Dentine

Question 1

Dentine

Answer 1

-forms the bulk of the tooth
-sensitive tissue
- formed throughout the life
- large no. parallel tubules in a mineralized collagen matrix
- the tubules contain the processes of odontoblasts

Question 2

Physical properties of dentine

Answer 2

fresh dentine is pale yellow
- stronger than cementum and bone but softer than enamel
-high compressive tensile & flexural strength
- permeable , depending on the patency & size of the tubules

Question 3

Inorganic compositions

Answer 3

calcium hydroxyapatite poor in calcium and carbonate rich , much smaller than the enamel hydroxyapatite

Question 4

where can u find the hydroxyapatite ?

Answer 4

on and between the collagen fibrils

Question 5

Organic compositions

Answer 5

collagen type I
gla-proteins
dentine phospho-proteins
acidic proteins
lipid & growth factors

Question 6

chemical composition -organic matrix

Answer 6

90% of the organic matrix is made of collagen type 1

Question 7

Phosphoryn

Answer 7

most acidic protein known
- due to high calcium concentration -> mineralization
- main phosphoprotein in dentine

Question 8

Proteoglycans

Answer 8

organic matrix
main proteoglycans are biglycan and decorin
- important role in collagen assembly / may have role in mineralization

Question 9

which organic component has an important role in collagen assembly ?

Answer 9

proteoglycans

Question 10

Gla proteins

Answer 10

organic compositions
alpha carboxyglutamate
low amount in dentine
bind strongly but reversibly to hydroxyapatite crystals

Question 11

Growth factors are absorbed from ?

Answer 11

circulating tissue fluid

Question 12

phospholipids may be involved in the formation and growth of ….

Answer 12

apatite crystals

Question 13

dentine tubules they extend from which junctions ?

Answer 13

from the pulp surface to the amelo- dentinal and the cemento dentinal junctions

Question 14

tubules follow a … course ?

Answer 14

curved sigmoid

Question 15

Dentine tubules are circular in which section?

Answer 15

cross sections

Question 16

intertubular dentine

Answer 16

dentine between tubules

Question 17

the tubules are 2.5 micrometer at the …. and 1 microm at the ..

Answer 17

pulpal end .. enamel end

Question 18

when does the denitne tubules become closer to each other?

Answer 18

odntoblast retreats inward .. occupying smaller area

Question 19

contour lines of owen?

Answer 19

secondary curvatures .. if they coincide (occur at the same time ) in adjacent tubules

Question 20

intratubular dentine ?

Answer 20

lacks collagen matrix

Question 21

The inorganic material in the peritubular dentine is ?

Answer 21

carbonated apatite , different crystalline than the intratubular dentine

Question 22

what are the contents of the dentinal tubules ?

Answer 22

odontoblastic processes
afferent nerve terminals
antigen presenting cells processes
extracellular dentinal fluid