COMPOSITE RESINS.pptx

COMPOSITE RESIN

1. COMPOSITE RESTORATIVE MATERIALS Dr Shrimant Raman DEPARTMENT OF PROSTHODONTICS

2. DEFINITION A dental composite is defined as a highly cross linked polymeric material reinforced by a dispersion of amorphous silica, glass, crystalline or organic resin filler particles and short fibers bonded to the matrix by a coupling agent. A 3 dimensional combination of at least two chemically different materials with a distinct interface separating the components.

3. Time Line of Development of Composites

4. CLASSIFICATION Accordingly to the particle size Megafillers - contains very large filler particles. Macrofillers - 10-100 µm Midifillers - 1-10 µm Minifillers - 0.1-1 µm Microfillers - 0.01-0.1 µm Nanofillers - 0.005-0.01 µm H ybrid

5. Homogenous Composite It is a composite that simply consists of filler and uncured matrix material . It contains only microfillers. Heterogeneous Composite It is a composite that consists of microfillers and pre-cured matrix material. Based on handling characteristics / viscosity Packable Composites Flowable Composites Based on polymerization method Self curing UV- light curing Visible light curing Dual curing

6. Based on applications and commercial availability Restorative composites: direct intraoral restorations - Hybrids - M icrofilled - F lowable - Packable - Nano composites Core build up composites Prosthodontic composites (veneers, crowna and FPD’s) Provisional composites (temporary crowns, restorations) Luting composites

7. INDICATIONS FOR COMPOSITES

8. CONTRAINDICATIONS

9. Advantages Show high esthetics Minimal tooth preparation Possess low thermal conductivity and shows bonding with enamel and dentin Finishing and polishing can be done immediately after curing the restorations No galvanism, as it doesn’t contain any metal

10. Disadvantages Polymerization shrinkage leads to gap formation on the margin resulting in secondary caries and staining. More expensive Requires proper isolation and have multiple steps Technique sensitive in comparison to other materials Low-wear resistance

11. IDEAL REQUIREMENTS Should have CTE closer to that of enamel Should not absorb water Should have minimum or no polymerization shrinkage Should have good wear resistant Should have smooth surface texture Should be radiopaque Should have high modulus of elasticity Should be less soluble in oral fluids

12. Supplied as : Composite resin – either chemical or light cured Etching liquid (37% phosphoric acid) Bonding agent

13. COMPOSITION

14. In addition they contain : Activator-initiator system – to activate setting mechanism, chemical or light curing chemicals Polymerization inhibitor (0.01%) – prevents premature polymerization, thus, increasing working time for chemically activated resin. Eg. Butylated hydroxytoluene (BHT) 0.01 wt% UV stabilizers/absorbers – to improve color stability, prevent discoloration. Eg. 2-hydroxy-4 methoxybenzophenone Opacifiers – titanium oxide and aluminium oxide Color pigments – to match tooth color

15. 1 ) Resin Matrix Used earlier – BIS-GMA (Bowen's resin) (Bisphenol-A glycidyl dimethacrylate) USED NOW A DAYS- UDMA (Urethane dimethacrylate ) TEGDMA ( Triethylene Glycol dimethacrylate ) HEMA ( Hydroxy Ethyl methacrylate) EGDMA (ethylene glycol dimethacrylate)

16. 2) Fillers Added to increase - Strength, hardness, rigidity, modulus of elasticity - smaller size improves surface smoothness - less resin leads to reduce curing shrinkage - smaller size increase wear resistance Addition of fillers decreases - Thermal Expansion & Contraction

17. Factors affecting role of filler : Amount of filler added (b) Size of particles and its distribution (c) Shape of fillers (d) Refractive index (e) Radiopacity (f) Hardness

18. Types of fillers: Quartz : extremely hard, difficult to grind in filler particles Silica : as pure, fused, colloidal Glasses or ceramic containing heavy metal Other such as tricalcium phosphate and zirconium dioxide Fillers containing fluorides – Ytterbium trifluoride (YbF₃)

19. 3) Coupling agents Chemical bond between filler particle and resin matrix. If not incorporated or use then it leads to microscopic defects Microleakage of fluids into these defects led to surface staining and failure. Organosilane ( 3-methacryl-oxypropyl-trimethoxysilane) Other are zirconates and titanates

20. Functions : Transfer of stresses Prevent water penetration into filler resin interface Bond fillers to the matrix thus reducing wear

21. Polymerization Mechanisms This process is carried out by initiators and activators by addition polymerization process. Based on mode of activation of polymerization, there are 3 main types : - Chemically activated resins - Light-activated resins - Dual cure

22. Chemically activated composite resins :- Two paste system - Base paste - benzoyl peroxide (initiator) - catalyst paste – tertiary amine activator

23. Light activated composite resins :- Under normal light they don’t interact Photoinitiator( C amphorquinone ) is activated under light of wavelength 400-500nm UV light activated system – used initially to activate free radicals, but it have certain drawbacks

24. Visible light – activated systems – Improved depth of cure and a controlled working time Single paste system – camphorquinone 0.25 wt% and amine accelerator DMAEMA( dimethylaminoethyl -methacrylate)0.15wt% Dual Cure Resins :- combination of above two curing systems

25. Curing lamps These are handheld devices, which are capable of emitting light Consists of small & rigid light guide, which is made up of fused optical fibers Filtered to transmit light only in visible range (400-500 nm) activate the photoinitiator, camphorquinone in light cure resins, by releasing free radicals to begin the polymerization

26. Factors influencing polymerization process: - Wavelength - Intensity - Time of exposure Maximum curing – 16,000mJ/cm² is required to cure 2mm thick layer of resin Light emitting 400mW/cm² - 40 seconds Light emitting 800mW/cm² - 20 seconds

27. Types of lamps used for curing :- LED lamps: - light-emitting diodes - 440-480nm,blue part of visible spectrum - Don’t require filters Benefits - Require low voltage, battery operated, don’t generate heat, don’t require cooling fan, long life span Drawback – produce low intensity radiation

28. 2 ) QTH lamps : quartz-tungsten-halogen lamps Earliest and most common forms of light cure systems Use quartz bulb with a tungsten filament Light source emits white light, which is filtered to remove heat and all wavelengths except those in the violet-blue range b/w 400-500nm

29. Intensity of bulb reduces with use, so calibration meter is required to measure the output intensity Power density : 300-1200 mW /cm² in the violet spectrum Eye protection – protective eye device for direct visual during curing procedure Direct and continuous observation of tip can cause retinal damage to the eyes.

30. Factors influencing reduction of intensity of light from QTH lamps: Light tip is chipped off Resin is deposited on the light tip Distance of the tip to resin is increased Lack of uniformity across the light tip Burn out of the bulb filament Change in line voltage

31. 3) PAC lamps : Plasma arc curing lamps Use xenon gas ionization to produce plasma that forms b/w two tungsten electrodes under pressure High intensity white light filtered to remove heat and to allow blue light to be emitted

32. Light intensity light is obtained at the lower wavelength Exposure from PAC light for 10 sec is equal to 40 sec exposure from QTH Therefore, save time in procedures

33. 4) Argon laser lamp : Highest intensity Emit at a single wavelength of 490nm Designed to emit light in only blue spectrum, which lies in the photo absorption range of camphorquinone Therefore, don’t require filters

34. Macrofilled Composites Also known as traditional or conventional composites Large size of filler particle size Rarely used now a days Composition – ground quartz (8-12 - as large as 50 may also be present Filler loading 70-80 wt% or 60-70 vol %  

35. Properties : A ll mechanical properties like strength, modulus, hardness have improved in comparison to unfilled restorative resin. Also water resorption is less than that of unfilled resins Drawbacks : Polishing results in rough surface compromised esthetics Poor resistance to wear Tendency to discolour – rough surface tends to stain

36. Microfilled Composites Also known as microfine composites Overcome the disadvantage of surface roughness Inferior mechanical properties than conventional due to less filler content So used in stress free area for esthetic purpose and where smooth finish is required for reduced plaque accumulation

37. Composition: colloidal silica (0.04 to 0.4 ) 200-300 times smaller 70 wt% or 60 vol % (organic fillers) Inorganic actual filler is 50 wt% Manufacturers tried to overcome it: Using pre polymerized or organic fillers, heterogeneous  

38. Hybrid Composite Contain 2 types of filler particles – colloidal silica and ground particles of glasses containing heavy metals. Filler content is approx 75-80 wt %. Or 60-65 vol % The glasses have an average particle size of about 0.4 to 1 µm . Multipurpose composite E.g Clearfill APX, Profill , and NV

39. Packable Composites Based on the newly introduced concept called PRIMM (polymer rigid inorganic matrix material). This system consists of a resin and a ceramic component . The fillers are incorporated as a continuous network/scaffold of ceramic fibers . Include elongated, fibrous, filler particles of about 100 µm in length, and/or textured surfaces that tend to interlock and resist flow causing the uncured resin to be stiff and resistant to slumping, yet moldable . (i)Solitaire (ii) Alert (iii) Surefill (iv) Filtek P60

40. Flowable Composites Low-viscosity resin composites for the first increment. Flow more readily than standard hybrid formulations and will therefore easily and thoroughly adapt to all areas of the cavity preparation. Lower filler content (30-55 vol %) than hybrid and reduced elastic modulus High polymerization shrinkage and low wear resistance than micro hybrid composites FloRestore Flow-it Tetric Flow ( Vivadent )

41. Manipulation of Composite R esins

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