permits the entrance of a periodontal probe. Under normal or ideal conditions it is about 0 mm (seen only in germ free animals). The so-called probing depth of a clinically-normal gingival sulcus in humans is 2 to 3 mm

5. Col valley-like depression that connects the facial and lingual papilla. The lateral borders and tips of the interdental papilla are formed by continuation of marginal gingiva and the intervening portion by the attached gingiva.   In the presence of diastema the interdental papilla will be absent

6. Oral sulcular epithelium : The soft tissue wall of the gingival sulcus is lined coronally with sulcular epithelium, extending from the gingival margin to the junctional epithelium.   Junctional epithelium : Denotes the tissue that joins to the tooth on one side and to the oral sulcular epithelium and connective tissue on the other. It forms the base of the sulcus . Thickness varies from three or four layers in early life and increases with age up to 15 to 20 layers at the base of the gingival sulcus, and only 1 or 2 cells at the most apical portion.

7. The length of the junctional epithelium ranges from 0.25 to 1.35 mm Three zones in junctional epithelium have been described, apical coronal middle   Apical is for germination , middle is for adhesion and coronal is permeable .

8. Supra-alveolar Connective Tissue The connective tissue supporting the oral epithelium is termed as the lamina propria and for descriptive purpose it can be divided into two layers: a. The superficial papillary layer —associated with the epithelial ridges. b. Deeper reticular layer —that lies between the papillary layer and the underlying structures

9. The lamina propria consists of cells, fibers, blood vessels embedded in amorphous ground substances. I. Cells : Different types of cells present are: a. Fibroblast b. Mast cells c. Macrophages d. Inflammatory cells. II. Fibers : The connective tissue fibers are produced by fibroblasts and can be divided into: a. Collagen fibers b. Reticulin fibers c. Oxytalan fibers d. Elastin fibers

10. Gingival Fibers The principal group fibers are: 1. Dentogingival fibers : They project from the cementum in a fan-like conformation towards the crest and outer surface of the marginal gingiva. They provide support to the gingiva by attaching it to the tooth. 2. Alveolar gingival fibers : They extend from the periosteum of the alveolar crest coronally into the lamina propria . Their function is to attach the gingiva to the alveolar bone. 3. Dentoperiosteal fibers : They arise from the cementum near the cementoenamel junction and insert into the periosteum of the alveolar bone and protect the periodontal ligament. 4. Circular fibers : They surround the tooth in a cuff or ring like fashion and course through the connective tissue of the marginal and attached gingiva.

11. 5. Trans-septal fibers : They are located interproximally , they extend from cementum of one tooth to the cementum of the neighboring tooth. Their function is to protect the interproximal bone and maintain tooth-to tooth contact.

12. Fibers of the secondary group 1. Periosteogingival fibers : They extend from the periosteum of the alveolar bone to the attached gingiva. They help to attach the gingiva to the alveolar bone. 2. Interpapillary fibers : They are seen in the interdental gingiva extending in a faciolingual direction and support the gingival papilla. 3. Transgingival fibers : These are seen in and around the teeth with in the attached gingiva. They maintain the alignment of teeth in the arch.

13. 4. Intercircular fibers : They extend from the cementum on distal surface of a tooth splaying buccally and lingually around the next tooth and are inserted on the mesial surface. 5. Intergingival fibers : They are seen within the attached gingiva adjacent to the basement membrane extending mesiodistally . They provide support and contour for the attached gingiva. 6. Semicircular fibers : They extend from the mesial surface of a tooth to the distal surface of same tooth in a half circle.

14.   7. Oxytalan fibers : They are present in all connective tissue structures of the periodontium. The function of these fibers is yet unknown . 8. Elastin fibers : Elastin fibers are only present in connective tissue of the gingiva and periodontal ligament. They are also seen in the connective tissue of alveolar mucosa in large numbers.

15. Blood Supply, Lymphatics and Nerves Three major sources of blood supply to the gingival has been described: 1. Supraperiosteal arterioles: Overlying the alveolar bone along the facial and lingual surfaces, sends branches to the surrounding tissue .   2. Vessels of the periodontal ligament: They extend into the gingiva and anastamose with the capillaries in the sulcus area. 3. Arterioles emerging from the crest of the interdental septa.

16. lymphatic drainage of periodontium. Mandibular incisors region drains into - Submental lymph nodes Buccal gingiva of maxilla, - Submandibular Buccal and lingual gingiva of mandibular premolar and molar region by Submandibular lymph nodes Third molar region – Jugulodigastric lymph nodes.