Dentin Flashcards
What is the origin of Dentin?
Outer cells of the dental papilla; mesoderm.
How is dentin formed?
- Collagenous matrix from odontoblasts.
2. Maturation through mineralization (+hydroxyapatite)
How long does the formation of dentin continue?
As long as the tooth is vital.
Can dentin formation be stimulated by the environment?
Yes
How is dentin formation stimulated by the environment?
- Cutting away dentin near the DEJ stimulates odontoblasts.
2. Heavy handed scaling; removing all the cementum from root surface to stimulate tertiary dentin formation.
What percentage of dentin is inorganic, organic, and water?
70% inorganic
20% organic (collagen
10% water
What is the function of Dentin?
“Shock Absorber” most of the tooth is made up of dentin.
What color is dentin?
yellow
What type of union is made with the DEJ?
Scalloped
Where are accessory foramina and Lateral canals found?
In the root portion of the tooth.
What is the purpose of accessory foramina and lateral canals?
Transmits nervous/circulatory elements to the pulp proper of the tooth.
What are the three components of mature dentin?
- Dentinal tubules
- Odontoblastic processes
- Dentinal permeabilty.
What is the orientation of dentinal tubules?
Travel from the pulp to the DEJ.
What does the dentinal tubules contain?
Water, odontoblastic processes and sensory neurons.
What is the correct unit for dentinal permeability?
tubules/mm^2
What happens to odontoblasts as dentin is being formed?
Odontoblasts squeeze together to create a cross section that is about 20,000 tubules/mm^2.
How does the cross section change as you get closer to the pulp?
The cross section grows to about 45,000 tubules/mm^2
What are the types of dentin?
- Peritubular
- Intertubular
- Circumpulpal
What is the purpose of peritubular dentin?
Creates the walls of the dentin tubules.
What is intertubular dentin?
Dentin between tubules (least mineralized)
What is the purpose of circumpulpal dentin?
Surrounds the pulp chamber.
Which type of dentin is the deepest in orientation, peritubular, intertubular, or circumpulpal?
Circumpulpal
What are the three types of dentin based on formation?
Primary
Secondary
Tertiary
How is primary dentin formed?
Formed before closing of the apical foramen (matrix)
Where is secondary dentin formed?
Deposited at the pulpal periphery of the after the root is completed.
When is tertiary dentin formed?
In response to noxious stimuli (iatorgenically:dentist or by dental caries)
How is primary dentin mineralized?
Via odontogenesis
How secondary dentin mineralized?
After primary dentin is mineralized, a second layer mineralizes over top with some areas of fusion.
What is globular dentin?
Complete fusion of crystals from both primary and secondary mineralization.
What is interglobular dentin?
Dentin closer to the DEJ; less calcified and mineralized.
What are the 4 main microscopic features of dentin?
- Imbrication lines of vonEbner
- Contour lines of Owen
- Neonatal line
- Granular layer of Tomes
What microscopic feature of dentin is associated with the trauma of birth?
Neonatal line
What microscopic feature of dentin is associated with daily difference in apposition/maturation?
Imbrication lines of vonEbner
What microscopic feature is located just deep to the CDJ and CEJ and is less calcified?
Granular layer of Tomes
What microscopic feature of dentin is associated with trauma?
Contour lines of Owen
Which microscopic feature of dentin is the most obvious?
Neonatal Line
How is the Granular Layer of Tomes formed?
Via the process of maturation; you get less maturation during the first couple days of dentinogenesis therefore creating a line when more maturation occurs later in development.
