DENTINOGENESIS

• Tertiary dentin

  Dentin produced in reaction or response to noxious stimuli, protective or defensive function
• Primary dentin


  1. Dentin formed prior to tooth eruption and root completion

  2. Mantle dentin - first formed dentin under DEJ and DCJ, bounded by DEJ and interglobular dentin

  3. Circumpulpal dentin - dentin that surrounds pulp, slightly more mineralized than mantle dentin
• Dentinogenesis

  The process of dentin formation
• Theories of pain transmission through dentin

  Direct neural theory - nerve endings in the dentin evoke painful responses, transduction theory - odontoblastic processes transmit stimuli to nerve endings, hydrodynamic theory - various stimuli cause fluid movement in odontoblasts
• Abnormalities in dentin formation

  • Tetracycline pigmentation
  • Dentinogenesis imperfecta
  • Dentin dysplasia
  • Regional odontodysplasia
• Sequence of events in dentinogenesis

  Differentiation of ameloblasts, odontoblasts, dentin matrix formation, enamel matrix formation
• Mineralization

  Deposition of hydroxyapatite crystals and gradual calcification
• Secondary dentin

  Dentin formed after root completion and tooth eruption, grows slowly and reduces size of pulp as the tooth ages (pulp recession), thickest deposition at the roof of pulp chamber, important in operative dentistry
• Innervation of dentin
• Type of dentin

  • Primary dentin
  • Secondary dentin
  • Tertiary/Reparative/Reactive/Response dentin
• Dentin

  The hard tissue forming the bulk of a tooth, beneath the enamel
• Dentin matrix formation

  Deposition of collagenous matrix and odontoblastic processes
• Age and functional changes in dentin

  Vitality of dentin, formation of dead tracts, sclerotic or transparent dentin, reparative dentin
• Clinical considerations
• When 1 mm2 of dentin is exposed about 300000 odontoblast cells are damaged
• Reparative dentin formation

  • Can be stimulated by cavity lining materials
• Abnormalities in dentin formation

  • Tetracycline pigmentation
  • Dentinogenesis imperfecta
  • Dentin dysplasia
  • Regional odontodysplasia
• Rapid spread of caries in the dentin

  Due to the tubule system
• Undue trauma from operative dental procedures may cause damage to pulp