Please enable JavaScript.

Coggle requires JavaScript to display documents.

Principles of Adhesion (Importance of Adhesion (To reduce tooth…

- - - - Function
        
        Produces pores in the surface into which the adhesive penetrates --> mechanical interlocking
        
        Increases surface enegry of enamel and so wetting
        
        Increases the surface area of the enamel
        
        Removal of surface debris
      - AFTER etching, adhesive is then applied to the flow and fill the produced irregularities and bond to enamel by MECHANICAL INTERLOCKING, then composite is applied to bond with the adhesive chemically
      - Low viscosity fluid resin contacts the surface and is attracted to the interior of microporosities created by capillary attraction
  - - - 1. Acid Etching
        
        Removes the smear layer
        
        Demineralises the surface (that produces porous dentine surface)
        
        Open the dentineal tubules and the collagen network (removes HAP, leaving collagen and water)
      - 2. Primer
        
        e..g HEMA applied to etch dentine. Bc most organic material has been removed by the acid, the primer penetrates into the organic material leading to its expansion
        
        It is umpyphilic (has a hydrophobic and hydrophilic arm to bond dentine to composite monomers)
        
        Dentine: HYDROPHILIC
        
        Composite: HYDROPHOBIC
        
        3 types of vehicles
        
        Acetone (dry technique)
        
        Ethanol
        
        Water
      - 3. Adhesive
        
        Low viscocity resin that contains hydrophilic molecules can penetrate inside the porous dentine and the hybrid layer to bond with the primer and the collagen fibres by mechanical interlocking. Composite is then applied to bond with the adhesive chemically
    - - Dynamic tissue that shows changes
      - Outward flow of dentinal fluid
      - Organic material and water
      - Close to pulp --> cause irritation
  - - - Present in both, more organised in enamel
    - - Makes wetting of dentine by adhesive more difficult
    - - shows changes due to ageing, caries or operative procedures
      - Outward flow of fluid reduces adhesion of composite resin
      - Dentinal tubules contain vital processes of pulp, odontoblasts