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ODONTOGENESIS (II)

ODONTOGENESIS (II). BY DR.SHAZA ABDULKHALIG. Odontogenesis . Odonto = teeth Genesis = beginning, formation, creation Tooth development or  odontogenesis :  is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth.

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ODONTOGENESIS (II)

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  1. ODONTOGENESIS (II) BY DR.SHAZA ABDULKHALIG

  2. Odontogenesis. Odonto= teethGenesis = beginning, formation, creation Tooth development or odontogenesis:  is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Primary (baby) teeth start to develop in the sixth week of prenatal development, and permanent teeth begin to form in the twentieth week. If teeth do not start to develop at or near these times, they will not develop at all, resulting in hypodontia(missed teeth) or anodontia (no teeth).

  3. Stages of tooth development (odontogenesis) • Initiation. • Bud Stage. • Cap Stage. • Bell Stage. • Apposition/Maturation.

  4. 1-INITIATION (formation of the dental lamina): • Sixth week in utero, a continuous band of thickened epithelium forms around the mouth in the presumptive upper and lower jaws; • This bands are roughly horseshoe shaped and correspond in position of the future dental arches of the jaws; • Each band of epithelium quickly gives rise to two subdivisions: • The vestibular lamina and • The dental lamina just behind it.

  5. Initiation of tooth development. Thickening of the epithelium.

  6. The position of the primary epithelial band

  7. Initiation of the tooth development

  8. 2-Bud Stage: At the beginning of the eighth week in utero, a cellular proliferation occurs in the dental lamina which develops ten buds (enamel organ) per arch representing the primary teeth.

  9. 3-Cap Stage: Ninth to tenth week in utero ,proliferation of tooth bud epithelial cells occur which results in increase of the size of the enamel organ and become concave resembling a cap. (Changes in shape from round to upside down "C"-shaped bud)

  10. Concavity at the top of the tooth bud under the control of mesenchymal factors

  11. 4-Bell Stage: Eleventh to twelfth week in utero , more differentiation occurs in the epithelium of the enamel organ which increases in size and form a bell shape. By the end of this stage : 1*The dental lamina disintegrate. 2*Dental papilla is formed which later will form : -The dentine and -the pulp of the tooth. 3*Dental follicle will developed and make a capsule around the enamel organ.

  12. 4*four cells types established that form the enamel organ: -Stratum intermedium. -Inner enamel epithelium. -Stellate reticulum. -outer enamel epithelium.

  13. 5-Appositional Stage/Maturation: During this stage enamel and dentine are laid down.

  14. What are the two primary epithelial bands of thickening called? • (Ninth to tenth week in utero proliferation of tooth bud epithelial cells occur) Which stage of odontogenesis is this?

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