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Composite resin

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composite resins

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Composite resin

  1. 1. INTRODUCTION HISTORY USES COMPOSITION AND STRUCTURE POLYMERIZATION MECHANISMS CLASSIFICATION PROPERTIES BIOCOMPATIBLITY MANIPULATION SPECIAL TECHNIQUES
  2. 2. ADVANTAGES DISADVANTAGES RECENT ADVANCEMENTS
  3. 3. WHAT ARE COMPOSITES??? A SOLID FORMED,FROM TWO OR MORE DISTINCT PHASES THAT HAVE BEEN COMBINED TO PRODUCE PROPERTIES SUPERIOR TO OR INTERMEDIATE TO THOSE OF INDIVIDUAL CONSTITUENTS.
  4. 4. TOOTH ENAMELAND DENTIN ARE ALSO SOME OF THE NATURAL COMPOSITES PRESENT IN NATURE. COMPOSITE BA
  5. 5. 1962 Bisphenol A glycidyl methacrylate- (bis-GMA) and organic silane coupling agent PMMA + QUARTZ 1940-1950 PMMA 20TH CENTURY SILICATES
  6. 6. 1950 198019701960 1990 2000 2010 Original development MACROFILLED Self-cure composites MID-FILLED Composites MICROFILLED Composites MID-FILLED Composites MIDI HYBRID Composites FLOWABLE PACKABLE MINI HYBRID Composites LOW SHRINKAGE Composites NANOFILLED & NANOHYBRID Composites Non bonded composites Acid etching & Enamel bonding Dentin bonded Composites Self-cured UV-cured Visible light-cured Composite refinements Reviewing last 55 years 3 part,2 part,1 part Dentin bonding system
  7. 7. USES
  8. 8. 1.Direct and indirect restorative material 2.Fiber Reinforced composite posts 3.Luting agents 4.Core build up in post endodontic restorations 5.Pit and fissure sealants 6.Bonding of orthodontic brackets 7.Splinting of mobile teeth
  9. 9. BASIC COMPOSITION MATRIX FILLERS COUPLING AGEN MATRIX: Coupling Agent: Plastic resin Binds by adhesion filler and matrix Continous phase FILLERS: Reinforcing fibers/particles Dispersed Phase
  10. 10. •Activator-Initiator-Soft moldable material hard durable mass •Pigments-Matching tooth color •Inhibitor- storage time, working time in chemically activated composites •UV Absorbers- Color stability
  11. 11. Most widely used Aliphatic/Aromatic dimethyl acrylate monomers like Bis-GMA TEGDMA UDMA MOST RECENTLY USED ARE THE SILORANE MONOMERS
  12. 12. • POLYMERIZATION SHRINKAGE • CROSS LINKING INCREASED – IMPROVED PROPERTIES • STRENGTH,RIGIDITY BUT DUE TO HIGH DENSITY THESE MONOMERS ARE VISCOUS AND DIFFICULT TO MANIPULATE TEGDMA(Dilutent monomer) + BISGMA(Viscous)  Decreases Viscosity  easy to manipulate and paste like consistency
  13. 13. IMPROVE THE MECHANICAL PROPERTIES DECREASE POLYMERIZATION SHRINKAGE DECREASE THERMAL EXPANSION AND CONTRACTION DECREASE WATER SORPTION RADIO OPACITY
  14. 14. QUARTZ: •Chemically inert •Very hard and difficult to grind •Difficult to polish •Abrades opposing tooth SILICA: •Less harder than quartz •Non crystalline structure GLASSES WITH HEAVY METALS: •Radio opaque •Less inert •Slowly leach out •Shorter lifetime
  15. 15. FLOURIDE RELEASING FILLERS: •Ability to release flourides •Ytterbium triflouride and Ba-Al- flourosilicates
  16. 16. Effect of filler size and distribution The COMPOSITE properties are IMPROVED to a great extent by increasing the filler loading. This can be achieved by PARTICLES SIZE and DISTRIBUTION
  17. 17. PARTICLES SIZE DISTRIBUTION VOIDS/GAP S
  18. 18. FILLER SIZE LARGER PARTICLES SCATTERING OF LIGHT OPACITY DECREASED CURING DEPTH ROUGH SURFACE TEXTURE STAINS,PLAQUE ETC SMALL PARTICLES LESS SCATTERING OF LIGHT LESS OPACITY INCREASED CURING DEPTH SMOOTH SURFACE TEXTURE HIGHER AESTHETICS PARTICLES SIZE IN REFERENCE TO WAVELENGTH OF VISIBLE LIGHT
  19. 19. •These bond the filler particles to the matrix •They improve properties of resin by transferring stresses from plastic resin matrix to stiff filler particles •Prevent Leaching •Organosilanes are most commonly used coupling agents •Gamma methacryloxypropyl trimethoxysilane
  20. 20. Gamma methacryloxypropyl trimethoxysilane
  21. 21. MECHANISM
  22. 22. FUNCTIONS: 1.Extend storage life 2.Increase working time Free radical formed by brief exposure to light Inhibitor + Free radical Inhibits chain propagation Reaction termination Inhibitor exhausted MECHANISM: BUTYLATED HYDROXYTOULENE 0.01 WT%
  23. 23. TO ACHIEVE NATURAL TOOTH LIKE APPEARANCE MECHANISM: GREATER TRANSLUCENY GREATER LIGHT PASSES THROUGH APPEARS MORE DARKER AS LIGHT IS NOT REFLECTED BACK OPACIFIERS ADDED TITANIUM DIOXIDE ALUMNIUM OXIDE(0.0001 TO 0.007 WT%) CLINICAL SIGNIFICANCE: Darker shades and greater opacities have decreased depth of curing so we should either increase exposure time or apply thinner layers of material while curing
  24. 24. ADDITION POLYMERIZATION CHEMICAL ACTIVATED RESIN ACTIVATOR- AROMATIC TERTIARY AMINE INITIATOR- BENZOYL PEROXIDE LIGHT ACTIVATED RESINS PHOTOSENSITIZER- CAMPHOR QUINONE INITIATOR-AMINE ACTIVATOR-VISIBLE BLUE LIGHT
  25. 25. Types
  26. 26. COLD CURING/SELF CURING SUPPLIED AS: SELF CURE BASE TERTIARY AMINE N-N DIMETHYL- P-TOLUDIEN BENZOYL PEROXIDE CATALYST :
  27. 27. POLYMERIZATION: ADDITION POLYMERIZATION REACTION STARTS AS SOON AS THE TWO PASTES ARE MIXED
  28. 28. ADDITION POLYMERIZATION INDUCTION ACTIVATION INITIATION PROPAGATION CHAIN TRANSFER TERMINATION
  29. 29. 1.INDUCTION
  30. 30. 2.PROPAGATION
  31. 31. 3.CHAIN TRANSFER
  32. 32. 4.TERMINATION
  33. 33. ADVANTAGES DISADVANTAGES Convenience and simplicity Mixing causes air entrapment leading to porosity which might weaken the material and increase staining Long term storage stability Aromatic amine accelerators Oxidize and turn yellow with time i.e color instability Manipulation of working/Setting time by varying proportions Difficult to mix evenly Degree of cure equal through out if mixed properly Marginal stress build up during curing is much lower than for photocured due to slower cross linking
  34. 34. LIGHT CURING/PHOTOCHEMICALLY ACTIVATED RESIN UV LIGHT CURED VISIBLE LIGHT CURED UV LIGHT CURED: USED BEFORE. LIMITED PENETRATION OF LIGHT INTO RESIN. LACK OF PENETRATION THROUGH TOOTH STRUCTURE CAUSED DAMAGE TO RETINA
  35. 35. VISIBLE LIGHT CURED: SINGLE PASTE PHOTOINITIATOR CAMPHORQUININONE 0.2 WT% DIMETHYLAMINOETHYL- METHACRYLATE 0.15 WT % AMINE ACCELARATOR
  36. 36. POLYMERIZATIO N Exposure to light (Wavelength 400-500nm) Excites photosensitizer Photosensitizer reacts with Amine Free radicals formed Addition polymerization starts
  37. 37. Advantages and DIsadvantages
  38. 38. FACTORS INVOLVED IN PHOTO CURING FACTORS CURING LAMPS LED LAMPS QTH LAMPS PAC LAMPS ARGON LASER LAMPS DEPTH OF CURE AND EXPOSURE TIME SAFETY PRECAUTIONS
  39. 39. •Hand held devices which contain the light source and have a rigid light guide made up of fused optical fibers. •The most widely used light source is QUARTZ bulb with a Tungsten filament in a Halogen enviroment. •Four types of lamps are used: 1.Light emitting Diode lamps (LED) 2.Quartz-tungsten-halogen (QTH) lamps 3.Plasma arc curing lamps (PAC) 4.Argon laser lamps
  40. 40. LED lamps These light sources emit radiation only in the blue part of the visible spectrum between 440 and 480 nm do not require filters LEDs require low wattage,can be battery powered,generate no heat and are quiet because a cooling fan is not needed. Produce lowest intensity radiation The latest versions utilize two or more LED units to increase intensity and extend wavelength range
  41. 41. Quartz-tungsten-Halogen (QTH) lamps QTH lamps have a quartz bulb with a tungsten filament that irradiates both UV and white light Must be filtered to remove heat and all wavelengths except those in the violet blue range (~450 to 500 nm) Intensity diminishes with use.
  42. 42. Plasma arc curing (PAC) lamps Use ionized xenon gas to produce plasma  High intensity white light is filtered to remove heat Blue light is then emitted (400-500nm)
  43. 43. Argon lamps Highest intensity Emit at a single wavlength Emit wavelength of 490nm.
  44. 44. DEPTH OF CURE AND EXPOSURE TIME •Amount of photons absorbed by initiator depends on Wavelength Light intensity Exposure time •For maximum curing radiant energy influx should be 16,000 mJ/cm2 • Light absorbtion and scattering in resin composites reduce the degree of conversion and depth of penetration so exposure time should be increased. •Curing depth should be kept 2-3mm •Exposure time depends on the intensity of curing units. •Higher the intensity lesser will be the exposure time
  45. 45. •Light attenuation varies for different composites so manufacturers instructions should be followed. To maximize the degree of polymerization and clinical durablity clinician should adjust curing time and curing technique to intensity of light source. Light is also absorbed and scattered as it passes through tooth structure especially dentin ,causing incomplete curing so in critical areas like proximal box so here the exposure time must be increased to compensate for reduction in light intensity
  46. 46. •Light emiitted by curing units can cause retinal damage. •Never look directly into light tip and reflected light for longer periods •Wear protective eye glasses and shields that filter light both for operator and patient.
  47. 47. A curing lamp with wavelength matching the absorbance range of photoinitaiator must be selected. Critical concentration of free radicals must be formed to initiate polymerization Intensity decreases with distance so lamp tip must be placed at minimum distance through out exposure interval Curing angle should be 90 degrees to resin surface to deliver maximum intensity Lamp intensity should be evaluated frequently.
  48. 48. Combination of light cure and self cure composites dual-cure resins are commercially available and consist of two light- curable pastes One paste contains benzoyl peroxide and other contains aromatic tertiary amine. Chemical curing occurs by mixing the pastes and is accelerated on command with the light source light curing is promoted by the amine/CQ combination  and chemical curing is promoted by the amine/BP interaction. Dual-cure materials are intended for any situation that does not allow sufficient light penetration to produce adequate monomer conversion, for example, cementation of bulky ceramic inlays.
  49. 49. ADVANTAGE: •Complete curing throughout is the advantage DISADVANTAGE: •Porosity •Colour instability
  50. 50. CLASSIFICATION
  51. 51. CLASSIFICATION OF COMPOSITES: I. Classification given by Skinner: Traditional or conventional composites 8-12 .m Small particle filled composites 1-5 . m Microfilled composites 0-04 –0.9 . m. Hybrid composites 0.6-1 . m
  52. 52. II Philips and Lutz classification: According to the mean particles size of the major fillers – Traditional composite resins: (5.30  m earlier, 1.5m current) Hybrid composite resins: (1.5  m. earlier, 0.05-0.1m. current) Homogeneous microfilled composites: 0.05-0.1 .m Heterogeneous micro filled composites: 0.05-01, 1-25 .m
  53. 53. III Classifications based on inorganic loading: a. Heavy filled materials – 75% of inorganic loading by wt b .Lightly filled material –66% of inorganic loading by wt.
  54. 54. IV. Based on method of curing 1. Chemical cured 2. Light cured 3. Heat cured 4. Dual cured V Classification based on area used Anterior composites Posterior composites
  55. 55. VI.GENERATIONS OF COMPOSITE RESTORATION (Marzouk) A. First Generation composites •Consist of macro-ceramic reinforcing phase. •Has good mechanical properties. •Highest surface roughness B. Second Generation composites •Consists of colloidal and micro-ceramic silica. •Low strength •Unfavourable coefficient of thermal expansion •Wear resistance better than first generation •Best surface texture.
  56. 56. C. Third Generation composites •Hybrid composite[combination of macro and micro (colloidal) ceramics] •Good surface smoothness and reasonable strength D. Fourth Generation composites •Hybrid composite (heat-cured, irregularly shaped, highly reinforced composite macro-particles with micro (colloidal) ceramics]. •Comparatively better surface characteristics and mechanical properties
  57. 57. E. Fifth Generation composites: •Hybrid composite (heat-cured, spherical, highly reinforced composite macro. particles with micro (colloidal) ceramics]. •Improved workability •Surface texture and wear is similar to second generation composites •Physical and mechanical properties similar to fourth generation composites F. Sixth Generation composites: •Hybrid composite [agglomerates of sintered •micro (colloidal) ceramics and micro-ceramics] •Highest percentage of reinforcing particles •Best mechanical properties •Wear and surface texture similar to fourth generation •Least polymerization shrinkage
  58. 58. VII. Classification according to Bayne and Heyman: Category Particle size Macrofillers 10-100 m Small/fine fillers 0.1-10 m Midfillers 1-.10m Minifillers 0.1-1m Microfillers 0.01 – 0.1 m (agglomerated) Nanofillers 005 - 0.1 m
  59. 59. Composite types
  60. 60. Traditional Composites Conventional or macrofilled composites.  The traditional composites have comparatively large filler particles.  This category was developed during the 1970 The most commonly used filler for these materials is finely ground amorphous silica and quartz.  Although the average size is 8 to 12 μm, particles as large as 50 μm may also be present.
  61. 61. Filler loading generally is 70 to 80 wt% or 60 to 70 vol% Advantage High stength Disadvantage rough surface Poor wear resistance Poor marginal integrity Finishing produces a roughened surface Discoloration due to rough textured surface to retain stain.
  62. 62. Small-Particle-Filled Composites  To improve surface smoothness and retain or improve the physical and mechanical properties of traditional composites inorganic fillers are ground to a size range of 0.1 to 10μm. •Fillers were made by grinding quartz to small particle size smaller than traditional.  Small-particle-filled (SPF) composites generally contain more inorganic filler (80 to 90 wt% and 65 to 77 vol%) than traditional composites.  High strength and high hardness
  63. 63. High polishiblity,durablity. USES Class 1 and class 2 restorations
  64. 64. Microfilled Composites Agglomerates of 0.01 to 0.1 um inorganic colloidal silica The problems of surface roughening and low translucency associated with traditional and small particle composites can be over come through the use of colloidal silica particles as the inorganic filler. 1.Homogenous 2.Heterogenous
  65. 65. Homogenous Silica compound SiCL4 Pyrolytic precipitation Amorphous silica 0.04 um or 40nm Highly polishable
  66. 66. Small size Large surface area + Agglomera tion and long chains Increased monomer viscocity 2 % wt produces a stiff paste Decrease filler loading Inferior mech. properties
  67. 67. Hetrogenous SiO2 + silane treated + liquid monomer Solid resin Resin filler particles (5-50micron) CURE PULVERIZE
  68. 68. PRECURED RESIN FILLER + MONOMER + SILANE TREATED COLLOIDAL SILICA = HETROGENOUS COMPOSITE •Inorganic filler loading is increased by 50 % ADVANTAGES •High polishiblity •Less shrinkage DISADVANTAGES: •Weak bonding between precured resin particles and matrix •Increased wear •Decreased mechanical properties •Not suitable for stress bearing areas
  69. 69. They should be finished with diamond burs rather than carbide burs as they are very much prone to chipping •Material of choice for smooth surface lesions like class 3 and class 5 SUBTYPES: 1. Splintered prepolymerized particle 2. Spherical prepolymerized particle 3. Agglomerated prepolymerized particle
  70. 70. This category of composite materials was developed in an effort to obtain even better surface smoothness than that provided by the large particle composites, while still maintaining the desirable properties. Hybrid composites contain two kinds of filler particles:  Most modern hybrid fillers consist of: 1.Colloidal silica 2.Ground particles of glasses containing heavy metals. Constituting a filler content of approximately 75 to 80 wt% Hybrid Composites
  71. 71. The glasses have an average particle size of about 0.4 to 1.0 μm. Colloidal silica represents 10 to 20 wt% of the total filler content.  The mechanical properties inferior to those SPF composites Surface smoothness + good strength Anterior restorations,including Class IV sites. • High stress areas where aesthetics dominates
  72. 72. • Nanofillers are the filler particles. • These particles are extremely small (0.005-0.01 nm) and virtually invisible • Their particle size is below range of wavelength of light and thus they do not absorb or scatter visible light • Aggregates are silane treated NANOFILLED COMPOSITES
  73. 73. • Additionally the extremely small size of nanofillers allow the particles to fit into spaces between other particles in composite and effectively increase the overall filler level. • Nanofiller permit overall filler level of 80 wt% that significantly reduce the effect of polymerisation shrinkage and dramatically improves physical properties • Commercially available nanocomposites:Filtek supreme plus Tetric N Ceram
  74. 74. NANOHYBRIDS •Like conventional hybrids in range of size of nano fillers •Mechanical properties like conventional hybrids •Aesthetics and polishiblity like microfilled composites •They can be used for both anterior and posterior restorations •Stronger than nanocomposites
  75. 75. FLOWABLE COMPOSITES A modifications of the SPF and hybrid composites. The reduced filler makes them more susceptible to wear, but improves the clinician’s ability to form a well adapted cavity base or liner, especially in Class II posterior preparations and other situations in which access is difficult. Decrease filler loading Decreased viscosity Easy to flow Adapt into cavity Diifcult accessiblity posterior areas Called dental caulk,as it can flow into small crevices along restoration margins
  76. 76. USES:  Sealing gingival floor of the proximal box of Class II restorations.  Class V cavities.  Small Class III cavities.  First increment of all deep restorations to prevent voids and porosities and to get good seal.  Small Class I cavities frequently referred to as ‘Preventive Resin Restorations’.  Blocking out cavity undercuts during inlay, onlay and crown preparations ADVANTAGES: • Decreased microleakage • Increased marginal adaptation DISADVANTAGE: • High curing shrinkage • Decreased mechanical properties • Cannot be used in large restorations because of decrease wear resistance
  77. 77. CONDENSABLE COMPOSITES •Because of the highly plastic, paste like consistency in the precured state, composites cannot be packed vertically into a cavity in such a way that the material flows laterally as well as vertically to ensure intimate contact with the cavity walls. •This can be explained in terms of class 2 cavity •Compared with amalgam, the technique of composite placement is far more time consuming and demanding. • A solution to this problem is offered by resin composites with filler characteristics that increase the strength and stiffness of the uncured material and that provide a consistency similar to that of lathe-cut amalgams.
  78. 78. •Elongated, fibrous, filler particles of about 100 μm in length •RoughTextured surfaces and branched geometry tend to inter lock and resist flow. • This causes the uncured resin to be stiff and resistant to slumping,yet moldable under the force of amalgam Condensing instruments (“Plugger”)
  79. 79. PROPERTIES
  80. 80. 1.WORKING TIME AND SETTING TIME Chemical cured composites:  Setting time:3-5 minutes  Working time:from start of mix till temperature begins to rise
  81. 81. Light cured composites:  Curing is considered on demand  Composite may appear to be fully hard and cured after curing by light source,but curing reaction continues for 24 hours.  Degree of conversion is 75 %  Premature polymerization can occur with 60- 90 seconds of exposure to the ambient light.
  82. 82. Degree of conversion/Degree of cure /Degree of monomer to polymer conversion •Percentage of carbon carbon double bonds converted to single bonds during curing to form a polymer resin •Higher the DC greater is the strength,wear and other properties A conversion of 50 % Bis-GMA means 50 % of polymer have been polymerized BUT This does not mean remaining 40-50 % monomer is left in resin because one of the two methacrylates group of Bis- GMA may form covalent bonds with polymer forming a pendant group
  83. 83. Conversion of monomer to polymer depends on several factors like: 1.Resin composition 2.Transmission of light through material 3.Concentration of Sensitizer,initiator and inhibitor 4.Lamp intensity 5.Absorbtion through composite 6.Scattering through composite
  84. 84. 2.POLYMERIZATION SHRINKAGE  The normal range of curing shrinkage is 1.5 to 4 vol % 24 hours after curing  Composites with a high filler loading shrink less  Chemically activated have a slow curing than light cure resins which allows the shrinkage stresses to relax
  85. 85. 3.POLYMERIZATION SHRINKAGE STRESS Curing Spacing between monomers reduced Polymerization shrinkage Unrelieved stresses in resin Stresses may break interfacial bond Microleakage
  86. 86. The polymerization shrinkage and stress affected by:  1.Total vol of composite  2.Type of composite  3.polymerization speed  4.C-Factor
  87. 87. REDUCTION OF RESIDUAL STRESSES  The internal pores in chemically cured resins act to relax residual stresses that build up during polymerization.  The slower curing rate of chemical activation allows a portion of the shrinkage to be compensated by internal flow among developing polymer chains before formation of extensive crosslinking
  88. 88.  After the gel point ,stresses cannot be relieved but instead continue to increase and concentrate within the resin and the tooth structure adjacent to the bonded interfaces.  Approaches to overcome the problem of stress concentration: 1)reduction in volume contracton by altering the chemistry and or composition of the resin system 2) clinical techniques designed to offset the effects of polymerization shrinkage
  89. 89. 1.Incremental build up and cavity configuration CONFIGURATION FACTOR (C-Factor) • Is the ratio between the bonded surface areas of a resin based composite restoration to the non-bonded or free surface area • Bonded surface/non bonded surface = C factor
  90. 90. • Residual polymerization stresses increases directly with this ratio. • During curing, shrinkage leaves the bonded cavity surfaces in a state of stresses • The non bonded ,free surfaces release some of the stresses by contracting inwards towards the bulk of material • A layering technique in which the restoration,is build up in increments ,curing one layer at a time efficiently reduces polymerization stresses by minimizing the c factor • The thinner layer lower the bonded surface and maximize the non bonded surface area. ADVANTAGE • This technique overcomes the limited depth cure and residual stress concentrations DISADVANTAGE • Adds to time and difficulty in placing restoration
  91. 91. 2.Soft start,ramp curing and delayed curing  Photo-polymerization stress buildup inspired by chemical initiation by providing an initial low rate of polymerization thereby extending the available time for stress relaxation before reaching gel point .
  92. 92.  In this technique curing begins with a low intensity and finishes with high intensity SOFT START SLOW POLYMERIZATION INITIALLY INCREASED STRESS RELAXATION GELATION POINT REACHED INCREASE INTENSITY TO MAXIMUM
  93. 93. Ramped curing and delayed curing  Variations of soft start RAMPING CURING:  The intensity is gradually increased or ramped up during exposure.  Consist of either stepwise, linear or exponential modes
  94. 94. Delayed curing: LOW INTENSITY INCOMPLETE CURING CONTOUR AND SCULPTING RESIN SECOND EXPOSURE FOR FINAL CURE  Delay allows substantial stress relaxation to take place.  The longer the time period available for relaxation the lower the residual stresses.  Delayed and exponential ramp curing appear to provide the greater reduction in curing stress.
  95. 95. Intensity of the curing lamps must be considered in such situations as exposure time and curing are related to the intensity of the lamps.
  96. 96. 4.COEFFICIENT OF THERMAL EXPANSION  Linear coefficient of thermal expansion of composite ranges between 25-30 x 10-6 /℃ and 55-68 x 10-6 /℃  Large differences between CTE of tooth and composite causes expansion and contraction resulting in stress  Filler loading is the only way to reduce the CTE.
  97. 97. 5.WATER SORPTION  Water sorption may occur when: 1.Material may have a high solublity rate. 2.Resin may contain voids 3.Hydrolytic breakdown of the bonds between fillers and resin  Water sorption can decrement the longetivity of the restorations.
  98. 98. 6.SOLUBLITY  Inadequate light intensity and duration especially in deeper areas causes incomplete polymerization and increased solublity.  ADA specifies solublity should be less than or equal to 7.5 µg/mm  Higher values lead to reduce wear and abrasion resistance.
  99. 99. 7.RADIO OPACITY  Radio opacity is to check the integrity of resin  Radio opacity can be provided by glass ceramics with heavy metals like Ba,Sr and Zr  Not chemically inert
  100. 100. 8.COLOUR STABILITY  Esthetics is the major factor for use of composites Discolouration can be; 1.Marginal 2.Surface 3.Bulk
  101. 101. 1. Marginal discolouration  May occur due to: 1.Improper adaptation of material to cavity margin 2.Breakage of interfacial bonds between resin and cavity
  102. 102. Marginal discolouration Improper adaptation Broken interfacial bonds Marginal staining Accumulation of debris Marginal gap
  103. 103. 2.SURFACE DISCOLORATION Related to surface roughness of the composite. Seen in composites with larger filler sizes. Debris gets entrapped between the spaces and cannot be removed by routine brushing. Dark pitted discolouration may be seen due to exposure of air void when composite wears away.
  104. 104. 3. Bulk discolouration  Seen in chemically activated resin mainly  Chemical degradation of components and absorbtion of fluids from oral enviroment
  105. 105. Composites show loss of surface contour of composite restorations in the mouth Abrasive wear from chewing and tooth brushing Erosive wear from degradation of the composite in the oral environment Wear of posterior composite restorations is observed at the contact area,where stresses are the highest.  Interproximal wear has also been observed. 9.WEAR RATES
  106. 106.  Ditching at the margins within the composite is observed for posterior composites,resulting from inadequate bonding and polymerization stresses. Packable composites have better wear resistance than micro filled or flowable composites Two types of wear seen in composites: 2 body wear 3 body wear Factors causing wear: 1.Fillers 2.Degree of polymerization 3.Tooth position
  107. 107. Picture from phillips pg 284
  108. 108. BIOCOMPATIBLITY
  109. 109. BIOCOMPATIBLITY  It is usually related to the effects on pulp from two aspects: 1. Inherent chemical toxicity of material 2. The marginal leakage of the fluids
  110. 110. •Pulp can be affected if chemicals leach out from the composites. •Inadequately cured composites at floor of cavity act as a reservoir of diffusable components that can induce long term pulpal inflammation. •This is for concern in case of light cure. •If clinician attempts to cure a thick segment or inadequate exposure the uncured material can leach out constituents adjacent to the pulp. •Adequately polymerized resins leach out in very small amounts which cannot cause toxicity. Inherent chemical toxicity of material
  111. 111. • The shrinkage of composite during polymerization and the subsequent marginal leakage is a well known phenomenon • The marginal leakage might allow bacterial growth and the microorganisms may cause secondary caries or pulpal reaction. • Therefore ,the restorative procedure must be designed to minimize polymerization shrinkage and marginal leakage The marginal leakage of the fluids
  112. 112. • Bisphenol A (BPA), a precursor of BiSGMA has been shown to be a xenoestrogen ,or a compound found in environment that mimics the effects of estrogen by having affinity for estrogen receptors • BPA has been shown to cause reproductive anomalies especially in development stages of fetal wildlife • Controversy surrounds this issue because it is unclear how much BPA or BPA-DM is released to the oral cavity and what dosage is enough to affect human health.
  113. 113. •Gic liners are applied as pulp protection in deep cavities •Zincoxide eugenol is contraindiated as it interferes with polymerization
  114. 114. Technique
  115. 115. 1.Preparation of operating site 2.Shade selection 3.Cavity preparation 4.Isolation 5.Pulp protection 6.Adhesion 7.Matrix placement 8.Insertion,prepolymerization contouring and curing 9.Finishing 10.Polishing
  116. 116. 1.Calculus removal with proper instruments 2.Cleaning operting site with pumice slurry Create a site more receptive for bonding Prophy paste containing flavouring agent,glycerine or flouride act as contaminants and conflict with acid etch technique.
  117. 117. Shade of the tooth should be selected before isolation Shade should be selected without prolonged drying the tooth Composite materials are available in: Enamel shades Dentin shades Translucent shades Opaque shades Good lighting should be present for proper color selection
  118. 118. 1.Operator should hold shade tab near the tooth to determine natural colour. 2.Shade tab should be partially covered with operators thumb or patients lip – natural effect of shadows 3.The selection of shade should be done in natural light 4.The selection should be made rapidly 5.Final shade can be verified by patient with a mirror 6.Bleaching if done should be done before any restoration placement The shade selected should be placed directly on the tooth close to area to be restored and cured PROCEDURE
  119. 119. Objectives in tooth preparation:  Extent is determined by size, shape, and location of defect  Remove all Caries, any fault, defective, old friable tooth structure.  Removal of discolored tooth structure as required for esthetics.  Create prepared enamel margin of 90° or greater by giving bevel wherever required.  Create 90° cavosurface on root surfaces
  120. 120. Outline form Extend from periphery to sound tooth structure Preparation should be done in most conservative way as possible Retention form Micromechanical retention by etching of enamel and dentin. Dentinal retention groove Enamel beveling
  121. 121. Beveling provides increased surface area of etching  Increased retention Decreased microleakage Gradual transition between composite and tooth Bevels of 45 degrees should be given: 1-2mm wide facially 0.5mm other areas Bevels should be prepared with medium grit diamond burs Bevels should be avoided in: Class 1 restorations Class 2 restorations Cervical margins with thin enamel
  122. 122. Resistance form Primarily by micromechanical bonding May be improved by: • Flat preparation floors • Floors perpendicular to occlusal forces • Boxlike forms
  123. 123. Cavity designs for composite cavity preparation • Conventional • Beveled conventional • Modified • Box shape • Facial/lingual slot
  124. 124. CONVENTIONAL Similar to that of cavity preparation for amalgam restoration. A uniform depth of the cavity 90° cavosurface margin is required INDICATIONS 1. Moderate to large class I and class II restorations 2. Preparation is located on root surfaces. 3. Old amalgam restoration being replaced
  125. 125. BEVELED CONVENTIONAL • Similar to conventional cavity design • Have some beveled enamel margins. INDICATIONS 1. Composite is used to replace existing restoration. (class III, IV, V) 2. Restore large area Rarely used for posterior composite restorations
  126. 126. MODIFIED • All parameters determined by extent of caries. • Conserve tooth and obtain retention (MICRO MECHANICAL). • No specified wall configuration. • No Specified pulpal or axial depth. • Scooped out appearance INDICATIONS • small,cavitated,carious lesion surrounded by enamel • correcting enamel defects.
  127. 127. BOX ONLY •When only Proximal surface is faulty and no lesion on occlusal surface •Extent is determined by caries
  128. 128. FACIAL OR LINGUAL SLOT 1. Lesion is proximal but access is made through facial or lingual surface 2. Cavosurface is 90 or greater. 3. Direct access for removal of caries.
  129. 129. Isolation can be accomplished by rubber dams,cotton rolls Retraction cords can be used for subgingival extensions Contamination with saliva leads to decreased bond strength
  130. 130. Calcium hydroxide Glass ionomer cement Resin Modified Glass Ionomer Zinc oxide eugenol is contraindicated
  131. 131. Acid etching Bonding agents
  132. 132. Acid may be grouped as: Minerals (phosphoric acid,nitric acid) Organic (maleic acid,citric acid) Polymeric(e.g polyacrylic acid) Most frequently used acid is 37% phosphoric acid Available as: Gel or liquid form Applied by brush or directly through syringe 15-20 seconds etching time Primary teeth or young teeth with mind flourosis require longer etching time Freshly cut enamel etches faster Clinically the most important parameter of proper etched tooth is presence of a frosty white appearance on tooth
  133. 133. Acid etch Smear layer + Enamel removed from surface 1.Selective dissolutio n of enamel rods 2.Increase d surface area Increased surface energy Resin penetrates to microporo sites Resin tags
  134. 134. Removes hydroxy appetite layer Microporous collagen network in H20 Partially open dentinal tubules
  135. 135. Clean tooth and isolate Place mylar strip to protect adjacent tooth Place etchant liquid/gel 15-20 seconds Wash for 10 sec longer if gel used Dry surface Chalky white appearance Over drying must be avoided if dentin invloved as it may result in collapse of collagen mesh which results in forming a dense film and prevents bonding agent to penetrate.
  136. 136. A thin layer of resin between conditioned dentin and resin matrix of resin composite restorative material. Restorative resin are hydrophobic and tooth is are hydrophillic so bonding agent should have both parts. The hydrophillic part bonds with calcium in hydroxyappatite crystals or collagen and hydrophobic component bonds with restorative resin.
  137. 137. ETCHANT/CONDITIONER: selectively dissolves tooth structure to provide retention for restoration PRIMERS: Bridge to connect tooth to adhesive hydrophillic monomers in a solvent like alcohol,ethanol or water Penetrate moist tooth structure especially dentin and collagen mesh and improve bond EG:HEMA(2-hydroxylethyl methacrylate,4-MET(methacryloxyethyl trimelletic acid) ADHESIVE: Hydrophobic monomers + small amount hydrophillic monomer
  138. 138. Used in combination with primers to form effective bond to tooth structure. Adhesive  bonds resin to primer Primerpenetrates tooth and completes binding sequence Eg: hydrophobic dimethacrylates like Bis-GMA with small amount of hydrophillic monomers like HEMA
  139. 139. Remove all debris and remove excess water Isolate tooth from saliva contamintation Saturate microbrush with bonding agent Apply with gentle rubbing motion Use gentle air pressure to remove excess acetone and water solvent Cure for 20 seconds
  140. 140. Finishing Good contour Occlusion smoothness Appropriate embrasure form Finishing—Process of removing surface defects or scratches created during the contouring process through the use of cutting or grinding instruments or both. Remove all unattatched bonding agent with bard parker blade no 12,composite resin knife or gold foil finishing instrument. Finishing burs,diamonds,,micron diamonds,burs,rubber point and disks are used to create surface texture,lobes and ridges
  141. 141. Polishing cups and polishing paste are used for lusture Metal or plastic finishing strips interproximally
  142. 142. Polishing—Process of providing luster or gloss on a material surface. Removal of surface irregularites and achieving smoothest possible surface Polishing can be DRY:superfine disks WET:Coarse disks Aggressive use of disks may be avoided Polishing paste can be used for 15-30 seconds using rubber cup moistened with water Microfilled composites can be polished with disks Small particle hybrids can be polished with fine diamonds,flexible disks and very fine polishing paste
  143. 143. Dry polishing:should be resrved only for microfilled composites.The heat from the disks produces highly durable,smear layer of resin over microfill
  144. 144. Recent advancements
  145. 145. “Alert” Polyester using carbonate (-O-CO-O-) Connects methacrylate ends to the central section of monomer. PROPERTIES: packable like amalgam photocurable in bulk Segments curable without generating high residual shrinkage stress.
  146. 146. Kalore High molecular weight Long rigid central section Flexible methacrylate end groups PROPERTIES: Reduced curing shrinkage Enhanced monomer to polymer conversion
  147. 147. “Venus Diamond 4,8-di(methacryloxy methylene)-tricyclodecane(TCDDMA) Bulky space-filling dimethacrylate monomer Bulky three-ring central group provides steric hindrance Which holds the monomers apart PROPERTIES slows the rate of polymerization Steric hinderence Dimethacrylate with a Bulky, Space-Filling Central Group
  148. 148. Durance  Dimer dicarbamate dimethacrylate (DDCDMA) Bulky central group: 6-carbon aliphatic ring two long hydrocarbon side chains Center section is connected to two methacrylate end groups via urethane groups PROPERTIES Greater stress relaxation reduced shrinkage. reduced water absorption High-Molecular-Weight Phase-Separating Dicarbamate with Hydrophobic Side Chains
  149. 149. “Filtek LS” chemistry based on epoxy, rather than acrylic functionality. tetra-functional “silorane” monomers ring-opening polymerization. STRUCTURE: Silorane chemistry utilizes a combination of epoxy functionality three-unit ring with two carbons and an oxygen combined with siloxane units PROPERTIES: Reduced polymerization shrinkage Silorane” Ring-Opening Tetrafunctional Epoxy Siloxane
  150. 150. Organically Modified Ceramic Oligomers Ormocer is an acronym for organically modified ceramics. molecule-sized hybrid structures inorganic-organic copolymers. ORGANIC MONOMER + CENRAL CYCLIC POLYSILOXANE High-mol-wt flexible relatively low- viscosity cross-linkable mol PROPERTIES: Reduced polymerization shrinkage, abrasion resistance low water sorption very high biocompatibility excellent esthetics.
  151. 151. Polyhedral Oligomeric Silsesquioxane (POSS) 12-sided silicate cages silane and functionalized to copolymerize with other monomers. molecule-sized hybrid organic-inorganic oligomeric compound “Artiste Nano-Hybrid Composite” (Pentron Clinical, Wallingford, CT). PROPERTIES: Highly polishable Excellent polish retention, Good mechanical properties Good wear resistance.
  152. 152. Patient's demands for aesthetics, phenomenal developments in the resin and filler technologies, advance in nanotechnology and clinical training in their use has made composite resins a material of choice for direct restorative purposes. The wide range of colours,shades,translucencies,opacities,flouroscence,tones,viscosity etc available with present generations of composite resins have enabled clinicians to provide a restoration that mimics natural tooth structure and optimizes function as well. Further research is always an ongoing process to reduce or eliminate drawbacks of composite resins

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