Dentin and Pulp Flashcards
The dentin supports the ________ and ______.
Enamel crown and roots of teeth
Within the dentin is _______.
Pulp cavity which is the living part of the tooth (alive cells)
Highly vascularized and innervated.
In enamel, the inner portion of the enamel organ differentiates into ameloblasts. What happens for the dentin precursor?
The dental papillae differentiate into odontoblasts.
Mineralization of dentin is similar to ______ and less than _____.
What properties does this give dentin?
Bone, Enamel
Elasticity (mechanically supports harder overlying enamel)
Tight Scalloped DEJ
Cementum and DEJ is less distinct
Dentin is made of how much
Inorganic material.
Organic material
Water
70% Inorganic (mineralized calcium hydrozyapatite crystals)
20% organic material (Type 1 ,3,4 collagen and non collagenous matrix proteins)
10% Water
What is the ___% organic material of dentin made up of?
20%
Type 1 collagen: Forms scaffold for mineral
Type 3 Collagen: First Secreted to make the pre-dentin matrix
Type 4 collagen
Non-Collagenous matrix proteins
What are the 3 types of dentin?
Primary
Secondary
Tertiary
What is primary dentin?
Circumpulpal - Dentin around pulp cavity
Peritubular
Intertubular
Mantle - DEJ - First dental laid down
What is secondary dentin?
Deposited after root formation
What is tertiary dentin?
Reparative dentin formed in reaction to caries and dental procedure
What is the first dentin laid down? What is laid second?
- Mantle dentin (forms DEJ)
- Circumpulpal Dentin
These two together make up primary dentin
What is the final dentin added?
Secondary layer after root formation that can occur even after tooth is growing since roots are growing them
A majority of dentin is made of _________.
Primary Circumpulpal dentin structure with peritubular and intertubular dentin.
There are tubules in circumpulpal dentin that run from the pulp cavity up to the enamel. Within them are odontocyte processes that lead into the pulp where odontocytes live.
Peritubular dentin surrounds these odontocyte process holding tubule
Intertubular dentin fills the space between each peritubular dentin surrounded tubule.
Where do odontocytes live?
Along the secondary dentin. They SHOULD NOT be in pulp.
Primary dentin, secondary dentin and tertiary dentin all contain odontocytes/blasts. True or false
FALSE
Primary does NOT. It does contain odontoblast processes in its tubules
Peritubular and Intertubular dentin are ________ mineralized.
Where are they located?
Highly
Peritubular- Wall of tubule
Intertubular- Between tubules
Primary Dentin is made of ____________ and is formed before completion of the ________.
What it its rate of deposition and mineralization?
Circumpulpal Dentin ( Peritubular + Intertubular dentin) + Mantle Dentin (First layer of dentin ever)
Apical foramen
Rapid formation, high mineralization
Secondary dentin is formed after the ____________ and is the ______layer.
What it its rate of deposition and mineralization?
completion of apical foramen
final
slow formation, low mineralization
Tertiary dentin is found as a ____________.
What does it look like?
result of localized injury to exposed dentin
irregular course of tubules
Tertiary dentin is cellularized. True or false?
True
Remember enamel spindles from enamel lecture! Where do they come from?
Enamel spindles are actually the distal end of odontoblast processes that are protruding out of the DEJ from the pulp.
Most of the dentin matrix is made of _________.
How are odontoblast processes held together?
Intertubular dentin
Canaliculus connecting different odontoblastic processes.
Pre-dentin is secreted at a rate of about ________.
It is mineralized or unmineralized ?
What is it made of?
4 micrometers a day
unmineralized
Collage Type I ( Low 3 and 5), dentin phosphoprotein, substratum for mineralization, odontoblasts secrete collagen
What secretes collagen _____ in the predentin?
1 (3,5)
Odontoblasts
Non-collagenous Matrix Proteins
KNOW FOR EXAM
- Dentin Phosphoprotein/phosphophoryn
- Dentin sialoprotein
- Dentin glycoprotein
- Dentin matrix protein
- Osteonectin - BONE PROTEIN
- Bone sialoprotein - BONE PROTEIN
- Osteopontin - BONE PROTEIN
Please Say Grace Made OraNge SorBet pOPsicles
P
S
G
O
BS
OP
Secondary dentin will be closest to the _____.
How fast does it deposit and what is the tubule ratio?
Describe histological image
Pulp chamber: Will be abundant at roof of pulp chamber to protect pulp horns
Slow; 1 micrometer a day
Few Tubules
There will be a bending of tubules between primary and secondary dentin. Will stain paler than primary dentin.
Tertiary dentin will appear ____________.
as sparse and irregular tubules
Forms in response to injury and odontoblasts differentiate at site of injury.
What is dentinogenesis and when does it begin?
Dentin creation; Bell Stage
Dentin precursor is an ___________ which differentiates from ___________ of ___________. They are induced by ____________.
odontoblast, ectomesenchymal cells of the dental papilla.
They are induced by pre-secretory ameloblasts of inner enamel epithelium.
Dentinogenesis starts at the __________ and later in the _________ driven by ________.
Cuspal region (cornonal dentin)
Root (Hertwig’s root sheath)
Describe the induction of odontoblasts.
Ameloblasts instruct a dental papilla cell to become an odontoblast after breaking down of the basement membrane.
This cell will increase in size and continue to multiply to create more odontoblasts. One of the cells will stay behind in the pulp to serve as a stem cell
Hertwigs root sheath ONLY produces dentin. True or false?
True; it induces root dentin formation before tooth eruption when the tooth is 2/3rds complete.
Deciduous teeth root formation finishes __________.
What about permanent teeth root formation?
18 months after eruption
2-3 years after eruption
Root development is a later occurring event in dentinogenesis. True or false
True
Preodontoblast cells are odontoblast precursors. What happens differentiated dental papilla cells have now become odontoblasts?
- Cells elongate
- More cytoplasmic organelles including RER and Golgi Complex
- Nucleus is polarized away from IEE(closer to pulp)
- Formation of odontoplast process that gets trapped just beyond DEJ
Odontoblasts are easy to replace. True or false?
FALSE; processes won’t grow back
The presecretory odontoblast has now become a secretory odontoblast. What are its characteristics?
Taller columnar cells with extensive RER, Golgi and secretory vesicles
Synthesize and elaborate extracellular material
SECRETE TYPE I COLLAGEN and ground substance extracellularly in the same way as fibroblasts
Secrete PRE-dentin.
Which collagen is secreted first? What is MOST of the dentin made of?
Collagen III
Collagen I
How do odontoblastic processes grow?
The apical surface of the process will embed in the enamel at the DEJ forming a SPINDLE.
As the dentin gets thicker towards the pulp, odontoblasts are migrating towards the pulp as well thus extending the processes into the dentin within tubules.
What is the first sign of dentinogenesis?
Type 3 collagen is deposited first and then Type 1.
Dentine matrix vesicles appear, grow and release matrix
THE DEPOSITION OF VON KORFF’S FIBERS - initiates predentin formation via Type III collagen fibers with fibronectin
What do Von Korff’s fibers look like?
There will be strings emitting from predenting
How does dentin calcify?
Mineralization tends to occur in small brown discrete areas called calcospherites.
The small regions eventually coalesce to form a globular solid mass of mineralized dentin.
They do not fuse completely we see regions of ucalcified Dentin called Interglobular dentin.
Where does dentin calcify?
Calcospherites
What is uncalcified dentin called?
Inter-globular dentin
What is a linear calcification? Which dentin does it occur most in?
Linear calcification is when mineralization progresses slowly. Calcospheroids are NOT formed here and mineralization is slower.
Occurs more in secondary dentin.
Peritubular dentin is ___% _____ mineralized than intertubulular dentin.
40% more
What is sclerotic dentin?
Occurs when dentinal tubules become occluded.
INCREASES WITH AGE
Will look dark due to dead tubules
Can occur due to caries lesions filling with bacteria, demineralized dentin due to increased acidity in mouth
What are the incremental lines of growth for dentin called?
Von ebner
Every 5 days there is a change in orientation of collagen fibers. Deposition is 4 micrometer every day.
What are Contour lines of Owen?
Exaggerated incremental lines that reflect changes in nutritional status or disease in the individual during the period of Dentin formation.
BIRTH CORRELATION
Pulp is derived from ___________.
Mass of dental papilla during the early bell stage.
Dental pulp is a ______.
Connective tissue
There are 4 zones in the pulp.
- Odontoblast
- Partially Cell “free” zone of Weil
3.Cell Rich Zone
4.Pulp Core
Why is the cell free zone important?
There are less cells and more extracellular matrix in order to allow for distribution of nerve fibers in the pulp.
Nerve fibers can penetrate ______-
dentin tubules
Dentin has sensitivity!
Does enamel have nerve involvement?
NO
What are other cells in the pulp?
Fibroblast that make pulp matrix
Undifferentiated ectomesenchymal cells (dental pulp stem cells). They transform into fibroblasts or odontoblasts if needed.
Macrophages
T- Lymphocytes
Dendritic cells (antigen presenting)
Why are undifferentiated ectomesenchymal cells important?
Undifferentiated cells can transform into fibroblasts or odontoblasts if cell population is reduced after injury.
What are dendritic cells?
Antigen presenting in PULP
What collagen types were seen in pulp?
Glycosaminoglycans
Glycoproteins
Water
Collagen 1 and 3
What is the specific name for BV in pulp?
Fenestrated Capillary Plexi
Innervation pattern of pulp
Cranial nerves enter through apical foramen of individual teeth and grow as bundles into pulp into the Cell-FREE Zone
When they get to the cell-free zone, they split off and find an odontoblast to track it to the dentin tubule
What can cause pain from dentin?
Cold air,water
Mechanical contact
Dehydration
What happens to pulp as we age?
There will be a decrease in volume of chamber due to continue deposition of dentin.
There will be a reduction of vascular supply
Cell density will be reduced with increase of fiber bundles
There will be a loss of axons and pulp sensitivity
Calcification
There will be a reduction in the diameter of the tubules
There could be a complete closure of the tubules by sclerotic dentin
Increased brittleness
Contraction of odontoblastic process, or death of ole blast found near Apex
What are pulp stones?
Calcification blobs in pulp
