(7) Histopathology Of Dental Caries - Enamel Flashcards
What type of caries develop slowly?
Slowly/Chronic caries
Most common
What type of section do we look at to study caries?
Ground
What are the stria of Retzius?
incremental growth lines or bands seen in tooth enamel
During crown formation
What do early lesions appear as?
Cone shaped
What does the apex of the carie cone point towards?
The amelodentinal junction
Name A-D in the army lesion
A = Stria of Retzius
B = surface enamel
C = apex of cone
D = amelodentinal junction
What does colour represent in a ground section?
Different degrees of mineralisation
White = highly mineralised
Where does the base of the carie attach to?
Enamel surface
Name the zones of the early lesion
A = surface layer
B = body of lesion
C = dark zone (active progress)
D = translucent zone
What is the deepest zone of a early dental caries?
Translucent zone
What is the advancing edge of the lesion?
Translucent zone
Is the advanced lesion more porous than enamel?
Yes
When can you not see the translucent zone?
Of the lesion is advancing rapidly
What has a higher volume of pours, dark zone or translucent zone?
Dark zone (2-4%)
Why does the dark zone have a variation in pose size?
Demineralisation due to acidic attack and remineralisation due to the precipitation of the demineralised part of the translucent zone.
When is the dark zone narrow?
If the lesion is advancing rapidly
Why is the dark zone wider when the Edison progresses slowly?
More time for remineralisation and demineralisation to take place
What section of the lesion has the highest pore volume?
The body of the lesion
(5-25%)
What is different about the hydroxyapatite crystals in the body of the lesion compared to enamel?
More pours, they’re will be water and organic material that replace the lost minerals
What section has very prominent Stria of Retzius?
The body of the lesion
How does the surface zone of the lesion compare to normal enamel with regards to their mineralisation?
The surface zone is hypermineralised
Because of mineral precipitation from the oral cavity and demineralised deeper layers
What are the 6 stages of enamel histopathogenesis?
- Subsurface translucent zone.
- Enlarges and a dark zone develops in the centre.
- Body of the lesion forms in the centre of the dark zone. (White spot).
- If stained, brown spot
- When reaching the dentinoenamel junction, caries spread laterally undermining adjacent enamel (bluish white)
- After a critical stage, enamel breaks forming a cavity (could take place before step 5).
What is the critical point of an enamel carie formation?
When the dentin can no longer support enamel and the enamel breaks
What zone of the enamel carie is most highly mineralised?
The surface zone
What enamel carie is shown here?
Fissure caries
How do fissure caries form?
Caries spread outwards to adjacent enamel and downwards towards dentin
Lesions meet at the base of fissures
Where do caries start forming on the fissure caries?
The walls of the fissures
Where does the base of the fissure caries face?
Faces the dentinoenamel junction
What type of carie is shown here?
Pit or fissure lesion
Why are enamel and dentin caries different?
Enamel almost fully mineralised
Dentin has big percentage of organic component - living tissue. A reaction from this tissue
