Dental Caries- Lesion Progression Flashcards
What are stagnation areas for plaque
Occlusal pits and fissures Inter proximal areas Gingival recession Adjacent to partial dentures Adjacent to restorations
What are the main bacteria involved in dental caries
Streptococci Mutans
Actinomycetes
Lactobacilli- dentine caries
Describe cariogenic bacteria
Aciduric- thrives at low ph
Acidogenic- transports sugars in diet and converts to acid
Contain intraceluular polysaccharides which convert plaque matrix to acid
Describe the two zones of dentine caries
Outer- infected Demineralised Denatured Infected Not remineralise lie
Inner zone- Affected Demineralised Minimally infected Collagen fibres intact Dentine remineralisable
Describe process of stepwise excavation
Removed outer zone of dentine
Leave inner zone
Remove superficial infected necrotic dentine
Ensure peripheral caries removal adj
Place calcium hydroxide and GI lining
Leave for 6-12 months to allow for dentine complex reactions
2nd visit-
Reclean and permanently restore
Describe the layers of enamel caries
Translucent zone
First carious change
Loss of prism periphery
Few large pores
Dark zone
Large and small pores
Demineralisation and remineralisation
Body of lesion
Largest and centre of lesion
Radio graphically translucent
Surface zone
Relatively intact
Highly mineralised - high fluoride
Rede position of minerals dissolved from deeper layers
Describe arrested caries
Histopathology- large well developed dark zone Remineralised Improvement in plaque control Changes to diet Increase in fluoride
Describe dentine defence responses
Reactionary/ tertiary dentine
Sclerotic zone- blocks dentinal tubules to prevent further bacterial penetration
Describe zones of established dentine caries
Advancing front
Zone of demineralised dentine
Acid demineralisation- no bacteria
Zone of bacterial penetration
Bacteria in tubules
Lactobacilli
Lateral spread via branched tubules
Zone of destruction
Mixed bacterial population
Proteolytic enzymes
Destroys organic matrix
What is the critical ph?
5.5
Below which hydroxyapatite dissolves
What does Stephans curve show?
After sugar intake- rapid ph drop
Slow ph rise
15-50 minutes to return to critical ph
What is the rise in ph due to ?
Salivary buffering- calcium and phosphate ions
Acid diffusing out
When can an item be described as tooth friendly?.
If plaque ph does not fall below 5.7 within 30 minutes
What acts as the buffer in saliva?
Bicarbonate
When does saliva flow increase
Masticatory reflexes
Gustatory stimulants
