Caries II Flashcards
How do caries lesions appear on radiographs?
As shadows
look at slides
How does the incipient enamel lesion develop?
Demineralisation actually occurs beneath the surface of the enamel & then starts to spread towards the surface of the enamel & also deeper towards the EDJ.
Why does the demineralisation occur?
The biofilm sitting on the tooth surface produces acid, reducing the pH to <5.5, therefore causing dissociation of the mineral within the enamel.
How are enamel crystals arranged?
As prisms (95% mineral (hydroxyapatite) and 5% organic matrix + water)
Recall dentine structure:
- Mesodermal, mineralised, connective tissue
- Dentine matrix is 90% collagen type 1 and 10% non-collagenous proteins
- Triple helix of 3 alpha chains
What do prism boundaries contain?
Organic matrix (amelin I, II, albumin)
Prism boundaries and prisms suffer the acidic demineralisation.
What are the clinical effects on enamel when demineralisation happens?
-Goes from healthy to frosty white appearance, “white spot lesion”, chalky & softened, increased porosity
-Goes from smooth surface to roughened & cavitated
-If the lesion arrests, any pigmentation from the diet can penetrate into porosities and leave us with a hard, shiny surfaced brown spot lesion
What happens to dentine in demineralisation?
-Organic acid attack (lactate, acetate, proprionate)
-Bacterial penetration via tubules & branches
-Proteolysis- collagen breakdown via host & bacterial enzymes
What are the clinical effects on dentine when demineralisation occurs?
-Brown pigmentation (maillard reaction)
-Demineralisation causes softening
-Dentine-pulp complex defence reaction results in translucent dentine in tubules & reparative dentine being laid down at the dentine-pulp border
What does the extent of the white spot lesion on the surface clinically give you some indication of?
It gives you some indication of the spread of the dentine lesion beneath
look at slides
How does the lesion change as you go from the EDJ towards the pulp in terms of the hardness of the tissue?
Translucent dentine is still quite hard compared to other dentine.
look at slides
What is the caries iceberg?
Diagnostic threshold/ index showing what is considered caries and what is caries free.
look at slides
What are some defence reactions to caries process in dentine?
- Translucent dentine (sclerotic) -This helps to slow down the acid advance, giving the pulp some protection from the acid
-Reparative dentine (tertiary) laid between the pulp and dentine
-inflammation/serum proteins in pulpal fluid
caries process in dentine?
International Caries Detection & Assessment System
the one in the picture is a modified version
look at the slides
What are some histological features of a D1 & D2 lesion?
-Early subsurface demineralisation
-Early porosity
-May be some bacterial penetration
-May be some tertiary dentine
