CEMENTUM

• Cementum


  Calcified mesodermal tissue forming the external covering of the anatomical roots of teeth
• Periodontium


  Tissues surrounding the tooth root, including cementum, periodontal ligament, alveolar bone, and gingiva
• Components of the periodontium


  • Cementum
  • Periodontal ligament
  • Alveolar bone
  • Gingiva facing the bone
• Cementum


  • Thinnest at the cervical region of the tooth and thickest near the apex and furcation area
  • Highly responsive mineralized tissue
• Cementogenesis


  1. Elongation of HERS

  2. Root dentin formation precedes cementogenesis

  3. Cementum is laid down in successive layers

  4. Acellular or primary cementum is laid down

  5. Cellular or secondary cementum is laid down when the tooth comes into occlusion
• Cementoid tissue


  Unmineralized cementum
• Types of cementum


  • Intermediate cementum
  • Cellular-acellular cementum
• Acellular cementum


  • Clear layer of cementum devoid of cells
  • Thinnest at the cervical area of the tooth and thickest at the apex
  • Composed of calcified ground substance and fibers (collagen and Sharpey's fiber)
• Cellular cementum


  • Has cells within the matrix (cementocytes)
  • Thickest at the apex (contributes to the lengthening of root)
• Components of cementum matrix

  • Collagen fibrils
  • Sharpey's fibers
  • Lacuna and canaliculi
• Lacuna


  Spaces within the matrix where cementocytes are located
• Canaliculi


  Elongated processes projecting from lacuna
• Living cells in cementum


  • Cementoblast (synthesis of cementum)
  • Cementocytes (in lacuna)
  • Cementoclast (resorption of cementum)
• Relationships between cementum and enamel


  • 60-65% cementum overlaps the enamel
  • 30% cervical end of cementum meets the cervical end of enamel
  • 5-10% failure of enamel and cementum to meet exposing cervical dentin
• Functions of cementum


  • Attaches the root of the tooth to alveolar bone by the fibers of periodontal ligament
  • Compensates the loss of tooth structure due to occlusal wear by its continued growth
  • Regulates the periodontal space as bone resorbs
  • Contributes to the continuous vertical eruption of teeth
  • Protects the root dentin
  • Repairs the resorbed part of cementum, fractured roots and provides reattachment of broken periodontal fibers
• Ankylosis


  Fusion of cementum and alveolar bone with no periodontal ligament in between
• Hypercementosis


  Abnormally prominent thickness of the cementum on root surface
• Types of cemental overgrowth


  • Cemental hyperplasia (hypercementosis when cemental growth does not help in increasing functioning of the tooth or it occurs in non-functional teeth, like hypercementosis due to periapical infection)
  • Cemental hypertrophy (if cemental overgrowth improves or helps in the functioning of teeth)
• Cementicles


  Round lamellated cemental bodies that lie free in the periodontal space or are attached to the root surface
• Cementoma


  Also called benign cementoblastoma or cemental dysplasia, included in the category of a slowly growing odontogenic neoplasm & may cause expansion of jaw