Periodontium.docx

Cementum, Alveolar bone, Periodontal ligament **Periodontium** - Consists of the supporting soft and hard tissues - Serves to support tooth in relationship to alveolar bone - Includes cementum, alveolar bone, periodontal ligament, and individual components of these tissues **Cementum*...

Cementum, Alveolar bone, Periodontal ligament **Periodontium** - Consists of the supporting soft and hard tissues - Serves to support tooth in relationship to alveolar bone - Includes cementum, alveolar bone, periodontal ligament, and individual components of these tissues **Cementum** - Attaches teeth to alveolar bone by anchoring periodontal ligament - Cover entire root - Hard tissue - Thickest at apex and interradicular areas - Thinnest at CEJ - No innervention, avascular - Receives nutrition from PDL thru own cells - Can form throughout life - Less dense than enamel, dentin but more than pulp - 65% mineralized or inorganic - 23% organic - 12% water - Crystalline formation -- **calcium hydroxyapatite** - Most closely resembles composition of bone\* - When exposed -- dull pale yellow - Feels grainy when instrumented **Development of cementum** - Develops from dental sac - Forms on root after disintegration of Hertwig's root sheath - Undifferentiated cells of sac contact root surface, induce cells to become cementoblasts - Undergo cementogenesis - Lays down cementoid - Cementoblasts entrapped by cementum -- cementocytes - When full thickness achieved -- becomes calcified/matured - Cementum - Dentinocemental (DCJ) formed **Microscopic Appearance of Cementum** - Cementum is composed of mineralized fibrous matrix and cells - Sharpey's and intrinsic nonperiodontal fibers - **Sharpey's fibers** - Portion of collagen fibers - Inserted into outer part of cementum and alveolar bone at **right angle** - Fibers function as ligament between tooth and bone **Intrinsic nonperiodontal fibers** - Collagen fibers - Laid down in nonorganized pattern - Run parallel to DCJ **Cells of Cementum** - Cemenocytes (entrapped cementoblasts) - Lie in lacuna - Have canaliculi or canals - No nerves - Do not radiate outward - Oriented to PDL - Contain cementocyte processes **Cementoblasts** - Line up along cementum surface in PDL - Form layers of cementum when needed **Cementoenamel Junction Patterns** **Cementum Histology** - Three possible transitional interfaces that may be present at points along the CEJ: - One situation is that **cementum may overlap enamel (\