Pulp

Question 1

Why is pulp unique as a tooth tissue?

Answer 1

vascular and not calcified

Question 2

pulp embryonic origin

Answer 2

ectoderm; neural crest ectomesenchyme - dental papilla

Question 3

What does pulp contain?

Answer 3

cells and cellular elements (endings of n fibers), blood and lymphatic vessels, ECM

Question 4

Fxn of pulp in mature tooth?

Answer 4

hydrates dentin, protective, defensive, reparative

Question 5

Functions in development

Answer 5

inductive - take from bud to cap stage

formative

Question 6

what is the formative function of odontoblasts?

Answer 6

secrete organic matrix of dentin, and participate in mineralization

Question 7

DSPP

Answer 7

abundant in dentin, >50% NCP in dentin, binding sites for collagen, highly phosphorylated, high in serine/aspartic acid (neg charged)

Question 8

what stage does dentinogenesis begin?

Answer 8

bell stage

Question 9

which direction does dentinogenesis occur?

Answer 9

cusp tips to cervix and from periphery to pulp center

Question 10

What induces odontoblast differentiation?

Answer 10

secreted molecules from enamel organ- inner layer OR in molars the 2˚ enamel knots (epithelial-mesenchymal interaction)

Question 11

2 forms of ectopic calcifications in pulp

Answer 11

pulp stones: spherical calcified masses (most common in pulp chamber)
diffuse calcifications: irregular areas of calcification (common in root)

Question 12

function of PG and GAGs

Answer 12

matrix for diffusion, collagen fibrillogenesis, water retention

Question 13

What measures suggest formation of new dentin and pulp with stem cells?

Answer 13

vascular flow improved, width of apical foramen deceased, sensation improved (decrease threshold for pulp testing) and length of root increased

Question 14

DPSCs functions

Answer 14

anti-inflammatory, secrete trophic factors promoting angiogenesis and neurogenesis

Question 15

What does G-CSF do?

Answer 15

keeps DPSC’s in the area, b/c have G-CSF receptors, attract other stem cells from surrounding tissues, anti-apoptotic and proliferative effects

Question 16

What is 2nd most numerous cell type in pulp?

Answer 16

odontoblasts

- fxns = dentinogenesis, nutrients to dentin, immune

Question 17

Why do odontoblasts have cytoskeletal elements?

Answer 17

for protein transport (microtubules) and structural integrity (microfilaments)

Question 18

What type of junctions are b/t odontoblasts?

Answer 18

desmosomes and adherens: “sticky” maintain position and polarity
gap jxn: channels b/T cells; coordinate dentinogenesis

Question 19

Where are the types of jxns located?

Answer 19

adherens: apical aspect of ODB
desmosomes: lateral aspect
gap jxn: basal aspect

Question 20

Where are tight jxns found and what do they do?

Answer 20

apical portion of ODB, form at least a partial barrier to diffusion of substances b/t odontoblasts into pulp; inter-cellular barrier

Question 21

What type of neural control is pulp under?

Answer 21

autonomic NS, sympathetic, sensory

Question 22

What is the importance of lymphatics in pulp during healing?

Answer 22

drains proteins accumulated during inflammation

Question 23

What fibers innervate pulp?

Answer 23

small A(delta) and C(fibers)
A delta: sensory pain fibers
C: some sensory pain others sympathetic
A beta: sensory pain, largest fibers, highly myelinated and fastest conducting

Question 24

Where does main sensations of pulp come from?

Answer 24

activating nerve fibers - PAIN

Question 25

At which stage does innervation begin?

Answer 25

Bell stage

Question 26

Where do nn enter and end?

Answer 26

enter through apical foramen and terminate in pulp-dentin border zone and dentin

Question 27

How far do n fibers extend into dentin?

Answer 27

EARLY in dentinogenesis ODB processes reach outer dentin, LATER they retract. nn processes extend pulp dentin border zone (predentin)

Question 28

Hydrodynamic theory of dentinal pain

Answer 28

fluid moves through tubules stimulating receptors in pulp; mechanically-activated ion channels are embedded in membranes of n fiber ending of A delta and A beta fibers in pulp/dentin border region

Question 29

What happens when n fiber endings are deformed?

Answer 29

ion channels open, sodium flows into n endings, depolarizing them and giving rise to action potentials

Question 30

Type of mechanoreceptors of nn fibers

Answer 30

PIEZO2 receptors: class of stretch-sensitive ion channels recently identified as underlying touch sensation and proprioception throughout body

Question 31

How do ODB function in dentinal sensitivity?

Answer 31

due to crowding and proximity in tubules, ODB process affects fluid dynamics around n process

Question 32

Other mechanisms of tooth pain

Answer 32

directly from inflammatory stimuli w/in pulp

- other pulp n fiber endings (C fibers) have receptors sensitive to inflammtory and thermal stimuli - TRP receptors

Question 33

What types of inflammatory mediators activate TRPA1?

Answer 33

ROS and prostaglandins

Question 34

dental stimulation

Answer 34

dentinal stimuli -> hydrodynamic forces -> Abeta and Adelta fibers activated (located in dentinal tubules and most superficial pulp) -> sharp pain
- use electric pulp and hot and cold tests to activate fibers

Question 35

Infection or trauma activation

Answer 35

infection or trauma -> inflammation (cytokines, prostaglandins, bradykinin, increased pressure) -> C fibers activated (pulp only, superficial and deep) -> dull pain
- electric pulp and hot and cold test not effective

Question 36

Where are peptides synthesized?

Answer 36

in cell body in trigeminal ganglion at central and peripheral endings

Question 37

What are the functions of sensory nn?

Answer 37

Pain nn, have inflammatory and immune functions:

• vasodilation (opp symp)
• angiogenesis
• interactions w/immune cells