Flashcards
OCB02-1017-Lec Dentinogenesis
Cards in this deck (37)
- 1What are the two types of dentin in coronal dentine?1. Mantle
2. Circumpupal - 2What are the three types of dentine in radicular dentine?1. Hyaline Layer
2. Granular Layer
3. Circumpupal Layer - 3When does dentinogenesis occur?During the late bell phase
- 4What is dentinogenesis?The laying down of dentine by odontoblasts (deposits matrix that mineralises)
- 5What 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 - 6Where does the cytodiffrentiation of odontoblasts begin?Tips of cusps/incisal margins and travel rootwards
- 7What cells do preodontoblasts come from?Ectomesenchyme cells in mesenchyme
- 8What 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 - 9How 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 - 10In initial dentine matrix deposition (mantle) what angle are collagen fibers at?90 degrees to internal enamal epithelium
- 11What 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 - 12What 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 - 13What 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 - 14How 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 - 15How does the collagen content of peritubular and intertubular dentin differ?Peritubular has no collagen fibrils
Intertubular is made of 90% collagen - 16How 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 - 17What 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 - 18Osteonectin is a protein that...Inhibits hydroxyapatite growth
Promote Ca2+/PO4 3- binding to collagen - 19Ostepontin is a protein that...promotes mineralisation
- 20Proteoglycans...Predentin: transport+hydroxyapaptite inhibitor
Collagen (during mineralisation): promote hydroxyapatite initiation - 21What 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 - 22What are calcospherites? What occurs when they fail to fuse?Circular areas of mineralisation in globular mineralisation
Interglobular dentine - 23What initiate formation of root dentine?The formation of the Herwig's Epithelial Root Sheath
- 24What 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 - 25What is the structure of the hyaline layer of root dentine?Relatively structureless with no tubules
Non-collagenous, fine fibrillar matrix
Proteins enamel like - 26What does the hyaline layer of root dentine do?Binds cementum to dentin
- 27When is secondary dentin laid down?After root formation
- 28Why does secondary dentin have a less regular tubular pattern?Odontoblasts more crowded with a slower rate of deposition
- 29What increases formation rate of secondary dentin?Denervation
- 30When is tertiary dentine laid down?In response to injury
Stimulated by acid, caries, attrition - 31What is the structure of tertiary dentin?Irregular because laid down quickly
Relatively atubular - 32What is reactionary tertiary dentin caused by?Mild irritant wherein odontoblasts survive and lay down dentin
- 33What is reparative tertiary dentin caused by?Strong irritant wherein odontoblasts die
Progenitor cells recruited/upregulated instead to produce mineral - 34What is the main signal involved in tertiary dentin formation?Mainly TGF-B which stimulates odontoblasts
- 35What does TGFB1/TGFB2 lead to? What about TGFB31. Reactionary dentine
2. Reparative dentin - 36Summary of dentin
- 37Label dentin
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- Description
- LOs to: Consider the differentiation of odontoblasts State the role of odontoblasts in secreting and modifying the protein matrix and the mineralisation of the matrix State the different mechanisms by which mineralisation occurs State the molecular features of the biological process involved in tertiary dentine formation
- Created by
- Evian Chai
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