It is a tooth colored restorative material that is composed of organic resin matrix and inorganic filler particles dispersed in it
1\ORGANIC RESIN MATRIX: a thick liquids made up of two or more organic molecules that form a matrix around filler particles Most commonly : bis-GMA (bisphenol A glycidyl methacrylate)
2\ INORGANIC FILLER PARTICLES: Fine particles of quartz, silica or glass dispersed in the matrix. Importance of fillers: 1\they give strength and wear resistance to the material 2\Reduce polymerization shrinkage
ACCORDING TO FILLER SIZE COMPOSITES CLASSIFIED INTO: 1\macro filled(large particles) 2\micro filled(small particles) 3\hybrid (combination of the two)
3\COUPLING AGENT: (Silane coupling agent) A chemical that adheres the inorganic fillers to the matrix to provide stronger bond.
The process of composite setting reaction is a polymerization reaction. ACTIVATION OF POLYMERIZATION: 1\chemical activation (self-cured) 2\light activation (light-cured) 3\combination (dual-cured)
Chemical cured composite resins Two paste systems(base + catalyst) Disadvantage: the operator has limited working time(usually it takes 2 minutes before the material becomes stiff to manipulate)
One paste Activated by visible blue light source Advantages: 1\requires no mixing 2\the operator can control the working time
Two paste system Light and chemical activation Advantage: After light curing the chemical setting reaction continues in areas not reached by the light
1\MACROFILLED COMPOSITE: The first generation composite(conventional composite) Large particle size Disadvantage: 1\difficult to polish 2\become rough as filler particles are lost from surface this causes the restoration to be more susceptible to discoloration
2\MICROFILLED COMPOSITE: Smaller filler particles When polished they produce very smooth shiny surface. Disadvantage: Poor physical properties(weaker,less wear resistant,greater polymerization shrinkage)compared to other types.
3\HYBRID COMPOSITE They contain both macro fillers and micro-fillers Advantages: Strong material that can be polished to a high shine
4\ flowable composites These composites flow readily and can be delivered directly into the cavity by small needle. Uses: 1\preventive resin restoration(in small preparations) 2\pit and fissure sealants
High viscous resins that contain a high volume of filler particles, which gives them a stiff consistency They are stronger and more wear resistant
1\restoration of posterior and anterior teeth 2\pit and fissure sealant 3\cementation of fixed prosthodontics
1\Large proximal lesions. 2\When the patient has an allergy to the material. 3\Restorations of root caries.( better to use glass ionomer cements)