Dentinogenesis is the formation of dentin, which begins before enamel formation. Dentin is formed by odontoblast cells in two phases: first the formation of an organic collagen matrix, followed by deposition of hydroxyapatite crystals. As dentinogenesis begins, odontoblasts elongate and secrete an unmineralized collagen matrix called predentin. Over time, predentin adjacent to the pulp mineralizes and forms dentin while new predentin is deposited, resulting in incremental dentin growth of approximately 4 micrometers per day. Dentinogenesis continues throughout life but slows after eruption.

1. Dentinogenesis Dr. Syed Sadatullah Assistant Professor

2. Dentinogenesis The formation of dentin is called dentinogenesis, which starts before amelogenesis Dentin is formed by odontoblast cells Dentinogenesis takes place in two phases: first the formation of organic collagen matrix and second the deposition of hydroxyapetite crystals At the beginning of dentinogenesis the odontoblast elongate resulting in the formation of Tomes fibres or odontoblastic processes Dr.Syed Sadatullah

3. Morphological changes in odontoblasts during dentinogenesis Dr.Syed Sadatullah

4. Dr.Syed Sadatullah Odontoblasts then secrete matrix protein at the apical end of the cell and along its process The secreted matrix is collagenous and not mineralized hence it is called predentin As the matrix is being secreted the odontoblasts move towards the centre of the future pulp The matrix that forms around the elongated cell process eventually mineralizes and the odontoblastic process will lie within a dentinal tubule

5. As each day passes predentin is formed along the pulpal boundary, the adjacent predentin that was formed during the previous day mineralizes and becomes dentin During the period of crown development approximately 4µm of dentin is laid down in every 24 hours Incremental deposition and mineralization of dentine begins below the cusps, at the tips of the pulp horns at the DEJ Dentinogenesis continues life long but slows down after the tooth is completely erupted Dr.Syed Sadatullah

6. Formation of enamel and dentine in increments Dr.Syed Sadatullah

7. Odontoblasts in dentinal tubules Dr.Syed Sadatullah