Tooth histology Flashcards
Enamel
made by amelogensis and dissappear forever after
has varying thickenss from pits and fissure. no capacity to heal
pH ranges for dentin and remin
under 5.5 will demineralize and above 5.5 will remineralize
microscopical enamel
aceulluar avascular non dynamic
Enamel chemistry
90-92% 95-98% by weight of inroganix hydroxyapetite crystals
1-2% organic proteins
4-6% water
Enamel Rod Structural Unit
millions parallel
From DEJ to surface
it is subtle wavy
Length of Enamel Rod
avg length is longer than DEJ to surface line
One rod circumference
wider at the surface than at DEJ without woul be porous at surface
meets the DEJ at 90degrees
Cross Section of Rod shape
have a little tail and not perfectly round,
Inter rod substance
Aka rod sheath - is the water and protein
apatite crystals
are usually hydroxyapetite, and make up the rod substance
Things that mess with enamel
caries dissolbe, acid, dentists, teeth wear, things wear, cracks and breaks
Dentin Function
support of enamel.
Sensitive porous permeable
dynamic - can change
Structural Units of Dentin
Dentinal Tubules - pore in dentin
Peritubular Dentin - located around the tubule and hypermineralized
Intertubular Dentin- dentin between tubules and peri
AT DEJ tubule looks
many holes
Tubules are smallest at DEJ and increase in diamter as it goes to the pulp
Meaning there is more intertubular dentin at the DEJ
Intertubular Dentin histology
Type I collagen,
small crystals fill the spaces sooooo much like so salty
water is up in it
What is in the tubules
the odontoblast cell process and dentinal fluid aka mostly water
What happens to tubule upon extraction
it will dry up and the cell process goes away
odontoblast ell looks
columnar cell body
with extention up tubule
in the outer pulp inner dentin
Primary Dentin
dentin upon eruption (original)
Secondary Dentin
slow down production, we dont stop making it but slow it down
phsyiologic secondary dentin
either normal aging dentin, more irregular in shape pulp slowly gets smaller
reparitive dentin
made in sreponse to trauam. Reults in smaller pulp
This is done for protection
sclerotic dentin
through time or insult peritublear lays down more dentin for protection
resulting in less sensitive pulp less vulnerable
Pulp loks for young vs old.
pulp is big for a kid
Collateral Circulation
the pulp has no help from other vessels if there is drama
There is also no space for expansiion so many issue can happen
Functions of pulp
crucial in primary dentin, but after not needed
indirect fucntion is feeling pain
histology of pulp
depends on the person, it is vascular collagen and gorund substace
has odontoblasts lymph and blood vessels
also has asensory stuff
Sensory innervation
c fibers - send inflammation pain signals for dull pain from deep carries
A alpha fibers and A delta fibers - respond to fluid in wall of pulp send quick sharp pain that goes away quick
zone of weil
cell free zone below odontoblast layer location of cpaillary and blood vessel is below this
Principle fibers vs sharpays fibers
main fibers are the principle onees and the sharpays goes in tooth and bone to embed in alveolar bone connctino
cementum
hard covers clinical root, supportive. aceullar
except apical third is cellular
hard as bone
