Flashcards
OCB02-1015- Amelogenesis
Cards in this deck (20)
- 1At what stage does Amelogenesis occur?The late bell stage AFTER dentinogenesis
- 2Which of the following layers of tissue becomes ameloblasts? 1. Internal Enamel Epithelium 2. Stratum Intermedium 3. Stellate Reticulum 4. External Enamel Epithelium1. Internal Enamel Epithelium
- 3What shape are ameloblasts?Tall columnar cells with processes called Tome's Processes
- 4What triggers ameloblast differentiation?The laying down of the first layer of predentin by odontoblasts
- 5What occurs in the early stages of amelogenesis? (5)1. Ameloblasts differentiate
2. Nucleus migrates AWAY from basement membrane
3. Stellate Reticulum collapses
4. IEE+EEE fuse together
5. Ameloblasts secrete matrix proteins from Tome's Processes
6. Ameloblasts continue moving away from dentine as secretion continues - 6What closes gaps between cells so matrix secretion does not go in between?End terminal bars
- 7How long does secretion last for? What about mineralisation?1. 1 year
2. 4-7 years - 8Are matrix proteins collagenous?No
- 9What is the primary protein secreted by ameloblasts? How does it aid mineralisation?Amelogenins (eg. glutamic acid, proline, histidine) that is secreted in tissue fluid
Acts as scaffold for mineralisation - 10How do globular proteins (amelogenins) contribute to the shape of the enamel prism?Globular proteins wrap around hydroxyapatite crystals, preventing lateral growth
- 11What are Nonamelogenins? What do they do? What are examples?The other proteins secreted by ameloblasts
Initial nucleators of crystal growth at EDJ
Glue for crystallites bc acidic
eg. Aspartic acid, Glutamic acid, Serine, Glycine - 12What direction do crystals grow in relation to the secreting surface of Tome's Process?90 degree angle
This creates the prism structure of enamel - 13What controls prismatic enamel growth? What 3 things do they do?Ameloblastins (type of nonamelogenin)
- communicate between ameloblast/extracellular matrix
- Inhibit lateral growth of crystallites
- Maintain escape channels for enamel proteins - 14How do crystal change throughout the amelogenesis process?First become long, then thicken
- 15What occurs during the maturation phase of amelogenesis?1. Ameloblasts reabsorb matrix proteins
2. Ameloblasts change structurally
3. Matrix protein/H20 in enamel decreases as result
4. Quality/hardness of enamel increases as mineralisation proceeds
5. IEE becomes reduced enamel epithelium
6. reduced enamel epithelium fuses with oral epithelium as tooth erupts - 16What is the difference between ruffle ended ameloblasts and smooth ended ameloblasts?Ruffle: plasma becomes infolded
Smooth: have smooth end/inter ameloblast spaces - 17Which enzyme takes up/degrades protein in ameloblasts? If this fails to occur what happens?MMPs
Porous enamel - 18What is a clinical implication of aprismatic enamel present in some areas of teeth? How to remedy this?Ameloblasts and crystals are parallel, forming glaze like enamel with rods/prisms
As a result, it does not etch/bond well
Fixed with acid etch technique - 19What is a clinical consideration when cutting cavities?Burs/handpieces cause cracking, so must use gentler high-torque handpiece
- 20At what stage of amelogenesis is it easiest for flouride to be uptaken?Maturation stage, however too much leads to flourosis
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- LOs to: Describe the composition and structure of enamel Understand the stages of enamel formation (amelogenesis), the physiology of cells involved in this process and secreted matrix proteins, the process of maturation and mineralisation of the enamel. Describe the clinical considerations of maturation changes in enamel (fluoride and tetracycline staining), as well as mechanisms of adhesion of dental materials to enamel.
- Created by
- Evian Chai · Apr 2020
- Updated
- Apr 2, 2020
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