Histology, Pathology, and Embrology: How The Tooth Develops

The sciencey term for tooth developing is called odontogesis

Note: Not all teeth develop at the same time

DL = Dental Lamina

OE = Dental Lamina

DP = Dental Papilla

DF = Dental Sac

SL = Successors Lamina

Ignore the rest

Development

Starts out as a tooth germ or bud (that whole picture would be considered a tooth bud). It comes from the ectoderm

So the tooth germ has three major parts

1. Enamel Organ - a knob like growth from the dental lamina, which came from epithelium
2. Dental Papilla - comes from the mesenchyme and will become dentin and pulp
3. Dental Sac - several rows of flat cells that come from the mesenchyme and will become periodontal ligaments, cementum, and lamina dura.

The enamel organ has 3 stages of development, the bud stage the cap stage, and the bell stage. The picture above is in the bells stage.

•  Bud Stage
• Initiation stage of tooth development
• Thickening of oral epithelium forming the dental lamina
• As it begins to invaginate it moves to the cap stage
• Cap Stage
• Occurs around week eight
• The cells begin to proliferate
• Enamel organ begins to surround mesenchyme
• Formation of dental papilla and dental sac
• Now have developed 3 out of 4 components of the enamel organ
• inner/outer enamel epithelial (part of enamel organ)
• stelliate reticulum (membrane inside enamel organ)
• Bell Stage
• Occurs around week 10-11
• Appearance of all four layer of enamel organ
• 1. Outer Enamel Epithelium (OEE)
• Outside layer on the surface of enamel organ
• cubodial cells
• protective layer for entire enamel organ
• 2. Inner Enamel Organ (IEE)
• line the enamel organ (inside of EO) - concave
• cuboidal and elongate to columnar as they differentiate
• become ameloblayst (enamel forming cells)
• IEE separated from dental papilla
• Basement membrane becomes the future dento-enamel junction
• Stellate Reticulum (SR)
• cells between the OEE and the IEE
• loose network of epithelial cells that are star-shaped
• provide protection/cushion
• part of nourishment for IEE- transport to stratum intermedium
• Stratum Intermedium (SI)
• layer of flat epithelial cells inside the stellate reticulum
• between SR and IEE
• nourishes the IEE