(4) Dentino-pulpal Complex - Structural Lines Flashcards
What are the lines associated with the primary curvature of dental tubules called?
Schreger lines
What are the lines associated with the secondary curvatures of dental uvulae’s called?
Contour lines of Owen
What are daily incremental lines called?
Von Ebner’s lines
What are the weekly incremental lines called?
Anderesen lines
Where is the most dramatic secondary curvature line?
Between the primary and secondary dentin
What contour line is pointed to?
Secondary curvature line
Contour lines of Owen
How do the Von Ebner’s lines show?
Short term striations
How do the Andresen lines appear?
Long term striations
What gives rise to the incremental lines?
Fluctuations in acid-base balance
Effect on mineral content and thus the refractive index
What incremental lines are shown?
Von Ebner’s lines
Where are the Von Ebner’s lines closest together and farthest apart?
Closest (2um between every 2 lines) at the root
Farther away (4um between every 2 lines) at the cusp
Why are the Von Ebner’s lines closer together in the root?
Not as much dentin is formed in the root each day
What is pointed to and what do they run over?
Von Ebner’s lines, run over dentinal tubules
What incremental lines are shown?
Andresen lines
How far apart are Andresen lines?
16-20um
Name structures and what type of section
A = enamel
B = circumpulpal dentine
C = mantle dentin
Black arrows = stria of Ritzius
White arrows = andresen lines
Ground section
What line is shown in this image?
Neonatal line
Shows what was formed before and after birth
What are physiological age related changes associated with dentin?
Secondary dentin
Translucent dentin
What are age related changes associated with dentin, associated with response to stimuli?
Tertiary dentin
Sclerotic dentin
Dead tracts f fish
When does secondary dentin form?
Starts to form once the root is completed and teh tooth come into occlusion
What happens to the direction of the dentinal tubules in secondary dentin?
Sudden change in direction
Do the secondary or primary dentin have closer incremental lines?
Secondary
What has slower deposition, primary or secondary dentin?
Secondary, thus less regular
Contour line of Owen
What causes tertiary dentin to form?
External stimuli might induce the pulp t produce more calcified material
What structure produces tertiary dentine?
Pulp produce more calcified material
Where does the tertiary dentine form?
Border of the pulp
When does tertiary dentin form irregularly vs regularly?
When a strong stimulus occurs, dentin needs to form quickly = irregular
What is reparative dentine?
Newly formed cells, produce hard tissues similar to dentin
What is reactionary dentin?
More dentin formed by the original odontoblasts
What is the appearance of tertiary dentin?
Variable
May be… tubular, contain few irregular tubules or tubular
A = tertiary dentin
B = pre-dentin
C = odontoblasts
What cells make tertiary dentine?
Odontoblasts
What type of tertiary dentin is formed by original odontoblasts?
Reactionary dentin
What type of stimulus makes reactionary dentin?
Small stimulus
What type of tertiary dentin is formed when the stimulus is very string? (Kills original odontoblasts)
Stem cells in pulp differentiate into odontoblast-like cells and produce reparative dentin
What cells form reparative dentin?
Odontoblast- like cells (from stem cells)
When’d ones sclerotic dentin form?
The stimulus induce the deposition of material inside tubules
What occludes the tubules to form sclerotic dentin?
The Stimulus
What is sclerotic dentin similar to and what is the difference?
Similar to transparent dentin
However, sclerotic dentin is in response to stimulus and not physiological
When can you normally see sclerotic dentin?
Under slowly progressing caries lesions
A = enamel
B = fissure
C = mantle dentin
Sclerotic dentin
What occludes sclerotic dentin?
Intratubular dentine
And precipitation of minerals from dissolved enamel
What happens when primary odontoblasts are killed by external stimuli? (Before filled with sclerotic dentin)
Dead tracts of fish
What are dead tracts of fish?
Empty tubules
What colour will empty tubules appear?
Black
What might seal the dead tracts of fish at the pulpal end?
Tertiary dentin
What is shown in black ?
Dead tracts of fish
What do odontoblast do at the pulpal end of the dead tracts of fish?
Occlude the dentine and tubules by sclerotic dentine formation to protect the pulp from insult coming from various lesion
