dentinogenesis ლ(╹◡╹ლ) Flashcards
covered everything❤️
when does dentinogenesis begin
at late bell stage or early crown stage
what is the role of the inner enamel epithelium (IEE) and odontoblasts in tooth development?
🦋IEE → Odontoblast Differentiation:
The IEE signals dental papilla cells to differentiate into preodontoblasts, which mature into odontoblasts.
Signals include BMPs and TGF-β.
🦋Odontoblasts → Ameloblast Differentiation:
Odontoblasts produce predentin, which sends signals back to the IEE.
This feedback induces the IEE cells to differentiate into ameloblasts.
where does dentinogensis begin
cusp tip or incisal edge then spreads towards cervical region and in multicuspid teeth begins independently at sites of each cusp tip then spreads down cusp slopes
what changes occur when preodontoblasts differentiate into odontoblasts
🦋shape changes from ovoid to columnar
🦋increase in RER and GOLGI complex for protein synthesis
🦋nuclei will move to the base (polarization)
🦋several processes form at the apical end for matrix secretion
why do odontoblast become rich in proline
proline is essential for collagen synthesis, forms organic matrix of dentin.
what happens to odontoblast as they secrete collagen
move backward leaving behind their cytoplasmic extension called odontoblastic processes
what are the main components of predentin
glycine , alanine, and proline ( amino acids for collagen synthesis)
predentin is non mineralized collagen matrix which acts as a scaffold for calcification.
what role does alkaline phosphatase play in dentin mineralization
🦋increases the phosphate availability 🦋promoting mineral deposition
what type of PH environment is essential for dentin mineralization
alkaline PH is required for crystal growth
how is collagen fibers aligned in predentin and how is that important
🦋collagen fibers align perpendicular to DEJ
🦋this structure supports organized crystal deposition
what is role of Dentin Phosphoproteins DPP
🦋 bind large amounts of calcium
🦋anchor calcium to collagen
🦋initiate hydroxyapatite crystal formation
how do hydroxyapatite crystals grow within collagen fibrils
initially deposited as fine plates on collagen surfaces then will grow within collagen fibers with long axis of crystals parallel to collagen fibrils
peritubular
highly mineralized than intertubular dentin
how do hydroxyapatite crystals in dentin differ from that of enamel
dentin crystals are 300 times smaller than enamel crystals which makes dentin less mineralized and more flexible
how does mantle dentin mineralization occur
odontoblast release matrix vesicles that contain hydroxyapatite crystals then the vesicles will rupture and the crystals will cluster forming globular masses that fuse to calcify dentin
what pattern of mineralization is characteristic of mantle dentin
globular mineralization
what are two types of mineralization in circumpulpal dentin
🦋globular ( calcospheric ) calcification: which can result in interglobular dentin if the masses fail to fuse
🦋linear mineralization :crystal growth from already mineralized dentin
where is the interglobular most commonly found
between mantle and circumpulpal dentin
when is secondary dentin formed
after root formation is completed
what is the rate of secondary dentin formation
1 micrometer per day
what distinguishes secondary dentin from primary dentin
it forms slower and has irregular organization of dentinal tubules creating demarcation line
when is tertiary dentin formed
in response to injury or irritation
how does the rate of tertiary dentin formation vary
increases with greater severity of injury
what happens to odontoblast during rapid tertiary dentin
it gets trapped within matrix leading to distorted tubule pattern
what structure starts odontoblast differentiation in root dentin
hertig epithelial root sheath HERS
how is radicular dentin different from coronal dentin
🦋forms slower
🦋collagen fibers align parallel to DEJ
🦋less mineralized than coronal dentin
what causes dentinogenesis imperfecta
🦋inherited structural deficiency in collagen formation
🦋 mutation in sialophosphoproteins DSPPG gene
how does dentinnogenesis imperfecta affect dentinal tubules
become disoriented and irregular
what happens to pulp chamber and root canals in dentinogenesis imperfecta
they are destroyed by abnormal dentin formation and leads to reduction pulp space
how does tetracycline stain dentin
it has strong affinity for incorporation into bone and dentin during early development
what are the color changes in tetracycline stained dentin
🦋initially yellow
🦋long term light exposure turns it grayish
why should tetracycline not be given to children
it should not be given in long term dosages to children whose teeth are forming due to risk of staining
when is fluoride incorporated into dentin
during active dentinogenesis
what is the effect of fluorosis in dentin
increases hardness of dentin
what dentin forms with age
secondary and tertiary dentin
why do dentinal tubules narrow with age
🦋secondary Dentin: It is deposited over time and narrows the dentinal tubules by filling the space between them.
🦋peritubular Dentin: becomes more mineralized with age, surrounding the tubules and increasing their density, which contributes to the narrowing of the tubule lumen.
sclerotic dentin
when tubules are filled with mineral as protective response reducing sensitivity
how does sensitivity change with age
🦋narrowing of tubules
🦋formation of dead tracts which is tubules filled with air
how many odontoblastic processes are exposed when 1mm of dentin is affected by caries?
30,000 exposed providing pathways for caries
