Cementum Flashcards
Secondary cemetum is less or more mineralized than primary cementum?
less
where are progenitors for 2ndary cementum likely from?
endosteum of alveolar bone
where are progenitor cells for secondary cementum unlikely to be from?
from residual dental follicle cells in PDL
Does primary cementum form before or after breakup of hertwigs epithelial root sheath?
after, the cells of dental follicle reach the root surface
initially, cementoblasts insert processes into the
unmineralized hyaline layer
does the hyaline layer mineralize before or after the mantle dentin?
after
is the hyaline layer more or less mineralized than the cementum or dentin?
more
what does the hyaline layer do?
“cements” cementum to dentin
what does HERS do for the mantle dentin of the root?
induces it to form initially
What percent of cementum is inorganic and organic?
60/40
What do cellular cementum cementoblasts express that are bone like?
Type 1 collagen, alkaline phosphatases, osteocalcin,PTH cell surface receptors
What can induce acellular cementum cementoblasts?
Epithelial derived molecules, like enamel proteins and emdogain
Is the hyaline layer enamel like?
yes
Primary acellular intrinsic fiber cementum, does not have a surface cementoid, and contributes minimum function of tooth attachment/ it Forms a ___ microm thick fibrous fringe to which PDL collagen fibers eventually connect via_____
15-20 microns thick, and relies on lysyl oxidase/Cu2+ crosslinking
Primary acellular EXTRINSIC fiber Cementum constitutes the _____ of the primary cementum type and gets its collagen fibers from PDL fibroblasts. It extends from the CEJ towards the ___ of the tooth and covers about ____ of the coronal portion of the root. And it is relatively_____
Bulk of primary cementum type, goes to apex of root, covers 2/3 of the coronal portion of the root. It is relatively structureless
The average thickness of primary acellular EXTRINSIC fiber cementum decreases/increases apically
increases
Does Primary acellular EXTRINSIC fiber cementum contain cementoblasts? if so where are they? Is there a surface cementoid?
Yes it has cementoblasts, they migrate towards the PDL and ultimately reside on periphery, facing the PDL. It does NOT have a surface cementoid.
Secondary cellular INTRINSIC fiber Cementum is a major/minor component o the 2ndary cementum fiber type, its is only found on anterior/posterior teeth, its only on the apical ____of the root or in the _____ area of multirooted teeth. It has/does not have a surface cementoid, and a miniamal function in tooth attachment.
It is a minor component, found variably but only in posterior teeth, located in apical 1/3 of root and in interradicular area of mutirooted teeth. it DOES have a surface cementoid.
Secondary celullar MIXED fiber cementum constitutes the BULK of the 2ndary cementum type , it is also located at apical 1/3 of root, its microscopic features include….
cementocytes in lacunae, also have cell processes enclosed in canaliculi going towards PDL, lamellar/laminated structure, surface cementoid preset, no OSTEONs and no SYNCYTIUM formed by cell processes
2ndary cellular MIXED fiber cementum is important because…
its variability is likely an indicator that it is required for adaptve function
Whats the deal with acellular afibrillar cementum?
usually not found in humans its on enamel and its not supposed to be there really
whats the deal with intermediate cementum? Where is it located? Does it have a function in tooth attachment? Hint: it collects garbage
its incorrectly called a synonym for the hyaline layer, its actually a for of Secondary Cellular INTRINSIC fiber cementum.it is only located at the apex of the tooth. It contains entrapped residual cell debris from either the HERS or the odontoblast layer. It does NOT have a function in tooth attachment
What’s with mixed stratified cementum?
Consists of alternating layer of acellular EXTRINSIC and CELLULAR INTRINSIC cementum. Located at APEX , it functions in response to adaptive needs of the tooth.
From inside to outside, what are layers of pulp to mantle dentin?
Pulp, tertiary dentin, secondary dentin (circumpulpal then mantle dentin)
Is circumpulpal dentin thicker than mantle dentin? How thick is mantle dentin?
Yes it is thicker, mantle dentin is only 150 microns wide and lacks phosphophoryn protein
Is mantle dentin more or less mineralized than the rest of the primary dentin?
less
how wide is the hyaline layer?
ten microns
is acellular cementum primary or secondary?
primary
is cellular cementum primary or secondary?
secondary
what is mean thickness of cementum as it increases apically? From CEJ to mid root to apex?
50 microns at CEJ
120-160 at mid root
200-250 at apex level
what is HERS?
2 cell layer extension of reduced enamel epithelium that induces mantle dentin formation in root. Coronal aspect eventually deteriorates bc of breakup of basement membrane. HERS cells secrete hyaline layer adjacent to mantle dentin. HERS cells finally migrate towards PDL and die a little bit, leave epithelial cell rests of Malassez
what are intrinsic fibers?
fully mineralized fibers that help organize mineralization process. Made by cementoblsts
what are extrinsic fibers?
made by PDL fibriblasts to help connect root to alveolar bone
