*Presented by Sobia salam738 COMPOSITE

DIRECT PLACEMENT RESTORATIVE MATERIALS*Esthetic materials are those materials that are tooth colored.Direct placement materials, are placed directly by the clinician in prepared teeth without the need for extra-oral construction of the restoration

DIRECT RESTORATIVE MATERIALS*CompositeGlass ionomer cements (GIC)Resin modified-GICCompomers

COMPOSITE*Composite: mixture of two or more components.Major components:Organic resin matrixInorganic fillers Coupling agents (silane), join filler and matrixPigments

COMPONENTS *Resin matrix: chemically active component. Fluid monomer then converts to a rigid polymer by a radical addition polymerization reaction. Monomers used:bis-GMA (bisphenol A-glycidyl methacrylate). Bowens resinUDMA (Urethane dimethacrylate)These resins are made of oligomers (organic molecules) and low molecular weight monomers (such as MMA, EDMA, TEGMA)In addition an inhibitor is added (hydroquinone)Resin matrix also contains initiators, activators

*Fillers: silica, quartz, more recently silica based glasses some containing barium, strontium etc.Properties affected by fillers:Strength Radiopacity (barium, strontium)Esthetics such as color, translucencyPolymerization shrinkage

*Varity of filler size, A, Macrofilled. B, Microfilled. C, Hybrid

*Coupling agents: what happens if bond between resin and filler is weak:The material would be weak and susceptible to creep and fracture andThe interface between filler and resin will be a source of fracture, stress will not be distributed properly.Silane coupling agents: has a hydrophobic end (methacrylate group) to bind the resin and a hydrophilic end (OH- group) to bind glass fillers

POLYMERIZATION Monomers join polymersInitiators and activators cause the reaction to begin.Side chains on polymers cross-link to form stronger material*

POLYMERIZATION TECHNIQUES*Chemical cure (self-cure): 2-paste system:Base: composite and benzoyl peroxide as initiatorCatalyst: composite and tertiary amine activator Require manual mixing which may lead to air bubbles incorporation.

CONTINUE, *Light cure: started with UV light to create free radicals. UV was abandoned due to UV causing burns and eye damage. Blue light (400-500 nm) is used instead. Components that start to react once subjected to the light:Diketone (Camphoquinone source of free radicals)Organic aminesProtection is needed for eyes

POLYMERIZATION *Dual cure: 2-paste system containing both types of initiators and activators. Advantage: light starts the polymerization rxn and the chemical reaction continues in areas were light cant reach them.

*Oxygen inhibited surface layer: sticky, should be removed by a cotton pellet or prevented by a matrix strip.

Depth of cure: much better with blue light (3-4 mm) compared to UV light units (2mm maximum).

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POLYMERIZATION SHRINKAGE*Composites shrink away from cavity wallsMay lead to breaking marginal seal leading to sensitivity and recurrent criesMay pull at tooth structure and lead to cracks and sensitivityDepends on type of resin and amount of resinBond between composite and dentine is weaker than between enamel and composite

HOW TO OVERCOME THESE PROBLEMS?*Incremental placement of composite (increment no more than 2 mm)Slow curing or soft start curing method to allow relaxation of stressesUsing highly filled composites when possibleDeveloping improved dentine bonding systemsUsing low modulus liners to at as stress absorbers

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CLASSIFICATION OF COMPOSITES*Macrofilled (traditional)MicrofilledSmall-particle compositeHybridFlowablePit and fissure sealantPackable compositeSmart compositeCore build up composite

MACROFILLED COMPOSITES*First generationFiller particle size 10-50 mDifficult to polishStronger than composites with smaller particles

MICROFILLED COMPOSITES*Filler particle size 0.01-0.05 m in diameterVolume of filler is 35-50% (smaller compared to other composites due to the larger volume of several small particles as opposed to one large particle of the same weight) Lower physical properties, better polishability

HYBRID COMPOSITE*Mixture of macro and microfillers (75-80% by weight)Hybrid composite: contains 2 particle sizes, large 15-20 m and microfine fillers (colloidal silica) 0.01-0.05 m Small particle hybrid: 0.1-6 m Hybrids have high polishability and strength so they can be used for anterior and posterior restorations.

Low-viscosity, light curedCan be lightly filled (40%), or more heavily filled (70%)Particle size 0.07-1 mDelivered into cavity using a syringe Weaker and wear more compared to hybridsPit and fissure sealingLiners (cushion stress caused by polymerization shrinkage of overlying composite)Class VFLOWABLE COMPOSITES*

PIT AND FISSURE SEALANTS*Range from no filler to more heavily filled composites similar to flowable compositesLow viscosityPreventive material

PACKABLE COMPOSITES*Highly viscous which is achieved by:Higher filler loadingIncreasing filler particle size rangeModifying particle shape (make them interlock)Modifying resin matrix to create stronger intermolecular attraction so higher viscosityDrawback: they appear opaque, not stronger than hybrid composites, air maybe trapped when composite is packed into cavity Suited for posterior restorations

SMART COMPOSITES*Combat caries by having the ability to release fluoride, calcium, hydroxyl ions when acidity increasesEffectiveness has not yet been proven

CORE BUILDUP COMPOSITES *Heavily filledReplace lost tooth structure in teeth needing crownsColored to distinguish then from natural tooth structure

PROPERTIES *Biocompatibility: potentially harmful components, however once set, its well tolerated. Leaching out of some components may cause cytotoxicity and delayed hypersensitivityWater sorpion and solubility

PROPERTIES *Coefficient of thermal expansion: Greater than tooth structure, causes debonding & leakage. Higher filler content reduces CTE

Radiopacity: helps to detect caries around and underneath composite fillings. Should be as radiopaque as enamel

PROPERTIES *Color matching: causes of discolorationMarginal discoloration Surface discolorationBulk discoloration: due to chemical breakdown of components and fluid absorption

MECHANICAL PROPERTIES *Compressive strength: Composites usually fail under tensionDiametral tensile strength: its an alternative method to measure tensile strength and used with brittle material

*Hardness: indicates wear resistance, improved by filler additionWear: lower filler content increases wearAbrasive wearFatigue wear: lead to cracks forming below the surfaceCorrosive wear : due to chemical attack and erosion

CLINICAL HANDLING OF COMPOSITES*Composite is used for all sorts of restorative procedures from class I to class IV.Selection criteria:Esthetic demands: Microfills and microhybrids are suitedStrength demands: in posterior teeth and stress bearing areas, hybrids are more suited

SUGGESTED CONTRAINDICATIONS FOR USING COMPOSITE*Large restorations: usually in molarsGreater polymerization shrinkage, so, difficult to achieve good marginal sealPossibility of bond breakdown with dentine leading to gap formation and painHigher load, so more wearDeep gingival preparations:Marginal sealGood adaptationDepth of cureDentine cavity margin

CONTRAINDICATIONS *Lack of peripheral enamel: bond to dentine is unreliable. Cavities due to erosion and abrasion may still be successfully restored with composite even if enamel is lacking since these areas will not be subjected to high stressonlays of load bearing cuspsPoor moisture controlHabitual bruxism/chewing

*Shade guide: Some practitioners apply a portion of composite on tooth surface and cure it to observe the appropriate shade.

Shelf life: follow manufacturer instructions but as a general rule, avoid heat and light. Average shelf life 2-3 years.

*Dispensing and cross-contamination: composites are usually dispensed in syringes. Disposable small containers are used to avoid cross-contamination. Once composite is dispensed, it should be covered with a light-protected container

*Single paste, light activated compositeInstruments for placing compositeSyringe for injecting compositeSelf-cure 2 paste composite, and bonding agent bottle

*Matrix strips/ bands: Mylar strip is used in class III, IV. Metal matrix bands are used for class II cavities (curing is from an occlusal direction then after the band is removed, light is directed from facial and lingual aspects). Clear crown forms are used for build up restorations. A wedge is also used to seal gingivally. Incremental placement: 2 mm thick is recommended:To minimize polymerization shrinkageAllow curing light to properly penetrate and cure

*Etching and bonding:Fourth and fifth generation bonding agents:Etching is achieved using phosphoric acid (34-37%). After etching, tooth surface is washed and gently dried, etched enamel will appear frosty white.Bonding agent is applied in a thin layer and light-cured according to manufacturer instructions. (remember micromechanical retention). Sixth and seventh generation bonding agents:Etching and priming is done in one application, and no rinsing is required.

*Contaminants: After etching and bonding. Re-etching? Eugenol containing cements should be avoided. Light-curing: Should be held as closely as possible to composite20-40 seconds for thin layersThicker layers, darker shades, deeper locations require more time

*Finishing and polishing: sandpaper discs, fine, ultra-fine diamonds. For gingival or interproximal areas, scalpel knife, abrasive strips and needle-shaped diamond burs are used. Polishing pasts can also be used.Surface sealers: unfilled resin maybe added to reseal margins opened by polymerization shrinkage, or surface porosities.

PRECAUTIONS FOR LIGHT CURING*Inadequate light output: monthly check on light source, to examine output (using radiometers), any scratches on light probes or darkening due to disinfection. Premature set of compositesEye protectionHeat generation

*Light curing unit, protective glasses and shield

COMPOMERS *Composites modified with polyacid (polyacid-modified resin). The resin contains MMA and polycarboxylic acid. Light activation chemicals are included and also fluoride containing glasses. Fluoride release? Setting rxn occurs in 2 stagesSame as light-cured compositeAcid-base rxn Bonding to tooth structure occurs as in composites

COMPOMERS PROPERTIES*Fluoride release: lower than that of GIC or resin modified glass ionomers. Adhesion: similar to composite but in low stress areas acid etching maybe discarded. Polymerization shrinkage: similar to composite. Rate of water uptake is fasterWeaker than composites, lower wear resistance

COMPOMERS CLINICAL APPLICATIONS*Low stress bearing areas such as abrasion lesions, proximal surfacesIn primary teethLong term temporary in permanent teethDisadvantage due to hygroscopic expansion, fracture of crowns when compomers are use as luting agents

SHADE TAKING*PatientDentistAssistantHueChromavalue

*Vita shade guide and shade selection

*Guidelines for taking the shade:Group effort by dentist, assistant and patientShould be taken before preparationTaken before rubber dam placementTeeth should be clean, free of stains and moistTwo different lights should be used (Metamerism): dental offices usually have fluorescent light (blue), or incandescent light (yellow). Natural light is a good source except in morning or late afternoon (more yellow and orange, and less green and blue)

CONTINUE, *A neutral background should be used (e.g. blue apron)Female patients should be asked to remove lipstick, and colorful clothes should be coveredSeveral tabs are held close to patients teeth and kept moist. Separate shades for cervical part of the tooth might be necessary.

CHARACTERIZING THE SHADE*Surface texture (affects light scatter from tooth) and luster (the degree to which the surface appears shiny) should be noted. These two properties affect how the tooth reflects light and scatter it.The amount of translucency (especially near the incisal edge) should also be noted.

CONTINUE, *Any surface characteristics should be replicated if the patient demands that the restoration matches existing teeth. A photograph of the patients teeth and adjacent shade guide tab maybe helpful.

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