Oral Biology: Tooth Development (NVU)

Nile Valley University Faculty of Oral and Dental Medicine Oral Biology Your mouth under microscope  Nile Valley University Faculty of Oral and Dental Medicine Tooth development Part 1 Dr. Heba Abdelfatah Lec...

Nile Valley University Faculty of Oral and Dental Medicine Oral Biology Your mouth under microscope  Nile Valley University Faculty of Oral and Dental Medicine Tooth development Part 1 Dr. Heba Abdelfatah Lecturer in Oral and Dental Biology Department Faculty of Dental Medicine for Girls Al-Azhar University  Odontogenesis, or teeth development, is a process that includes the development of deciduous and permanent teeth.  At 3rd week of intrauterine life after the developing, oral cavity creates a communication with developing pharynx ‫البلعوم‬.  Rupture of buccopharyngeal membrane. Head Tail Rupture of buccopharyngeal membrane migrate Ectoderm  First sign of the tooth development is proliferation of oral ectodermal cells to form an epithelial thickening called primary epithelial band. Upper Lower  The primary epithelial band-- two subdivisions:  Buccal extension called vestibular lamina.  Lingual extension is dental lamina. Lip  Vestibular Tongue lamina  Dental lamina Primary epithelial band- Two subdivisions Buccal Lingual Vestibular Dental lamina lamina  A - oral epithelium B - primary epithelial band A - primary epithelial band arrow - bifurcation of primary epithelial band  A - primary epithelial band B - dental lamina C - vestibular lamina Lip Tongue A - dental lamina B - vestibular lamina What is the first sign of the tooth development ? What is the two subdivisions of primary epithelial band ? Tooth development of the primary dentition begins at........W.I.U. life.  1) Dental lamina  The dental lamina proliferates into the underlying ectomesenchyme and forms a U- shaped band along the future dental arches in each jaw.  Formation of round structures which form along the dental lamina and develop into tooth buds,  that gives rise to enamel organ of 10 deciduous teeth in each arch.  1- Dental Lamina 1 2 Epithelial Proliferation Dental lamina Mesenchymal Condensation  2-Bud Stage  It’s a rise from dental lamina.  These buds form the enamel organ which gives rise to Enamel.  Enamel organ is round or ovoid structure and separated from the surrounding connective tissue by a basement membrane.  2-Bud Stage  Histology of enamel organ. 1. The periphery cells are Low columnar. 2. The central cells are polyhedral. Low columnar  2-Bud Stage 1. The ectomesenchymal cells adjacent to enamel organ called dental papilla which gives rise to dentin and pulp. 2. The peripheral which encloses the dental papilla and enamel organ called dental sac or dental follicle, gives rise to cementum, periodontal ligament and alveolar socket.  3- Cap Stage  During this stage the tooth bud does not grow into a large sphere. Instead, there is unequal growth, leading to the formation of a cap shape attached to the dental lamina by broad connection.  In cap stage, the (dental) enamel organ shows three different types of cells 1- Outer enamel epithelium - The peripheral cells of enamel organ are cuboidal, lined the convexity of the cap. 2- Inner enamel epithelium: - The cells on the concavity of the cap are short columnar.  Both types of epithelium are separated from the dental papilla by a basement membrane. 3- Stellate Reticulum  Stellate reticulum is layers of star-shaped cells present at the center of enamel organ of cap.  Stellate reticulum Give reason for the star shape of these cells ? Polygonal cells change to Stellate reticulum cells  -These cells secrete glycosaminoglycan into the ‫بره الخليه‬ extracellular compartment between them. ‫ماده محبه للماء‬ -The glycosaminoglycan are hydrophilic and so pull water into the enamel organ. ‫مؤقت‬ Outer enamel epithelium Stellate reticulum Enamel Knot Dental Sac Inner enamel epithelium Dental papillae  Cap Stage Tooth Germ 1- Dental Organ 3- Dental 2- Dental Sac Papilla