Pulp

Question 1

where does tooth pulp originate from

Answer 1

• ectoderm dental papilla (mesenchyme)
• commas of the mesenchyme tissue differentiate into fibroblasts and odontoblasts
• the fibroblasts form intercellular substance of the pulp
• the odontoblasts form the dentin
• blood vessels and nerves in dental papilla remain to supply pulp tissue

Question 2

where is dental pulp

Answer 2

• inside the tooth, surrounded by dentin
• occupies pulp chamber in crown
• occupies pulpal canals in root
• connects with PL at apical foramen

Question 3

is pulp mineralized? is it living

Answer 3

• no

- yes its living tissue

Question 4

what is pulp made up of

Answer 4

• cells
• intercellular substance: ground substance and collagen fibres
• tissue fluid
• also contains blood vessels, few lymph vessels for transporting WBCs, and some nerves
• also denticles

Question 5

what are the 2 types of nerves in the pulp

Answer 5

1. sensory nerves -> transmit pain

2. motor nerves -> innervate smooth muscle cells in walls of blood vessels -> constriction and dilation

Question 6

what cells are found in the pulp

Answer 6

• fibroblast cells - star shaped
• histocyte cells/phagocytes (WBC)
• odontoblasts

Question 7

what are fibroblast cells

Answer 7

mesenchymal cells which become fibroblasts

• produce fibrous (meshwork of minute fibers) and ground substance (jelly like material) of intercellular substance
• most numerous type cell in young pulp

Question 8

what are histocytes

Answer 8

• start as undifferentiated mesenchymal cells
• located around capillaries
• part of pulp’s defence mechanism - respond to injury by changing into defence cells as seen in any inflammatory reaction
• phagocytes are the white blood cells that protect the body by ingesting harmful foreign particles, bacteria and tissue debris

Question 9

what are odontoblasts

Answer 9

• columnar cells
• next to dentin-pulp wall
• originated from cytoplasm in pulp and dentin
• produce dentin (primary, secondary, tertiary)
• pulpal wall changes position over time – formation of secondary dentin and narrowing of the pulp

Question 10

what are korff’s fibres

Answer 10

• thick collagenous fibers that begin in the dental papilla, spiral (corked rope) shape between the cells of the odontoblasts and help form the matrix of the dentin

Question 11

what do the blood vessels and lymphatic vessels in the pulp do

Answer 11

• supply o2 and nutrients and take away o2 and wastes
• branches from superior and inferior alveolar artery
• plentiful in young pulp
• enter via apical foramen

Question 12

what is the nerve supply from the pulp

Answer 12

• branches from the trigeminal nerve
• 2nd division of he trigeminal nerve - sensation mx
• 3rd division of the trigeminal nerve - sensation mn
• nerve endings located between odontoblasts cells bodies, some enter DT

Question 13

what are true pulp stones

Answer 13

• also called denticles
• formed during tooth development
• calcified bodies (mass of dentin) of irregular round shape and are found in the pulp
• may be free in soft tissue of the pulp or attached to dentin wall and become surrounded by secondary dentin
• vary in shape, size – increase in size with age
• problem with endo tx
• rarely a source of infection – no problems

Question 14

what are false pulpal stones

Answer 14

• diffuse calcifications
• small thin scatterings of calcified matrix
• found usually in root canals of older teeth
• clinically unimportant

Question 15

what are the 3 zones of the pulp that are evident when pulp tissues are viewed microscopically

Answer 15

1. odontoblastic zone
2. cell free zone
3. cell rich zone

Question 16

what is the odontoblastic zone

Answer 16

• lines outer pulpal wall (closest dentin)
• formed by cell bodies of odontoblasts
• forms dentin (sclerotic dentin and reparative dentin)
• serves as first line of defence, forms secondary and tertiary dentin

Question 17

what is the cell free zone

Answer 17

• buffer area
• passageway
• allows movement and communication between 2 other zones

Question 18

what is the cell rich zone

Answer 18

• inner most layer
• cell reservoir
• undifferentiated cells; capable of differentiating into new odontoblasts (to form reparative dentin) and histocytes (defence cells)
• interstitial fluid between cells
• extensive blood supply and WBC for infection

Question 19

what are 5 major functions of the pulp

Answer 19

1. formative
2. sensory
3. nutritive
4. defensive
5. vitality

Question 20

what is the formative function of the pulp

Answer 20

• odontoblasts for forming dentin
• korff’s fibers - fibrils in dentin - forming ground substance/matrix for dentin
• end - ceases function

Question 21

what is the sensory function of the pulp

Answer 21

• pulp sensitive to external stimuli
• nerve fibers in pulp -> sensation of pain
• hot, cold, touch are all interpreted as pain
• periodontal ligament is responsible for sensation of pressure

Question 22

what is the nutritive function of the pulp

Answer 22

• via bloodstream
• supplies itself (pulp) and odontoblast with nutrients
• provide nutrients to dentin through odontoblastic processes up to DEJ or DCJ

Question 23

what is the defence function of the pulp

Answer 23

• 3 types of reactions:
  1. inflammatory reaction - if pulpal damage (histiocytes)
  2. production of sclerotic dentin
  3. production of reparative dentin

Question 24

what is the vitality of the pulp

Answer 24

• the pulp is what keeps the tooth alive
• after the tissue is removed, tooth becomes excessively brittle (fragile) and can break/fracture easily
• endodontic tooth - non-vital - perfectly fine but can become brittle over time

Question 25

how does age change the pulp

Answer 25

• age does not alter function of the pulp
• changes happen to pulp as changes happen in different parts of the body -> normal changes, not pathological
• continues formation of secondary dentin - smaller pulp chamber and canals
• # cells decrease with age
• amount of fibrous intercellular substance increases as cells decrease
• blood and nerve supply decreases
• denticles - larger and more numerous
• increase in diffuse calcified false pulpal stones

Question 26

what happens to a tooth without pulp

Answer 26

• can function for years without pulp, though enamel tends to become more brittle, can fracture easily
• pulp removed, less fluid - ‘dries out’
• if no pulp - no formation of secondary or reparative dentin