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Composite resins


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Composite is a tooth coloured filling material widely used in restorative dentistry, it's actual name is 'Particulate reinforced polymer matrix composite resin.'

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Composite resins

  1. 1. ADA specification no. 27 R.K.Haritha
  2. 2. Silicate cements Polymethylmethacrylate (PMMA) Filler particles principally containing silica Bisphenol A glycidyl methacrylate (bis- GMA)
  3. 3. Direct and indirect esthetic restorative material Splinting of mobile teeth Luting agents and root canal sealers Chemical cure and dual cure resins – core buildup Pit and fissure sealants and in preventive resin restorations (PRR) Bonding of orthodontic brackets
  4. 4. Major constituents Minor constituents Resin matrix Color modifiers Filler particles Inhibitors Coupling agent Activator – initiator – accelerator system
  5. 5. Chemically active component Aromatic or aliphatic diacrylates. Most commonly bis-GMA --- Bowen’s resin Lower polymerisation shrinkage Extensive cross linking Other difunctional molecules – Urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) Other diluent monomers – MMA, EGDMA
  6. 6. Quartz (silica dioxide/silica) – chemically inert and extremely hard to grind. Size range – 0.1 – 100 mu mg 0.06 – 0.1 mu mg produced by pyrolytic or precipitation process.
  7. 7. Decrease polymerisation shrinkage Decrease the coefficient of thermal expansion Water sorption is less Improve the mechanical properties Radiopacity Ideal means of controlling color, translucency and flurescence.
  8. 8. Organic silicone compound called silane. Most commonly used is gamma – methacryloxypropyl trimethoxysilane.
  9. 9. Chemical cure composites – benzoyl peroxide initiator and catalyst paste tertiary amine activator, N,N-dimethyl-p-toluidine. Light cure composites – single paste containing the photosensitizer camphoroquinone and an amine activator.
  10. 10. INHIBITORS – butylated hydroxytoulene in concentrations of 0.01% COLOR MODIFIERS – titanium dioxide and aluminium oxide (0.001 – 0.007wt%) Darker shades placed in thinner layers or cured for a longer time.
  11. 11. ADVANTAGES DISADVANTAGES 1. Esthetics 2. Conservative cavity preparation 3. Reparability 4. Low coefficient of thermal conductivity 1. Technique sensitive 2. Proper contact and contour 3. Isolation 4. Nonantimicrobial 5. Polymerisation shrinkage
  12. 12.  Addition and condensation  Curing lights 1. QTH curing light 2. LED curing light 3. PAC curing light 4. Argon laser curing light  Modes of curing 1. Soft start 2. Pulse delay 3. Ramped cure  Oxygen inhibition
  13. 13. QTH LLED Plasma arc (PAC) Argon laser
  14. 14. Based on resin matrix used Bis-GMA based UDMA based Silorane based Based on type of curing Chemical cure UV light cured Visible light cured Dual cure Tri cure Heat and pressure cured Based on filler particle size (Lutz and Philip) Conventional Microfilled Small particle Hybrid Based on mode of curing a. Instant cure b. Soft cure 1. Ramped cure 2. Stepped cure 3. Oscillating cure 4. Delayed cure
  15. 15. Working time – no less than 90 seconds Setting time – 3 minutes to 5 minutes Polymerisation shrinkage – Composites with higher filler 1.0 – 1.7% lower filler content – 2 – 4% Coefficient of thermal expansion – Ranges b/w 25 – 38*10-6/degreeC and 55 – 68*10-6/degree C
  16. 16.  Water sorption – microfilled composites – 26- 30 mu mg/mm3; hybrid composites – 5-17 mu mg/mm3 ADA specfication – less than or equal to 40 mu mg/mm  Solubility – less than 7.5 mu mg/mm  Radiopacity – glass ceramics – Ba, Sr, Zr  Colour stability – marginal discoloration, General surface discoloration, bulk or deep discoloration
  17. 17. Strength – 200 Mpa to 300Mpa Hardness – directly related to vol. fraction of inorganic fillers. Wear resistance – fillers, porosity, tooth position, degree of polymerisation, finishing and polishing Biocompatibility – cytotoxic in vitro but there is still some controversy regarding its clinical implications