Dentinogenesis Flashcards
What is dentine made up of?
70% mineral - hydroxyapatite
20% organic matrix, collagen type I, dentine phosphoproteins, proteoglycans and lipds
10% water
Odontoblasts are dervived from what cells?
ectomesenchymal cells of the dental papilla
what tooth development stage does dentine formation take place?
end of bell stage
what location of the tooth does dentine formation start?
cusp tip
what are the 3 stages of dentine formation?
- cytodifferentiation
- matrix formation
- mineralisation
what cells signals to the dental papilla cells to divide and mature in odontoblasts?
Inner enamel epithelial cells
What cells signal to the IEE cells to mature into ameloblasts?
Dental papilla ectomesenchymal cells
What is the first stage of dentinogenesis?
dental papilla cells divide
What is the second stage of dentinogenesis?
cells enlarge and cross acellular space
what is the third stage of dentinogenesis?
in enlarged cells increase synthetic and secretory organelles (RER, mitochondria vesicles etc) - matured into odontoblasts
What is the 4th stage of denintinogenesis?
the odontoblasts secrete the organic matrix - pre-dentine
what is the 5th stage of dentinogenesis?
the odontoblasts retreat secreting predentine, giving rise to odontoblast processes
what is the 6th stage of dentinogenesis?
predentine mineralises forming dentine
the basal lamina disitegrates
The basal lamina disintegrating, signals for the start of what process?
signals start of enamel formation
what happens in the initial mineralisation stage of dentinogenesis?
matrix vesicles are involved
the crystals grow in these MV and aggregate obscuring collagen
the basal lamina disintegrates - signals start of enamel formation
What occurs in mineralisation of dentine?
hydroxyapatite crystals are formed
they mineralise in spherical form (globular)
= calcospherites
- these eventually fuse
what type of dentine do you get when calcospherites fail to fuse?
interglobular dentine
what is the first primary dentine formed?
mantle dentine
where is mantle dentine found?
adjacent to enamel (ADJ)
what is the differences with collagen fibres in matle vs circumpulpal dentine?
mantle - large collagen fibrils at 90 degrees to the ADJ
circumpulpal - small collagen fibrils parallel to the ADJ
what dentine is slightly less mineralised, mantle or circumpulpal?
mantle - by 5%
what is larger mantle or circumpulpal
Circumpulpal - rest of the dentine
mantle is only 150 micro millimitres
what type of dentine is mineralised via heterogeneous nucleation, and contains no matrix vesicles?
circumpulpal
what are the incremental lines of dentine?
incremental lines of von ebner
what shape is the odontoblast track as it retreats back?
S shaped
