Dentine And Pulp Flashcards
Colour of dentine
Yellow
Function of dentine
Support enamel
Characteristics of dentine
Compressive, tensile strength, permeable, harder than cementum but softer than enamel
Content of dentine vs enamel
70% hydroxyapatite 10% water 20% organic matrix in dentine.
Enamel is 95% HA
When we prepare tooth, remove mineral content, enamel goes. Organic content of dentine stays so you can see it in slides that are demineralised an decalcified.
Shape of dentinal tubules
Sigmoidal shape s shape
Where is intratubular dentine
The space between the original tubule outline and the narrower thinner tubule outline
Inter vs intratubular
As you grow older, what happens to dentinal tubules
Becomes narrower
Relation of dentine and pulp
Dentine is a live tissue. Living cells present, called odontoblasts. Dentine is produced in an organic matrix. Before it’s mineralised, it’s called pre dentine.
InterGlobular dentine
Interglobular dentine arises because of incomplete fusion of calcospherites with the mineralising front as dentine is laid down and mineralised. This incomplete fusion traps areas of poorly mineralised dentine matrix within the dentine in the form of ‘arches’ that reflect the original spherical nature of the calcospherites.
What are the cells that produce dentine
Odontoblast
Produce dentine throughout your life. The odontoblast is the cell responsible for forming dentine and maintaining it. It initially secretes a collagenous matrix (the predentine) which is then subsequently mineralised (partly by the fusion of calcospherites).
Contents of the dentinal tubules
Odontoblast process, UNMYELINATED nerve terminal , dendritic cells, ecf from pulp called dentinal fluid
No blood vessels
What cells are found in the dental pulp
Fibroblasts predominate
Odontoblast
Defence cells
Contents of the dental pulp
Cells
ECM (fibres and jelly like ground substance with Chondroitin sulphate)
Nerves
Blood vessels
Lymphatics
Is dentine live tissue
Unlike enamel, the dentine and the pulp (which are treated together, because the dentine develops from the pulp) are living tissues, with cells, blood vessels, and nerves
What are the nerves present in dental pulp?
Sensory nerves for pain
Autonomic sympathetic nerves for blood flow
Which nerves control blood flow in the pulp?
Autonomic sympathetic nerves
How dentine is formed?
Primary dentine when the tooth is formed.
Secondary dentine is after the tooth had been formed
Tertiary dentine
Repair and protection through the regenesis of dentine
What happens when there is inflammation of the dental pulp?
Swelling, increase in volume leads to increase in pressure, damages the circulatory system so the pulp degenerates
What’s found at the odontogenic zone?
Pre dentine
Dentine
Odontoblasts
Cel free zone
Cell rich zone
What is the cell rich zone?
Where cells like fibroblasts and nerve/blood vessels are found in the pulp
What is predentine
Predentine is the area where the dentine matrix has not been mineralised yet.
Functions of dental pulp
Nutritive
Dentine growth and repair
Defence (immune and lymphatics)
Neural (pain and control of blood flow)
Importance of knowing where the blood vessels are located in the pulp
Blood vessels do not penetrate into the dentine layer, remains only in the pulp. If you see a tooth bleeding, it means you have exposed the pulp
Are there nerve fibres in dentine?
Yes, it does penetrate dentinal tubules but not deeply. Short distance into inner dentine
Where does the concept of dentine-pulp come from
Cell body of the odontoblast lies at the interfere with the dental pulp
Two major properties that distinguish enamel from dentine
Dentine is sensitive
Dentine is formed throughout life
What happens to the dental pulp as you grow older?
The dentine layer becomes thicker and the pulp becomes smaller
What passes from the pulp into the dentine
Odontoblasts, dendritic processes of antigen presenting cells, unmyelinated nerve fibres
What gives dentine its tensile strength and compressive strength
Organic matrix and tubular architecture
What stresses are more like to fracture dentine?
Stresses Parallel to direction of the dentinal tubules are more likely to fracture than stresses at a right angle
What is the histological classification of dental pulp
Loses Connective tissue
When does secondary dentine begin to form
At the completion of root formation and as the tooth comes into occlusion
Shape and structure of secondary dentine
Tubular pattern Less regular than that if primary dentine because of the slower rate of deposition
Where does majority of the branching in dentinal tubules occur at
At the ADJ, immediately under the enamel
Where are dentinal tubules closer together
Inner dentine
Where are dentinal tubules larger
Inner dentine
Types of dentine (pri secondary tertiary)
Primary dentine
- mantle
- interglobular
Peritubular
Intertubular
Secondary
- circumpulpal
Tertiary
- reparative
- sclerotic
In a person with Vitamin D deficiency, what will their dentine look like?
More interglobular dentine
Dentinogenesis
Performed by odontoblasts,
Dentine grows from outside to inwards
What are dead tracts
When odontoblasts die of trauma or old age, dead tracts develop in dentine. The tubules calcifyas they fill with mineral to form sclerotic dentin.
What are Tomes processes?
Tomes processes are projections that develop when ameloblasts move away from the ADJ when the first layer of enamel, has formed
