Presentation on theme: " Ideal esthetic material for conservative restorations has resulted in improvements in materials and techniques. To improve the physical characteristics."— Presentation transcript:
Ideal esthetic material for conservative restorations has resulted in improvements in materials and techniques. To improve the physical characteristics of the esthetic materials, they develop a polymeric dental restorative material reinforced with silica particles (1962) generally termed composites. History
Composites are presently the most popular tooth- colored materials and with acid etch technique (1952) represent major advances.
Filled (composite) resin restorative materials are all basically two-phase systems. Dispersed phase ofContinuous phase high strengthof polymeric ceramic particlesmatrix Inorganic filler Organic resin matrix Silane coupling agent Composition
Reduce the coefficient of thermal expansion. Provide higher strength, stiffness, FX. resistance thermal dimension change. Inorganic Filler Reduce the polymerization shrinkage. Reduce the polymerization shrinkage.
Translucency matching tooth structure. Chemical inert ness Opaque to x-ray to help making a post operative diagnosis (radiopacity). Most material contain 70-80 percent filler by weight.
Mixing chemically reactive polymeric materials. After insertion continuous ductile phase to bind dispersed filler particles together. This ductile resin act as a medium to transfer the stress b/w the particles (prevent distortion of the material). The resin systems are highly cross-linked, aromatic dimethacrylates. (BisGMA) diluted with less viscous co monomers, Initiator. Organic Resin Matrix
For a composite to have a good mechanical and physical properties, a strong bond must exist b/w Organic resinInorganic filler matrix Silane coupling agent strength of composite solubility water absorption Silane Coupling Agent wear resistance
Divided into 3 types based primarily on SizeAmountComposition Inorganic Filler Types of Composite
Types of Composites (cont’n) Early composite contained Large Large Micro fineFine sphericalirregular particlesparticles particles [0.04-0.2 m][0.5-3 m] [20-30 m] Blends (hybrid)
Types of Composites (cont’n) 1.Conventional 2.Micro fill Composites 3.Hybrid
Contain 75 to 80 % inorganic filler by weight ( 50 - 65 vol.) Particle size range from 1 to 10 m, with the average of 3 m. Uses: Class IV and II Conventional Composites
Disadvantages: Because of the : large size and extreme hardness of inorganic filler. It exhibits a rough surface texture then surface discoloration higher initial wear But they have good physical and mechanical properties.
Designed to replace the rough surface characteristic of conventional composites with : smooth lustrous surface Colloidal silica particles 0.02 - 0.4 m instead of large filler particles. Results in smooth, polished surface respective to plaque or staining. Micro fill Composites:
Microfill Composites: (cont’n) They have 35 to 60% inorganic filler by wt., so it cannot be heavily filled, because of greater surface area per unit volume of this microfine particles (20 - 50 vol.). Result in: inferior physical and mechanical properties Higher wear resistant clinically Uses: ( Anterior rest class III, V ) ( low modulus of elasticity )
Developed to combine the good physical and mechanical characteristics of conventional composites with the smooth surface of micro fill composites. These materials have 70 to 80 % by wt., inorganic filler content (50 – 65 vol.). Hybrid Composites:
Hybrid Composites: (cont’n) The filler is a mixture ConventionalMicro fill particles that have a smaller average particle size than conventional composites [0.5 - 3 m] and bigger than micro fill.
Hybrid Composites: (cont’ n) Due to the presence of sub-micron sized particles inter spread among the larger particles allows a smooth surface texture to be attained in the finished restoration. They have good physical and mechanical characteristics. Uses: ( Anterior, posterior, IV )
The physical properties of the composite resins are improved over those of certain other esthetic materials. 1) Solubility is not observed. 2) Water sorption is lower 3) Fluid exchange within the polymer decreased, this will promote Chemically Color Stability Advantages of Composites:
Advantages: (cont’n) Mechanical properties of the filled resin also enhanced. 1) It has greater capacity to resist masticatory stress. 2) Surface hardness is higher (resistance to indentation)
3)Stiffness is improved (resistance to distortion) 4)Dimensional stability is improved. 5)Initial shrinkage on polymerization is reduced to 1/4 (less leakage)
Advantages: (cont’n) 6)Thermal coefficient of expansions is decreased by 60% (3x tooth structure) clinically better adaptation to cavity walls and margins. dimensional change during thermal cycling minimized resulting to less marginal leakage
Advantages: (cont’n) 7)Thermal conductivity is quite low resin has capability to insulate from thermal change.