ex2. dental pulp

Question 1

The fact that it is vascularized and non-calcified are unique to which tooth tissue?

Answer 1

The PULP of the tooth is both vascularized and non-calcified (aka non-mineralized, no mineral salts are present) - both properties are unique to the pulp as a tooth tissue

*note, periodontium not a ‘tooth tissue’ but is a connected/continuous w the dental pulp, and like the dental pulp, is also vasuclarized and unmineralized

Question 2

what is the embryonic origin of the dental pulp?

Answer 2

The embryonic origin of the dental pulp is ECTODERMAL > neural crest cells > ectomesenchyme> dental papilla > dental PULP

Question 3

does the tooth pulp have a blood supply?

Answer 3

Yes, the Pulp of the tooth is vascularized– it has blood supply.

Question 4

is the pulp of the tooth suppplied with lymphatics?

Answer 4

Yes, the pulp of the tooth is supplied with lymphatics. The pulp has immune response via lymph cells, and other mechanisms

Question 5

Are ther nerve fibers in the tooth pulp?

Answer 5

Yes! The tooth pulp is innervated .. it receives several different types of pain fibers (Abeta, Adelta, and C.. and other communication mechanisms)

Question 6

Is the dental pulp cellular or acellular?

Answer 6

The dental pulp is CELLULAR> The pulp contains whole. active cells as well as cell constiuents (parts and pieces)

Question 7

Why could someone say that Pulp has a formative function?

Answer 7

Pulp houses the odontoblasts which form dentin (outside of the pulp) and an extracellular matrix.

Question 8

What is meant by saying the pulp has an inductive role?

Answer 8

The dental pulp is involved int he recipocal induction developmental processes that occur bt the epithelium (think: the ameloblasts>odontoblasts> dentin> enamel)) the two tissues are necesary to spur one another forward through developmental processes.. pulp is a type of ectomesenchyme and is also involved in induction

Question 9

Is the pulp considered to be positive or negative pressure?

Answer 9

The pulp is considered to be of positive pressure. Basically, things entering the pulp have a tendency to be pushed out.. this is good for protecting the pulp ((as a defense against caries that want to enter..pressure tends to reject entry)) The high pressure of the pulp is partially due to vascularization of the tissue

Question 10

Is the pulp of the tissue continuous or discrete from the periodontium>

Answer 10

The pulp of the tooth is CONTINUOUS with the periodontium. The connection is via the opening in the root- the apical foramen.

Question 11

T/F The pulp of the tooth is fined to the coronal cavity

Answer 11

False. The pulp of the tooth is both in the coronal cavity AND in the root cavity(s) of the tooth

Question 12

T/F The root canal is a single canal with no branching

Answer 12

False. The root canal may have branching. There are some root patterns where there may be two formina exiting the aprical foramen.. furhter, there are small off-shoots more cervical in the root canal that are called accessory canals. These extra canals are importnat to consider when evaluating endodontic tretment (infection, etc.. caries can get into these small accessories band be difficult to clear out

Question 13

Do younger or older teeth have a more substantial pulp chamber? The significance?

Answer 13

A younger tooth has a larger pulp cavity. There is an apparent differene bt a 9 to 28 year old.. and even more so with older age. The significance of a diminished pulp cavity has a variety of implications including less reparative function (odontoblasts live in pulp..less pulp=less doonoblasts) and diminshed function of most components of the pulp.. including sensation of pain etc.

Question 14

Name two characteristics that the pulp and continuous periodontium have in common.

Answer 14

Both the pulp and continuous periodontium have the characterisitics of vascularization (blood supply) and both are non-mineralzied

Question 15

T/F Pulp only ever contains soft tissues

Answer 15

False! Pulp may have ectotopic calcifications (irregularly located mineralized ‘stones’) . As much as 50% of the population may have these. Consider implcation for endodontics if it is in the root canal

Question 16

Where are the pulp stones most commonly located?

Answer 16

Pulp stones are spherical and are most often located in the coronal pulp chamber.. another type of calcification in the pulp is diffuse calcfification (smaller, more stippled arrangement).. and these occur more often in the root canal clustering around blood vessels

Question 17

can pulp stones be seen radiographically?

Answer 17

Pulp stones Can be seen radiographically if they are large and dense

Question 18

what is the most numerous cell type in the pulp?

Answer 18

Fibroblasts are the #1 most nmerous cell type in the pulp

Question 19

name the layers of the pulp from deepest to superficial (int he pulp layer)

Answer 19

The pulp has a central core.. the cell rich zone, majority of pulp) then out towards periphery there is the cell free zone (looks like an empty band) and then the odontoblast zone (contians odontoblast body).. then the predentin and dentin

Question 20

T/F the pulp contains fibroblasts, capillaries, nerves, lymphatics, immune cells including macrophages, lymphocytes, eosinophils, dendritic cells, and inflammatoryc ells including plasma and mast cells, as well as stem cells

Answer 20

True! The pulp contains all of htese different types of cells. Fibroblasts = the most numerous. CApiilaries exist bxc pulp has blood supply, there are nerves, and lymphatic vessels and cell (including immune cells such as macrophages, lymphocytes, eosinophils, dendridic cells) and inflammaory cells such as plasma and mast cells

Question 21

What is the purpose of hte stem cells in the pulp?

Answer 21

Stem cells are pluripotent. Mostly, the make more of hte tissue in which they are located. Here inthe pulp, stem cells make replacement odontoblasts and fibroblasts. Note* odontoblasts do die off and are not habitually renewed during lifetime, though some replacemement does exist

Question 22

What are GAG’s and what do they have to do with the pulp?

Answer 22

GAGs are glycoaminoglycans that are a type of proteoglycan found in the extracellular matrix of the pulp (also in pulp ECM: glycoproteins and type 1 and 3 collagen). GAGs function for collagen formation (collagen fibrilogenesis) and water retention ((imp that pulp is wet.. bc it is a soft tissue and the support it gives the overlying mineralzied tissues.))

Question 23

What is fibronectin?

Answer 23

Fibronectin is a glycoprotein found in the exracellular matrix of the pulp. Glycoproteins function in cell-adhesion within the extracellular matrix, such as imporntat for connecting fibroblasts to collagen cells.

Question 24

T/F Fibronectin is a glyoaminoglycan (GAG) in the ECM that functions in waer retention and collagen fibrilogenesis.

Answer 24

False. Fibronecting is a GLYCOPROTEIN in the extracellular matric that functions in cell-adhesion within the ECM (esp binding fibrolbasts to collagen cells). The GAGS are a type of proteoglycan that fucntions in water retention and collagen formation.

Question 25

why is it functionally good for GAGs to be present in the pulp?

Answer 25

GAGS, glycoaminoglycans function to help retain water ((as well as build collagen)). In terms of its water retention function, GAGs via water retention help to maintain the high pressure in the tooth pulp (imp as defense) and provides a watery environment to facilitate the nutrients to the pulp and surface layers (calcium,m phosphates, etc) while making itself a spongy support for the harder surface layers of dentin and enamel

Question 26

what is the function of collagen in the pulp?

Answer 26

Collagen funcitons to provide tensile strenght to the pulp. Both type 1 and type 3 collagens are present ((type 1 assoc with harder tissue while type 3 is softer

Question 27

what type of collagen predominates the dentin?

Answer 27

Type 1 collagen, (found in harder tissues) dominates dentin, a hard tissue

Question 28

proteoglycans (such as GAGs), glycoproteins (such as fibronectin), and collagen (types 1 and 3) are all present in which part of the pulp?

Answer 28

proteoglycans, glycoproteins, and collagen are all present in the extracellular matrix of the pulp

Question 29

These two statements describe what type of cell?

1. high capacity for self-renewal
2. multi-potent (can generate multiple cell types)

Answer 29

The cell that has both a high capacity for self renewal AND is multipotent is a STEM CELL

Question 30

T/F there is a population of tissue specific stem cells found in regenerating organs such as blood, bone, skin, etc.

Answer 30

True. In tissues that have a high rate of REGENERATION, there are well known populations of stem cells that function to replace worn out cells with new ones. (makes snese in a renewing tissue)

Question 31

What does the idea of plasticiy have to do with stem cells? (i.e… in research..)

Answer 31

Stem cells are often found in host tissues that have high regenerating rates (such as blood, skin.. etc). These stem cells make more of the tissue they reside in that is regernative. However, in research, tissue-specific stem cells have been isolated and fed different growth signals etc.. and depending on the cocktail they receive, they produce cells types similar to those in totally other areas of the body ((as in,, stem cells can truly make multiple cell types.. beyond the host tissues they normally make based on the signals they recieve. BIG IMPLICATIONS for regenerative capacity of body parts.. etc

Question 32

T/F dental pulp contains stem cells

Answer 32

True. The pulp does contain stem cells, notably in the form of odontoblasts that are formative cells of dentin.

Question 33

Odontoblasts are a form of stem cell.. so why are they considered to be a terminal cell?

Answer 33

Odontoblasts are a type of stem cell and they can renerate dentin and even new odontoblasts – to an extent. Overall, the odontoblasts are Not regenrative, and the odontoblasts we have today, will have later in life, are all essentially the same as what we started with. As such, odontoblasts are considered a terminal cell

Question 34

T/F Odontoblasts are the most numerous cell type in the T/Ftooth pulp

Answer 34

False. Fibroblasts are the most numerous type of cell in the tooth pulp. Odontoblasts are the 2nd most numerous type of cell in the pulp

Question 35

T/F Odontoblasts can be found in all 4 tissue types of the tooth (enamel, dentin, pulp, and cementum)

Answer 35

False. Odontoblasts are ONLY found in the pulp

Question 36

T/F , Odontoblasts are unique to the tooth pulp

Answer 36

True. Odontoblasts are unique tot he tooth pulp. The odontoblast bodies reside in teh pulp while their processes can extend into the dentin

Question 37

The following 3 functions describe what cell type?
delivers nutrients to the dentin
immune capacity
dentinogenesis

Answer 37

Odontoblasts function to deliver nutrients to the dentin, have an immune function, and fuel dentinogenesis (dentin formation)

Question 38

Histologically speaking, how is a TEM of a odontoblast cell body (soma ) differnt from a slide of an odontoblast process?

Answer 38

The slides of the odontoblast soma vs process differ in a few detectable ways:

1) the odontoblast soma is active in protein synthesis and as such, has cellular machinery such as RER , ER, and Golgi apparatus. (typical columnar-tubular tacked appearance of RER)
2) the odontoblast process looks like it has a bunch of polka dots – these are a cross section of hte cytoskeleton of the odontoblast process.. – the microbtubules that give the pulp both strucutural sability and a pathway for nutrient deiverly to the dentin

Question 39

T/F there are junctions bt the odontoblasts

Answer 39

True. Odontoblast cells have junctions bt them for cell-to-cell adhesion. Differnt types of junctions in play include- desmososmes, adherens junctions, gap junctions, and tight junctions

Question 40

Name the 4 types of junctions present bt odontoblasts, and the different function of hte types

Answer 40

The 4 types of junctions bt the odontoblast cells are :
Desmosomes and adherens junctions , Gap junctions, and tight junctions,\
-both desmosomes (spot welds) and adherens junctions function to amintain the position and polarity of odontoblasts (their spatial relationship to each other)
-gap junctions = coordinate dentinogenesis (recall– gap junctions connect cell-to-cell.. open pathwyas for cell comminication) and
- tight junctions are a BARRIER

Question 41

claudin and occludin are two transmembrane proteins involved in what?

Answer 41

Claudin and occludin are two transmembrane proteins associated with tight junctions (which act as a barrier). The two proteins span across the membrane of 2 difff cells weaving back and forth basically tying the cells togehter … the degree of weaving impacts how tight hte junciton is (can be loose like a sieve of really tight and impregnable)

Question 42

Histologaically, a tight junction is found where in the pulp?

Answer 42

n the pulp, tight junctions can be found in the odontoblast layer that is adjacent to the predentin ((and recall.. a barrier bt dentin and pulp can be important as caries and foreign material can enter via dentin, dentin lamella, etc.. and if gets to pulp– has access to soft tissues and systemic vessles.. so a tight juntion - a good barrier and defense

Question 43

How can opertative tooth preparation impact the integrity of the tight junctions of the odontoblat layer?

Answer 43

operative tooth preparations can harm and destroy the integrity of the BARRIER function performed by the tight juntions of the odontoblast layer in the periphery pulp. This is clinically significant as bacteria can more easily enter the pulp when the tight junction barrier is breached. An importnat consideration is to maintin the tight junction odontoblast layer during dental preparations – such as by using water during procedure as well as being conservative and not going too deep into the dentin.

Question 44

T/F capillaries and lymph vessels have main trunks int he core of the pulp, andthen form branches that interwine and are really dense in the perifphery of the pulp

Answer 44

True. Both lymph and blood vessels enter the core pulp as a few larger trunks.. and as they spread towards the periphery they brnah and cluster so that the periphery is more dense is smaller vessels

Question 45

what controls the flow of blood in the pulp?

Answer 45

The flow of blood in the pulp is under NEURONAL control. The sympathetics have a big role and function to constrict blood vessels n the pulp. Contrarily, the parasympathetics do not have impact on blood flow in the pulp.

Question 46

What is the name of the neurotransmitter and receptor employed by the sympathetic system to impact blood flow int eh the tooth pulp

Answer 46

The tooth pulp blood flow is controlled neuronally– and mostly my the sympathetic nervous system that works to constrict the blood vessels. The sympathetic nervous system here communicates via NOREPINEPHRINE and their alpha-adrenergic receptors

Question 47

T/F The lympahtic vessles in the pulp are important for healing

Answer 47

True. The lymphatics in the pulp are important int he healing process– for example, the lyphatics help to drain proteins accumulated during inflammation

Question 48

How is the course of lymphatic vessles different in soft tissue like the cheek versus the hard-tissue encased small space of the tooth pulp?

Answer 48

The lymphatics in soft tissues follow a simple course.. whereas the lymph vessles of the pulp follow a complex, tortuous course that is possible so to alleviate the strain fo the high pressure withinthe tooth pulp

Question 49

in a single word, what is the main sensation experienced by activated nerve fibers int he pulp

Answer 49

Pain. Activated nerve fibers in the tooth pulp experience pain

Question 50

Name 3 different nerve fiber types found in the tooth pulp (hint, all 3 covrered in neuro and all three associated with pain signals)

Answer 50

A-beta, A-delta, and C fibers are all nerve fiber types that are associated with pain

Question 51

Which nerve fiber is most notable for having a low threshhgold (detects light touch)

Answer 51

The A-besta fiber has a low threshhold and sneses light touch ((ex, many A beta fibers in the palm and fingertips..) ).. are also present in the tooth pulp to detect PAIN snesation (aka, Abeta in pulp = low threshold for sensing pain)

Question 52

At what stage of odontogenesis does the nerve begin to enter the dental papilla?

Answer 52

The nerve fibers begin to enter the dental papilla (logical, the future pulp) during the epithelial BELL stage of development of the tooth germ.

Question 53

Are primary and secondary dentition innervated?

Answer 53

Yes! Primary as well as seocndary dentition are BOTH innervated.. so young kids can definitely feel tooth-associated pain

Question 54

T/F The density of innervation increases until eruption… and decreases with aging

Answer 54

True. The density of innervation increases until eruption (recall. nerve enters dnetal papilla in the eptihelial bell stage.. and the density of innervation increases from there until tooth eruption.) with age, likely nerve denstiy decreases ((also think, amount of pulp decreases with age, and pulp houses the nerve fbers)

Question 55

A big question:: How far do nerve fibers extend into the dentin

Answer 55

Based on different experiments, it seems most likely that nerve fibers only extend into 1/3 of the way through the dentin )towards the surface).

Question 56

T/F nerves are only found in the pulp

Answer 56

False. While nerve occupy the pulp, nerve endings can extend up to 1/3 of the way into the dentin

Question 57

How far will an odontoblast process extend into the dentin?

Answer 57

An odontoblast process extends about 1/3 of ht way into the inner dentin (much like the extent of nerve fibers)

Question 58

which is more highly innervated- crown or root dentin (detnial tubuels )? or is it all essnetially the same?

Answer 58

Crown dentin ( is more highly innervated than root dentin. nerve fiber endings (ends= the business ends that detect sensation) are dense in the coronal areas of the pulp and the area of denti the nerves cross into

Question 59

what is Rashkow’s plexus?

Answer 59

Rashkow’s plexus is a plexus of nerves (a dense area of nerve fiber endings ) that is located just deep to the cell free zone of the pulp (bt the odontoblast ayer and the cell-rich layer of hte pulp– so BASICALLY at the PERIPHERY of the pulp). This Rashkow plexus is highly innervated

Question 60

T/F nerve fibers terminate throughout the enamel-dentin border zone. – significance (of the true statement?)

Answer 60

False. Nerve fibers terminates throughtout the PULP-DENTIN border zone. This is significant bc the nerve fiber ENDINGS are the bisuness end where snesation is detected.. so there is a wide range of area in the pulp-dentin that are innevated by nerve endings that detect pain. (awesome :p)

Question 61

what is the hydrodymanic theory?

Answer 61

the hydrodynamic theory .. this is a theory that explains the incredible amount of sensitivy of the dentin –even when the nerve fibers have not been directly stimulated. Bascailly, when the dentinal tubules are breached, the pressure in the tooth is altered and this causes fluid movement (there is fluid in the dentinal tubules!!) this movement of fluid and pressure change transmits the change signal through the fluid of the tubules down the length to where it is transmitted to the nerve fibers which pick up the sensation and feel PAIN as a result. The more fluid motion, the more neuronal activity (sensation reciept) is detected

Question 62

T/F there is experimentally determined an inversely proportional relationship between positive pressure, fluid movment, and tooth pain

Answer 62

False. There is experimentally determined a DIRECTLY proportional relationship bt positive pressure, fluid movmeent (in dentinal tubules) and the tooth pain experienced. AKA.. more positive pressure in the tooth (such as injections or inflammation), more fluid movment (such as openied and exposed dentinal tubuesl dentin breach via caries or operative procedures .. === result in directly increasing amount of tooth pain experienced/

Question 63

Which of the pain fibers is most closely associated with hydrodymanic/ dentinal pain

Answer 63

A-beta fibers are hypothesized to be the nerve fibers important for sensing hydrodynamic/ dentinal pain.

This makes sense bc A-beta fibers are known to have very LOW thresholds for mechnaical stimulation (so detect small changes/ small sensations)

Question 64

What are 3 historically relevant theories of pain? Which of these theories persist? Which are debunked? and why

Answer 64

Three different pain theories (in the tooth) are the direct stimulation theory, the indirect stimulation theory, and the hydrodynamic theory. Of these, only the hydrodynamic theory persists whereas botht he direct and indirect stimulation theories have been debunked.-

• the direct stimulation theory is disproven.. bc ths theory maintains that direct stimulation of the nerve fibers causes pain.. this would mean that there are nerve fiber endings all through the dentin.. which has been disproven (only ending 1/3 of way into inner dentin)

– the indirect stimulation theory maintains that the odontoblast is THE receptor of pain signals (the way the tongue and ear have special receptor cells to pick up their speial sensations)… howver, this is debunk bc the odontoblast process does NOT reach the DEJ (also terminates in the inner 1/3 of the dentin) AND, there is no evidnece of synapses involving hte odontoblast as necessary for neuronal signal transduction.

– only the hydrostatic theory persists.. experiemnts have maintained the tenets (the change of pressure, fluid movement in the dentinal tubules causes pain - such as due to operative dental procedures)

Question 65

while it has been disproven that hte odontoblast is a component of the nervous syste, (via the indirect stimulation pain theiry).. it does still impact sensation in the pulp– how?

Answer 65

While the odontoblast does not have special nerve receptors (like the special sense cells).. it does still impact dentinal sensitivity.

1) odontoblast presence n the detninal tubules along with nerves and fluid == crowding.. so fluid dynamics are impacted ((and recall, the hydrodynamic theory of pain supports that fluid motion triggers sensations))
2) non-synaptic communication is possible– such as via cell-to-cell connections similar to desmosomes (spot welds)… with fluid motion, odontlbasts can move that cause its crowded neighbor to move as well == sensation.. and again, a-beta fibers that are BIG PREVALENT nerve fiber of the pulp have a low threshhold of sensation detection..so these tiny movements of neighbors and fluid are detected ((as pain))

Question 66

does the hydrodynamic thoery account for all of the sources of pain experinces by a tooth?

Answer 66

No. Hydrodynamic theory of pain accounts for pain experienced from surface disturbances (of the dentin etc.. even if nerve fibers themselves have not been touched) … but there are other ways a tooth can feel pain (recall, all of the nerve fibers that are stimulated transmit the snesation as a PAIN signal).. things like inflammation and thermal stimuli (noninvasive) trigger the C fibers which also detect the stimulus as pain.

Question 67

T/F TRP receptor family is associated with the hydrodynamic theory of pain.

Answer 67

False. The TRP family of Transmembrane receptors is associated with Thermal and Inflammatory pain

Question 68

what activates the TRPA1 transmembrane receptor?

Answer 68

Inflammatory stimuli activates the TRPA1 transmembrane receptor

Question 69

T/F The TRP family of transmembrane receptors have an ion channel bt transmembrane segments # 5 and 6

Answer 69

True. The TRP family of transmembrane receptors have 6 transmembrane segments .. bt the #5 and 6 segments is a GATED ion channel .. this ion channel can be activated via prostaglandins, ROS, and brandykin (invovled w inflamm)

Question 70

Prostoglandins, reactovie oxygen species (ROS) and brandykin are all ligands that – do what?

Answer 70

Prostaglandins, ROS, and brnadykinins are all ligands that bind tot he TRP family of transmembrane receptors– these are senstive to inflammatory stimuli and casue the GATED ion channel to open so an AP is generated and the sensation of inflamm. thermal is detected neuronally (likely C fibers w the message))

Question 71

T/F Sensitivity of the tooth pulp changes with inflammation

Answer 71

True. The sensitivity of the tooth pulp changes with inlfammation

Question 72

T/F Terminal nerve fiber endings and the nervous system of the pulp are static and unchanging

Answer 72

False. The nerve fiber endings are not static.. in fact, if nerve fiber endings of the pulp receive a lot of stimulation (as in, they receive stimulation = pain_ then the nerve fiber endings SPROUT so that therere are more nerve fiber endings and a BIGGER capacity to feel more of the pain

Question 73

Both substance P and CGRP are examples of what?

Answer 73

Both Substance P and CGRP are examples of neuropeptides that are present in the pulp and pulp sensory nerves. BOTH of these neruopeptides are invovled with PAIN stimuli trnasmission

Question 74

Neuorpeptides are synthesized in teh cell body of the trigeminal ganglion.. how are the NuP synth in the central endings differnt from those synth in the peripheral endings?

Answer 74

Te neuropeptides synth by the trigeminal ganglion in teh cetral endings have a TRANSMITTER function. The peptides bind w receptors on brain neurons (in the CNS, trigeminal nucleus) and sense PAIN.

– the neuropeptides synthesized at the peripheral endings of the trigeminal gnalgion (aka in the tooth!) have local regulatory funciton.. these peptides bind receptors on vaculature.local cells and are pro-inflammatory

Question 75

where are the nueroproteins that bind to local cells and are pro-inflammatory synthesized?

Answer 75

The neuroproteins that bind to local cells/ vascualtory and are pro-inflammaotry in impact are synthesized in the trigeminal ganglion at the peripheral endings (aka , in the tooth) . They have a local regulartory function

Question 76

The trigeminal ganglion syntehsizes different neuropeptides. One group is sytnhesized at the central endings (aka the trigeminal nucleus/ the brain/CNS) and have a transmitter functions – hwat sensation do these peptides transmit?

** recall, trigeminal ganglion nerves– cbo in the trigem gnaglion, but is unipolar with a single exiting process that splits into 2.. one branch to the CNS and one branch to the periphery target

Answer 76

The neuropeptides that are synthesized int eh central endings of the trigeminal ganglion (the central endings are hte trigeminal nucleus in the brain/ the brain. the CNS).. and theses peptides pick up the sensation of PAIN

Question 77

T/F NuT in the pulp can function as vasodilators

Answer 77

True. Neurotranmitters in the pulp can funciton as vasodilarors– a function that opposes the blood vessel constriction action of the sympathetic system that predominates nervous control of hte blood flow in pulp

Question 78

what is plasma extravasation and what does it have to do with the pulp?

Answer 78

Plasma extravasation is a condition where the blood vessels become leaky to promote transport of materials to release into tissue. this is promoted by cytokines that are stimulated by NuT that act in the pulp (inflamm)

Question 79

Vasodilation, plasma extravsation, angiogenesis, and interaction with immune cells (such as stimulationof cytokines and chemotactic impact on immune cell migration) are all functions of what class of molecules acting for infammationa and immjnity in the pulp?

Answer 79

Vasodilation, plasma extravasation (leaky vessels), angiogenesis, and interaction w immune cells are all descriptive of NEUROTRANMITTERS that function to mediate inflammation and immune fnciton in the pulp