Dentin & Pulp Flashcards
What structures make the dentinal structure?
Dentinal tubules
Odontoblast processes
What are canaliculi and where are they located?
They connect adjacent tubules
Dentinal tubules
Dentinal Structural Features
What are the Incremental Lines of von Eber?
- Daily incremental growth lines.
- Distance is dentin deposited over a period of 24 hrs
- Similar to cross striations in enamel
Dentinal Structural Features
What are the Contour lines of Owen?
- Wider thickened incremental lines.
- Represent metabolic disturbance occurring during apposition.
- Similar to stria of Retzius in enamel
Dentinal Structural Features
What is the neonatal line?
- Accentuated contour line of Owen.
- Represent sudden physiologic change occurring during parturition
What are the 2 classifications of tubular dentin?
Peritubular or intratubular dentin
Intertubular dentin
Classification of Dentin:
What is Peritubular or intratubular dentin?
Lines the wall of the dentinal tubule
Highly mineralized dentin
Classification of Dentin:
What is Intertubular dentin?
- All dentin located between dentinal tubules.
- Majority of dentin.
- Less mineralized than intratubular dentin.
What are the 3 classifications of surface dentin?
Mantle dentin
Circumpulpal dentin
Predentin
Classification of Dentin:
What is Mantle dentin?
First-formed layer of crown and root dentin.
Nearest to DEJ/DCJ.
Collagen fibers larger and oriented perpendicular to DEJ.
Classification of Dentin:
What is Circumpulpal dentin?
The bulk of dentin underlying the mantle dentin.
Collagen fibers smaller in diameter and more randomly oriented.
Classification of Dentin:
What is predentin?
A layer of newly secreted organic matrix.
Unmineralized
What are the 3 classifications of developing dentin?
Primary, Secondary and Tertiary dentin
Classification of Dentin:
What is primary dentin?
Dentin formed prior to and during tooth eruption.
Regular S-shaped pattern of tubules.
Classification of Dentin:
What is secondary dentin?
- Dentin formed after the tooth is in occlusion.
- Junction between 1° & 2° dentin is characterized by a sharp change in direction of dentinal tubule.
- Forms more slowly than primary dentin.
Classification of Dentin:
What is tertiary dentin?
Localized, rapid formation of dentin.
Deposited on pulpal surface under secondary dentin only at sites corresponding to areas of stimulation.
Response to some trauma which exposes dentinal tubules to oral environment.
Seals off tubules from pulp.
Sparse and irregular dentinal tubules.
What are the 2 classifications of Tertiary dentin?
Reactive dentin
Reparative dentin
What is reactive dentin?
Tertiary dentin class
Formed by preexisting or original odontoblasts.
Newly formed tubules continuous with those of secondary dentin
What is reparative dentin?
Tertiary dentin class
Formed by newly differentiated odontoblasts.
Preexisting dentinal tubules discontinuous
What is dead tract dentin?
- Tract of dentin containing empty tubules.
- Forms when odontoblasts either killed or injured and processes retracted, leaves empty dentinal tubules.
- Acute response to some trauma.
- Dentinal tubules are filled with air during histological processing
Appears black under microscope
What is sclerotic dentin?
Area of dentin containing dentinal tubules completely occluded with minerals.
Slower response to chronic trauma.
Appears transparent under microscope
Explain a bit about general dentin sensitivity
- Mechanical, thermal, and tactile stimuli are perceived as pain
- Bradykinin and histamines do NOT produce pain in dentin
What are the 3 theories of Dentin sensitivty?
- Nerves in dentin
- Odontoblast as receptor
- Hydrodynamic
What is pulp?
Only soft tissue of the tooth
Specialized loose connective tissue
Derived from neural crest cells
Functions: SeñoR. Do Not Fck
- Sensation, Reparative, Defense, Nutrition and Formation
Pulpal Anatomy
Pulp, Apical foramen, Accessory root canals
Where is the radicular pulp located?
Root (radicular) canals
Where is the coronal pulp located?
Coronal pulp chamber and pulp horns
What are the 4 Pulp zones?
Odontoblast layer (odontogenic zone)
Cell-free zone
Cell-rich zone
Pulp core/Central zone
Pulp Zones
What is the odontoblast layer
Outermost layer against pre-dentin
Dentinal nerve fibers located between cells
Pulp Zones
What is the Cell-free zone?
Not “cell-free” - fewer cells.
Capillary and nerve plexus
Pulp Zones
What is the Cell-rich zone?
Increased cell density - mainly fibroblasts.
More extensive vascularity.
Pulp Zones
What is the Pulp core/Central zone?
Central-most region of pulp.
Numerous cell types, nerves and blood vessels and lymphatic vessels
Pulp Histology
Well-vascularized
Myelinated/Unmyelinated nerve fibers
Unmyelinated nerves in dentinal tubules
What are the cell types in the pulp? Which are the most numerous?
Fibroblasts (most numerous)
Odontoblasts (2nd numerous)
Undifferentiated mesenchymal cells
Macrophages
T-lymphocytes
What are pulp stones? What are the 2 types? What is their location?
Denticles
True pulp stones and false pulp stones
They are free, attached or embedded
What are true pulp stones and false pulp stones?
True pulp stones
- Ectoptic mass of dentin in pulp
- Odontoblasts & dentinal tubules
False pulp stones
- Calcified mass in pulp
- Concentric rings of lamellae
What are the age changes in pulp?
Fibrosis
- fibroblast cell # decreases
- collages fiber content increases
Pulp volume decreases due to:
- secondary dentin
- tertiary dentin
- pulp stones
