Recent dental composite resins

Compomer - Giomer- Flowable - Packable - Ormocer - Smart - Nanofilled - Silorane - Bulkfill - Cention N

1. Recent advances in dental composite 1

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3. 3 Fillers inside composite resin 1 4 3 2

4. 4 Fillers Resin matrix Advantages Disadvantages * ↑Filler amount → ↑strength & viscosity * ↓Filler size → ↑smoothness & esthetics * ↑ Polymerization shrinkage (major disadv . of composite) * ↑ Water sorption → ↑ staining (↑discoloration)

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6. Disadvantages of Conventional Composite Resin 6 Polymerization Shrinkag e (major disadvantage) → * Microleakage * Post-operative sensitivity (pain) * Marginal discoloration * Recurrent caries Technique sensitive & time consuming (incremental placement)

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8. Notes 8 ↑ Filler loading (amount, content) → ↓ resin content → ↓ problems of resin, such as: * ↓ Polymerization shrinkage . * ↓ Water sorption → ↓ Staining (↓ discoloration). ↑ Filler loading → * ↑ Mechanical properties (strength, hardness, wear resistance). * ↑ Viscosity → Improve workability (give body to the material). ↓ Filler size → ↑ smoothness & better esthetics.

9. Items to be covered 9 * Dental cement: composite resin cement * Restoration 1. Direct composite Restoration - Combination between composite & GIC: Compomer & Giomer - According to viscosity : Flowable & Packable (condensable) composite - Ormocer - Smart composite - Novel trends in direct composite restorations * Nano-filled * Silorane (low-shrink) * Bulk-fill * Cention N 2. Indirect composite restoration → Just for reading (Reading o nly)

10. Composite resin cement 10 The first trial to use the resin as cement was unfilled resin (without filler) but it showed Some drawbacks (disadvantages), such as: * Polymerization shrinkage (due to high resin content) * Irritation So, they tried to use filled composite (contains filler) as cement. It had high filler loading (60 wt %). Types: visible light cure, chemical and dual cure.

11. Composite resin cement (continued) 11 a. Visible light cured (VLC) type -There is no difference in its composition from VLC composite restoration. - Present in different shades. b. Dual cure composite cement - This material has the ability to polymerize even in absence of light source. - Indications (uses): cementation of endodontic post and ceramic inlay & crowns. c. Chemical cured composite cement - Initiator: benzoyl peroxide. - Activator: tertiary amine. - Indication: Mainly used for luting (cementation) of metallic restoration - Contains 4-META ( methacryloxy ethyl trimellitic anhydrite). - Good bond with metal restoration.

12. Composite resin cement (continued) 12 GENERAL PROPERTIES (in comparison with other dental cements) 1- Good biological properties, if there is a good degree of curing → ↓ residual monomer 2- No adhesion (chemical bond ) with tooth structure, but ……… 3- Low degree of solubility in the oral fluids, but there are some inhibition of polymerization caused by moisture & saliva, so it is very important to apply air inhibition gel. 4- Good esthetic quality. 5- Good compressive and tensile strength .

13. Composite resin cement (continued) 13 Note: the material of choice (the best material) for cementation of all-ceramic (translucent) restoration is composite resin cement, why? ↑ Strength & ↓ solubility Translucent & good esthetics Good bond strength

14. POLY ACID-MODIFIED COMPOSITE (COMPOMER) 14 A type of composite which is modified by application of polyacrylic acid Not a glass ionomer material Light-cured low fluoride-releasing composite resins The term compomer is derived from the words compo site & glass iono mer

15. 15 Compomer (continued) Composition - UDMA - Polyacid -modified monomer = TCB (HEMA and butane carboxylic acid) - Strontium alumino fluorosilicate glass - Others: initiator & pigments Uses - Mainly used in low stress-bearing areas (class III & V)

16. 16 Compomer (continued) Setting process Compomer Composite resin Glass ionomer Polymerization reaction Acid-base reaction

17. 17 Compomer (continued) Disadvantages 1- Fl release: lower than glass ionomer (10% of that released by glass ionomer) - Lower amount & duration of Fl release - No recharge from fluoride treatment [Textbook: Craig 14 ed 2019] 2- Bond: still needs etching & dentin bonding agent prior to its placement 3- Esthetic : lower than composite resin. - Lower color stability: due to change in refractive index by water absorption & staining [Textbook: Phillips 12 ed 2013] 4- Wear resistance: lower than composite resin

18. GIOMER 18 P re- r eacted g lass ionomer ( PRG ) F luoro aluminosilicate glass reacted with polyacrylic acid prior to (before) inclusion into the silica gel urethane resin. S hould be classified as a light cured composite . D iffer from compomer (give reason) * because in giomer , the acid base reaction has already occurred . While in compomer , ……….. Not classified as compomer (give reason) ………

19. 19 GIOMER (PRG) [continued] Indications (uses) Restoration (filling) of root caries Class III & V cavities Advantages 1- Fl release & recharge 2- Biocompatible 3- Excellent esthetic & smooth surface finish

20. 20 Flowable composite Flowable = has high flow …… Why?? Low filler loading (50%) → * ↓ viscosity & ↑ flow → [ Pit & fissure sealant ] * ↓ modulus of elasticity & ↑ flexibility → stress breaker (absorb stresses) → [ Liner under class I & II ] * ↓ mechanical properties → [ Non stress-bearing areas ] * ↑ resin amount → ↑ polymerization shrinkage

21. 21 Flowable composite Indications (uses) Pit and fissure sealant ……. Why ?? L iner under class I & II composites …….. Why?? Class V restorations (non stress-bearing areas, not incisal & not occlusal) …… Why?? Repair of broken restoration.

22. 22 Packable composite (condensable composite) Packable (condensable) = able to be packed & condensed (like amalgam) → to produce better proximal contour & contact. Interlocking elongated fibers (100 μm ) → causes the uncured material to: * Resist flow (↑ viscosity) * ↑ Stiffness of uncured material * Resist slumping, but moldable under condensation forces Disadvantage ↑ viscosity → ↑ probability of voids.

23. 23 Packable composite (condensable composite) Notes (Phillips 12 ed 2013) At present, these materials have not demonstrated any advantageous properties over the hybrid resin other than being condensable (packable). Despite the manufacturers’ claims , packable composites have not proven to be an answer to the general need for: * High wear resistance * Easily placed * Low polymerization shrinkage * Depth of cure more than 2 mm

24. 24 Ormocer ( or ganically- mo dified cer amics) Contains inorganic-organic copolymer Inorganic: (Si-O-Si) polysiloxane Organic: methacrylate groups 3D cross-linked copolymer

25. 25 Ormocer ( or ganically- mo dified cer amics) Advantages Presence of inorganic part → ↓ organic part (↓ resin content). * ↓ Organic part → ↓ polymerization shrinkage. Large space between cross-links → ↓ polymerization shrinkage.

26. 26 Smart composite I on-releasing composite: release alkaline ions, e.g. F, Ca, OH. Plaque ( food ) accumulation (caries initiation) = ↓ pH (acidic medium) → release of alkaline ions → buffer (neutralize) the acids ( ↓ acidity) → ↓ tooth decomposition (↓ tooth demineralization & decalcification). Advantages Fluoride release → anticariogenic (prevent caries) Note The adhesive will reduce (inhibit) the benefits of fluoride release.

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28. Novel trends in composite restoration Nano-filled composite Silorane (low shrinkage) composite Bulk-fill composite Cention N 28

29. Nano-filled composite True nano -composite, not nano -hybrid. High filler loading (90 % wt ), because it has: * Nanomers : non agglomerated particles of 20-75 nm. * Nanoclusters: loosely bound agglomerate that act as single units. 29

30. Nano-filled composite ↑ Filler loading → * ↑ mechanical properties (surface hardness, flexural strength & modulus of elasticity) * ↓ resin amount → ↓ polymerization shrinkage ↓ Filler size ( nanosize ) → * ↑ Smoothness & polishability * Smaller than wavelength of light → no scattering or absorption of light → ↑ translucency 30

31. Shrink-free (low shrinkage) composite Silorane resin-based composite Formed of silo xane & oxi rane resins. Oxirane resin: * Ring opening addition polymerization reaction. * Opening the ring → gains space → compensate the shrinkage ( when the resin molecules move toward each other to form chemical bond) → ↓ shrinkage → less microleakage & better marginal integrity 31

32. Shrink-free (low shrinkage) composite Silorane resin-based composite Siloxane → hydrophobic → ↓ water sorption & staining (discoloration) Silorane needs special adhesive system for bonding, Why? → because it is not methacrylate-based composite. It is silorane -based composite ………. 32

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34. Bulk-fill composite Bulk fill = bulk increment (layer, 4 mm ) Can be placed with thickness of 4 mm instead of using incremental placement (2 mm). The depth of cure is increased by: * High translucency * Extra initiator 34 important

35. Bulk fill composite Types: packable and flowable . Overcomes polymerization stress by using: * Resin: stress-relieving monomer * Filler: special fillers with low elastic modulus 35

36. Cention N Alkasite = contain alkaline fillers, such as calcium fluorosilicate glass, which releases ions (F, OH, Ca) in the presence of acidic medium → neutralize the acidity & prevent caries. A subgroup of composite Fluoride release: comparable to that of GIC 36

37. Cention N (continued) Form: powder & liquid Self- or dual-cure: self-cure with optional additional light-cure Full-depth curing = Bulk-fill, Why? …….. Isofillers (prepolymers) → ↓ polymerization shrinkage Low modulus of elasticity & polym . shrinkage → ↓ polymerization stress It is claimed that: * It can be used as a restoration for stress-bearing areas. * It can be applied with or without an adhesive (dentin bonding agent). 37

38. 38 Indirect composite restoration An attempt to overcome the disadvantages of direct adhesive restorations, such as:   Polymerization shrinkage. Inability to obtain proper (correct) anatomical contour, especially proximal contact . Just for reading (Reading only)

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40. 40 Indirect composite restoration (continued) Constructed in dental laboratory . Good anatomical contour & proximal contact The problems with polymerization shrinkage is not totally eliminated, → because there is some doubt about the bond between the resin luting cement and the indirect composite. Reading only

41. 41 Resin-to-resin bonding (Introduction to dental materials, p. 229) One might imagine that resin-to-resin bonding should be free of problems , this is, in fact, not the case. In particular, there have been problems of debonding between the luting resin & composite inlay. Oxygen inhibition layer does not exist . The luting resin has to bond directly to fully cured resins. This is similar to repairing a fractured composite restoration with new composite resin. Reading only

42. 42 Resin-to-resin bonding (continued) Roughened by grit-blasting (alumina sandlasting ). Phosphoric acid etching → clean the surface. HF acid is not recommended. * HF causes degradation of the composite surface by etching away the silica glass → leaving a weak & porous polymer matrix. (Craig, p. 282) Tribochemical technique → silica layer, then silane application. Why? Reading only

43. 43 Resin-to-resin bonding (continued) The problem of resin-to-resin bonding has not yet been resolved satisfactorily, & thus will continue to be an area of research interest. (Introduction to dental materials, p. 229) Reading only

44. 44 Indirect composite restoration (continued) Fibre-reinforced composite Developed as an alternative to both all-ceramic and ceramometal restorations. The fibers may be: * Made from: glass, carbon or polyethylene * Shape: unidirectional, mesh or wave Reading only

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46. Fiber -reinforced composite (continued) Factors affecting the degree of success of fibers Good bond between fibers & resin matrix Alignment of fibers : * should be parallel to tensile force (not perpendicular to the force direction) 46 Reading only

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48. Notes 48

49. 49 P olymerization shrinkage & polymerization stress

50. How to ↓ polym . shrinkage or stress? Filler: * ↑ filler loading → ↓ resin content → ↓ polym . shrinkage. * Different filler size (hybrid composite) → ↑ filler loading → …… * Prepolymers ( isofillers ) → ↓ polym . shrinkage. 50

51. How to ↓ polym . shrinkage or stress? 2. Resin: * Silorane resin: ring-opening polymerization → ↓ polymerization shrinkage. * Ormocer : inorganic-organic copolymer, presence of inorganic part → ↓ organic part → ↓ polymerization shrinkage. * Bulk fill: stress-decreasing resin → ↓ polymerization stress. 51

52. How to ↓ polym . shrinkage or stress? (continued) 3. Technique: indirect composite → ↓ polym . shrinkage. 4. Placement (insertion): * Note: bonding agent → ↓ microleakage . * Flowable composite as a liner under class I & II → ↓ polymerization stress. * Incremental placement (layer by layer, 2 mm) 5. Curing: soft-start polymerization (gradual, start with low light intensity) → ↓ polym . stress. 52

53. Items that have been covered 53 * Dental cement: composite resin cement * Restoration 1. Direct composite Restoration - Combination between composite & GIC: Compomer & Giomer - According to viscosity : Flowable & Packable (condensable) composite - Ormocer - Smart composite - Novel trends in direct composite restorations * Nano-filled * Silorane (low-shrink) * Bulk-fill * Cention N 2. Indirect composite restoration → Just for reading (Reading only)

54. 54 References Sakaguchi R, Ferracane J, Powers J. Craig 's restorative dental materials. 14 th ed. St. Louis, Elsevier; 2019 . Anusavice KJ, Shen C, Rawls HR. Phillips ' science of dental materials. 12 th ed. St. Louis, Elsevier; 2013 . Van Noort R, Barbour ME . Introduction to dental materials . 4 th ed. Mosby Elsevier; 2013 .