Teeth DevelopmentTeeth Development

Bud stage :Bud stage :

Characterized by formation of a tooth bud. The Characterized by formation of a tooth bud. The epithelial cells begin to proliferate into the epithelial cells begin to proliferate into the ectomesenchyme of the jaw. ectomesenchyme of the jaw.

Cap stage :Cap stage : The ectomesenchymal cells aggregated forming the dental The ectomesenchymal cells aggregated forming the dental

papilla. At this point, the tooth bud grows around the papilla. At this point, the tooth bud grows around the ectomesenchymal aggregation, taking on the appearance of a cap, ectomesenchymal aggregation, taking on the appearance of a cap, and becomes the enamel (or dental) organ. The enamel organ will and becomes the enamel (or dental) organ. The enamel organ will produce enamel, the dental papilla will produce dentin and pulp, and produce enamel, the dental papilla will produce dentin and pulp, and the dental follicle will produce all the supporting structures of a tooth.the dental follicle will produce all the supporting structures of a tooth.

Bell stageBell stage : : The cells on the periphery of the enamel organ separate into three important layersThe cells on the periphery of the enamel organ separate into three important layers::1.1. Cuboidal cells on the periphery of the dental organ and form the outer enamel epithelium. Cuboidal cells on the periphery of the dental organ and form the outer enamel epithelium. 2.2. The cells of the enamel organ adjacent to the dental papilla and form the inner enamel The cells of the enamel organ adjacent to the dental papilla and form the inner enamel

epithelium. epithelium. 3.3. The cells between the inner enamel epithelium and the stellate reticulum and form a layer The cells between the inner enamel epithelium and the stellate reticulum and form a layer

known as the stratum intermedium. known as the stratum intermedium. The dental laminaThe dental lamina begin to disintegrates, leaving the developing teeth completely separated begin to disintegrates, leaving the developing teeth completely separated

from thefrom the epitheliumepithelium of the oral cavity. of the oral cavity.

Crown stage :Crown stage : 1.1. During this stage mineralized hard During this stage mineralized hard

tissues ocurred. tissues ocurred. 2.2. The inner enamel epithelial cells The inner enamel epithelial cells

change in shape from cuboidal to change in shape from cuboidal to columnar. The columnar. The nucleinuclei of these cells of these cells move closer to the stratum move closer to the stratum intermedium and away from the dental intermedium and away from the dental papilla.papilla.

3.3. The adjacent layer of cells in the dental The adjacent layer of cells in the dental papilla suddenly increases in size and papilla suddenly increases in size and differentiatesdifferentiates into odontoblasts, which into odontoblasts, which are the cells that form dentin.. are the cells that form dentin..

4.4. The inner enamel epithelium and the The inner enamel epithelium and the formation of odontoblasts continue formation of odontoblasts continue from the tips of the cusps.from the tips of the cusps.

5.5. The odontoblasts secrete an The odontoblasts secrete an organic matrixorganic matrix, into their immediate , into their immediate surrounding and forming the dentin . surrounding and forming the dentin .

6.6. After dentin formation begins, the cells After dentin formation begins, the cells of the inner enamel epithelium secrete of the inner enamel epithelium secrete an organic matrix against the dentin. an organic matrix against the dentin. This matrix immediately mineralizes This matrix immediately mineralizes and becomes the tooth's enamel.and becomes the tooth's enamel.

7.7. Outside the dentin are ameloblasts, Outside the dentin are ameloblasts, which are cells that continue the which are cells that continue the process of enamel formation; process of enamel formation; therefore, enamel formation moves therefore, enamel formation moves outwards, adding new material to the outwards, adding new material to the outer surface of the developing tooth.outer surface of the developing tooth.

EnamelEnamel : is a hard outer : is a hard outer layer consisting primarily layer consisting primarily of calcium and phosphate of calcium and phosphate in the form ofin the form of hydroxyapatitehydroxyapatite. . Dentin : is the inner layer, Dentin : is the inner layer, the bulk of the tooththe bulk of the tooth. . Pulp : is the core, Pulp : is the core, containing nerves and containing nerves and blood vesselsblood vessels. . Cementum : is the thin Cementum : is the thin layer around the root; alayer around the root; a bone-like material which bone-like material which connects the teeth to the connects the teeth to the jawjaw. .

Structural components of teethStructural components of teeth::

Type of teeth according to their attachmentsType of teeth according to their attachments::

1.1. Acrodont: On the alveolar Acrodont: On the alveolar surface of the jaw. each tooth surface of the jaw. each tooth resides on the occlusional resides on the occlusional surface of the jaws in a very surface of the jaws in a very shallow socket. Replacement shallow socket. Replacement teeth arise adjacent to the teeth arise adjacent to the active teeth (snakes).active teeth (snakes).

2.2. Thecodont : Teeth may be Thecodont : Teeth may be attached in sockets . ( replace attached in sockets . ( replace within the same socket within the same socket reptiles). with sockets reptiles). with sockets (mammals, crocodiles, (mammals, crocodiles, dinosaurs ).dinosaurs ).

1.1. Pleurodont: Attachement on Pleurodont: Attachement on the inner side of the jaws the inner side of the jaws (lizards). Teeth continuously (lizards). Teeth continuously replaced.replaced.