(7) Histopathology Of Dental Caries - Dentin Flashcards
Can dentin respond to various attacks?
Yes
What would you call the destruction of organic material in dentin
Proteolytic attack
What reaction occurs before the lesion attacks dentin?
Pulpal reaction
What is the shape of early lesion in dentin?
Cone shaped
Where does the early lesion pint to in the dentin?
Dentinoenamel junction
Can demineralisation occur before the bacteria reach the dentin?
Yes
Many parts are sterile
Acid dissolution before bacteria invade
How many lesions are involved in fissure caries?
2 opposing lesions
Describe stages A-C in dentine caries
A = 2 opposing lesions, cone shapes, cementodentinal junction
B = once at cementodentinal junction it will spread laterally. Cone-based shape. Apex pointing towards pulp. Undermine enamel
C = dentine has fractures as it can no longer support enamel = Causing a wider cavitation.
A = undermined enamel
B = cone shaped lesion, apex towards pulp
C = pulp
D = dead tracts
What are dead tracts?
If the odontoblasts cannot mount an ‘ordered’ defence by producing sclerotic dentin then it will withdraw cell process (or may be killed) = empty tubule
What are these 2 types of caries?
- Fissure/pit
- Smooth surface
Where is the base of the lesion in a smooth surface carie?
Enamo-dentino junction
where is the base of the lesion in fissure/pit caries?
Base at the enamel-dentino junction
What ar the 4 zones of dentine caries?
- Zone of destruction
- Zone of bacterial invasion
- Zone of demineralisation
- Zone of sclerosis
What zone is sterile in dentine caries?
Zone of demineralisation
What is the deepest layer of dentine caries?
Zone of sclerosis
What occurs at the zone of sclerosis ?
Reaction of odontoblasts to dental caries
What odontoblasts react to dental caries in the zone of sclerosis?
Original or newly formed odontoblasts-like cells
Does the Zone of sclerosis have a higher or lower mineral content compared to dentin?
Yes
A = lesions
B = zone of sclerosis
What is the difference in sclerosis zone formation a and b?
A - zone of sclerosis formed form precipitation of minerals form the various lesion itself
B = sclerotic dentin towards the pulp, formed by the odontoblasts or newly formed odontoblasts-like cells
What do you call the dentin adjacent to the enamel?
Mantle dentin
A = dentin
B = Stria of Retzius
C = mantle dentin
D = globular dentin
Where can the zone of sclerosis also be found?
Under dead tracts
A = zone of demineralisation (changing colour)
B = dead tracts
What happens in the zone of demineralisation?
Where the acid starts to demineralised the inorganic component
What does part of dentin does acid effect first?
The intertubular dentin
A = sclerotic dentin
B = dead tracts
C = zone of demineralisation
A = sclerotic dentin
B = dead tracts
C = zone of demineralisation
A = zone of bacterial invasion
B = zone of demineralisation
C= dead tracts
D = sclerotic dentin
What happens when bacteria reach the tubules?
They start to proliferate in the tubules
What are the 2 waves of bacteria?
- Acidogenic bacteria
- Mixed acidogenic and proteolytic organisms
What is the role of the acidogenic bacteria?
Produce the acid that demineralises the inorganic component
What is the role of the mixed acidogenic and proteolytic organisms in the zone of bacterial invasion?
Breakdown proteins
What does this image show?
Bacteria proliferating in tubules
What is the effect of bacteria proliferating in the tubules?
The intertubular dentine is demineralised, walls of tubules become weak. Bacterial can keep proliferating and distend tubules
What has occurred here?
Bacteria have proliferated demineralised tubule and is now distended
What is this called?
Liquefaction foci
Beaded appearance
What is shown here?
Many Liquefaction foci on a tubule
A = zone of destruction
B = zone of bacterial invasion… liquefaction foci on distended tubules
C = zone of demineralisation
D = zone of sclerosis
What occurs on the zone of destruction?
Increase in the number of liquefaction foci
Cracks appear at right angles of the tubules (transverse clefts)
What is shown here and what zone?
Zone of destruction and a crack appeared at a right angle of the tubules
What do you call the crack at a right angle to the tubules?
Transverse clefts
What is tertiary dentin?
Reaction of the dental pulp to caries
What can cause tertiary dentin?
- Reactionary - original odontoblasts
- Reparative - newly formed odontoblasts-like cells
What does tertiary dentin look like that forms slowly?
Get some dentino-tubules
Did this dentin form slow or fast?
Slowly
What does tertiary dentin forming quickly look like?
More similar to bone and no structure
A = dentin
B = tertiary dentin
C = sclerotic dentin
D = zone of bacterial invasion
E = zone of destruction
F = zone of demineralisation
