ex2 mature periodontium

Question 1

T/F cementum is vascularized

Answer 1

FALSE! The cementum is Avascualr - Not vascularized

Question 2

T/F both bone and cementum remodel

Answer 2

False. Bone does remodel,but cementum does not remodel.

– cementum is secreted through life, but it is not resorbed (unlike bone)

Question 3

T/F CEmentum is only secreted during cementogenesis

Answer 3

False. CEmentum is secreted throughout life – like dentin! but is is not remodeled (no resorption)

Question 4

Cementum is 50% inorganic, what is the main component of its inorganic composition?

Answer 4

Hydroxyapatite! like the other dental minerlaized tissues, hydroxyapatite is the reason for cementum mineralization

Question 5

what percentage of cementum is organic?

Answer 5

cementum is about 50% organic!.. composed of 90% collagen, most of it type 1 and some type 3

Question 6

what is the main kind of collagen in cementum?

Answer 6

Cemetum is 50% organic, and 90% of the organic layer is collagen – and 90% of the collagen is type 1 collagen!

Question 7

is the cementum thicker along the apex or along the CEJ?

Answer 7

CEmentum is much thicker along the apex of the root than it is around the CEJ where it is thin and vulnerable.

50 micometers at CEJ to 200 at the apex root

Question 8

How does the cementum function as protection?

Answer 8

The cementum covers the root dentin and thereby serves to protect it. Dentin is sensitive (recall= stimulation = PAIN) when exposed

Question 9

How do the cementum and enamel meet- up ?

Answer 9

When the cementum and enamel layers meet up at the CEJ, 60% usually the cementum overlaps a bit the enamel. 30% they meet evenly (no overlap = a butt joint) and 10% of the time they do not meet, exposing the dentin layer (sensitivity- esp w gingival recession) !

Question 10

Is primary or secondary cementum more minerlaized?

Answer 10

The primary cementum is more minerlaized than the secondary cementum (secindary cementum starts depositing about time of tooth eruption)… the dividing line bt the layers is about where the tooth emerges into the oral cavity

Question 11

The primary cementum is acellular– is it associated with intrinsic or extrinsic fibers?

Answer 11

Te primary cememntum contains AEFC- Acellular EXTRINSIC fiber cementum. conversely, the secondary cementum is associated with CELLULAR INTRINSIC fiber cementum

–

Question 12

why is primary cementum called acelluar extrincisc fiber cementum while secondary cememntum is called secondary Intrinsic fiber cementum?

Answer 12

The priamry cementum is acellular bc the cementoblasts escape and reside in the PDL.. fromt here, they secrete primary cementum matrix and therefore since not in the matrix itself, are called Extrinsic.

Conversel, the seondary cementum is formed by cementoblasts that reside within the minerlizing cmeentum.. so the cementum is cellular (contains the cementoblasts cells) and intrinsic bc the cementum matrix is made by cells residing within it

Question 13

T/F The secondary cementum, like the primary, has a major function in connecting the tooth to the PDL

Answer 13

False. while the primary cementum is very active in attaching the tooth to the PDL, the secondary cementum does NOT function for attachment. The secondary cementum however does attach to the PDL via the Sharpey fibers that reside in the secondary cementum

Question 14

what two fibers reside in the secondary cementum?

Answer 14

The secodary ceentum contain 2 fibers – the first is cementum fibers that lie parallel to the surface of root while the second fibers are SHARPEY FIBERS that are involved w attachment to the PDL. mixed fiber cemtnumn of hte secondary cementum is esp found at the root tips or multi-rooted teeth

Question 15

once cementoblasts get entrapped int he cementum matrix, they are called cementocytes. Are they still active in cementum production?

Answer 15

No. once cementoblasts become cementocytes, they no longer are active and do not make cementum

Question 16

T/F environmental factors have shown to influence the deposition of cementum?

Answer 16

True. Environmental factors such as inflammation have ben linked to increased speed of cementum deposition. – generally, cementum deposition is Very slow during life after the initial bulk of cemnetum has been laid down.. .. but with inflammation or crown attrition, the speed can increase resulting in a cnarrowing apical formaen (bc, development of cementum occurs from DCJ to apex.. and later in life = later in development and therefore at the apex of root)

Question 17

what is the cementoid?

Answer 17

The cementoid is a layer of unminerlaized cementum that is associated witht eh cellular cemntum (secondary). It is a lighter staining layer bt the secondary cementum and the periodontal ligaments that house the active cementoblasts (recall, escaped ffrom primary dentin)

Question 18

where are the active cementoblasts found?

Answer 18

Active cementovblasts are found in the PDL along th cementum border. recall, the cementoblasts escaped fromt he priarm cementum (making it acellular) while th cementoblasts fo the seocnary cementum becasme trapped cementocytes and inactive. // the cementoblsats have their long axis parallel to the CEJ

Question 19

Both enamel and dentin exhibit growth lines.. does cementum also have growth lines?

Answer 19

Yes@ like the other 2 minerlaized oral tissues that is secreted and laid down in layers, cementum also has visible growth lines demonstrating layered deposition. the layers stain more light.dark depending on variation in amount of calcification

Question 20

the word that describes “ excessively large amounts of cementum deposition “ is –

Answer 20

hypercementosis

hypercemetosis is where there is excessivley large amounts of cemntum deposited (can be seen as a large bulb at the apex.. practically as large as the developing crown)

Question 21

T/F the occurence of hypercementosis is common

Answer 21

False. Hypercementosis where there is a LARGE amount of cementum deposited is RARE