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  2. 2. CEMENTUM
  3. 3. DEFINITION <ul><li>Cementum is the calcified a vascular mesenchymal tissue that forms the outer layer cover of the anatomic root </li></ul><ul><li>Types of cementum </li></ul><ul><li>The two main types of cementum are </li></ul><ul><li>1.A celluar and </li></ul><ul><li>2.cellular cementum </li></ul><ul><li>The two main source’s of collagen fibers in cementum are sharpey’s fibers which are the embedded portion of principal fibers of the </li></ul>
  4. 4. <ul><li>Periodontal ligament and are formed by the fibroblasts </li></ul><ul><li>Fibers that belong to cementum matrix and are produced by cementoblasts </li></ul><ul><li>Cementoblasts also form the non collagenous components of the inter fibrillar ground substance such as proteoglycans, glycoproteins and phosphoproteins </li></ul><ul><li>Proteoglycans are the most likely to play a role in regulating cell-cell and cell-matrix interactions </li></ul>
  5. 5. <ul><li>COMPOSTION </li></ul><ul><li>The major proportion of the organic matrix of a cementum is composed of type one (90%) and type III about (5%) collagens </li></ul><ul><li>ACELLULAR CEMENTUM </li></ul><ul><li>It is the first cementum formed, covers approximately the cervical third or half of the root and does not contain cell’s </li></ul>
  6. 6. <ul><li>This cementum is formed before the tooth reaches </li></ul><ul><li>the occlusal plane and it’s thickness ranges froms </li></ul><ul><li>30 to 230 um </li></ul><ul><li>Sharpey’s fibers are completely calcified, with the mineral crystals. Oriented parallel to the fibrils as dentin and bone except in a 10 -50 um wide zone near the cementodentinal junction where they are only partially calcified </li></ul>
  7. 7. <ul><li>Acellular cementum also contains intrinsic collagen fibrils that are calcified and irregularly arranged or parallel to the surface </li></ul><ul><li>CELLULAR CEMENTUM </li></ul><ul><li>Celluar cementum formed after the tooth reaches the occlusal plane is more irregular and contain cell’s (cementocytes) in individual spaces (lacunae) </li></ul>
  8. 8. <ul><li>that communicate with each other through a system of anastomising canaliculi </li></ul><ul><li>Cellular cementum is less calcified than the acellular type </li></ul><ul><li>Sharpey’s fibers occupy a smaller portion of cellular cementum and are separated by other fibers that are arranged either parallel to the root surface </li></ul><ul><li>Both acellular and cellular cementum are aranged in lamellae separated by incremental lines parallel to long axis root this lines are called restperiods </li></ul>
  9. 9. <ul><li>PERMEABILITY OF CEMENTUM </li></ul><ul><li>In very young animal’s acellular cementum and cellular cementum are very permeable and permit the diffusion of dyes from the pulp and external root suface </li></ul><ul><li>THICKNESS OF CEMENTUM </li></ul><ul><li>Cementum deposition is a continuous process that proceeds at varying rates </li></ul>
  10. 10. <ul><li>Cementum formation is most rapid in the apical regions where it compensates for tooth eruption, which it self compensate for attrition </li></ul><ul><li>The thickness of cementum on the coronal half of the root varies from 16-60um </li></ul><ul><li>It attains greatest thickness (upto 150-200 um) in the apical third and in the fraction areas </li></ul><ul><li>Abnormalities in the thickness of cementum may range from an absence of cellular cementum to an excessive deposition of cementum </li></ul>
  11. 11. <ul><li>The term hyper cementosis refers to a prominent thickening of cementum </li></ul><ul><li>Hyper cementosis occurs a generalisied thickening of the cementum </li></ul><ul><li>CEMENTUM RESORPTION AND REPAIR </li></ul><ul><li>Cementum resorption may be caused by local and systemic factors </li></ul>
  12. 12. <ul><li>Local condition causing cementum resorption include trauma from occlusion orthodontic movement pressure from malaligned erupting teeth cysts and tumors teeth with out junctional antagoinsts </li></ul><ul><li>Systemic condition citied as predisposing to or including cemental resorption include calcium deficiency hypothyroidism, hereditary fibrous osteodystrophy </li></ul>
  13. 13. <ul><li>EXPOSUR OF CEMENTUM TO ORAL ENVIRONMENT </li></ul><ul><li>Cementum becomes exposed to the oral environment in cases of gingival recession and as result of loss of attachment in pocket formation </li></ul><ul><li>CEMENTO ENAMEL JUNCTION </li></ul><ul><li>The cementum at and immediately subjacent to cemento enamel junction is of particular clinical importance in root scaling procedures </li></ul>
  14. 14. <ul><li>Three types of relationships involving the cementum may exists at cementoenamel junction </li></ul><ul><li>in about 60 -65% of cases, cementum over laps the enamel in about 30% an edge-edge but joint exists and 5-10% the cementum and enamel fail to meet </li></ul><ul><li>CEMENTO DENTINAL JUNCTION </li></ul><ul><li>The terminal apical area of cementum where it joins the internal root canal dentin is known as cemento dental junction </li></ul>
  15. 15. THANK U <ul><li>GUIDED BY </li></ul><ul><li>Dr.Krishna murthy. MDS </li></ul><ul><li>Dr. Rupa Devi MDS </li></ul><ul><li>Dr.Ravendhar Reddy MDS </li></ul><ul><li>Dr.Sharath MDS </li></ul><ul><li>Dr.Venkat SubhaReddy MDS </li></ul><ul><li>Dr.Pradeep MDS </li></ul><ul><li>SUBMITTED BY </li></ul><ul><li>GAYATRI SAROJINI.N.V </li></ul><ul><li>IV BDS </li></ul>