21786909
Description
Flashcards by Evian Chai, updated more than 1 year ago
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Created by Evian Chai
about 4 years ago
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| Question | Answer |
| At what stage does Amelogenesis occur? | The late bell stage AFTER dentinogenesis |
| Which of the following layers of tissue becomes ameloblasts? 1. Internal Enamel Epithelium 2. Stratum Intermedium 3. Stellate Reticulum 4. External Enamel Epithelium | 1. Internal Enamel Epithelium |
| What shape are ameloblasts? | Tall columnar cells with processes called Tome's Processes |
| What triggers ameloblast differentiation? | The laying down of the first layer of predentin by odontoblasts |
| What 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 |
| What closes gaps between cells so matrix secretion does not go in between? | End terminal bars |
| How long does secretion last for? What about mineralisation? | 1. 1 year 2. 4-7 years |
| Are matrix proteins collagenous? | No |
| What 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 |
| How do globular proteins (amelogenins) contribute to the shape of the enamel prism? | Globular proteins wrap around hydroxyapatite crystals, preventing lateral growth |
| What 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 |
| What direction do crystals grow in relation to the secreting surface of Tome's Process? | 90 degree angle This creates the prism structure of enamel |
| What 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 |
| How do crystal change throughout the amelogenesis process? | First become long, then thicken |
| What 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 |
| What is the difference between ruffle ended ameloblasts and smooth ended ameloblasts? | Ruffle: plasma becomes infolded Smooth: have smooth end/inter ameloblast spaces |
| Which enzyme takes up/degrades protein in ameloblasts? If this fails to occur what happens? | MMPs Porous enamel |
| What 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 |
| What is a clinical consideration when cutting cavities? | Burs/handpieces cause cracking, so must use gentler high-torque handpiece |
| At what stage of amelogenesis is it easiest for flouride to be uptaken? | Maturation stage, however too much leads to flourosis |
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