Development of periodontium. periodontics

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this ppt describes about the developmental aspect of periodontal ligament gingiva cementum and alveolar bone

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  • succedaneous tooth moves into the vacated area,new alveolar bone deposited around the erupting succedaneous tooth
  • The role of underlying connective tissue in maintaining these phenotypes is important. JE can reappear despite its complete excision during periodontal surgery indicates that factors other than a tissue's embryonal genesis are important for its appearance
  • relative lack of proliferation of the epithelial cell rests of Mallassez.
  • Development of periodontium. periodontics

    1. 1. INTRODUCTION
    2. 2. Dr. Guru Ram Tej. K (P.G.) Dept. of Periodontics & Implantology Mamata Dental College
    3. 3. CONTENTS Overview of tooth development.  Neural crest development.  Development of cementum.  Development of periodontal ligament.  Development of alveolar bone.  Development of gingiva.  Conclusion  References 
    4. 4. DEVELOPMENT Development is the progressive evolution of a tissue and usually refers to an increase in its complexity and specialization Complex biologic processes  Epithelial mesenchymal interactions  Morphogenesis  Mineralization
    5. 5. Neural crest development  Dental structures (dentin and cementum,) and their supporting tissues (periodontal ligament and alveolar bone) are produced by cells originating in the neural crest. Enamel from the ectodermal cells.  By about 8 days  By 27th day  During the first 3 weeks  By the third week
    6. 6. Neural crest development  During the next few weeks, the ectoderm thickens and forms raised margins- neural folds  The neural tube  Neural crest cells
    7. 7. Primary epithelial band  After 37 days  Continuous band of thickened epithelium PEB Dental lamina Vestibular lamina
    8. 8. Dental lamina  During the 6th week of embryogenesis, tooth development begins with a thickening of the oral epithelium lining the future dental arches to form the dental lamina  Fate  Vestibular lamina
    9. 9. Tooth Development Although tooth development is a continuous process, the developmental history includes several morphologic stages including the  GROWTH  CALCIFICATION  ERUPTION  ATTRITION
    10. 10. Bud stage   The bud stage of tooth development is the stage at which portions of the epithelium in the dental lamina first begin to aggregate and form an invagination underlying connective tissue. At 8th week
    11. 11. Cap stage  Proliferate forming a parabolic- cap like structure 9th -10th week.  Ectomesenchymal cells begin to proliferate under the dental papilla (ultimately give rise to the dentin and dental pulp)
    12. 12. Bell stage.  Bell-shaped appearance at 12th week.  The outer enamel epithelium  The inner enamel epithelium  The stratum intermedium  The stellate reticulum
    13. 13. Hertwig's epithelial root sheath  Separates the cells comprising the dental papilla and dental follicle.  Cells of the inner enamel epithelium induce adjacent cells in the dental papilla to differentiate into odontoblasts and subsequently deposit the root dentin.
    14. 14. Cementogenesis  Pre functional development  Functional development
    15. 15. HERS
    16. 16. Development of cementum Development cells at site of development Disruption of HERS Cell-cell: Cell-matrix interactions: growth factors/ cytokines Reorganization of cells Migration/attachment/orientation Proliferation factors Progenitor Cells Differentiation factors Cementum
    17. 17. Initial cementum formation  The first increment of cementum forms against the root dentin surface. Epithelial cell rests of Malassez (remnants of the rootsheath) can be seen within the follicular tissue.
    18. 18. Cementum Forming Cells The cells responsible for cementum formation may be  Cementoblasts,  Cementocytes, or  Fibroblasts -located within the periodontal ligament- origin in the dental follicle.
    19. 19. TYPES OF CEMENTUM  Acellular afibrillar cementum  Acellular extrinsic fiber cementum (AEFC)  Cellular mixed fiber cementum  Cellular intrinsic fiber cementum (CIFC)  Intermediate cementum
    20. 20. Periodontal Ligament Development Periodontal ligament fibroblasts origins in the dental follicle and begin to differentiate during root development (Ten Cate et al 1971).
    21. 21. Orientation Of The Early Periodontal Ligament
    22. 22. Intermediate Plexus  Fiber insertion occurs along the lining of the bony socket wall.  Root surface-derived and bone-derived fibers ultimately coalesce in the middle third of the ligament space to form the intermediate plexus.
    23. 23. Schematic representation of the sequential organization of the periodontal ligament fibers in developing marmoset teeth. G,free gingival fibers; A, alveolar crest fibers; H, horizontal fibers;0, oblique fibers. (From: Levy BM, Bernick )
    24. 24. Development of oxytalan fibres and the ground substance Fullmer et al.
    25. 25. The alveolar bone  Formed during root development  OSTEOBLASTS  Development is independent of other portions of the alveolar process
    26. 26.  Succedaneous tooth germs are located within the same osseous cavity as their deciduous precursors  During the eruption of a succedaneous tooth: resorption of  the walls of the bony crypt,  the roots of the superficial primary tooth,  and the alveolar bone housing the primary tooth.  With the loss of the primary tooth  With the emergence of succedaneous teeth  complete deposition of new alveolar bone  significant remodeling of the whole alveolar process
    27. 27. Development of Gingiva  Composed of a superficial epithelium of ectodermal origin and an underlying connective tissue of mesodermal origin. (Listgarten 1972; Mackenzie 1988).
    28. 28. Epithelial Attachment
    29. 29. Formation of Gingival Sulcus Begins to form as the tooth erupts,  A separation occurs between the attached epithelium and the tooth surface.  Epithelial cells derived from stratum intermedium also begin to form into cells with the appearance of junctional epithelium. 
    30. 30. Modalities of tooth-tissue interface Gingival tissues (both epithelial and connective tissue) associate with the tooth via separate mechanisms.  Epithelial tissues   via an epithelial attachment called the junctional epithelium  in health, is usually located at, or coronal to, the CEJ  Gingival tissues  attach to the root surface at or below the CE]  via fiber insertion into the cementum of the root source.
    31. 31. Summary
    32. 32. EPITHELIAL - MESENCHYMAL TISSUE INTERACTIONS
    33. 33. Role of Epithelial-Mesenchymal Tissue Interactions in Maintaining Tissue Phenotype  Junctional epithelium is initially derived from the reduced enamel epithelium,  Gingival epithelium originates from the ectodermal tissues covering the maxillary and mandibular arches.  Two tissues considered to have  distinct origins, phenotypes, and function.
    34. 34. Controlling Influence Of Connective Tissue Substrate On Epithelial Phenotype Connective tissues are considered to play in important role in regulating the adjacent epithelial phenotype.  If components of palatal and buccal mucosa are cross-grafted, the pattern of epithelial differentiation is controlled by the underlying connective tissue (Ten Cate 1994). 
    35. 35.  The connective tissue of the gingival tissues does permit epithelial growth and proliferation  Periodontal ligament connective tissue suggested to be non permissive for epithelial growth and differentiation (Mackenzie 1988, 1990).  explains the inability of junctional epithelium to extend apically beyond its periodontal connective tissue interface with the tooth,
    36. 36. Conclusion Knowledge about the development of these tissues is important since it will help us understand better the mechanisms required for inducing repair and regeneration of damaged tissues.
    37. 37. References       Carranza, Newman, Takei, Klokkevold: carranza’s clinical periodontology, 10th Ed. Pg53, Elsevier Inderbir Singh: Human embryology: 6th Ed. A R Tencate. Oral HistologyDevelopment, structure and function. 3rd Ed. Connective tissues of the periodontium: periodontology 2000; Vol 24: 2000 Regeneration of periodontal tissues: cementogenesis revisited: periodontol 2000. 2006;41:196-217 Mark Bartold, Sampath Narayanan: Biology of periodontal tissues: pg 151-161
    38. 38. THANK YOU

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