Cementum Flashcards
What is the percentage of organic and mineral components of cementum?
50-50
What are the organic components of cementum?
-type I collagen
-proteoglycans
-glycosaminoglycans
-phosphoproteins
What are the functions of cementum?
-provide attachment for PDL
-provide limited compensation for occlusal wear through continuous apical apposition
-may participate in repair of root fracture
What is the origin of cementum?
neural crest cells
Is cementum vascular?
nope
Where is cementum the thinnest?
at the CEJ
-increases in thickness as it goes down the root
(90-150 microns at mid root )
(150-300 microns at the apex)
What are cementoblasts?
cells responsible for secreting the organic matrix of cementum
What zone of dental follicle do cementoblasts come form?
inner
When does differentiation of cementoblasts start?
when there is disruption in hertwigs root sheath
-allow the cells to make contact with the dentin
-dentin matrix growth factors induce the differentation (BMP, FGF, DMP)
How do all the mesenchymal cells become cementoblasts?
the growth factors leak out of the pores and activate the cells into the cementoblasts
What are depositional and reversal lines?
growth lines in cementum
-indicate incremental growth
-run longitudinally within the cementum
What are cementocytes?
cementoblasts that have been mineralized
What are lacunae?
space occupied by acell
What are canaliculi?
space occupied by cytoplasmic projections
What are sharpey’s fibers?
extensions of PDL into the cementum
Is cementum poruous?
yes very
What is the most common type of CEJ?
overlaping
-there is some overlap between the cementum and enamel
Is there is a gap between the cementum and dentin waht can happen? q
the dentin is exposed
-this can cause sensitivty to the tooth
What is abfraction?:
loss of tooth surface at cervical areas of teeth causes by tensile or compressive forces during tooth flexure
deep & narrow
non-carious
Is abfraction carious?
no
What are the charactertistics of abfraction?
deep
V shaped
narrow
What is abrasion?
loss of dental tissue by foreign object (brushing teeth too hard)
wide & shallow
What are characteristics of abrasion?
located at cervical areas
-wide and diffuse
-canines and premolars most commonly affected
What are cementicles?
calcified bodies on or in the cementum and in the PDL
-can be free, attached, or embedded
What causes the formation of cementicles?
local trauma or hyperactive occlusion and increase with age
What are cemental spurs?
projections fo the cementum into PDL in response to trauma
-makes it hard to extract the tooth
Is it okay if cementum is exposed to the oral cavity?
no not really
What happens to exposed cementum?
becomes hypermineralized which prevents the reattachment of collagen and PDL
-will also allow for build up of plaque and calculus
-facilitates endotoxin absorption
-becomes less porous
What is a treatment for exposed cementum?
scaling and root planing
-will remove the built up plaque and calculus
-can also remove the top layer and may allow for new tissue to grow in
What is hypercementosis?
excess production of cellular cementum that generally involves the apical 1/3 of the root
What causes hypercementosis?
trauma from occlusion, periapical inflammation, or compensation for occlusal attrition
What are accessory canals in the cementum>
lateral canals that allow for vasculature to supply the entire tooth
-the number of canals increase as you move toward the apex of the root
