Composite resins I

A powerpoint presentation focusing mainly on the material aspects of composite resins. The second part of this presentation deals with the clinical aspects

1. Composite resins By Mettina Postgraduate student

2. contents Introduction History Definition Composition Classification Activation systems Photocuring units Properties of Resin based composites Recent Advancements References Conclusion Chemical activation Photoactivation

3. DEFINITION “It may be defined as a compound of two or more distinctly different materials with properties that are superior or intermediate to those of the individual constituents.” OR “ A highly crosslinked polymeric material reinforced by dispersion of Amorphous silica, glass, crystalline, mineral or organic resin filler particles &/ or short fibres bonded to the matrix by a coupling agent.” Anusavice 12 th edition

4. introduction Dental resin based composites are structures composed of three major components

5. history 1980- Posterior composites 1990- Hybrid, Flowable, Packable , Compomers 1998- Ormocers were developed. 2000- Nanofilled composites 2009- Self adhesive composites 1955- Buonocore – Acid etch technique. 1956- Bowen resin- Bis GMA 1960- Traditional or Macrofilled composites 1962- Silane coupling agents 1970- Microfilled & Light initiated composites

6. Classification- ANUsavice 11 th edition ,

7. Classification- sturdevant Classification of composites based on filler particle size- Megafill – In this one or two large glass inserts 0.5 to 2 mm in size are placedinto compoosites at points of occlusal contact. Macrofill – particle size range between 10 to 100 microns in diameter. Midifill - particle size range between 1 to 10 microns in diameter, traditional or conventional composites. Minifill – particle size range between 0.1- 1 microns in diameter. Microfill - particle size range between 0.01- 0.1 microns. Nanofill - particle size range between 0.005- 0.01 microns.

8. Ada specification no.27 Type 1 – polymer based materials for occlusal surface. Type 2- other polymer based materials. Class 1- self cure materials Class 2 –light cure materials group 1 – energy applied intraorally group 2 - energy applied extraorally Class 3 – Dual cure materials.

9. Based on method of curing - Chemical - Lightcure UV, Visible -Dual cure DCNA- Type 1 – microfill with fumed silica Type 2- others with crushed quartz/ glass

10. Based on inorganic loading - Heavy filler material-75% - Light filler material - 66% Based on consistency- Light body- Flowable Medium body- homogenous microfills , macrofills and midifills Heavy body- Packable hybrid, minifills

11. Based on matrix - Composites based on Bis GMA - Composites based on UDMA Based on their area of application. - Anterior - Posterior

12. Methods of polymerization

13. Flowable composites Introduced in late 1996. It is a modification of small particle composite and hybrid composite. Have a lower viscosity – reduced filler loading Ready flow, uniform spread & intimate adaptation to cavity form.

14. FLOWABLE COMPOSITES Advantages Low viscosity Easy to use Improved marginal adaptation High wettability High depth of cure Penetration High flexibility Disadvantages Wear Poor mechanical properties Increased polymerization shrinkage Sticks to instruments

15. Packable composites Condensable or packable composites were developed as amalgam substitutes. Increased filler content. Fibrous filler particles of 100 microns in length. Compared to amalgam, placement technique is more time consuming.

16. Packable composites ADVANTAGES Non-sticky Easily transferrable & packable Moisture tolerant Increased depth of cure High critical bond strength Cures rapidly with minimal residual stress. Less shrinkage DISADVANTAGES Reduced polishability Limited shades Increased post Op sensitivity Increased sensitivity to ambient light.

17. Composite -classification TRADITIONAL COMPOSITE SMALL PARTICLE COMPOSITE MICROFILLED COMPOSITE HYBRID COMPOSITE

18. Traditional/ macrofilled composites These consist of finely ground amorphous silica or quartz fillers. Filler size 8-12 microns. Filler loading- 70-80 wt % 60-70 vol% Indications- used in class II and class IV restorations.

19. Traditional composites- DISADVANTAGES Difficult to polish Surface roughness Staining / Plaque Occlusal wear Poor esthetics - Discoloration

20. Small particle composites Filler- Amorphous silica, glasses containing heavy metals. Filler size- 0.5-3 microns Filler loading 80-90 wt %, 65-77 vol% Indication- high stress and abrasion prone areas. Advantages – Good mechanical properties Smoothness Less polymerization shrinkage Radiopacity Disadvantages- Prone to wear

21. MICROFILLED COMPOSITE Filler and colloidal silica particles agglomerate. 0.04- 0.4 microns Filler loading- 60-70 wt %, 50 vol% Indication- esthetic restoration for anteriors . Restoring subgingival areas. Carious lesion on smooth surface.

22. SMALL PARTICLE COMPOSITES ADVANTAGES Best surface finish Excellent wear resistance DISADVANTAGES Tensile strength Decreased water sorption & CTE Fracture resistance Radiolucence Decreased polymerization shrinkage

23. Hybrid composites Filler- colloidal silica & ground particles of glass containing heavy fillers. Filler loading- 70-80 wt % Filler size 0.4-1 microns. INDICATION Anterior restoration Non stress bearing area in posterior teeth. ADVANTAGES- Good physical properties Improved wear resistance Superior surface morphology Good esthetics .

24. NanoFilled composites These particles are extremely small 0.005- 0.01 microns & virtually invisible. Particle size range- below the wavelength of visible light, thus they do not absorb or scatter visible light. Nanofillers provide ways of incorporating Radiopacifiers that do not interfere with esthetic properties.

25. COMPOSITION

26. COMPOSITION

27. RESIN MATRIX “A plastic resin material that binds the filler particles & forms a continuous state.” The matrix forms a continuous state in which the reinforcing filler is dispersed. Principal monomers- Bis – GMA or UDMA is used. It is necessary to use lower molecular weight monomers such as TEGDMA/ EGDMA & HEMA to balance the viscosity.

28. RESIN MATRIX “A plastic resin material that binds the filler particles & forms a continuous state.” The matrix forms a continuous state in which the reinforcing filler is dispersed. Principal monomers- Bis – GMA or UDMA is used. It is necessary to use lower molecular weight monomers such as TEGDMA/ EGDMA & HEMA to balance the viscosity.

29. FILLERs Reinforcing particles or fibres dispersed in the matrix. Improve material properties. Functions: Reinforcement of matrix strength/ hardness. Decreased polymerization shrinkage-3%, wear. Decreased thermal expansion. Increased viscosity & radiopacity. Decreased water sorption Contribute to esthetics .

30. Filler particle synthesis Filler particles are commonly produced by grinding or milling quartz. Submicron silica particles obtained by pyrolytic or precipitation process.

31. Filler materials Pure silica Amorphous silica Organic fillers Fiber fillers Single crystals Crystalline polymers Fluoride containing fillers.

32. FILLERS 1. Quartz- It is made by grinding or milling quartz, was used in early composites Drawbacks- Hardness - Difficult to grind to a finer size - Difficult to polish - causes abrasion of opposing tooth. 2. Silica- Obtained by pyrolytic or precipitation process. Helps in high scattering & light transmission.

33. 3.Glasses- Aluminosilicates & Borosilicates - provides radiopacity 4. Other fillers- Tricalcium phosphate & Zirconium dioxide. Recently- fluoride fillers like yttrium trifluoride & ytterbium trifluoride. Esthetics - translucency of fillers , similar to tooth structure.

34. Coupling agents Bonding agent that promotes adhesion between filler and resin matrix. Types – Organosilanes Titanates Zirconates Methoxy group silanol group + silanols Siloxane bond

35. Functions of coupling agents Bind filler particles to resin. Allow more flexible polymer matrix to transfer stresses to higher modulus filler particles. Impart improved physical and mechanical properties. Inhibit leaching by preventing water from penetrating along resin- Filler interface. Benzoyl peroxide initiator, Aromatic tertiary amine activator ( N,N dimethyl –p – toluidine)

36. ACTIVATOR- INITIATOR SYSTEM 1. CHEMICALLY ACTIVATED SYSTEM Two pastes-Benzoyl peroxide initiator, Aromatic tertiary amine activator ( N,N dimethyl –p – toluidine). In self cure resins when the two pastes are mixed together, the amine reacts with benzoyl peroxide to form free radicals.

37. ACTIVATOR INITIATOR SYSTEM Drawbacks of chemical activation During mixing it is almost impossible to avoid incorporating air into the mix., forming pores that weaken the structure. No control over working time. Formation of oxygen inhibited layer. The thickness of the unpolymerized film is dependent on the viscosity, solubility of oxygen & initiating system used. Diacrylate monomer + Accelerator + Initiator CROSS LINKED POLYMER

38. Activator- initiator system Camphoroquinone initiator- 0.2% wt Organic aliphatic amine initiator- Dimethylaminoethyl initiator ( DMAEMA) -0.15% wt These compounds absorb light & generate free radicals. For system using UV light initiation, benzoin alkyl ester is used. For systems using visible light- a Diaketone such as Camphoroquinone is used. Camphoroquinone absorbs blue light -400- 500nm & produces an excited state of CQ+ Amine radicals

39. CURING LAMPS Light emitting Diode lamps Quartz Tungsten halogen lamps Plasma arc curing lamps Argon laser lamps

40. LED LAMPS These light sources emit radiation only in blue part of the visible spectrum, between 440-480nm Advantages Low wattage Generate no heat Quiet Cooling fan not required.

41. Quartz tungsten halogen lamps QTH lamps have a quartz bulb with a tungsten filament Irradiate both UV and white light 400-500nm Require a filter to remove heat and all other light wavelengths.

42. Plasma arc curing lamps PAC lamps use XENON Gas that is ionized to produce plasma The high intensity White light is filtered to remove heat. The filter limits the wavelength (440-500nm)

43. ARGON LASER LAMPS Argon laser lamps have the highest intensity and emit at a single wavelength. Currently available lamps emit at a wavelength-490nm

44. Dual cure resins Dual cure resins are commercially available and comprise of two light curable pastes. One containing Benzoyl peroxide, the other- tertiary amine accelerator. Intial slow self cure which is accelerated by light curing Advantages- completion of cure throughout. Disadvantages- Porosity, less color stability.

45. INHIBITORS Inhibitors are added to resin systems to minimize or prevent spontaneous or accidental polymerization of Monomers. React with free radicals. Butylated Hydroxytoluene ( BHT). Two functions- To extend the resin’s storage life To ensure sufficient working time.

46. Optical modifiers Optical modifiers affect light transmission through a composite . For a natural shading, dental composites should have visual shading and translucency similar to the tooth. Shading – achieved by pigments- metal oxide particles

47. Properties of resin based composites Degree of conversion Matrix constraint Toughness Curing shrinkage & Shrinkage stress Wear Longevity of composites Placement time of composites Biocompatibility of composites

48. Degree of conversion Measure of carbon- carbon double bonds that have been converted to single bonds. Higher the DC better the strength, wear resistance etc. Conversion of 50-60% commonly achieved using either curing system.

49. Matrix constraint The presence of filler partices bonded to the matrix through coupling agent , reduces thermal expansion/ contraction of composite. Filler has lower COTE ,during expansion this prevents, the matrix from expanding. During cooling the space occupied by the filler contracts while the filler does not, preventing contraction.

50. toughness The strength of composites depends on the ability of the coupling agent to transfer stresses from the weak matrix to the strong filler particles. During crack propagation, the energy required for the crack to travel through the bonded filler interface is greater Crack blunting. Cross linked polymer matrix increases toughness.

51. Curing shrinkage Curing shrinkage occurs as the monomer is converted to polymer & the free space it occupies reduces. Produces unrelieved stresses. Polymerization shrinkage is affected by- Total volume of composite material Type of composite Polymerization speed Ratio of bonded /unbonded surfaces- C factor

52. Wear/ abrasion Occlusal & interproximal wear is a common problem in case of posterior composites. Wear rate differences of 10-20 microns per year . Composites in which the filler particles are small, high in concentration and well bondedto the matrix are more resistant. Size of the restoration,, chewing habits, force levels & variations in oral environment- some other factors.

53. longevity Studies indicate a survival rate of 91.7% for posterior composites at 5 years & 82.2% at 10 years. Opdam et al 2007 76% success rate for 85 UV cured posterior composites after 17 years. Wilder et al 1999 The survival rate for composites in permanent teeth after 7 years was 67.4% whereas for amalgam- 94.5% Chadwick et al 2001 Class II composite restorations show a high percentage of failure at the gingival margin of the proximal box . Chadwick et al

54. Placement time

55. Biocompatibility of composites Biocompatibility of restorative materials- Effect on pulp from 1. Inherent chemical toxicity of the material 2. Marginal leakage of oral fluids. Inadequately cured composite materials at the floor of a cavity causes long term pulpal inflammation.

56. Bisphenol a toxicity Bisphenol A a precursor of Bis GMA, is a Xenoestrogen. Mimics the effects of estrogen by having an affinity for estrogen receptors. Causes testicular cancer, decreased sperm count, has anti androgenic activities. Sealant application led to Xenoestrogen exposure in children, BPA collected in saliva after sealant placement . - Olea et al

57. Recent advances in composites Advances in curing protocol Advancements in monomer formulations Advancements in polymerization mechanism Filler modifications Gingival masking composites Esthet X Flow Compomers Giomers Ormocers Smart composites Antibacterial composites Fluoride releasing composites Compobonds Art Glass Ceromers Fiber reinforced systems Composite splints Root posts Carbon nanotubes Quantum dot materials Self repair composites

58. ADVANCES IN CURING PROTOCOL 1. Photoinitiation Camphoroquinone absorbs photon to generate short lived excited state species that complexes with tertiary amine and forms Alpha amino alkyl initiating radical. Naturally occurring 1,3 benzodioxole & its derivatives replacements for conventional amine Co-initiators Their properties were similar to systems initiated by CQ/EDMAB (Ethyl-4- dimethylaminobenzoate ). Liu et al 2. Alternatives to Camphoroquinone / Amine systems Phosphine oxide initiators ( Guo et al 2008 ) Benzoyl germanium derivatives ( Canster et al 2008) PPD ( 1 Phenyl 1,2 propanedione ), Lucirin TPO ( Monoacylphosphine oxide) & Irgacure 819 ( Bisacylphosphineoxide ). OPPI (p- octyloxyphenyl - phenyl iodonium hexafluoroantimonate ) Ogunyinka et al 2007

59. Advances in curing protocol Soft start curing originated with Unterbrink & Mussner . Reduced irradiation intensity at the strt of polymerization allows stress relaxation to occur prior to Vitrification.

60. MONOMER FORMULATIONS The Resin phase is composed of Dimethacrylate monomers- Bis GMA, Bis EMA or UDMA- Low Methacrylate conversion, large amounts of unreacted monomer that can leach out. 1. Multimethacrylates - Bile acids were used as starting materials to form multimethacrylate monomers. Polyhedral oligomeric silsoquioxane methacrylates (POSS-MA) evaluated as alternatives to Bis GMA , Fang et al

61. Monomer Formulations 2 .Ultrarapid Monomethacrylates - Monovinyl monomers changed with the development of a monovinyl methacrylate monomers, exhibited greatly enhanced Polymerization Kinetics. These were studied as alternatives to TEGDMA. ( Lue et al 2005 ). Incorporating acidic monomers into the methacrylates showed improved overall performance. Lopez et al

62. Advances in polymerization mechanisms Specific methacrylate monomers which were miscible liquids but phase separated at higher conversions were incorporated into the conventional resins. When phase separation occurs the volume expands leading to elimination of volume shrinkage that arises from methacrylate polymerization. Dimer acid derived Dimethacrylate (DADMA monomers ), High conversion, low shrinkage, low shrinkage stress. Hybrid polymerization reactions formed from co- monomers from different reactive groups that polymerize via different curing mechanisms to synergistically achieve desired properties.

63. ADVANCES IN POLYMERIZATION MECHANISMS Ring opening polymerization A ring opening reaction relies on the opening of a cyclic structure to facilitate intermonomer bonding and crosslinking. Commercial release of cationically photopolymerizable Silorane material ( FilltekLS By 3M) Weinmann et al 2005

64. FILLER MODIFICATIONS A study on the influence of mono, bi & Tri modal distribution of fillers on the wear properties of composites showed tht Filler size & shape influence wear resistance . Nano sized filler incorporation- enhanced properties . Turscci et al 2005 Incorporation of single walled carbon nanotubes showed enhanced properties. ( increased flexural strength ) Zhung et al 2008 Silane treatment of inorganic fillers – Surface treatment of fillers is necessary to 1. Reduce filler surface energy 2. To provide a functional interface that permits covalent attachment between polymer matrix and the higher modulus filler. Methacryloxypropyltrimethoxysilane (MPS) most widely used.

65. GINGIVAL MASKING COMPOSITES An esthetic Gingiva shaded light cured composite resin was recently introduced . This allows for correction of gingival recession with minimall invasive procedure. Pink colored composite available in one transluscent gingival color and three flowable opaquers .

66. GINGIVAL MASKING COMPOSITES Indications

67. ESTHET X FLOW Flows on command Good strength & wear resistance Radiopaque Low shrinkage and porosity. 8 VITA shades, 1 opaque & 1 Bleach shade Excellent polish & fluoride release,

68. ESTHET X FLOW Uses Low stress applications Resurfacing composite or GIC restorations, rebuilding worn composite areas. Areas of difficult access/ requiring greater penetration Crown margin repairs Preventive resin restorations Liner in Class II proximal box Cementing porcelain veneers Inisal edge repair in anteriors .

69. COMPOMERS Contains the major ingredient of both composites ( Resin cement) & Glass ionomer cement (Polyalkenoate acid and glass filler component). Resin component- Bulky macromonomers Bis GMA or UDMA with viscosity reducing diluents such as TEGDMA. Fillers- Fluoride containing glasses. Strength and wear performance GIC- 140 Mpa Composite 300 Mpa Compomer- 200 -250 Mpa Dyract – three times the wear rate of hybrid composite. Shows fluoride release for more than 12 months

70. COMPOMER- Indications

71. Giomers Modified Glass ionomer True hybrid of two compounds- Glass ionomer & Composite GIOMER- Fluoride release & Fluoride recharging of glass ionomer. Ease of polishing, Strength of composite. Composition- Bisphenol A glycidyl Dimethacrylate & TEGDMA Aluminoxide , Silica fillers Pre reacted glass ionomer filler Camphoroquinone

72. GIOMERs

73. GIOMERS INDICATIONS

74. GIOMERS Advantages Fluoride release Biocompatibility Clinical stability & durability Excellent esthetics Smooth surface finish Excellent bonding Disadvantages Anticariogenicity not as good as that of GIC. Long term fluoride release is questionable. Auj Yap et al , Hardness value of Giomer less than that of GIC. Clinical evaluation of Giomer & Resin modified GIC in class V Non carious cervical lesions- an In Vivo study….. Jyothi et al RESULT- Giomer showed superior surface finish to RMGIC

75. ormocer Dr. Herbert Wolters from Fraunhofer institute for silicate research introduced this class of material in 1994 Stands for Optically Modified Ceramic- 3 dimensionally crosslinked copolymers

76. SMART COMPOSITES Smart composites are active dental polymers that contain Bioactive Amorphous calcium phosphate (ACP) filler capable of responding to environmental pH changes by releasing calcium & phosphate ions. Contains alkaline glass fillers and reduces formation off caries at the margins of the restorations to reduce the formation of secondary caries. Composition- Ba, Al & F silicate glass filler with ytterbium trifluoride, Silicon dioxide & alkaline glass or Dimethacrylate monomers. Ivoclar 1998 Ariston pH control which was claimed to release fluoride. Hydroxl calcium, pH< 5.8 neutralizes acid.

77. siloranes Guggenburger & Weinmann (2000) Siloxane + Oxiranes As silorane based composite polymerizes, ring opening monomers connect by opening, flattening & extending toward each other. As methacrylate based composites cure, the moleculesof these linear monomers connect by actually shifting closer together in a linear response.

78. Filtek p90- low shrink posterior composite restoration Combines the properties of low shrink Silorane based composite with a dedicated two step, self etching, bonding system

79. Glass inserts An alternative to conventionl composites in which the bulk of the cavity preparation is filled with Beta quartz glass inserts. The inserts are surrounded by Lightcured composites, which bond to the insert via a Silane coupling agent. When fitted into the cavity , they minimize volume of shrinkage.

80. ANTIBACTERIAL COMPOSITES Chlorhexidine has been tried in an attempt to reduce plaque accumulation on the surface of filling materials. Imazato et al 1994- attempted to induce antibacterial properties in composite by incorporating a non- releasing newly synthesized monomer MDBP ( Metacrylyolyoxy dodicylpyridinum Bromide) MDBP was found to be effective against Actinomyces, Neisseria & Veillonella . Silver has also been added to impart antibacterial properties.

81. Bioactive composites Bioactive composites ACP ( Amorphous calcium phosphate -2000) ACP+Bis GMA/TEGDMA+ Zirconyl methacrylate. Fluoridated Bis GMA analogues. ACP- Replaces decayed tooth structure by remineralization. Intermediate in Hydroxyapatite formation. HAP can be used as a reinforcing filler

82. COMPOBONDS Compobonds eliminate the bonding stage necessary and combine the benefits of Self etching Dentin bonding agents and nanofilled composites and are termec Self- adhering composites. Vertise flow was the first compobond introduced in 2009by Kerr USA. Opti Bond combines the properties of self adhering flowable composite with a self etching DBA.

83. compobond Incorporates the properties of 7 th generation DBA- acts as a shock absorber beneath resin based composite restorations. Bonding to Dentin is two fold- Chemical adhesion by phosphate group & micromechanical adhesion by formation of hybrid layer. Longer curing time needed.

84. CEROMERS The term Ceromer stands for Ceramic optimized polymer- introduced by Ivoclar . Composed of fine particle ceramic fillers.- Barium glass, Ytterbium trifluoride & Silicon Dioxide. Setting by polymerization of Carbon- Carbon double bonds of Methacrylate. Combines the advantages of ceramics & composites Durable esthetics High abrasion resistance Excellent polish.

85. FIBER reinforced composites Geometrical arrangement of fibres which permit transfer of stressed from the matrix to the fibres. Covalent bond to polymer matrix, Silane coupling agent to improve adhesion. Classification Pre impregnated lab products ( Vectris ) Preimpregnated chairside products (Connect – Kerr) Impregnation required – Chairside ( glaspan ) Preimpregnated prefabricated posts ( everstick )

86. Composite splints FRCs can be used for composite splinting.

87. Quantum dot composites Quantum dots are unique class of semiconductor particles. range from 2-10 nm in diameter. Core shell quantum dots- improve quantum yield, reduce photodegradation

88. conclusion Resin composites are promising materials with a great potential to translate into the gold standard for restorative materials exhibiting superior esthetics & Amalgam like strength & Durability with continued Research……..

89. references Phillips’ science of dental materials – 12 th edition Basic dental materials – John j. Manapallil Craig’s restorative dental materials -13 th edition. www. pubmed.org www.google.co.in www.wikipedia .org

90. PART II

91. CLINICAL ASPECTS & Placement technique Initial clinical technique Isolation Shade selection Cavity designs for composite restoration Etching Bonding Dentin bonding agents Priming/conditioning Curing Matrix placement Finishing & polishing

92. COMPOSITE PLACEMENT

93. ARMAMENTARIUM

94. Dentin bonding agents

95. curing

96. matricing

97. FINISHING & POLISHING

98. FINISHING & POLISHING KIT

99. DIRECT COMPOSITE veneers

100. Composite posts

101. Composite inlays

102. Bio emulation layering technique- composite artistry