Karies: Biochemistry Dental hard Tissue, Histophatology, Microbiology, Saliva, Classification

 

Biochemistry Dental Hard Tissue

• Structure and Composition of Enamel and Dentine

  • 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
    • Basic Structure- Prism

      • The basic structural unit of enamel is the enamel prism

      • Prism is consisting of several million crystallites

      • Prism boundary contains more organic material and water

      • 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

  • 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
      • 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

  • 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

• Chemistry of Dental Mineral

  • Basic Concept
  • Enamel Mineral

• Demineralisation and Remineralisation

  • Oral Enviroment
  • Demineralisation

Histophatology

• Zone of Enamel lesion (Whitespot lesion)

  

  • Translucent Zone
  • Dark Zone
  • Body of Lesion
  • Surface Zone

• Zone of Dentine Lesion

  • Zone of destruction
  • Zone of bacterial invasion
  • Zone of demineralization
  • Translucent Zone
  • Reactionary dentine

Microbiology

• Dental Plaque

  • microbial community
  • are enclosed in a matrix containing extracelullar polymeric substance (EPS)

• 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

• Structure and composition of dental biofilm

  • Bacterial cell
  • EPS

• Biochemical interaction on biofilm

  • Synergistic
  • Antagonistic

• Perspective

  • Previous
  • Current

Saliva

• 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

• Flow Rate of Saliva

  

  • Hyposalivation/Xerostomiz

    • Unstimulated

      < 0,1 ml/min

    • Stimulated

      < 0,5-0,7 ml/min

• Function

  • Maintenance Oral Health
  • Tissue repair
  • Digestive function
  • Articulation of speech

• Saliva and Caries development

• 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

ICDAS and ICCMS

Caries Risk Assesment