21758151
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 |
| What are the two types of dentin in coronal dentine? | 1. Mantle 2. Circumpupal |
| What are the three types of dentine in radicular dentine? | 1. Hyaline Layer 2. Granular Layer 3. Circumpupal Layer |
| When does dentinogenesis occur? | During the late bell phase |
| What is dentinogenesis? | The laying down of dentine by odontoblasts (deposits matrix that mineralises) |
| What is the process of dentinogenesis? | 1. Internal enamel epithelium starts differentiating into ameloblasts 2. Meanwhile, odontoblasts start to differentiate from pre odontoblasts 3. Odontoblasts polarise, elongate, develop mitochondria/organelles 4. Odontoblasts grow processes that secrete matrix 5. Cells drift AWAY from pulp, leaving hollow tube where process was |
| Where does the cytodiffrentiation of odontoblasts begin? | Tips of cusps/incisal margins and travel rootwards |
| What cells do preodontoblasts come from? | Ectomesenchyme cells in mesenchyme |
| What type of collagen is in the organic matrix? What 5 other things does it contain? | Collagen type 1 Contains: 1. phosphoproteins 2. glycoproteins 3. proteoglycans 4. growth factors 5. metahoproteinases |
| How does mantle (first) dentin differ from other dentine? | Composition differs: very porous due to holes from processes Different mineralisation process: Matrix vesicles compared to nucleation on collagen fibres |
| In initial dentine matrix deposition (mantle) what angle are collagen fibers at? | 90 degrees to internal enamal epithelium |
| What angle are collagen type 1 fibers laid in circumpupal dentine? What about them causes Andersen Lines? | Parallel to dentine pupal border Change orientation slightly every 6-10 days |
| What is predentin? Where is it located? What mineralisation process does in undergo? | Predentin is the newest dentine laid down prior to mineralisation Located next to the pulp It undergoes globular mineralisaiton |
| What is metadentin? Where is metadentin? What does it contain a lot of? | The mineralisation front In between predentine/dentin Rich in proteoglycans, calcospherites, and phosphoprotein |
| How does mineralisation occur in mantle dentin? | 1. Matrix vesicles develop off odontoblasts that contain enzymes (eg phosphatase) for mineralisation 2. Vesicles explode in matrix (collagen acts as scaffold) and fuse with crystals |
| How does the collagen content of peritubular and intertubular dentin differ? | Peritubular has no collagen fibrils Intertubular is made of 90% collagen |
| How does mineralisation occur in circumpupal dentin? | 1. Minerals transported between (intertubular) or to the outside of (peritubular) of tubules to mineral front 2. Non collagenous proteins here aid in formation of crystals |
| What is the role of DPP? | 1. Transports Ca2+ to mineralisation front: -Highly acidic+change shape to bind Ca2+ 2. Nucleation location to specific collagen areas 3. Stabliisation of formed crystals 4. Inhibit crystal formation in high concentrations |
| Osteonectin is a protein that... | Inhibits hydroxyapatite growth Promote Ca2+/PO4 3- binding to collagen |
| Ostepontin is a protein that... | promotes mineralisation |
| Proteoglycans... | Predentin: transport+hydroxyapaptite inhibitor Collagen (during mineralisation): promote hydroxyapatite initiation |
| What is the difference between globular and linear mineralisation? What area shows mainly globular mineralisation? | Globular mineralsation is where collagen is arranged in whirls, whereas in linear mineralisation it appears uniform In mantle dentin |
| What are calcospherites? What occurs when they fail to fuse? | Circular areas of mineralisation in globular mineralisation Interglobular dentine |
| What initiate formation of root dentine? | The formation of the Herwig's Epithelial Root Sheath |
| What are 2 differences of root dentine formation compared to coronal? | 1. Root dentine forms slower due to smaller calcospherites 2. Mineralisation continuous with coronal dentine |
| What is the structure of the hyaline layer of root dentine? | Relatively structureless with no tubules Non-collagenous, fine fibrillar matrix Proteins enamel like |
| What does the hyaline layer of root dentine do? | Binds cementum to dentin |
| When is secondary dentin laid down? | After root formation |
| Why does secondary dentin have a less regular tubular pattern? | Odontoblasts more crowded with a slower rate of deposition |
| What increases formation rate of secondary dentin? | Denervation |
| When is tertiary dentine laid down? | In response to injury Stimulated by acid, caries, attrition |
| What is the structure of tertiary dentin? | Irregular because laid down quickly Relatively atubular |
| What is reactionary tertiary dentin caused by? | Mild irritant wherein odontoblasts survive and lay down dentin |
| What is reparative tertiary dentin caused by? | Strong irritant wherein odontoblasts die Progenitor cells recruited/upregulated instead to produce mineral |
| What is the main signal involved in tertiary dentin formation? | Mainly TGF-B which stimulates odontoblasts |
| What does TGFB1/TGFB2 lead to? What about TGFB3 | 1. Reactionary dentine 2. Reparative dentin |
| Summary of dentin | |
| Label dentin |
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