1. Composite Restorative Material part I
Amalgam
Composite
Gold

2. Restoration
Classified into:
Direct Restoration
Indirect Restoration

5. Direct Restorative Materials
Direct gold restoration
Amalgam restoration
Direct aesthetic restoration
Silicate restorative material
Acrylic restorative material
Composite restorative material

6. Ideal requirements of aesthetic restorative material
Shade match, shade stable
Biocompatible
Not dissolve is oral fluids
Have adequate mechanical properties
Have strength & modulus of elasticity similar to tooth
Good abrasive resistance
Coefficient of thermal expansion similar to tooth
Minimal dimensional changes with setting
High polishability
Radioopaque
Adhere to tooth structure

7. Silicate restorative material
Introduced since 1903
Advantages:
Translucency of glass powder
Anticariogenic property
Disadvantages:
Poor biological response
Dissolution
No longer used any more

8. Acrylic restorative material
Early clinical failure related to dimensional instability =>
Gap between restoration and tooth =>
Stain, sensitivity, & recurrent caries
No longer used any more

9. Composite filling material
Introduced in 1960s
Composite: is combination of 2 or more chemically different materials with interface separating the components
Dental composite: refer to resin restorative material consisting of 2 phases: inorganic fillers dispersed in continuous resin matrix system that will induce polymerization,

11. Basic components of composite
Resin matrix
Inorganic fillers
Coupling agent
Initiator accelerator system
Inhibitor
Optical modifiers

12. Organic matrix phase
Principal high molecular weight monomer (oligomer)
Diluent (lower molecular weight monomer)

13. Principal high molecular weight monomer (oligomer)
Majority is Bisphenol A-glycidyl methacrylate (BIS-GMA) also called bowen’s resin Or
Urethane dimethacrylate (UDMA)
Advantages of oligomers over methyl methacrylate
Lower polymerization shrinkage
Lower volatility
More rapid hardening
Result in stiffer and stronger resin

14. UDMA advantages over BIS-GMA
Lower viscosity
Lower water sorption
Greater toughness
Greater susceptibility to visible light curing

15. Oligomers contain carbon double bond at each end => free radical addition polymerization => rigid cross-linked polymer
Oligomers are viscous => incorporation of inorganic fillers is difficult => addition of diluent

16. Diluent Low molecular weight monomers added to: Diluents are either:
reduce viscosity => proper blending with inorganic component
Facilitate clinical manipulation
Diluents are either:
Diethylene glycol dimethacrylate
Triethylene glycol dimethacrylate

17. Inorganic Fillers
Consist of several materials: quartz, borosilicate glass, lithium aluminum silicate, barium aluminum silicate, strontium or zinc glass, or colloidal silica
Heavy elements => radioopacity

18. Role of inorganic fillers
Improve mechanical properties eg. Compressive strength, modulus of elasticity, hardness
Higher filler => better mechanical properties
Reduce coefficient of thermal expansion
Glass is able to reflect color of surrounding tooth structure
Reduce polymerization shrinkage
Less heat generation
Barium or strontium => radioopacity

19. Filler particle size and shape
Macrofilled
Microfilled
Hybrid
Nanofilled
Nanohybrid

20. Macrofilled Large particle size 20-30 µm Adv. Disadv.
Irregular filler shape => better retention to resin matrix
Disadv.
Large filler => difficulty in finishing and polishing
Discoloration and staining

21. Midifilled
0.5 – 3 µm
Same as macrofilled composite

22. Microfilled 0.04 - 0.2 µm Adv. Disadv.
Give shiny surface
Disadv.
Difficult to add => 25% fillers
Solved by adding filler to oligomer of low viscosity => cured => gound 10 – 20 µm => added to more viscous oligomer
Fillers are called organic fillers or prepolymerized fillers
Result in % fillers

23. Hybrid composite Contain mixture of macro & micro fillers
Combine the adv. Of both types
Higher mechanical properties (macro)
Good surface finish (micro)
Contain up to 70 % of fillers

24. Nanofilled Nanomers 2-75 nm individual particles or
Nanoclusters 5-20 nm particles clustered together into µm
Adv.
Highly transluscent
Higher mechanical properties: up to78.5 % fillers
Lower polymerization shrinkage
High polishability

25. Nanohybrid composite
Contains large particles µm with added nanomers