Direct Restoratives

1. Direct Restoratives Chapter 5 – 6 Dental Materials DAE/DHE 203

2. Part I: Metallic Restorations: • Amalgam Restorations • Gold Foil Restorations • Matrices and Margins

3. Amalgam: Metal Alloy + Mercury = Amalgam • Alloy– a mixture of metals • Copper, silver, tin, zinc • Mercury (Hg) – a metal with a low melting point making it liquid at room temperature • Makes the metal mixture moldable at room temp. • Allows for a direct restoration • A toxic metal – the root of current public concern

4. Amalgam: • Used in dentistry for almost two hundred years • Versatile, inexpensive, durable material • Self-seals its interface (with corrosion products) • Does not chemically bond to tooth • No studies of any major national & international health organizations have ever linked it to disease or chronic illness • Considered safe & effective by industry & the profession

5. Amalgam: • Using “high-copper” alloy since 1960’s Compared to low-copper amalgams: • Require less mercury in the mix • Have increased strength • Less marginal breakdown • Less corrosion • Less creep (dimensional change under a constant stress) • Pre-dosed capsule: • Convenient • Less handling of mercury • Proper/consistent mix of amalgam

6. Amalgam: COMPOSITION OF HIGH-COPPER ALLOY 55 – 60 % ALLOY + 40 - 45% MERCURY

7. Amalgam: Three forms (shapes) of alloy: • Lathe-cut – “shavings” of metal • Rough & sharp edges, irregular shape • Spherical – sprayed & “frozen” metal droplets • Round or ovoid shaped • Admixed – lathe cut + spherical Handling characteristics of amalgam vary with alloy shape.

8. Amalgam: Mixing • GOAL: thorough mixing of alloy with mercury • “trituration”,“amalgamation” 5-20 seconds • Ideal - “plastic” mass • Shiny, moldable, cohesive • Over-triturated – • sticky, shiny • Under-triturated – • dull, dry, crumbly

9. Amalgam: The Procedure • Tooth prepped, isolated, apply matrix • Liner, base, varnish, as needed • Triturate (per manufacturer) • Dispense (amalgam carrier), repeat as needed • Condense, repeat as needed • Carve • Check & adjust/carve occlusion & interproximally • Burnish • Polish – after 24 hours Patients to avoid chewing/grinding for about 8 hours!

10. Amalgam Setting: High Copper Amalgam: • Gamma-1 phase • Silver combining with mercury • Form a crystalline matrix • 40% of total volume of filling • Tin reacts with Copper • Tin-copper compounds • Initial setting time = 5 minutes from trituration • Final amalgamation continues for several hours

11. Amalgam & Longevity: • Research:  20 years • Private: 8 - 10 years • Why replace amalgams? • Secondary decay • Bulk fracture • Marginal breakdown • Marginal gap  decay?? • Bonding agents help? •  sensitivity •  life of margin •  strength & reinforce bond

12. Amalgam & Corrosion: • Less of a problem with high-copper amalgams • Surface darkened by tarnish • Marginal breakdown • Surface pitting – galvanism • Reduced by: • Thorough condensing • Burnishing & polishing • Good OH,  acidity

13. Mercury Handling Safety: • Avoid skin contact with mercury – wear gloves & eyewear, use kit to clean-up a spill! • Avoid mercury vapor – wear mask! • Re-cap capsule immediately after opening/dispensing • Dispose of empty capsules in a sealed plastic bag • Place amalgam scraps in a sealed container under x-ray fixer solution • Use HVE & water when removing/drilling amalgam When amalgam is set, mercury is bound to other metals!

14. The Public Controversy: "There is no sound scientific evidence supporting a link between amalgam fillings and systemic diseases or chronic illness," ADA President Robert M. Anderton says. "This is a position shared by the ADA and all major U.S. public health agencies and is a matter of public record." Spaeth, Dental Practice Report, Jul/Aug, 2002

15. The Public Controversy: “CDC officials also say there is no proof that removal of amalgam can cure some illnesses as ADA protesters claim. ‘While there have been a number of case studies and anecdotal reports about adverse effects from amalgam, no published controlled studies have demonstrated systemic adverse effects,’ says the CDC. ‘There is also no scientific evidence that general symptoms are relieved by removal of existing amalgam restorations.” Spaeth, Dental Practice Report, Jul/Aug, 2002

16. The Public Controversy: Legislative bills are being introduced in states around the country by anti-amalgamists to abolish the use of mercury in dental amalgams or the use of dental amalgam altogether. Anti-amalgam organizations have filed lawsuits against amalgam manufacturers and the ADA and local dental associations for “conspiring” to hide the truth about amalgam from the public.

17. The Public Controversy: “To Haley, the great amalgam debate is simple. Mercury is toxic. Keep it out of the mouth. End of story.” “Can I prove that chronic exposure causes any one specific disease? Well, that takes a long time to do that kind of research. It’s hard to prove that.”… Removing amalgam would take “an oxidated stress off the the body – a very significant one.” Boyd Haley, PhD; Chemistry Dept., University of Kentucky Spaeth, Dental Practice Report, Jul/Aug, 2002 (www.dentalproducts.net)

18. Direct Gold Fillings: • AKA “gold foil” • Not used presently • Great material, but • NOT esthetic • Costly • Difficult procedure & time-consuming • Gold firmly condensed into “prep” & burnish – • Foil, mat or powdered gold • Pure gold can “weld” w/o heat • Class V, buccal or lingual pits, small Class I

19. Matrices & Margins: • Margins of a restoration are to be “flush” with the tooth surface – this may be most difficult interproximally • A matrix builds a border or “wall” for the restoration • Wedges are placed to conform the matrix to the tooth • Margin errors: • Open margin – a gap is left between tooth & restoration • Flash – a small amount of restorative above cavosurface margin • Overhang – a large amount of restoration outside of margin • Submarginal – the prep is “under-filled” • “Margination” – the removal of overhangs

20. Part II: Esthetic Restorations • Polymers & Polymerization • Dentin & Enamel Adhesives • Dental Composites • Glass Ionomers • Compomer Restoratives

21. Polymers & Polymerization: POLYMERS: • Long-chain of organic “monomers” • “Bis-GMA”; “urethane dimethacrylates” • Comprised of carbon-carbon double bonds (C=C) • Monomers linked together thru Polymerization POLYMERIZATION: • Creating a polymer through chemical reaction • Three methods (auto-, photo-, dual-cure)

22. Polymerization: • Autopolymerization: “self-, or chemical- cure” • Monomer base + initiator (2 pastes/solutions) • Chemical initiator in the catalyst • Mixing of pastes begins reaction • Setting time varies with product • Disadvantages: no control of “working time”; have to be mixed

23. Polymerization: • Photopolymerization: “light-cure” • One paste • Reaction initiated by visible blue light (not UV!) • Advantages: control of working time; no mixing – less chance for bubbles • Disadvantages: must cure incrementally; keep material from light

24. Tips for Photopolymerization: • Hold light source (tip) as close to tooth surface as possible (1-2 mm) • Cure buccal, lingual & occlusal surfaces with Class II & III • Use eye protection – operator and assistant! • Follow manufacturer’s directions for exposure time • Test light intensity periodically

25. Polymerization: • Dual-Cure: • Combination of auto- & photo- polymerization • 2 paste system + light-cure • Operator mixes pastes, applies material & light cures • Advantage: reassurance that material is curing at depth of restoration

26. Enamel & Dentin Adhesives: • Why? To improve the bond of the restoration with the tooth (dentin/enamel) • When?After the cavity prep is complete • What? A 3-step process: etch, prime & bond; enhances chemical bond between bonding agent (resin) and restoration • Remember! Don’t desiccate (dry-out) dentin!

27. Enamel & Dentin Adhesives: 1. Acid Etching: • Improves the retention of the restoration • Increases the surface area of the dentin • Removes “smear layer” from prep • Allows for penetration of bonding agent into dentin • Protect pulp exposures before using! • Phosphoric acid (35-37%) gel or liquid • Isolate teeth, apply etchant, wait (5-15 seconds) • Rinse – don’t desiccate! – blot prep to remove water

28. Enamel & Dentin Adhesives: 2. Primer: • Resin - monomer • Improves wettability of prep • Penetrates etched dentin tubules • Applied in a thin layer; thinned with air; blot • May require light-curing

29. Enamel & Dentin Adhesives: 3. Bonding Adhesive: • Un-filled or lightly filled resin • Adhesive bonds to collagen fibers in dentin – mechanically “locks-in” – “Hybrid Layer” • Applied in a thin, uniform layer • Light-cured 10-20 seconds • New “generations” being developed

30. Esthetic Restoration: Posterior Composite Decay: #30 MOD, plus restoring buccal pit Cavity Prep drill, etch, prime & bond Restored

31. Dental Composites: • Mixture of materials: polymers (resins) + glass particles (fillers) • plus pigments for shade variety • plus silane as a coupling agent (bond fillers to resin) • plus chemical to initiate the polymerization • Many types available: • Filler material, particle size, and filler volume vary • Conventional, Microfill, Hybrids

32. Dental Composites: A challenge for users of resins… “Polymerization Shrinkage” • When monomer molecules are polymerized they take up less space/volume than when uncured (2% shrinkage) • Solutions: • Incremental Curing: Allow for curing between layers • Use dentin bonding adhesives in prep site

33. Dental Composites: CONVENTIONAL COMPOSITES: Resin base + large quartz fillers (50-60%) • Good strength & hardness • Difficult to polish well – rough surface • Stains and discolors; poor esthetics • Uses: not used for restorations anymore; may be used as an ortho cement

34. Dental Composites: MICROFILLED COMPOSITES: • Resin base + silica particle fillers (30-55%) • Weaker material ( fillers) • Very high polish – excellent esthetics • May be used as final layer of deep restoration • Use: Great for anterior restorations (III, V) (NOT Class IV)

35. Dental Composites: HYBRID COMPOSITES: • Resin + quartz or glass fillers (65-70%) • Small or midsize particles • Minifills (largest particles are 1 – 2 um) • Midfills ( average particle size is 3 – 8 um) • Metals added to glass to make them radiopaque • Combination of esthetics & durability • Universal use

36. Dental Composites: • “Flowable” Composites: • Hybrid with smaller and fewer particles • Dispensed thru canula tip • Maybe OK for Class V • “Packable” Composites: • Hybrid with larger and more particles • Condensed with an instrument

37. Dental Composites: Handling Tips: • Prevent cross-contamination of self-cure solutions • Take care to not incorporate bubbles upon mixing • Protect light-cure solutions from white lightexposure • Protect composites from heat • Store composite materials in the refrigerator • Should have 2-year shelf life • May use metal instruments and matrices

38. Dental Composites: • Able to use a more conservative prep • Offer great esthetics – perhaps even tinting • Biggest reasons for failure in anteriors are discoloration & recurrent caries – adhesion is the key! • Reason for failure in posterior is marginal failure & secondary caries • Should have a 5 –10 year duration (Posterior & Class IV have lesser duration) • May have limited success with Class V fillings • The composites can be layered to build strength & adaptation to prep/margins

39. Glass Ionomers: • Used for liner, luting cement & restoration • Powder: liquid Inorganic Glass & Organic Polymer + water/acid • glass: calcium aluminofluorosilicate • particle size: restorations  40 um - thicker lining/luting  25 um – more flow • Liquid: polyacrylic acid + tartaric acid + water • plus pigments for shades • Adheres to tooth surface & releases fluoride

40. Glass Ionomers: • Used for Class III and V restorations (non-stress bearing areas) • Some forms strengthened with metal particles for use as a core build-up material (gray color) • Shrinkage of 3-4% - not as detrimental to bond • Tooth must be moist for adhesion • Soluble in water – protect with resin or varnish • Not yet equal to esthetics of composites

41. Glass Ionomers: • Conventional G.I.’s: • Liquid + powder • Mix on paper pad or glass slab with spatula • Add ½ powder at a time • Finish mix in 30 seconds OR • Triturate capsule for 10 seconds • Place into tooth (“working time” = 2.5 minutes) • Use matrix to form surface • Will appear glossy when mixed

42. Glass Ionomers: RESIN-MODIFIED GLASS IONOMER: • Resin added to mixture • Light-cure material - one paste – no mixing! • Uses: liners, bases • Added fillers have allowed use of Resin-Modified G.I.’s as core material or “packable” primary molar Class I material • Not recommended for high-stress areas

43. Compomer: • A combination restorative material = Composite + Glass Ionomer • Packaged and handle like composites • Formulated to releases fluoride – less than G.I.’s • Excellent esthetics • Not widely used as direct restorative • A few products on the market (Brands: Compoglass, Dyract, 3M F2000)

44. Part III: Preventive Restorations • Dental (Enamel) Sealants • Preventive Resin Restorations

45. Dental Sealants: • Applied to the pits & fissures of healthy enamel • Prevent decay as long as sealant retained on tooth • Provides a physical barrier against decay-causing food/bacteria • Non-invasive; conservative • Use acid-etch technique on enamel surface to be sealed

46. Dental Sealants – Composition: • Highly flowable monomer (resin) material • Unfilled vs, Filled • Self-cure or light-cure • Layer of air-inhibited uncured resin • Many various delivery systems • Opaque, clear, tinted • May be glass ionomer www.nidcr.nih.gov/health/pub/sealants

47. Preventive Resin Restoration “PRR”: • Conservative, preventive restoration • When frank decay is present in a groove or pit of the occlusal surface • Combines a composite filling with an enamel sealant. Both procedures are performed. • Decay is removed with a small, round bur • Composite is placed to fill the prep site • Sealant is placed to protect the filling & rest of tooth