Cementum

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Cementum

  1. 1. CEMENTUM Submitted to:DEPARTMENT OF CLINICAL PERIODONTOLOGY & ORAL IMPLANTOLOGY HOD & PROF.- DR. RANJAN MALHOTRA
  2. 2. CONTENTS INTRODUCTION  DEVELOPMENT  TYPES OF CEMENTUM  STRUCURE AND COMPOSITION  ACELLULAR AND CELLULAR CEMENTUM  CEMENTOENAMEL JUNCTION  DENTINOCEMENTAL JUCNTION  PATHOLOGY  ANKYLOSIS  CEMENTUM RESORPTION 
  3. 3. CEMENTUM  CEMENTUM is defined as calcified avascular mesenchymal tissue that forms the outer covering of root.  The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.
  4. 4. DEVELOPMENT OF CEMENTUM Cementoid is excreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex.  These cementoblasts develop from undifferentiated mesenchymal cells in the connective tissue of the dental sac or follicle.  During the later steps within the stage of apposition, many of the cementoblasts become entrapped by the cementum they produce, becoming cementocytes. 
  5. 5. TYPES OF CEMENTUM: 1.ACELLULAR or PRIMARY CEMENTUM 2.CELLULAR or SECONDARY CEMENTUM
  6. 6. STRUCTURE AND COMPOSITION:    Both acellular and cellular cementum consists of: 1.CALCIFIED INTERFIBRILLAR MATRIX 2.COLLAGEN FIBRES The two main sources of collagen fibers in cementum are: 1.EXTRINSIC or SHARPEY’s FIBRES 2.INTRISIC FIBRES Sharpey’s fibres are embedded portion of principle fibers' of periodontal ligament and are formed by fibroblasts.
  7. 7. ACELLULAR CEMENTUM It is the first formed cementum.  It does not contain cells and covers approx. cervical third or half of the root.  Formed before the tooth reaches the occlusal plane.  Thickness: 30-230 micrometers  Sharpey’s fibers make up most of the structure of acellular cementum and play a principle role in supporting the tooth.  CELLULAR CEMENTUM It is formed after the tooth reaches the occlusal plane, is more irregular and contain cells called cementocytes in lacunae.  Cellular cementum is less calcified than acellular cementum.  Sharpey’s fibres occupy a smaller portion and may be less calcified. 
  8. 8. CEMENTOENAMEL JUNCTION    The cementum joins the enamel to form the cementoenamel junction (CEJ), which is referred to as the cervical line. Three possible types of transitional interfaces may be present at the CEJ. In about 60-65% of cases cementum overlaps enamel, in about 30% of cases edge to edge butt joint exists and in about 510% of cases cementum and enamel fail to meet.
  9. 9. DENTINOCEMENTAL JUNCTION When the cementoid reaches the full thickness needed, the cementoid surrounding the cementocytes becomes mineralized, or matured, and is then considered cementum.  Because of the apposition of cementum over the dentin, the dentinocemental junction (DCJ) is formed.  This interface is not as defined, either clinically or histological, as that of the dentinoenamel junction.  The dentinocemental junction (DCJ) is a relatively smooth area in the permanent tooth, and attachment of cementum to the dentin is firm. 
  10. 10. Dentinocemental junction
  11. 11. PATHOLOGY  HYPERCEMENTOSIS:The excessive build up of cementum on the roots of a tooth is a pathological condition known as hypercementosis Cementum thickness can increase on the root end to compensate for attritional wear of the occlusal/ incisal surface and passive eruption of the tooth.  When cementum is exposed through gingival recession, it quickly undergoes abrasion by mechanical friction because of its low mineral content and thinness.. 
  12. 12. The incidence of cemental caries increases in older adults as gingival recession occurs from either trauma or periodontal disease. Cementicles are mineralized bodies of cementum found either attached to the cemental root surface or lying free in the periodontal ligament.
  13. 13. ANKYLOSIS The fusion of cementum and alveolar bone with obliteration of periodontal ligament is known as ankylosis.  Ankylosis occurs in teeth with cemental resorption.  It results in resorption of root and its replacement by bone tissue.  Resorption lacunae are filled with fluid.  It may develop after occlusal trauma. 
  14. 14. CEMENTUM RESORPTION: Permanent teeth do not undergo resorption as do the primary teeth.  Causes: Trauma from occlusion, orthodontic movement, periapical disease, cysts and tumors.  It is painless. 
  15. 15. REFERENCES- Website- Wikipedia ,Google Carranza’s book Dental anatomy and histology by dr.satish chandra

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