Term
| Physical Properties of Mature Dentin |
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Definition
-forms bulk of the tooth -yellow in color -slightly elastic allowing for deformation of the tooth under occlusal stresses -living tissue = traversed by odontoblast processes -radiographically darker than enamel more radiolucent -radigraphically lighter than cementum more radiopaque
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Term
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Definition
By Weight: -70% inorganic -20% organic -10% water (a bit harder than bone) By Volume: -45% inorganic = hydroxyapatite
-33% organic = mainly type I collagen, glycosaminoglycans., proteoglycans, phosphoproteins
-22% water |
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Term
Odontoblast Processes and differences b/t odonoblast process and odonoblasts (cytologically) |
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Definition
-extend into dentin Differs in that odonoblast process: -lacks organells except for mitochondria enclosed by predentin -many parallel microtubules and microfilaments -process and apical part associates with predentin modified for exocytosis and endocytosis |
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Term
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Definition
-extend through the full thickness of dentin -reflect course taken by odontoblasts = bend pathways due to the crowding of odontoblasts as they move towards the pulp -curve most evident in coronal dentin except under incisal edges and cusp tips where its almost straight -run almost straight in the root dentin (cervical 1/3 of root) -primary curve = due to crowding, large curve -secondary curve = small bends in path of tubeules (reflects individual paths of odontoblasts)
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Term
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Definition
-change in diameter of tubule: 2.5 micrometer near pulp, 900nm at DEJ -change in number of tubules per unit area: more tubules near pulp reflecting crowding of odontoblasts as they approach the pulp |
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Term
Dentinal Tubules Lamina Limitans |
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Definition
-organic sheath -lines the dentinal tubules Tubule contains the odontoblast process, tubular fluid, small nerve fibers, and lamina limitans (exact tubular contents are under debate) |
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Term
Dentinal Tubules Tubule Branching major & fine & microbranches |
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Definition
Major - terminal branches of tubules - seen more frequently at root dentin Fine - more common in root dentin as well - branch from main tubule at 44 degree at 1-2 micrometer intervals Microbranches (canaliculi) - branch at right angles from the tubules
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Term
Dentinal Tubules Dead tracts |
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Definition
-type of age change -odontoblast process retracts or associated odontoblat dies -space that forms is filled with air -appears black on ground section -usually seen in coronal dentin -tells you somehting happened in that area |
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Term
Intratubular (peritubular) Dentin |
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Definition
-hypermineralized (40% more than intertubular) -hypocollagenized rim of dentin within tubule only when viewed in cross section -narrows the lumen of the tubule -result of slow depression of highly mineralized dentin
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Term
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Definition
-main component of dentin -tightly packed network of type I collagen -HAP matrix -more organic matrix than intratubular dentin |
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Term
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Definition
-run at right angles to the tubules and represent rhythmic patterns of dentin deposition 1. Lines of Von Ebner 2. Contour Lines of Owen 3. Neonatal Line |
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Term
Incremental Lines Lines of Von Ebner |
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Definition
-lines existing about 20 µm apart -represent 5 day cycles of dentinogenesis |
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Term
Incremental Lines Contour Lines of Owen |
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Definition
-linear band -due to a coincidental movement of odontoblast -basically an exaggerated secondary curvature |
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Term
Incremental Lines Neonatal Lines |
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Definition
-prominent contour line -formed by disturbance in mineralization -disturbance due to abrupt physiological change occuring at birth
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Term
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Definition
-unmineralized or hypomineralized areas b/w calcoshperites where they have failed to fuse -pronounced if there were: -low levels of vit D -high fluoride levels during dentinogenesis -usually below mantle dentin at interface with circumpulpal dentin -tubules are present in interglobular dentin (b/c it a defect of mineralization not deposition) -NO INTRATUBULAR DENTIN |
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Term
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Definition
-seen only on ground section -granular layer just below DCJ within dentin -increasing density from CEJ to root apex -may be due to looping terminal portions of dentinal tubules -may be due to arrangment of collagen and other matrix protein -real reason unknown -no clinical sig |
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Term
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Definition
-present along entire pulpal surface -develops after root fromation is complete -apical foramen has been established -continuing slow deposition of dentin formed throughout life -less regular structure - tubules waiver -unevenly deposited around pulp periphery -molars = deposited on roof + floor of pulp chamber -causes reduction of size of pulp chamber
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Term
Dentin is NOT normally exposed to the oral cavity |
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Definition
Unless: 1. absence of enamel/cementum (at exposed CEJ, amelogenesis imperfects) 2. attrition 3. trauma/caries |
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Term
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Definition
-protective function for pulp -produced in response to trauma, caries, irritation, and dental procedures -produced only by odontoblasr that are directly affected by the stimulus -undergoes rapid deposition (more severe injury = faster deposition) -tubules may be reduced in number, irregular, or absent -osteodentin - tertiary dentin that has incorporated its formin odontoblast |
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Term
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Definition
Tertiary dentin that has incorporated its formin odontoblast
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Term
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Definition
-dentinal tubules that have become occluded with calcifies material -when it occurs over broad area: tubules have a glassy, transparent appereance on ground section -due to deposition of calcium salts in and around degenerating odontoblas processes -protects the pulp by reducing dentin permeability -resulting tissue is harder and denser than normal dentin |
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Term
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Definition
1. Exposed tubules - painful (exposed dentin) 2. Dental procedures - production on tertiary dentin 3. Sensitivity - may be due to exposed tubules 4. Formation of dentin through life - secondary dentin 5. Indirect pulp capping - placement of irritant causing tertiary dentin to form 6. Must avoid dehydration - no water = brittle dry out by removing pulp (RC) - need a crown
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