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Oral biology > Dentine and pulp > Flashcards

Dentine and pulp Flashcards

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1
Q

What is dentine

A

-Forms bulk of tooth​
-Harder than bone and cementum, but softer than enamel​
-Greater compressive and tensile strength compared with enamel​
-Permeable: contains tubules​
-Contains cell processes​
-Yellowish in colour (‘ivory’)​

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2
Q

What is compressive strength

A

Ability to withhold force and return to original strength

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3
Q

Content of dentine

A

Hydroxyapatite (HA) ​
-70% weight (50% volume)​

Water ​(dry tooth is more fragile)
-10% weight (20% volume)​

Organic matrix ​
-20% weight; (30% volume)​

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4
Q

Is enamel permeable

A

No only dentine

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5
Q

Tubules within the dentine
-structures

A

Original tubule outline
Peritubular/Intratubular dentine
Intertubular dentine

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6
Q

What is found within dentinal tubules

A

-Odontoblast process​
-Unmyelinated nerve terminals (sensory)​
-Dendritic cells (immune system)​
-‘dentinal fluid’ or extracellular fluid from pulp​

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7
Q

What is dental pulp and what does it contain

A

Connective tissue ‘core’ of tooth​

Cells:​
Odontoblasts, fibroblasts, defence cells​

Extracellular components​
-Fibres (collagen, oxytalan)​
-Matrix (proteoglycans, chondroitin SO4, dermatan SO4)​

Nerves​
-Sensory; autonomic (sympathetic)​

Blood vessels​

Lymphatics​

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8
Q

What is the function of odontoblasts

A

Cell that produces predentine within the pulp

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9
Q

What forms dentine

A

the matrix produced by odontoblasts (predentine) is then mineralised to form dentine

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10
Q

Functions of dental pulp

A

-Nutritive ​
-Dentine growth​
-Dentine repair​
-Defence​:
Immune cells; lymphatics ​
-Neural​:
Sensory ​
Control of dentinogenesis​

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11
Q

What are proteoglycans

A

Proteins bound to mucopolysaccharides (present in connective tissue)
Proteins that have sugar (carbohydrate)

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12
Q

What is the inflammatory response of tissue when damaged

A

swelling
redness
pain
heat
pressure builds due to swell impacting the blood vessels which are responsible for delivering nutrients to cells which starve and die

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13
Q

A few tubules may contain dendritic cells (part of the immune system). Are the processes from odontoblasts, nerves and dendritic cells found all the way along the dentinal tubules?

A

No

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14
Q

Where are dentinal tubules larger

A

Inner dentine

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15
Q

What is the function of tertiary dentine

A

Protective - lies closest to the pulp

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16
Q

Which dentine is more permeable, closer to pulp/closer to enamel

A

The dentine closer to the pulp as the interconnection is poorer due to the larger tubules

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17
Q

When is primary dentine produced

A

When tooth is yet to be completely formed

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18
Q

What is the difference between primary and secondary dentine

A

rate of production is considerably slower in secondary dentine

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19
Q

Does tertiary dentine have dentinal tubules

A

No

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20
Q

difference between reactionary / reparative dentine

A

Difference - odontoblasts produce reactionary dentine as it sees the risk for injury and wants to fill the space

If odontoblasts die stem cells can become odontoblasts and these odontoblasts form tertiary dentine (reparative)
Tertiary dentine takes much longer to form as the stem cells must be recruited

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21
Q

What does dental pulp consist of

A

Cells
Extracellular components
Nerves
Blood vessels
Lymphatics

22
Q

What is needed for dentine repair

A

Tertiary dentine

23
Q

What is the main function of the pulp

A

To produce dentine so that the specialised cells, ondontoblasts are present

24
Q

What is present in dental pulp for defence

A

Immune cells, lymphatics

25
Q

What are the types of links between dentine and pulp

A

Developmental
Structural
Functional

26
Q

Why are dentine and pulp linked developmentally

A

They both originate from the dental papilla (formed by ectomesenchyme cells)

27
Q

What are the origin of dental tubules

A

Ondontoblast projections from the pulp

28
Q

How are dentine and pulp linked structurally

A

Pulpal elements extend into the dentine:
odontoblast processes
nerve terminals
immune cells (dendritic cells)
dentinal fluid

29
Q

What is dentinal fluid

A

Fluid from the leakage of pulp capillaries into the interstitial space someof which passes into the dentinal tubules. Flow is proportional to pulp pressure.

30
Q

What are secondary and tertiary dentine formed from

A

Pulp tissue

31
Q

What can wear and create aggression to the pilp

A

Mastication (abrasion)
Bruxism (attrition)
Abfraction (occlusal overload)
Operative procedures (heat damages pulp)

32
Q

When does reactionary and reparative dentine appear

A

Reactionary dentine​
-in response to mild stimulus​
-laid down by primary odontoblasts​

Reparative dentine​
-in response to intense stimulus that destroys the primary odontoblasts​
-laid down by secondary odontoblasts

33
Q

What is Hoehl’s cell layer

A

A sub-odontoblastic layer from which secondary odontoblasts originate from

34
Q

How doews tertiary dentine protect pulp

A

Seals the tubules to prevent external access

35
Q

What materials are allowed through the odontoblast layer

A

Pulp –> dentine​
-nutrients, to sustain cells​
-formation of 2o, 3o dentine​
-function of tubular nerves (e. g. K+)​

Dentine –> pulp​
-medicaments applied to dentine​
-diffusion of ‘toxins’, from bacteria, components of filling materials

36
Q

How do nerves enter the pulp

A

Through apical foramen

37
Q

What percentage of tubules under cusps contain nerves

A

40%

38
Q

What is the tubular innervation in coronal and root dentine

A

C- 15%
R- 4%

39
Q

Where do most axons end within the tooth

A

In the pulp-predentine region

40
Q

How does stimulus convert into pain

A

Stimulus (thermal, mechanical, chemical)
Exposed dentine open tubules
Increase rate of dentinal fluid flow
Generation of action potentials in intra-dental nerves
Action potential passes to brain to cause PAIN

41
Q

How does hydrohynamics affect the flow of dentinal fluid

A

Cooling, drying and evaporating, hypertonic solutions and reduction of hydrostatic pressure will drive the fluid outwards

Conversely, heating, mechanical pressure and increase of hydrostatic pressure will drive the fluid inwards.​

42
Q

Which direction of dentinal fluid flow will have greatest effect on the intradental nerves

A

OUTWARD from pulp to dentine (Well, think about you crossing a rapid water stream and how it affects the clothes you wear or your skin hair and you will realise that the nerve will “feel” most the effect of the outward flow because the nerve will be stretched)

43
Q

What stimuli can affect nerves directly without help of fluid

A

intense heating​

intense cooling​

electrical current​

pain-producing chemicals

44
Q

Why do high fillings cause pain

A

The greater bit force distorts the dentine and alters tubular fluid flow

45
Q

What are the properties of the different intradental nerves

A

A and A fibres (large & small myelinated):​
-activated by hydro-dynamic stimuli applied to dentine​
-probably mediate ‘normal’ dentinal sensitivity​

C- fibres (unmyelinated):​
-probably activated directly by stimuli, rather than hydrodynamic mechanism​
-they respond to most forms of intense stimulation​
-probably mediate pain associated with pulp inflammation (e.g. caries)

46
Q

Where does the blood supply of the teeth come from

A

Branches of the maxillary artery

47
Q

What factors control pulp blood flow

A

Local factors, e.g. metabolites​

Nerves:​
-sympathetic​
-somatic afferents peptidergic​

Circulating hormones, e.g. adrenaline​

Drugs​
-e.g. local anaesthetic preparations with vasoconstrictors

48
Q

Why are ‘cooled’ burs used

A

To maintain blood flow

49
Q

What is the response produvced when the dentine-pulp complex is injured

A

Immediate​
-nociceptor activation - pain​

After approx. 1 minute​
-Early inflammatory response​
-kinins, prostaglandins, neuropeptides​
-Vasodilation​

After approx. 10 minutes​
-nociceptor sensitisation​
-extravasation of fluid, oedema​
-polymorph migration

After approx. 100 minutes​
-Enzyme activation; nerve growth factor​
-monocyte presence​

After approx. 1 day​
-nerve sprouting (NGF)​
-increased axonal transport​
-altered excitability of CNS synapses​

After approx. 1 week​
-Repair; tertiary dentine formation​

Variable​
-Completion of repair and recovery

50
Q

What is pulpitis

A

It is an acute inflammation of the dental pulp with the exception that the space is confined and the pulp chamber does not allow swelling
Therefore oedema increases pulp pressure
This has an effect on the blood flow and on nerve excitability

Oral biology (12 decks)

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