Dentinogenesis

Question 1

What is dentine made up of?

Answer 1

70% mineral - hydroxyapatite
20% organic matrix, collagen type I, dentine phosphoproteins, proteoglycans and lipds
10% water

Question 2

Odontoblasts are dervived from what cells?

Answer 2

ectomesenchymal cells of the dental papilla

Question 3

what tooth development stage does dentine formation take place?

Answer 3

end of bell stage

Question 4

what location of the tooth does dentine formation start?

Answer 4

cusp tip

Question 5

what are the 3 stages of dentine formation?

Answer 5

• cytodifferentiation
• matrix formation
• mineralisation

Question 6

what cells signals to the dental papilla cells to divide and mature in odontoblasts?

Answer 6

Inner enamel epithelial cells

Question 7

What cells signal to the IEE cells to mature into ameloblasts?

Answer 7

Dental papilla ectomesenchymal cells

Question 8

What is the first stage of dentinogenesis?

Answer 8

dental papilla cells divide

Question 9

What is the second stage of dentinogenesis?

Answer 9

cells enlarge and cross acellular space

Question 10

what is the third stage of dentinogenesis?

Answer 10

in enlarged cells increase synthetic and secretory organelles (RER, mitochondria vesicles etc) - matured into odontoblasts

Question 11

What is the 4th stage of denintinogenesis?

Answer 11

the odontoblasts secrete the organic matrix - pre-dentine

Question 12

what is the 5th stage of dentinogenesis?

Answer 12

the odontoblasts retreat secreting predentine, giving rise to odontoblast processes

Question 13

what is the 6th stage of dentinogenesis?

Answer 13

predentine mineralises forming dentine
the basal lamina disitegrates

Question 14

The basal lamina disintegrating, signals for the start of what process?

Answer 14

signals start of enamel formation

Question 15

what happens in the initial mineralisation stage of dentinogenesis?

Answer 15

matrix vesicles are involved
the crystals grow in these MV and aggregate obscuring collagen
the basal lamina disintegrates - signals start of enamel formation

Question 16

What occurs in mineralisation of dentine?

Answer 16

hydroxyapatite crystals are formed
they mineralise in spherical form (globular)
= calcospherites
- these eventually fuse

Question 17

what type of dentine do you get when calcospherites fail to fuse?

Answer 17

interglobular dentine

Question 18

what is the first primary dentine formed?

Answer 18

mantle dentine

Question 19

where is mantle dentine found?

Answer 19

adjacent to enamel (ADJ)

Question 20

what is the differences with collagen fibres in matle vs circumpulpal dentine?

Answer 20

mantle - large collagen fibrils at 90 degrees to the ADJ
circumpulpal - small collagen fibrils parallel to the ADJ

Question 21

what dentine is slightly less mineralised, mantle or circumpulpal?

Answer 21

mantle - by 5%

Question 22

what is larger mantle or circumpulpal

Answer 22

Circumpulpal - rest of the dentine
mantle is only 150 micro millimitres

Question 23

what type of dentine is mineralised via heterogeneous nucleation, and contains no matrix vesicles?

Answer 23

circumpulpal

Question 24

what are the incremental lines of dentine?

Answer 24

incremental lines of von ebner

Question 25

what shape is the odontoblast track as it retreats back?

Answer 25

S shaped