Contemporary trends • Minimally invasive approach • Adhesive materials and techniques Composites Chemically bonded combination of organic matrix and inorganic filler Natural composites Composition Organic matrix is a resin Bowen's monomer Bis GMA (result of Reaction of Bisphenol A and glycidyl methacrylate) UDMA Oligomer - dimethacrylate TEGMA Composition Filler Milled quartz Aluminium silicate glass Silica (Si02) Prepolymer Coupling Agents Silane Composition Iniciators and accelerators (activators) Other components Pigments UV absorbers Antioxidants Curing • Light cured composites - Light activated. Light activation is accomplished with blue light (470 nm) Initiator is camphorquinon, Phenylpropandion, Lucirin Chemically cured composites Iniciátor is organic peroxide, accelerator amine Curing Chemically curing (activated) composites Iniciátor is organic peroxide, accelerator is tertiary amine Light curing (activated) composites Composite according to mode of curing Chemically curing (2 components) Light curing (1 component) Dual curing (2 components) Initiation • Camphorchinone / CQ • Phenylpropandion PPP • Photoiniciators absorb light and give energy to activtor that changes in free radicals • For some iniciato^ls^ activator necessary for some not • Trimetylbenzoylphosphi noxid TPO Composites acc. to size of filler Macrofiller (macrofilled) composites 1 - 10 |um Microfiller (microfilled) composites 0,01 -0,04 nm Hybrid composites (contain macro and microfiller, nano filler) Adhesion Adhesion Adhesion Mechanic > lroubalikova@gmail.com pecific Adhesion Mechanic Irregularities of the surface Adhesion pecific Physical Chemical Adhesion Specific Physical - intermolecular forces - Van der Waals, hydrogenium bridges Adhesion Specific Chemical Adhesion Sandblasting Electrolytic Silanization Plazma coating Silanization Creates irregularities Increases surface energy n of surfaces Adhesion of dental materials Composites - micromechanical Adhesives - micromechanical, specific Glassionomers - specific Adhesion in enamel Adhesion to dentin More water and organic substances in comparison to water Tubular liquid Connection with the pulp chamber Smear layer Variety in composition Adhesion to dentin Adhesive system Adhesives • Acid etching technique • Selfetching adhesive systems Adhesives • Acid etching technique Etching Washing Priming Bonding Adhesives • Selfetching adhesive systems Priming Bonding Adhesives Active and passive bonding Active - rubbing with microbrush Passive - without any rubbing Polymerization Polymerization strain and stress Polymer network Chellenges of direct composite restorations • Polymerization strain and polymerization stress \ GEL POINT Postgel phase Byung, Suh Principles of adhesion dentistry 2013 Selfcuring composite • In selfcuring composites is the pregel phase longer. In light curing composites is pregel phase shorter. lroubalikova@gmail.com 46 Polymerization strain and stress sre influenced by Material Geometry of the cavity Mode of application Mode of polymerization Polymerization strain and stress are influenced by Material Geometry of the cavity Mode of application Mode of polymerization Material a - s. E Hihg content of filler - low polymerization shrinkage, high polymerization strain and st 10 20 % of filler 40 80 Polymerization stress Modulus of elasticity Polymerization shrinkage lroubalikova@gmail.com 49 Polymerization strain and stress sre influenced by Material Geometrv of the cavit Mode of application Mode of polymerization Configuration factor Ratio of bonded to non bonded area 1/1 a méně je optimální C- faktor Sum of bonded area Polymerization strain and stress sre influenced by Material Geometry of the cavity Mode of application Mode of polymerization First layer must be thin Shrinkage of the thin layer - minimum of strain and stress - flowables are useful. Elastic stress breaker (modulus of elasticity) Risks of high C-factor • Cracs in enamel • Gaps in dentin Sealing of the filling Polymerization strain and stress sre influenced by Material Geometry of the cavity Mode of application Mode of polymerization Prolongate of the gel phase Soft start ? Polymerization units Quartz-Tungsten-Halogen (QTH) Plasma Arc (PAC) Light Emitting Diode (LED) Photonitiator system • Photosenzitores are moleculs that absorb light and transfer the excitation energy to a coinitiator molecule that will become a free radical • Camphorquinone CQ • Phenylpropandion PPP Some photoinitiators require a co initiator (CQ requiers amine) Trimetylbenzoylphosphi noxid TPO lroubalikova@gmail.com Absorption spectra ABSORPTIVE REGION THAN FROM QTH LIGHT 350 400 450 500 WAVELENGTH (nm) lroubalikova@gmail.com 65 2 step polymerization 10 s cca 140 mW/cm 750mW/cm230s Soft start Continuos increasing to 750 mW/cm2 during 10 s and polymerization 30s Continual polymerization Min. 500 mW/cm2 40 s 2 step polymerization with interruption 100- 300 mW/cm2 3-5 s, prerusoi na 3 min, pakpolymerovat 750 mW/cm2 po 30 s ^^^^^^^^m Energy and time of polymerization • Recommended energy dose 12000- 16000 mJ/cm2 12 000 mWs/cm2 = Time of polymerization in s Intenzita mW/cm2 Energy and time of polymerization • Recommended energy dose 12000- 16000 mJ/cm2 12 000 mWs/cmp» J'wne of polymerization in s Intenzita mW/cm2 2 step polymerization 10 s cca 140 mW/cm 750mW/cm230s Soft start Continuos increasing to 750 mW/cm2 during 10 s and polymerization 30s Continual polymerization Min. 500 mW/cm2 40 s 2 step polymerization with interruption 100- 300 mW/cm2 3-5 s, prerusoi na 3 min, pakpolymerovat 750 mW/cm2 po 30 s ^^^^^^^^m