Definujte zápatí – název prezentace nebo pracoviště1 Preclinical dentistry I. Composite materials I. Composite materials Chemically bonded mixture of organic matrix and inorganic fillers Coupling agent – binds organic matrix and the filler together Homogenous distribution of the filler particles in the material Excellent mechanical properties Binding of the coupling agents to glass particles CH2=C(CH3)-R CH2=C(CH3)-R CH2=C(CH3)-R H O-Si H O-Si H O-Si Double bond -polymerizable Glass particle Filler – material ̶ Milled quartz ̶ Aluminimum silicate glass ̶ Silicium dioxide ̶ Prepolymer (composite material is polymerized with high pressure in fabrics, than milled – particles of the fiiler are made of cured composite) ̶ Complexes of microfiller (aglomerates) – e-g-. siliciumdioxide or zirconiumoxide Filler acc to the size of particles ̶ Macrofiller ( size of particles µm ot tenth of µm ) ̶ Microfiller (hundredths od µm) ̶ Nanofiller (nm) ̶ Combination– hybrid ➢Conventional (µm ) ➢Microhybrid (hundredths od µm, µm) ➢Nanohybrid (hundredths od µm, µm, nm) Macrofiller ̶ Particles µm or tenths of µm ̶ Good mechanical resistance , abrasion resistance, bad polishability. Microfiller • Silicium dioxide (pyrogenous) • Particles hundreths µm Less amount of filler due to big surface Lower mechanical resistence, good polishability. Microfiller in complex particles ̶ Prepolymer ̶ Aglomerates - Higher amount of filler, good mechanical resistance, good polishability Nanoparticles ̶ Particles 10 nm and less Special technology, size, shape and binding to monomer Today ̶ Microhybrid or nanohybrid composites: Good mechanical properties, good polishability, propagation of cracks is minimized. Matrix Bis GMA – Bowen´s monomer • (2,2-bis[4-(2hydroxy-3-metakryloyloxypropoxy) • fenyl]propan) • UDMA Urethandimetacrylate Other dimetacrylate • Dimethacrylates - mixture of materials with high and lower molecular weight Coupling agent ̶ G -methacryloxypropyltrimetoxysilan (A 174) Other components ̶ Activator and initiator ̶ Pigments ̶ Fluorescents ̶ Absorbers of light ̶ Inhibitors Selfcuring composites- two components material ̶ Tertiary amine Dibenzolyperoxide ̶ Activator Initiator Light curing composites Initiator and sometimes also activator Camphorchinon CQ Is zhe most common initiator in light curing composites Composite materials – basic characteristics Matrix Filler Compressive strength Elasticity Polymerization shrinkage Polymerization stress Water sorption Classification of composite filling materials ➢ According to the size of the filler particles Macrofilled, microfilled hybrid ➢ According to the mode of curing Selfcuring, light curing, dual curing ➢ According to the viscosity flowable, thick Pronciple of retention ̶ Micromechanical retention Microscopic spaces are created in enamel and dentine – composite material flows into them. For the creation of the retentive pattern acid etching gel is used. 35% - 37% phosphoric acid silica particles blue dye How it works? ̶ Composite materiál is thick, it is nit able to flow into these microscopic spaces – we need a flowablecomponent – the bond. ̶ Bond is a resin of the same composition as organic matrix, it does not contain the filler – it flows into this retentive pattern. ̶ Bond comes together with the composite. Acid on aprismatic enamel Acid on prismatic enamel Bonding agent Adhesive system connects resin to enamel and dentin ̶ Bond is a hydrophobic resin principally of the same composition as composite filling material but without the filler or with a small amount of filler. It works in enamel. In dentin primer is necessary before bond. Why? Dentin – special composition ̶ More water – always wett ̶ Less minerals ̶ Low surface energy ̶ Smear layer Composite is hydrophobic, we need hydrofilic substance Adhesive systems contain resin monomers ̶ Hydrophobic monomers - bond works in enamel it does not work in dentin without primer ̶ Amphiphilic monomers – hydrophobic + hydrophilic part - in primer Primer is necesssary for dentin. The hydrophillic part flows into dentin (tubules, spaces in collagen network) and keep the collagen network open, the hydrophobic part of primer binds to hydrophobic bond that flows into dentin pretreated with primerIf primer applied on enamel – residual of water can be removed. Monomer Light Polymerization Polymer Polymer network Polymerization units ̶ Quarz halogen units (halogen lamp) appr. 40 s per layer ̶ LED units (diode – monocgromatic light, need of more diods) Appr. 20 s per layer Absorbtion spectrum of fotoiniciators Photoinitiator Absorbtion spectrum (nm) Maximum (nm) CQ 440 - 500 470 PPD 380 – 430 400 TPO 350 - 410 380 We use blue light Indication of composite materials ̶ Filling of all classes: ̶ I., II. class: small to moderate restorations ̶ III. Class ̶ IV. Class ̶ V. Class ̶ Other factors for consideration: ̶ Level of oral hygiene ̶ Occlusal loading ̶ Quality of hard dental tissues Contraindication of composite materials ̶ Bad level of oral hygiene ̶ Large cavities in posterior teeth (alternative is amalgam or inlay/onlay, ̶ Heavy occlusal stress (deep bite , bruxis) ̶ Cavities out of enamel (esp. cervical area) ̶ Social aspects Sequence of operation ̶ Preparation ̶ Bevel the enamel in most cases (no in class I.) ̶ Acid etching (20s enamel, 10s dentine) ̶ Washing (the same time as etching, at least 10s) ̶ Removing access of water ̶ Priming and bonding – microbrush and air syringe ̶ Curing of the bond ̶ Layering of composite (1,5mm – for good curing) ̶ Finishing and polishing (extrafine diamonds, rubber instruments) Air thin / Dry TO TRANSLUCENCY