direct restoratives

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Direct Restoratives

Chapter 5 ± 6

Dental Materials

DAE/DHE 203



Part I: Metallic Restorations:

Amalgam Restorations Gold Foil Restorations

Matrices and Margins



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



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 & internationalhealth organizations have ever linked it todisease or chronic illness

Considered safe & effective by industry & theprofession



Amalgam:

Using ³high-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



Amalgam:

COMPOSITION OF HIGH-COPPER ALLOY

METAL % CHARACTERISTIC

SILVER 40-70% o strength, q corrosion,

o expansion

TIN 22-30% q expansion,

mixes with copper

COPPER 13-30% o strength & hardness

ZINC 0-1% used in manuf. process

55 ± 60 % ALLOY

+40 - 45% MERCURY



Amalgam:

Three forms (shapes) of alloy:

1. Lathe-cut ± ³shavings´ of metal

Rough & sharp edges, irregular shape

2. Spherical ± sprayed & ³frozen´ metal droplets

Round or ovoid shaped3. Admixed ± lathe cut + spherical

Handling characteristics of amalgam vary with alloy shape.



Amalgam: Mixing

GOAL: thorough mixing of alloy with mercury

³trituration´,³amalgamation´5-20 seconds

Ideal - ³plastic´ mass ± Shiny, moldable, cohesive

Over-triturated ± ± sticky, shiny

Under-triturated ± ± dull, dry, crumbly



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

P atients to avoid chewing/grinding for about 8 hours!



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



Amalgam & Longevity:

Research: s 20 years

Private: 8 - 10 years W hy replace amalgams?

1. Secondary decay

2. Bulk fracture

3. Marginal breakdown

Marginal gap p decay?? Bonding agents help?

± q sensitivity

± o life of margin

± o strength & reinforce bond



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, q acidity



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

W hen amalgam is set, mercury is bound to other metals!



The Public Controversy:

"T here is no sound scientific evidence

supporting a link between amalgamfillings and systemic diseases or chronic

illness," ADA P resident Robert M.

Anderton says.

"T his 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




³C DC officials also say there is no proof that removal of

amalgam can cure some illnesses as ADA protestersclaim. µ W hile 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 C DC . µ T here is also no scientific evidence that general symptoms are relieved by removal of existing

amalgam restorations.´

Spaeth, Dental Practice Report, Jul/Aug, 2002




Legislative bills are being introduced in

states around the country by anti-amalgamists to abolish the use of mercuryin dental amalgams or the use of dentalamalgam altogether.

Anti-amalgam organizations have filed lawsuits against amalgam manufacturers

and the ADA and local dental associations

for ³ conspiring´ to hide the truth about

amalgam from the public.




³To Haley, the great amalgam debate is simple.

Mercury is toxic. Keep it out of the mouth.End of story.´

³Can 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 ³an 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)



Direct Gold Fillings:

AKA ³gold foil´

Not used presently Great material, but

± NOT esthetic

± Costly

± Difficult procedure & time-consuming

Gold firmly condensed into ³prep´ & burnish ±

± Foil, mat or powdered gold

Pure gold can ³weld´ w/o heat

Class V, buccal or lingual pits, small Class I



Matrices & Margins:

Margins of a restoration are to be ³flush´ with the tooth

surface ± this may be most difficult interproximally A matrix builds a border or ³wall´ for the restoration

W edges 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 ³under-filled´

³Margination´ ± the removal of overhangs



Part II: Esthetic Restorations

Polymers & Polymerization

Dentin & Enamel Adhesives

Dental Composites

Glass Ionomers

Compomer Restoratives



Polymers & Polymerization:

POL YMERS:

Long-chain of organic ³monomers´ ± ³Bis-GMA´; ³urethane dimethacrylates´

± Comprised of carbon-carbon double bonds (C=C)

± Monomers linked together thru Polymerization

POL YMERIZATION: ± Creating a polymer through chemical reaction

± Three methods (auto-, photo-, dual-cure)



Polymerization:

Autopolymerization: ³self-, 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 ³working time´;

have to be mixed



Polymerization:

Photopolymerization: ³light-cure´

± One paste

± Reaction initiated by visible blue light (notUV!)

± Advantages: control of working time; nomixing ± less chance for bubbles

± Disadvantages: must cure incrementally;keep material from light



Tips for Photopolymerization:

Hold light source (tip) as close

to tooth surface as possible(1-2 mm)

C ure buccal, lingual & occlusal surfaces with C lass II & III

Use eye protection ± operator and assistant!

Follow manufacturer¶sdirections for exposure time

T est light intensity periodically



Polymerization:

Dual-Cure:

± Combination of auto- & photopolymerization

± 2 paste system + light-cure

± Operator mixes pastes, applies material & light cures

± Advantage: reassurance that material is curing at

depth of restoration



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 bondingagent (resin) and restoration

Remember! Don¶t desiccate (dry-out) dentin!




1. Acid Etching:

Improves the retention of the restoration Increases the surface area of the dentin

Removes ³smear 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




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




3. Bonding Adhesive:

Un-filled or lightly filled resin

Adhesive bonds to collagen fibers in dentin ±

mechanically ³locks-in´ ± ³Hybrid Layer´

Applied in a thin, uniform layer Light-cured 10-20 seconds

New ³generations´ being developed



Esthetic Restoration: Posterior Composite

Decay: #30 MO

D,plusrestoring buccal pit

Cavity Prep

drill, etch, prime & bond

Restored



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



Dental Composites:

A challenge for users of resins«

³ P olymerization 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



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

Dental Composites:



Dental Composites:

MICROFILLED COMPOSITES:

Resin base + silica particle fillers (30-55%)

Weaker material (q 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)



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



Dental Composites:

³Flowable´ Composites: ± Hybrid with smaller and

fewer particles ± Dispensed thru canula tip

± Maybe OK for Class V

³Packable´ Composites: ± Hybrid with larger and

more particles

± Condensed with aninstrument



Dental Composites:

H andling Tips:

Prevent cross-contamination of self-cure solutions Take care to not incorporate bubbles upon mixing

Protect light-cure solutions from white light exposure

Protect composites from heat

Store composite materials in the refrigerator

Should have 2-year shelf life

May use metal instruments and matrices



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 IVhave lesser duration)

May have limited success with Class V fillings

The composites can be layered to build strength &adaptation to prep/margins



Glass Ionomers:

Used for liner, luting cement & restoration

Powder: liquidInorganic Glass & Organic Polymer + water/acid

± glass: calcium aluminofluorosilicate

± particle size: restorations e 40 um - thicker

lining/luting e 25 um ± more flow ± Liquid: polyacrylic acid + tartaric acid + water

± plus pigments for shades

Adheres to tooth surface & releases fluoride



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



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 (³working time´ = 2.5 minutes)

± Use matrix to form surface

± Will appear glossy when mixed



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 ³packable´

primary molar Class I material

Not recommended for high-stress areas



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)



Part III: Preventive Restorations

Dental (Enamel) Sealants Preventive Resin Restorations



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



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



Preventive Resin Restoration ³PRR´:

Conservative, preventive restoration

When frank decay is present in a groove or pitof 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

direct restoratives

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