Dental Unit - Enamel Flashcards
Where is root sheath located? What is it filled with?
Between rods and inter rods
contain organic material
Why is enamel brittle?
It doesn’t contain collagen (protein – organic)
What is lamellae?
Appears as a crack from the enamel surface
Filled with organic material
Where is tuft? Why is it present?
from dentinoenamel junction towards outer surface
Caused by changing in orientation of rods
Where is spindle? Why is it present?
From dentinoenamel junction towards outer surface
Trapped odontoblastic process in ameloblasts during mineralization
Where is gnarled enamel? How does it look?
At cusp tip
Appears as twisted rods
Where are hunter-schreger bands? Why are they present?
inner two-thirds of enamel (dark & light lines)
optical illusions - change in direction of enamel rods
Why are Straie of Retzius present?
Name of the significant one?
What would be formed if it extends onto outer surface of enamel?
deposition of enamel over time (incremental growth)
Neo-natal line
Perikymata on outer surface
5 Main Changes of Enamel over time
- Less permeable
- Darken
- More sensitive
- Reduced risk for dental caries
- Harder - more mineralized
5 Types of Dentine (According to position)
- Mantle Dentine
- Primary Dentine / Circumpulpal Dentine
- Secondary Dentine
- Tertiary Dentine
- Predentin
2 Types of Tertiary Dentine
- Reactionary Dentine - by existing odontoblasts
2. Reparative Dentine - by newly formed odontoblasts
A characteristic of predentin
unmineralized - principally consists of collagen
When would secondary dentine be developed?
After completion of root formation
How is secondary dentine different from primary dentine? (Give 2 differences) What function does this serve?
Less regular tubular structure
Tubules in secondary dentine sclerose more readily -> reduce permeability -> protect pulp
What are dead tracts sealed off by? What function does this serve?
Reparative dentine
Protect pulp from infection
5 types of dentine histologically
- Dentinal tubules
- Peritubular dentine - highly calcified
- Interglobular dentine - unmineralized/hypomineralized (in primary dentine)
- Intertubular dentine
- Sclerotic dentine
Cells forming tertiary dentine and eventually being included inside.
Osteodentine
Orientation of incremental growth lines
Where are they found?
Right angle to dentinal tubules
In dentine
What is contour lines of Owen caused by? Name of the wide line?
accentuated efficiencies in mineralization
Neo-natal Line
Where is granular layer of Tomes found?
What is it resulted from?
In root dentine
Near cementum
Resulted from the special arrangement of collagen & noncollagenous matrix proteins
4 Zones in pulp
- Odontoblastic Zone
- Cell-free zone of Weil
- Cell-rich zone
- Pulp core
Where do blood vessels enter & exit the pulp?
Through apical & accessory foramina
Name of extensive plexus of nerve in pulp.
In which part of pulp is it located?
Subodontoblastic plexus of Raschkow
in cell-free zone of Weil
Another name of pulp stone. What is it?
Denticle
Discrete calcified mass
