Tooth Morphology

Question 1

Branches of pulpal nerves fan out into the subodontoblastic layer. What are these called?

Answer 1

Raschow’s plexus

Question 2

Dentinal tubules contain nerves. Which part of dentine contains the most nerves?

Answer 2

dentine under cusps (40% of tubules contain nerves here)

Question 3

What is the percentage of nerves found in coronal dentine and root dentine?

Answer 3

coronal dentine = 15% of tubules

root dentine = 4% of tubules

Question 4

How may outward fluid flow be caused in dentinal tubules?

Answer 4

cooling, drying, evaporation, hypertonic solutions, decreased hydrostatic pressure

Question 5

How may inward fluid flow be caused in dentinal tubules?

Answer 5

heating, mechanical, increased hydrostatic pressure

Question 6

How are A beta and A delta nerve fibres activated in dentine/pulp? What do these mediate?

Answer 6

activated by hydrodynamic stimuli applied to dentine

probably mediate ‘normal’ dentinal sensitivity

Question 7

How are C fibres activated in dentine/pulp? What do these mediate?

Answer 7

probably activated directly by stimuli, rather than hydrodynamic mechanism
they respond to most forms of intense stimulation
probably mediate pain associated with pulpal inflammation (eg caries)

Question 8

Where does the blood supply for all teeth come from?

Answer 8

branches of maxillary artery

Question 9

A cell free zone in present in dental pulp tissue beneath the odontoblast layer. What is this called?

Answer 9

Basal layer of Weil

Question 10

Describe the immediate responses of dentine/pulp to injury.

Answer 10

immediate: nociceptor activation - pain

after approx. 1 min: early inflammatory response, kinins, prostaglandins, neuropeptides released, vasodilation

Question 11

Describe the dentine/pulp responses to injury after approx. 10 mins.

Answer 11

nociceptor sensitisation (biting will now hurt the patient)
extravasation of fluid, oedema
polymorph migration

Question 12

Describe the dentine/pulp responses to injury after approx. 100 mins.

Answer 12

enzyme activation; nerve growth factor

monocyte presence

Question 13

Describe the dentine/pulp responses to injury after approx. 1 day.

Answer 13

nerve sprouting (NGF)
increased axonal transport
altered excitability of CNS synapses

Question 14

Describe the dentine/pulp responses to injury after approx. 1 week.

Answer 14

repair; tertiary dentine formation

NB: completion of repair and recovery occurs at variable times

Question 15

During tooth development, what is dentine and pulp developed from?

Answer 15

dental papilla