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Dentin

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aknight1302's version from 2015-11-17 16:42

Dentin

Question Answer
Where do you find the oldest Dentin?at the DEJ
Where do you find Pre-dentin?against the PULP... or at Pulp-Dentin Junction (b/c this is where new dentin is being formed)
Direction of Dentin, old to newfrom DEJ to Pulp
Direction of Dentin, new to oldfrom Pulp to DEJ
Are Dentin Tubules wider toward the pulp, or toward the DEJ?Wider toward the pulp, narrower toward the DEJ
Are Dentin Tubules narrower toward the pulp or toward the DEJ?Narrower toward DEJ, Wider toward Pulp
Dentin Tubules branch and interconnect where?area near DEJ... believed to involve communication? (more branching in root, less in crown)
Peritubular (INTRAtubular) dentindentin that makes WALLS of tubules... more mineralized, denser than dentin between tubules
INTERtubular Dentindentin between tubules. and not adjoining the tubules. LESS DENSE, LESS MINERALIZED
Mantle Dentininitial deposition @ DEJ (first dentin formed..., first we'll hit with bur when prepping)
Primary Dentin (formation and where)?from start until functional loading (against DEJ) (same as Mantle Dentin)
Secondary Dentinformed under functional loading (and after root completion, they coincide) (formed throughout life)
Tertiary Dentincreated in response to trauma or caries
Predentinunmineralized dentin matrix, being formed, adjoining pulp
Which forms faster, 2-ary or primary Dentin?primary dentin forms faster, as functional load is added, formation slows
Tubules alter their orientation at what formative step?shift from primary to secondary dentin
What type of dentin forms in response to caries or trauma?TERTIARY Dentin (may engulf odontoblasts) LOCALIZED to irritated area
Why is it harder for bacteria to go through TERTIARY DENTIN?because tubules become narrower (if present) or disconnect... matrix MAY or MAY NOT have tubules (like blocking a door in a horror movie)
What type of cells make Tertiary Dentin?Odontoblast-LIKE cells (generated from stem cells in response to caries/trauma) (like blocking a door in horror movie)
These cells do not divide, also they create mineralized product by first laying down a collagen matrix and then mineralizing...Odontoblasts
Dead Tracts (what are they?)(more/less susceptible to bacterial invasion?)left behind dentin tubules after death of ODONTOBLASTS, walled off by tertiary dentin, dead tracts are more susceptible to bacterial invasion
Sclerotic Dentinminerals deposited in Dentin Tubules...
Dentin that has a "glassy appearance"Sclerotic Dentin, Dentin tubules filled w/ minerals... harder and more brittle
Age associated changes in Dentinsclerotic toward pulp, dentin becomes chalky (compromises the mechanical properties of dentin) this is why you can more easily break tooth as you get old
What type of dentin is deposited in response to trauma or infection?TERTIARY dentin
What FIBERS make up the majority of PRE-DENTIN?Coll fibers (perpendicular to odontoblasts)
What FIBERS are larger and run PARALLEL to ODONTOBLASTS?von Korff's fibers
What cell in the tooth is most like Osteocytes, having extensive branching connections between cells?Odontoblasts
What are Tomes' Fibers?extensions of odontoblasts within dentin tubules, part of cell body, connect to DEJ (branching near DEJ w/ extensive connections between cells)
What is the mineral composition of PRE-DENTINUNMINERALIZED
Most mineralization of dentin is done by ____ mineralizationGLOBULAR (secretory vesicles)
Rank Enamel, Bone, and Dentin in terms of hardnessEnamel > Dentin > Bone
True or False: Dentin is a non-vital tissuefalse. DENTIN is a VITAL mineralized tissue
Is dentin tubule branching more extensive in the CROWN or in the ROOT?ROOT
Sheath of high-calcium dentin surrounding each tubuleIntratubular (Peritubular)
Dentin BETWEEN tubules is what type of dentin?INTERtubular Dentin
Which is harder, Intratubular Dentin or Intertubular Dentin?INTRATUBULAR
In terms of tertiary dentin, if the causing "insult" is MAJOR then the tertiary dentin is typically laid down by ____ cells, at what rate and how organized?Odontoblast-like cells, laid down very quickly, ad haphazardly
What are DEAD TRACTS?these are EMPTY dentin tubules, where the odontoblasts have died or tomes' processes have receded
What can be used to fill dentin tubules (in sclerotic dentin)?Intratubular Dentin or Calcium deposits (this is done WITHIN the Odontoblastic process, not a "dead tract")
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Microanatomy Test 4 pt. 2