Term
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Definition
| Series of complex cellular reactions through which enamel and dentin are formed |
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Term
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Definition
I. The Odontoblast II. Dentin Formation 1. Mantle Dentin 2. Primary (circumpulpal) Dentin 3. Secondary Dentin 4. Tertiary (reparative) Dentin III. Mineralization of Dentin |
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Term
Dentinogenesis Odontoblast |
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Definition
Process: 1. cells of IDE change polarity after IDE stops mitotic activity 2. cells of superficial dental papilla enlarge and differentiate in pre-odontoblasts --> odontoblasts -forms dentin -derived from undifferentiated cell of dental papilla in response to growth factors TGF-β2, BMP2, IGF from internal dental epi -nucleus polarized away from IDE -increased cytoplasm content that obliterates acellular zone b/w IDE and dental papilla |
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Term
Dentinogenesis Odontoblast States (2) |
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Definition
1. Resting 2. Secretory -abundent cytoplasm -large basally located nucleus -RER, Golgi, and secretory granules take up lots of cytoplasm -junctional complexes -gap junctions -extensive terminal web
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Term
Dentinogenesis Dentin Formation Mantle Dentin |
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Definition
-first dentin that is formed -15-21 microns thick |
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Term
Dentinogenesis Dentin Formation Mantle Dentin The process |
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Definition
1. Organic matrix is deposited [fibronectin, type III coll (von Korff's fibers), lastly type I coll] -elongated apical processes emerge from which matrix vesicles are extruded from odontoblast cytoplasm 2. Depo cont. and 1 large odontoblast process remains behind -hydroxyapatite crystals rupture matrix vesicle membrane -crystals increase in size until mineralizing front is evident -unmineralized (recently deposited dentin) matrix is known as predentin 3. Ca and PO4 transported through Ca channels in basal cell membrane of odontoblast prior to entering matrix |
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Term
Dentinogenesis Dentin Formation Mantle Dentin - Later on |
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Definition
-Odontoblasts migrate toward dental pulp leaving behind odontoblast process within a newly formed dental tubule Coronal Dentin = tubules run in a gradual "S" shape while root tubules remain straight |
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Term
Dentinogenesis Dentin Formation Primary (circumpulpal) Dentin |
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Definition
-dentin that encircles the pulp chamber -formed prior to completion of the apical foramen -different manner of mineralization -different organic matrix |
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Term
Dentinogenesis Dentin Formation Secondary Dentin |
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Definition
-forms after establishment of apical foramen -increased dentin formation that restricts the size of the pulp -more pronounced in crowns of molars |
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Term
Dentinogenesis Dentin Formation Tertiary (reparative) Dentin |
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Definition
localized dentin formation in response to irritation or trauma
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Term
Dentinogenesis Mineralization of Dentin |
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Definition
-mineral ions are transported in through basal membrane of odontoblast and released into predentin -shows a pattern of globular calcificatoion -small isolated crystalline nuclei continue to grow radially and eventually coalesce with neighboring calcospherites -areas where predentin secretion is slow may show a linear pattern of mineralization
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Term
Dentinogenesis Mineralization of Dentin interglobular dentin |
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Definition
The intervening uncalcified dentin in areas of incomplete fusion (usually adjacent to mantle dentin) |
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Term
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Definition
-process of enamel formation -begins at the early crown stage -presence of dentin (specifically predentin) necessary for amelogenisis to occur -inital stage of deposition of a partially mineralized enamel -undergoes subsequent stage of water and organic matrix removal and increased mineralization
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Term
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Definition
-derived from enamel organ of the tooth germ -primarily from cells od IDE -assisted by stratum intermedium and stellate reticulum -amelogenisis is initated at the cusp tips and procedes laterally along the cusp inclines |
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Term
Live Cycle of the Ameloblast Overview pt. 1 |
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Definition
-late Bell = series of morphologic changes occurs in IDE cells from cusp tip towards cervical loop =preparation to assume secretory function -IDE cells becom columnar and shift so nucleus is polarized towards stellate reticulum -superficial dental papilla cells differentiate into odontoblasts -begin secreting predentin which induces enamel matrix deposition by ameloblasts -ameloblasts migrate away from DEJ -enamel matrix begins process of mineralization |
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Term
Live Cycle of the Ameloblast Overview pt. 2 |
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Definition
-ameloblasts develop conical cellular projection (Tomes' process) -imparts a picket fence ocnfiguration to the ameloblast-enamel matrix interface -enamel organ collapses -consists of several layers pf flattened cells superimposed on a layer of post-secretoty ameloblasts =constitutes reduced enamel epithelium |
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Term
Developmental Stages of the Ameloblast |
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Definition
Presecretory Phase 1. Morphogenetic Stage 2. Differentiation Stage Secretory Phase 3. Secretory Stage Maturation Phase 4. Maturation Stage 5. Protective Stage |
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Term
| Developmental Stages of the Ameloblast Presecretory Phase 1. Morphogenetic Stage |
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Definition
-IDE cell comprise a cuboidal or low columnar epi -round, central nucleus -Golgi body oriented toward stratum intermedium |
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Term
| Developmental Stages of the Ameloblast Presecretory Phase 2. Differentiation Stage |
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Definition
-cells of IDE elongate -increase in size of nucleus and Golgi -organells shift nucleus = towards stratum intermedium Gogli = most of central and apical cytoplasm -junctional complexes at proximal and distal ends -cells now considered pre-ameloblasts |
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Term
| Developmental Stages of the Ameloblast Secretory Phase 3. Secretory Stage |
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Definition
-enamel matrix produced and deposited (4 microns/day) against mantel dentin -undergoes mineralization -inital enamel is structureless -ameloblast migrates towards stellate reticulum =forms Tomes' process
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Term
| Developmental Stages of the Ameloblast Secretory Phase 3. Secretory Stage Secretion of Enamel Matrix (2 sites) |
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Definition
1. Along periphery of the cell -forms an encircling wall around a pit -future interrod enamel
-Tomes' process fits into it 2. One surface of Tomes' process -secretes enamel matrix into the pit -future enamel rod Tomes' process degenerates at end of sevretory activity, therefore the innermost and outermost enamel is structurless
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Term
| Developmental Stages of the Ameloblast Maturation Phase 4. Maturation Stage |
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Definition
-occurs after enamel production is complete -ameloblast decreases in size -ameloblast decreases in organelle count -water + organic compounds removed via a. exocytosis b. extracellular enzymatic degradation -inorganic material (Ca) added to enamel matrix -trace amounts of enamel proteins introduced -configuration of junctional complexes changes -some ameloblasts die off |
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Term
| Developmental Stages of the Ameloblast Maturation Phase 4. Maturation Stage Cell Modulation |
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Definition
-cells develop alternating ruffled and smooth boarders of their apical membranes - ruffled = 80% of time - infusion of calcium - smooth = 20% of time - protein and water removal
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Term
| Developmental Stages of the Ameloblast Maturation Phase 5. Protective Stage |
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Definition
-ameloblasts secrete a basal lamina against the enamel surface -establish hemidesmosomes -ameloblasts protect enamel from cellular influences of the follicular connective tissue -enamle composition can still be modifies -epithelial breaks may result in connective tissue cells depositing cementum on the enamel surface |
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Term
Amelogenesis Maturation of Enamel |
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Definition
-organic matrix of early enamel = Amelogenins --> low MW proteins = Enamelins --> trace amounts -no matrix vesicles involved in mineralization (dentin does use vesicles for mineralization) -crystallization begins within the enamel matrix -at the ameloblast surface -some argue: inital nucleus is at dentin at the DEJ -as matrix matures, enamel proteins and water are gradually removed and calicum is added |
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Term
Amelogenesis Enamel Proteins (2)
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Definition
Amelogenins = 90%
Nonamelogenins = 10% |
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Term
Amelogenesis Enamel Proteins Amelogenins
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Definition
-large group of proteins -heavily degraded into tyrosine-rich amelogenin polypeptide (TRAP) and
-heavily degraded into leucin-rich amelogenin polypeptide (LRAP) -TRAP + LRAP eventually constitute most of organic matrix in maturing enamel -thought to regulate enamel growth in size -may serve as crystal nuclei -may prevent crystal nuclei from fusing during growth |
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Term
Amelogenesis Enamel Proteins Nonamelogenins (4 types) |
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Definition
-promote and guide crystal growth 1. ameloblastin 2. enamelin 3. tuftelin 4. proteinases |
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Term
Amelogenesis Enamel Proteins Nonamelogenins Ameloblastin |
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Definition
Contribute to mineral formation and crystal growth
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Term
Amelogenesis Enamel Proteins Nonamelogenins Enamelin |
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Definition
Contributes to crystal nucleation and growth |
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Term
Amelogenesis Enamel Proteins Nonamelogenins Tuftelin |
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Definition
Found in non-dental tissue as well Its role in tooth formation is unknown |
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Term
Amelogenesis Enamel Proteins Nonamelogenins Proteinases (2 Types) |
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Definition
1. Matrix Metalloproteinases rapid modification of newly-secreted matrix proteins 2. Serine Proteinase 1 bulk protein degradation
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