What is the definition of histogenesis?
Differentiation of undifferentiated cells to make new tissues
What are the mineralised dental tissues?
Enamel, dentine and cementum
What are the unmineralised dental tissues?
Dental pulp and periodontium
What is the first stage of tooth development?
Initiation stage
What are the two laminas in development and what do they contribute towards?
Dental lamina - contributes to the development of the teeth
Vestibular lamina - contributes to the vestibule of the mouth, delineating the lips and cheek from the teeth formation of sulcus
What is the second stage of tooth development?
Bud stage
What is the third stage of tooth development
cap stage - tooth germ grows into a cap shape
What is the fourth stage of tooth development?
Bell stage - differentiation occurs to furthest extent and starts to resemble a bell
What is the last stage of tooth development?
crown stage/late bell stage
What is mesenchyme?
A type of loosely organised embryonic connective tissue of undifferentiated cells which gives rise to most tissues
What is ectomesenchyme?
A type of mesenchyme confined just to the cranial region
What does the primary epithelial band give rise to?
- dental lamina
- vestibular lamina
At what week is the first signs of tooth development?
Week 6
What happens at week 6 in relation to tooth development?
We have a condensation of ectomesenchyme
The pimary epithelial band is being formed and starting to push inwards towards this condensation of mesenchyme
What happens in week 7?
We have differentiation between dental lamina (interacting with the mesenchyme) and the vestibular lamina (pushing mesenchyme down and proliferating a lot)
What happens in week 8?
The bud stage starts
The bud of the dental lamina (the enamel organ)
The enamel organs are swellings formed by dental lamina under the influence of mesenchymal cells. From these enamel, organs develop each tooth.
What happens in week 9?
Signals have told the cells in the vestibular lamina to die off (still a bit of a mystery)
What happens in week 12 in relation to the vestibular lamina?
The vestibular lamina cells have died off resulting in a gap (the buccal/labial sulcus/vestibule)
Interactions between the epithelium (ectoderm) gives rise to what?
- enamel
- hyaline layer of the root
Interactions between the mesenchyme (ectomesenchyme) gives rise to what?
- dentine
- pulp
- cementum
- periodontium - PDL and bone
What tissue is thought to initially initiate tooth development?
- Epithelium initially has the odontogenic potential, then the ectomesenchyme
What are the components of the tooth germ?
- enamel organ
- dental papilla
- dental follicle
What happens in week 11 in relation to tooth development?
The dental lamina is continuing to lengthen downwards (still attached to the oral epithelium)
The enamel organ is changing shape to resemble something that looks like a cap (cap stage)
- Poorly histodifferenciated
-
What happens around week 14 in relation to tooth development?
- Early bell stage
Lots of morpho- and histo-differentiation
The enamel organ is differenciated into 4 layers - inner enamel epithelium
- stratum intermedium
- stellate reticulum
- outer enamel epithelium
The condensed ectomesenchyme cells give rise to the dental papilla (which forms odontoblasts (dentine) and will go on to form the pulp) and the dental follicle (which forms the cementum, PDL and bone
