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Oral Histology > Dental Pulp > Flashcards

Dental Pulp Flashcards

1
Q

what is dental pulp?

A

soft connective tissue that supports dentin

-vascular, not calcified, comes from ectoderm and contains cells, blood, lymph and an ECM

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2
Q

what are the functions of dental pulp?

A 
inductive (lamina to bud)
formative (makes dentin)
nutritive (water)
protective (sensory and barrier)
defense/reparative (immune and formation of new dentin and pulp)
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3
Q

what is positive pressure?

A

when the pulp expels microbiota into the oral cavity to prevent infection

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4
Q

what happens to the pulp with age?

A

pulp chamber becomes smaller, the cellularity decreases and the ECM increaes

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5
Q

ectopic calcifications in pulp (not normally calcified)

A

pulp stones (in the crown or pulp chamber) and diffuse calcifications (in root pulp)

  • *usually around blood vessels or collagen
  • normally no harmful effect, only annoyance to endodontist
  • can be viewed radiographically if large enough
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6
Q

why do pulp stones form?

A

we are not sure
age? deleterious effects??
doesn’t seem likely because they can be in unerupted 3rd molars

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7
Q

what are the layers of the pulp?

A

odontogenic zone that surrounds a central core

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8
Q

what is the pulp/dentin border?

A

predentin (not mineralized yet)

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9
Q

what are the layers of the odontogenic zone?

A

ODB, cell free ad cell rich zones

**cell rich zone has a lot of fibroblasts which is the most common cell type (CT) in the pulp

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10
Q

what are the cells of the pulp?

A

ODB (processes do into dentin), fibroblasts that are contained in the pulp (secrete ECM), immune system cells like macrophages and dendritic cells that are normal residents and plasma and mast cells that are present during inflammation and stem cells

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11
Q

what is important about dendritic cells in the pulp?

A

they are in the outside pulp layer (odontogenic zone) to survey the environment and be the first to notice an infection

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12
Q

explain the ECM of the pulp

A

PG and GAGs, glycoproteins and collagen

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13
Q

PG and GAGs

A

PG ex. decorin, BYGLYCAN, versican and syndecan
GAGs ex. dermatan, chondroitin and heparin sulfate
PG’s help with collagen fibrillogenesis (when an how much secreted) and matrix diffusion because gelatinous and GAGs with water retention

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14
Q

glycoproteins

A

ex. fibronectin

helps with cell adhesion to the ECM

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15
Q

COllagen

A

type one and three (for softness and tensile strength) –> bendy

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16
Q

what can dental pulp stem cells induce the formation of?

A

ODB, adipocyte and glial cells

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17
Q

can stem cells replace adult tissue?

A

yes

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18
Q

where are stem cell niches?

A

multiple locations of mature pulp

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19
Q

what are the second most numerous cell type in the dental plp?

A

ODB

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20
Q

ODB functions

A
  • dentinogenesis
  • nutrients to dentin (fluid)
  • immune (start expressing when inflammed)
21
Q

ODB processes structure

A

microtubules (larger) for protein transport and filaments (whisps) for structural integrity

22
Q

desmosomes and adherens junctions

A

maintain position and polarity of the layers (towards apical root)

23
Q

gap junctions

A

channels coordinate dentinogenesis

24
Q

tight junctions

A

serve as barrier btwn ODB and prevents diffusion of large substances through the ODB

ex. claudin, occludin and JAM
ex. HRP (40 kda) injected and stopped at the P-D barrier but when drilled deep, barrier was destroyed

25
Q

where are larger vessels in the pulp?

A

deeper (more bleeding as you go deeper) more branching in the periphery

26
Q

blood flow in the pulp

A

under neural control
sympathetic causes constriction of the blood vessels
-Noepinephrine binds to alpha adrenergic receptors
-sensory pulp and peptides take care of vasodilation

27
Q

lymphatic vessels (and blood vessles)

A

more diffuse in the periphery

-drain proteins accumulated during inflamm

28
Q

why do lymphatic vessels have complex anatomy in the pulp?

A

because encased in hard tissue (dentin) so has a tortuous route

29
Q

difference in C, Adelta and Abeta fibers

A

C ummylein and small, A delta is mylein and small and A beta is mylein and big (usually light tough, not pain)

30
Q

main sensation in pulp (and dentin)?

A

pain

31
Q

where does pulp innerv begin?

A

bell stage (under dental papilla and nn. enters through tooth

32
Q

density of innervation

A

increases until eruption and then slowly increases after eruption (decrease with age)

33
Q

primary and secondary dentin innervated?

A

yes

34
Q

where do nn. enter and terminate?

A

apical foramen and at pulp-dentin border zone and in dentin (only 1/3 into dentin)

  • *nn. endings are sensitive
  • *ODB process only 1/3 into dentin too
35
Q

ODB processes in the young v. old

A

old retracts so young reaches the outer dentin layers

36
Q

where are the dentin tubules most highly innervated?

A

near the crown (fewer nn. as go down to root)

37
Q

nn. termination in the pulp-dentin border zone leads to

A

rashkows plexus in the cell rich zone under the cell free zone

38
Q

hydrodynamic theory of dentinal pain

A

all stimuli cause the fluid to move in the tubule which stretches the sensitive receptors on the nn. to lead to action potentials that cause pain
- why pain at DEJ and differing sensitivity in the exposed dentin

39
Q

theory to prove the hydrodynamic theory

A

16 subjects drilled down to tubules, sealed and then manipulated movement in tubules to detect pain
**more pressure (positive and negative) leads to expression of more pain

40
Q

why do A beta fibers make sense as important for hydrodynamic theory?

A

because elsewhere in the body are used to low thresholds for mechanical stimulation (touch) so small stretches in the nn. are detected but express pain rather than touch

41
Q

what are the theories other than hydrodynamic?

A
  1. direct stimulation
    - nn. fibers empinged at the DEJ, but do not extend that far
  2. ODB processes receptors
    - communicates with nn. receptors (but no synapses found)
    * *however, ODB can possibly MODULATE the sensitivity of nn. fibers because of closeness and junctions
42
Q

pain arises from direct stimuli in the pulp (not hydrodynamic fluid flow)

A

C-fibers have receptors for for inflammatory (cytokines) and thermal stimuli (exogenous irritants like chilli peppers)
**TRP receptor family member

43
Q

TRP receptor

A

**TRPA1 receptor activated by many inflamm mediators like prostaglandin, ROS and Bradykinin

44
Q

dentinal stimuli leads to?

A

hydrodynamic forces, activates Abeta and Adelta in the dentinal tubules and superficial pulp
**sharp initial pain
easily activated by pulp vitality testing

45
Q

infection or trauma leads to?

A

inflammation, increased pressure, sytokines, prostaglandins and bradykinin which leads to C-fiber activation in the PULP ONLY
**vitality testing less effective

46
Q

can pain receptors increase during inflammation?

A

yes

47
Q

neuropeptides and sensory nerves

A

ex. CGRP and SP
peptides made in trigem ganglion cell body and central endings have peptides bind to brain neurons to affect pain and peripheral endings go to local cells to promote inflammation
**sensroy fibers convey info to the brian about pain and help to resolve injured tissue

48
Q

what do sensory fibers in the periphery do?

A
  • vasodilation (opposite symp control)
  • plasma extravasation (holes in blood vessels)
  • angiogenesis to injured pulp
  • stimulated cytokines produced by macrophages and chemotactic events for cell migration

Oral Histology (13 decks)

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