Karies: Biochemistry Dental hard Tissue, Histophatology, Microbiology, Saliva, Classification
Biochemistry Dental Hard Tissue
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Structure and Composition of Enamel and Dentine
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Enamel
- Physical Properties
- Around 1,3-2,5 mm thick
- Hardest biological tissue
- More resistant to fracture than geological materials
- Have a porosity of about 3-5% by volume
- Refractive index of 1,62
- Chemical Properties
- 95-96% hydroxyapatite crystal
- composition about 88-90% of the tissue by volume, or abour 95-96% by weight
- richer in magnesium and carbonate than pure H2P
- tightly packed with gaps (pores)
- tooth shade is affected by crystal size, carbonation and porosity
- 2% water
- 2% by weight, 5-10% by volume
- lie between crystals and surround the organic material
- 1% organic materials
- 1-2% by weight
- made up peptide group termed amelogenism and non-amelogenism
- contains lipid contents
- 95-96% hydroxyapatite crystal
- Basic Structure- Prism
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The basic structural unit of enamel is the enamel prism
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Prism is consisting of several million crystallites
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Prism boundary contains more organic material and water
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Orientation of prism (rods)
regularly organised in alternating layers run perpendicular ( tergak lurus) to dentine, slight inclination towards the cusps may bend resulting in sinusoidal lines
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- Physical Properties
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Dentine
- Chemical Properties
- Gross composition (by weight)
- 70% inorganic (Hydroxyapatite crystal)
- comprises about 50% of the tissue by volume, or about 70% by weight
- calcium poor, carbonate rich
- smaller crystallites than enamel
- located on and bwtween colagen fibrils
- 20% organic acid
- 10% water
- 70% inorganic (Hydroxyapatite crystal)
- Basic Structure- Tubules
- Makes dentine permeable
- From the pulpal surface to enamel-dentinie junction and cementum-dentine junction
- Pertubular dentine and insertubular dentine
- Contains the processes of the odontoblast
- Gross composition (by weight)
- Chemical Properties
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Cementum
- Physical
- Thickness at the root apex and in the interradicular areas of multirooted teeth
- Thinnest cervically
- Softer than dentine
- Pale yellow with a dull surface
- Permeability varies with age
- Physical
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Chemistry of Dental Mineral
- Basic Concept
- Enamel Mineral
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Demineralisation and Remineralisation
- Oral Enviroment
- Demineralisation
Histophatology
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Zone of Enamel lesion (Whitespot lesion)
- Translucent Zone
- Dark Zone
- Body of Lesion
- Surface Zone
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Zone of Dentine Lesion
- Zone of destruction
- Zone of bacterial invasion
- Zone of demineralization
- Translucent Zone
- Reactionary dentine
Microbiology
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Dental Plaque
- microbial community
- are enclosed in a matrix containing extracelullar polymeric substance (EPS)
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Stages of biofilm formation
- Pellicle forms on a clean tooth surface
- major constituent: salivary proteins, lipid and carbohydrate
- provide receptor for bacteria
- Colonization of pioneer of microorganism
- Attachment of pioneer organism, mainly streptococci and actinomyces
- Specific adhesin (on bacteria)- receptor (on pellicle) interaction
- Conaggregation / Conadhesion and microbial succesion
- Cell-to cell recognition
- Coaggregation between other genera and the early colonizer
- Maturation or biofilm and matrix formation
- Developmental of an extracelullar matrix of polymers
- Microbiota become more diverse
- Detachment from the surface
- Passive removal by shear forces
- Active detachment
- Pellicle forms on a clean tooth surface
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Structure and composition of dental biofilm
- Bacterial cell
- EPS
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Biochemical interaction on biofilm
- Synergistic
- Antagonistic
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Perspective
- Previous
- Current
Saliva
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Physiology
- biofluid secreted by salivary gland (3)
- Average volume : 0,6L/day (0,5-1,0/day)
- Average pH 7,4 (unstimulated 6,8-stimulated 7.8)
- Supersaturated
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Flow Rate of Saliva
- Hyposalivation/Xerostomiz
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Unstimulated
< 0,1 ml/min
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Stimulated
< 0,5-0,7 ml/min
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- Hyposalivation/Xerostomiz
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Function
- Maintenance Oral Health
- Tissue repair
- Digestive function
- Articulation of speech
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Saliva and Caries development
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Saliva and Caries Management
Clinical Feature, Classification
- Clinical Feature
- Active caries
- Plaque covered
- Dull surface (not shiny)
- Light to mid brown colour
- Soft
- Arrested caries
- Plaqur free
- Darker in colour
- Shiny surface
- Hard
- Active caries
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