Co mposite Restorative Materials

1. Composite Restorative Materials

2. Introduction • Anterior restorative materials ????? • 2 types of direct filling resins • Type I – Unfilled acrylic resins • Type II – Filled / Composite resins

3. Unfilled acrylic resin • Silicate cement – tooth colored filling material – introduced 1870s – mixing of phosphoric acid to acid –soluble glass particles • Problem of high solubility of silicate cement led to the introduction of unfilled acrylic resin based on PMMA in 1940s

4. Unfiled acrylic resin • Supplied as powder – liquid system • Powder – PMMA ( > 50 um) • B.P - initiators • Color pigments • Radio- Opacifiers • Liquid – MMA monomer • Ethylene glycol dimethacrylate - cross • linking agent • Dimethyl paratoluidine -activator • Hydroquinone – inhibitors

5. Advantages :- • Simple & direct filling method • Good aesthetic properties ( initially ) later becomes yellowish due to oxidation of amine activators • Not expensive • Suitable W.T & S.T

6. DISADVANTGES • Pulpal irritation due to residual monomer requires liners for protection • Large polymerization shrinkage leading to marginal gap , microleakage & debonding occurs • Higher COTE – cause microleakage • Low / poor mechanical properties

7. Composite Retsorative Resin

8. Composite restoration

9. Light cured composite Chemically cured Composite

11. Composite resin – Introduction • Developed to overcome the drawbacks of unfilled acrylic resin • First manufactured - 1970s – Adaptic , Johnson & Johnson USA • Gained popularity as anterior restorative materials

12. Composite – definition • The term composite refers to a three-dimensional combination of at least 2 or more chemically different materials, insoluble in each other, with a distinct interphase separating the composite. • Or • Compound of 2 or more distinctly different materials with properties that are superior or intermediate to those of the individual components which are chemically bonded by another interface.

13. Uses Of Composite resins • Composites are used as direct restorative material for both anterior & posterior teeth • Adhesive bonding agent • Endodontic / root canal sealants • Chemical & dual cure resins are used as core build up materials • As pit & fissure sealants • Bonding of ceramic veneers & cementation (luting agent) for crowns , bridges & other fixed prosthesis • Bonding of orthodontic brackets during orthodontic treatments

14. Advantages of composite resin: • Superior esthetics. • Improved mechanical properties . • Reduced polymerization shrinkage • Reduced thermal shrinkage (COTE) • Conservation of tooth structure. • Used almost universally. • Greater range of application • Bounded to tooth structure (good retention). • Repairable, No corrosion. • Command set property for VLC composite

15. COMPOSITION… • MAJOR COMPONENTS INORGANIC FILLERS RESIN MATRIX COUPLING AGENT

17. Dental Composite :- • Dental composites are composed of 3 major components: a highly cross – linked polymeric matrix reinforced by a dispersion of glass , mineral or resin filler particle &/or short fibers bound to the matrix by coupling agent

18. Coupling agent Fillers Matrix

19. Resin composite consist of 3 Major components • Matrix phase (resin matrix)-A plastic resin material that forms a continuous phase & binds the filler particles • Inorganic filler –Reinforcing particles and/or fibers that are dispersed in the matrix • Coupling agent –Bonding agent that promotes adhesion between filler and resin matrix

20. MCQ • In composite resin -----------------that promotes adhesion between filler and resin matrix • Coupling agent • Bonding agent • Adhesive agent • Wetting agent • Answ- 1 - Coupling agent

21. CLASSIFICATION

22. According to filler particles Macro filled (Traditional / conventional) : 10 – 100 µm Small/fine particles: 0.1 – 10 µm Midifillers : 1-10 µm Minifillers : 0.1-1 µm Microfilles: 0.01 – 0.1 µm (agglomerated) Hybrid: 0.6 – 1 µm. Nanofilles: 0.005-0.1µm or 1 – 100 nm CLASSIFICATION

23. According to clinical Applications • Anterior composite. • Posterior composite. • Core build up composite • Pit and fissure sealant composite. • Prosthodontics composites ( veneering of gold or base metal alloy crowns ) • Glaze resin composite • Bonding agent

24. According to method of activation :- • Chemically activated composites • Light activated composites E.g.: U.V. light & visible light activated composites. • Dural-cure composite resin

25. According to method dispensing :- • 2 – paste system :- supplied as a base & reactor paste, dispensed in separate jars or cylinders ,e.g.- chemically activated composites • Single paste & liquid:- e.g. – chemically cured composite • Single paste system:- supplied in syringes in different shades ,e.g. – visible light activated & UV light cured composites • Disposable capsules:- e.g. - compomer

26. ANUSAVICE (Skinner’s-11th ed)

27. Composition- Composite Restorative Resin • Matrix phase (Resin matrix) • Fillers • Coupling agent • Activator - Initiator-accelerator system • Other additives • Inhibitor • Pigments and Opacifiers

28. Resin matrix :- • Matrix forms a continuous phase in which the reinforcing filler is dispersed • Resin matrix consist of • Bis-GMA (bisphenol glycidyl methacrylate) • Urethane dimethacrylate (UDMA) • Triethylene glycol dimethacrylate(TEGDMA) - Diluent

29. Bis-GMA Oligomer :- • Can be synthesized by the reaction between bis phenol A & glycidyl methacrylate. • First developed by Dr.Bowen in1960 & hence termed as Bowen‘s resin. • Undergoes free radical addition polymerization reaction

30. Advantage of using Bis-GMA :- • Lower polymerization shrinkage (0.9%) than MMA • Hardens rapidly under oral condition • Improved mechanical property & also increases viscosity • Disadvantage of using Bis-GMA • High-molecular-weight monomer • Extremely viscoushence difficult to blend & manipulate & therefore requires a Diluent monomers • High water sorption

31. Urethane dimethacrylate(UDMA) • May be aliphatic or aromatic in nature • Monomer of this type (aliphatic) have relatively low viscosity & do not require the use of diluent monomer • UDMA monomer with aromatic groups have a slightly more complicated structure & are often more viscous, normally requiring the presence of a diluent monomer

32. Diluent monomer • Why ???? Diluent monomer • Diluent monomer • Oligomers (Bis-GMA & UDMA) are extremely viscous (800,000 Cp similar to honey on a cold day ) at room temp,& are difficult to blend & manipulate • Hence requires the use of lower molecular weight diluents. • Examples for diluents used :- • TEGDMA(Triethylene glycol dimethacrylate) • Viscosity – 5-30 Cp

33. Usually mixture of three parts of Bis GMA & • one part of TEGMA are used in dental • composite resin

34. Advantage :- Produce extensive cross linking among polymer chains, results in highly rigid restorative matrix High resistance to softening or degradation by heat & solvent (such as water & alcohol) Disadvantage :- More Diluent, more the polymerization shrinkage & greater the risk of marginal leakage TEGDMA

35. MCQ • Example for Resin matrix used in composite resin 1. Bis-GMA (bisphenol glycidyl methacrylate) 2. Urethane dimethacrylate (UDMA) 3. Triethylene glycol dimethacrylate (TEGDMA) 4. All • Ans - All

36. Fillers

37. Fillers • Fillers are hard fine particles in the form of powder, beads, cylinders etc. having high strength and are chemically inert • Filler materials • Eg- ground quartz, precipitated or pyrolytic silica, aluminium silicate, lithium aluminium silicate, borosilicate glasses, barium glasses etc fillers matrix

38. As per filler size

39. Fillers • Incorporation of filler particles into a resin matrix strengthens the material and other properties, if the filler particles are well bonded to the resin matrix • Otherwise it can weaken the material , hence effective coupling agent is required to keep the resin matrix and filler particle intact for the success of composite resins.

40. Functions of Fillers Fillers can provide the following benefits • Reinforcement • Reduction in polymerization shrinkage /contraction • Reduction in thermal expansion & contraction • Control of workability/viscosity • Decreased water sorption • Imparting radiopacity

41. Functions of Fillers • Reinforcement – Increased filler loading increases physical & mechanical properties such as - hardness, abrasive resistance compressive strength, tensile strength, MOE (Stiffness or rigidity) and toughness

42. Functions of Fillers 2. Reduction in polymerization shrinkage/ contraction :- Increased filler loading decreases the curing shrinkage, which also reduces the marginal leakage

43. Functions of Fillers 3. Reduction in thermal expansion & contraction :- Increased filler loading decreases the overall C.O.T.E of the composite because glass and ceramic fillers thermally expands and contracts less than do polymers.

44. Functions of Fillers 4. Control of workability/viscosity- • More the filler, thicker is the paste • Filler loading, filler size, particle size and shapes all affects the consistency of a composite paste, which in turn affects the clinical manipulation and handling properties.

45. Functions of Fillers 5. Decreased water sorption :- • Increased filler loading decreases water sorption • Absorbed water softens the resin and makes it more prone to abrasive wear and staining

46. Functions of Fillers 6. Imparting radiopacity:- • Resins are inherently radiolucent • However marginal leakage, secondary caries, poor proximal contacts, wear of proximal surfaces and other problems can de detected if the restoration appear radiopaque in dental radiographs • Radiopacity is imparted through the incorporation of Sr, Ba or Zn & other heavy metals, that absorbs X-rays

47. Filler Barium Boron Radiopacity Yttrium Zinc Zirconium

48. Filler production • Produced by grinding or milling quartz or glasses to produce a particle size of 0.1-100µm. • Silica or micro filler (0.04µm) obtained by pyrolytic or precipitation process.

49. Quantity of filler used :- • % by weight • % by volume (10-15% lower than weight percent)

50. Quantity of filler (Filler loading) % by volume % by weight • 10-15% lower than weight percent)