1. Chapter 5 – 6 Dental Materials DAE/DHE 203
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
Amalgam has been shown to be very durable and that is the strongest argument for not changing the “recipe” for this restorative material that has shown years of successful service.
Amalgam is different than composites as their retention relies on mechanical means rather than any chemical adhesion to the tooth surface. The tooth must be cut to allow for “undercuts” that will assist in the tooth structure in mechanically “holding-on” to the restoration.
This is different than “bonding adhesion” that is seen with composites – which can get away with less tooth cutting in the prep because of the way in which they chemically adhere.
We will talk more about mercury handling safety in lab and in lecture.

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. COMPOSITION OF HIGH-COPPER ALLOY
Amalgam:
COMPOSITION OF HIGH-COPPER ALLOY
METAL %
CHARACTERISTIC
SILVER
40-70%
 strength,  corrosion,
 expansion
TIN
22-30%
 expansion,
mixes with copper
COPPER
13-30%
 strength & hardness
ZINC
0-1%
used in manuf. process
55 – 60 % ALLOY % 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
Condensing – the “packing” of amalgam into the prep site
The instruments used for condensing will vary with the type of alloy selected.
With lathe-cut, the condensers should have small heads on them and firm pressure should be used to condense the amalgam – gradually working-up to larger condensers.
With spherical, a small condenser will only fall in between the spheres moving the amalgam out the sides away from the instrument (analogy of a small foot into the ball-playgrounds at McD’s – the balls move away from the foot and the leg sinks). Use larger condensers with lighter pressure for spherical alloys.
With admixed a combination of condensers with a medium pressure is used.
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!
Can’t carve too soon – or margins will pull-in
Burnishing assists in the adaptation of the margin

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
The amalgam undergoes slight shrinkage as it sets – proper carving & burnishing will assist in prevention of the opening gap or margin interface.

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
Under controlled research amalgams (Class I & II) have been shown to last for up to 20 years or more – I still have one that is hanging in there… well, for AT LEAST 20 years!
Private practice docs will tell you that their experience is that they last 8-10 years.
The top reasons for the replacement of amalgams is listed.
It is still controversial and unknown how large the marginal gap between tooth & amalgam has to become before it contributes to secondary decay – science shows the margin “seals” by products of corrosion thereby preventing this type of decay.
Amalgam bonding agents have been growing in popularity but it is still undetermined if they can do what they claim to do, which is to improve the integrity of the margin, thereby strengthen the overall restored tooth. Since the bonding agent “seals” dentin, it may produce less post-op sensitivity for the patient (like a varnish does).
Creep that occurs with amalgam is also responsible for marginal breakdown.

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
Polishing amalgams is accomplished by the use of a commercial product (I.e. Amalgloss), the use of wet pumice slurry, wet tin oxide slurry, or Shofu cups/points. This will be performed in lab. It is important to keep the tooth wet so to not over heat the amalgam.

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, (

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
One goal of a restoration is to restore the proper contour and anatomy to the tooth. This may be difficult in a Class II or III restoration where the margin of the restoration will be hidden by the interdental gingival tissue – however it is also very critical for periodontal health and the prevention of secondary or recurrent caries, that the margin be continuous with the natural tooth surface.
Margination can be accomplished with hand instruments, such as a scaler, curet or perio file. It can also be removed by a bur or a cavitron depending on the size and location of it. If an overhang is very bulky, it may be better to replace the amalgam rather than to try to reduce the margin.
Composites will have a tendency to fracture if the same procedure is performed on them. They are better reduced with the use of a handpiece and bur.
An amalgam filling that has on open margin or is underfilled will need to be replaced.

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

21. Polymers & Polymerization:
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
Altho the book says to wait for 15 seconds, I have also learned that is TOO long for etchant of dentin (fine for enamel!). I have heard that 5 seconds on the dentin is enough.
If the tooth is desiccated, the collagen fibers of the dentin that has been exposed (hybrid layer) will collapse, allowing for a weaker bond. A dried-out tooth may also lead to tooth sensitivity.
* See diagram of “Hybrid Layer” on page 115 of text.

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
The dental materials market is going crazy in this area – there are now one-step “etch, prime & bond” agents that are being made available. There are etch/prime solutions also available. All of these improvements are meant to decrease the tediousness of the procedure, and improve the usability.

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 seconds
New “generations” being developed
New generations include:
4th generation: separate acid etch, primer & bond (3 solutions)
5th generation: etchant + primer/bond together – as we used in lab
6th generation: etch/primer – no separate etching & rinsing; bonding agent applied OR
Two bottles: mix etch/primer with bonding agent & apply, light-cure (still 2 bottles)

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. “Polymerization Shrinkage”
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
A Chart comparing particle size and volume is on page 92.
um – micrometer (1/1000 of a mm); used to be termed “micron”
The glass fillers have metals added to make them radiopaque – aluminum, barium, strontium, etc. – able to detect the filling on an x-ray.

36. Dental Composites: “Flowable” Composites: “Packable” 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 light exposure
Protect composites from heat
Store composite materials in the refrigerator
Should have 2-year shelf life
May use metal instruments and matrices
The drawback of metal matrices is the light wont cure thru the metal matrix band – caution must be taken with its removal; followed by thorough curing interproximally (from buccal and lingual aspects) – IF incremental curing is thorough, all layers should be cured consistently, including interproximal space

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
Marginal adhesion is dependent upon the operators use of the materials – proper acid etching, proper use of the adhesives, reducing shrinkage by layering incrementally, etc.
Class IV restorations with composites may be compromised by occlusal/incisal forces – may not last 10 years.
Some operators prefer to layer composites – start with a flowable to fill in the cavity floor, cure; use packable to fill the restoration, cure; use tinting to create occlusal appearance of grooves, use flowable to seal and complete.

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
We have already learned about and used glass ionomers as liners and cements.
Glass ionomers can release fluoride for up to ONE YEAR –it has been shown that the greatest rate of release is during the first few days to weeks.

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
Metals such as amalgam alloy particles can be added to the glass ionomer by the manufacturer to create a stronger product with a gray tone (for visibility) to be added to the tooth for a core build-up.
The shrinkage of the glass ionomer does not tend to harm the bond to tooth the way that it does with composites – because the curing is a much slower process with GI’s.
Research has found a better bond created with a moist tooth surface – so like with resin adhesives – do not desiccate the dentin after prepping!!
Varnishes or resin cements can be added to the finished surface of the glass ionomer to protect it from the saliva for the first 24 hours (while setting).
Text books say not to finish/polish the surface of a GI for at least 24 hours – some manufacturers instruct a wait time of only 10 –15 minutes.

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
The advantage of a resin-modified GI is that there is no mixing or waiting for cure. The GI can be applied and cured without wasting chair time. They are only slight improvement, in terms of strength or adhesion, over the conventional GI.
If you are using a GI that needs light to cure it – it is a resin-modified GI.

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
Retention rates have been reported at 50-60% retention after 5-10 years. Sometimes there may be wearing of the sealant; studies have shown that sealant “tags” of material is still however present in the enamel “pores” opened by the acid-etch process and caries prevention can still be maintained.
Some dr’s prefer that an “enameloplasty” be performed to clean and widen the grooves before a sealant is placed – this task can’t legally be performed by a DA or RDH since it is a permanent change in the tooth structure. There is not much research that supports this philosophy of treatment, but it is present in the dental community.
Enamel etching is different from dentin etching in that etching takes longer and you want the enamel to be able to be DRY, DRY, DRY – you must have great moisture control and prevent salivary contamination. If contamination occurs; re-etch for 10 seconds.

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

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
This would most likely be performed on a permanent premolar or molar.
This preserves so much health tooth structure that would otherwise be eliminated with a drill for a conventional filling. Only the decay is removed and the area filled. The sealant protects the occlusal surface of the filling and the rest of the tooth. Looks like a sealed tooth when complete.