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DENTAL AMALGAM
HISTORY
TERMINOLOGIES
MANUFACTURE OF ALLOY POWDER
ALLOY COMPOSITION
AMALGAMATION & RESULTING MICROSTRUCTURE
DIMENSIONAL STABILITY
STRENGTH
CREEP
CLINICAL PERFORMANCE OF AMALGAM RESTORATIONS
FACTORS AFFECTING SUCCESS OF AMALGAM RESTORATIONS
MERCURY/ALLOY RATIO
MECHANICAL TRITURATION
CARVING & FINISHING
CONDENSATION
CLINICAL SIGNIFICANCE OF DIMENSIONAL CHANGE
MARGINAL DETERIORATION
SIDE EFFECTS OF MERCURY
SUMMARY
CONCLUSION
REFERENCES
HISTORICAL BACKGROUND
Silver Amalgam in Clinical Practice- I.D. Gainsford
Used as a dental restorative material from the beginning of the 19th century.
Amalgams were made by mixing mercury with the fillings from Spanish or Mexican silver coins (high silver content).
Failure causes:1. Harsh mass which was difficult to mix2. Hardened very slowly3. Expanded enormously4. Stained the teeth black
YEAR EVENTS
1819 First dental silver amalgam is supposed to have been introduced into England by Bell – “Bell’s Putty”
1833 Introduced to the North American continent by Cawcour brothers termed as “Royal Mineral Succedaneum”.
1843 Resolution passed by the American Society of Dental Surgeons (the first organised Dental Society in the U.S.A declaring the use of amalgam a “Malpractice”.Thus the Amalgam War began
1845 “Amalgam Pledge” was adopted by the society.
YEAR EVENTS
1850 Pledge was rescinded officially ending the amalgam war.
1861 First research programme was conducted by John Tomes ( Trans.Odontol.Soc. G.B.,Vol III)Who measured shrinkage of a number of amalgams
1871 Charles Tomes measured shrinkage & expansions by specific gravity tests.
1874 Thomas B.Hitchcock (Trans.N.Y.Odontol.Soc) did some important work in measuring more accurately by means of a micrometer changes of amalgam form
YEAR EVENTS
1896 Classic work of G.V.Black that a more systematic study was made of the properties & manner of manipulation of silver amalgam and its relation to cavity preparation.Many of G.V.Black’s techniques for amalgam restorations are generally accepted today.New methods are often described as variations or modifications of those used by Black.
YEAR EVENTS
1930 A.D.A research organisation conducted a survey and showed that only a few of the proprietary amalgam alloys on the market & tested by the National Bureau of Standards were reliable.A.D.A specification No. 1 for Alloy.A.D.A specification No. 6 for Mercury.
1934 &1960
Revision of this specification
HISTORY OVERVIEW
1833 Crawcour brothers introduce
amalgam to U.S powdered silver coins mixed with mercury
expanded on setting
1895 G.V. Black developed
formula for modern amalgam alloy
67% silver, 27% tin, 5% copper, 1% zinc
overcame expansion problems
1960’s conventional low-copper
lathe-cut alloys smaller particles
first generation high-copper alloys
Dispersalloy (Caulk) Innes & Youdelis -1963 admixture of spherical Ag-
Cu eutectic particles with conventional lathe-cut
eliminated gamma-2 phase
Mahler J Dent Res 1997
1970’s first single composition
spherical Tytin (Kerr) ternary system
(silver/tin/copper)
1980’s alloys similar to Dispersalloy
and Tytin
1990’s mercury-free alloys Mahler J Dent Res 1997
TERMINOLOGIES & DEFINITIONS
AMALGAM DENTAL AMALGAM DENTAL AMALGAM ALLOY TRITURATION AMALGAMATION
Special type of alloy in that one of its constituents is mercury.Before these alloys combine with mercury they are known as dental amalgam alloys - ANUSAVICE (2003)
Amalgam
TERMINOLOGY DEFINITION
Amalgam Amalgam is an alloy which has mercury as one of its components – Marzouk (1997)
Dental Amalgam An alloy of mercury, silver, copper, tin, which may also contain palladium, zinc, and other elements to improve handling characteristics and clinical performance – Anusavice (2003)
Dental Amalgam Alloy /Alloy for Dental Amalgam
An alloy of silver, copper, tin, and other elements that is formulated and processed in the form of powder particles or as a compressed pellet– Anusavice (2003)
But to be more simple… AMALGAM = A + MASS OF GAM (GUM)
(HAND TRITURATION) AMALGAM = AMALGAMATED GAM (GUM)
(AMALGAMATOR)
FUTURE COULD BE…
AMALGAM = AMALGAMATED MASS DELIVERED FROM GUN
(COMPOSITE COMPULES)
TERMINOLOGY DEFINITION
Amalgamation The process of mixing liquid mercury with one or more metals or alloys to form an amalgam. – Anusavice (2003)
Trituration The process of grinding powder, especially within a liquid. In dentistry, the term is used to describe the process of mixing the amalgam alloy particles with mercury in an amalgamator. – Anusavice (2003)
Why Amalgam? Inexpensive Ease of use Proven track record
>150 years Familiarity Resin-free
less allergies than composite
Constituents in Amalgam
Basic Silver Tin Copper Mercury
Other Zinc Indium Palladium
Basic Silver Tin Copper Mercury
Other Zinc Indium Palladium
AmalgamConstituents
1895 G.V. Black develops
formula for modern amalgam alloy
67% silver, 27% tin, 5% copper, 1% zinc
Basic Constituents Silver (Ag)
increases strength increases expansion
Tin (Sn) decreases expansion decreased strength increases setting time
Phillip’s Science of Dental Materials 2003
Basic Constituents Copper (Cu)
ties up tin reducing gamma-2
formation increases strength reduces tarnish and
corrosion reduces creep
reduces marginal deterioration
Phillip’s Science of Dental Materials 2003
Basic Constituents Mercury (Hg)
activates reaction only pure metal that is liquid
at room temperature spherical alloys
require less mercury smaller surface area easier to wet
40 to 45% Hg admixed alloys
require more mercury lathe-cut particles more difficult to wet
45 to 50% Hg
Phillip’s Science of Dental Materials 2003
Other Constituents Zinc (Zn)
used in manufacturing decreases oxidation of other elements
sacrificial anode provides better clinical performance
less marginal breakdown Osborne JW Am J Dent 1992
causes delayed expansion with low Cu alloys if contaminated with moisture during condensation
Phillips RW JADA 1954
Phillip’s Science of Dental Materials 2003
H2O + Zn ZnO + H2
Other Constituents Indium (In)
decreases surface tension reduces amount of mercury necessary reduces emitted mercury vapor
reduces creep and marginal breakdown increases strength must be used in admixed alloys example
Indisperse (Indisperse Distributing Company) 5% indium
Powell J Dent Res 1989
Other Constituents
Palladium (Pd) reduced corrosion greater luster example
Valiant PhD (Ivoclar Vivadent) 0.5% palladium
Mahler J Dent Res 1990
Classifications
Based on number of alloys Based on copper content Based on particle shape Based on method of adding
copper Based on manufacturing process Based on powder’s particle size Based on addition of Noble Metals
Copper Content
Low-copper alloys 4 to 6% Cu
High-copper alloys thought that 6% Cu was maximum amount
due to fear of excessive corrosion and expansion Now contain 9 to 30% Cu
at expense of Ag
Phillip’s Science of Dental Materials 2003
Composition
LOW COPPER
HIGH COPPER
Admixed Unicomposition
Particle shape
Lathe- Cut /Spherical
Lathe-cut(2/3)
Spherical(1/3)
Spherical
Silver 63-70% 40-70 % 40-65 % 40-60 %
Tin 26-23 % 26-30 % 0-30 % 22-30 %
Copper 2-5 % 2-30 % 20-40 % 13-30 %
Zinc 0-2 % 0-2 % 0 % 0-4 %
COPPER CONTENT
Particle Shape Lathe cut
low Cu New True
Dental alloy high Cu
ANA 2000
Admixture high Cu
Dispersalloy, Valiant PhD
Spherical low Cu
Cavex SF high Cu
Tytin, Valiant
Method of Adding CopperSingle Composition Lathe-Cut (SCL)
Single Composition Spherical (SCS)
Admixture: Lathe-cut + Spherical Eutectic (ALE)
Admixture: Lathe-cut + Single Composition
Spherical (ALSCS)
Single Composition Lathe-Cut (SCL) More Hg needed than spherical alloys High condensation force needed due to
lathe cut 20% Cu Example
ANA 2000 (Nordiska Dental)
Single Composition Spherical (SCS)
Spherical particles wet easier with Hg less Hg needed (42%)
Less condensation force, larger condenser Gamma particles as 20 micron spheres
with epsilon layer on surface Examples
Tytin (Kerr) Valiant (Ivoclar Vivadent)
Admixture: Lathe-cut + Spherical Eutectic (ALE)
Composition 2/3 conventional lathe cut (3% Cu) 1/3 high Cu spherical eutectic (28% Cu) overall 12% Cu, 1% Zn
Initial reaction produces gamma 2 no gamma 2 within two years
Example Dispersalloy (Caulk)
Admixture: Lathe-cut + Single Composition Spherical (ALSCS)
High Cu in both lathe-cut and spherical components 19% Cu
Epsilon layer forms on both components 0.5% palladium added
reinforce grain boundaries on gamma 1 Example
Valiant PhD (Ivoclar Vivadent)
MANUFACTURE OF ALLOY POWDER Classification Lathecut powder Homogenizing Anneal Particle Treatments Atomized powder Lathecut powder Vs Atomized Spherical
powder
Manufacturing Process
Lathe-cut alloys Ag & Sn melted together alloy cooled
phases solidify heat treat
100 ºC for 8 hours grind, then mill to 25 - 50 microns heat treat to release stresses of grinding
Phillip’s Science of Dental Materials 2003
Manufacturing Process
Spherical alloys melt alloy atomize
spheres form as particles cool sizes range from 5 - 40
microns variety improves condensability
Phillip’s Science of Dental Materials 2003
ALLOY COMPOSITION Metallurgical phases in dental amalgams
The Silver-Tin system
The influence of Silver-Tin phase on amalgam properties
METTALURGICAL PHASESMETTALURGICAL PHASES
Sn8Hg
Ag2Hg3
Ag3Sn
STOICHIOMETRIC FORMULA
2
1
PHASESNUMBER OF ATOMS
NUMBER OF ATOMSSTOICHIOMETRIC
FORMULA
PHASES
Ag-CuSilver-Copper Eutectic
Cu6Sn5
Cu3Sn
(4) - 1 (5) - 1
Cu Ag
PHASE:Silver- Copper Eutectic
STOICHIOMETRIC FORMULA:
Ag-Cu
PHASE:Silver- Copper Eutectic
STOICHIOMETRIC FORMULA:
Ag-Cu
Basic Composition A silver-mercury matrix containing filler
particles of silver-tin Filler (bricks):
Ag3Sn called gamma can be in various shapes
irregular (lathe-cut), spherical,or a combination
Matrix: Ag2Hg3 called gamma 1
cement Sn8Hg called gamma 2
voids
Phillip’s Science of Dental Materials 2003
Basic Setting Reactions
Conventional low-copper alloys Admixed high-copper alloys Single composition high-copper alloys
Dissolution and precipitation Hg dissolves Ag and Sn
from alloy Intermetallic compounds
formed
Conventional Low-Copper Alloys
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
Mercury (Hg)
AgAgAg
Sn
Sn
Sn
Hg Hg
AgAg33Sn + HgSn + Hg AgAg33Sn + AgSn + Ag22HgHg33 + Sn + Sn88HgHg
Phillip’s Science of Dental Materials 2003
1 2
Conventional Low-Copper Alloys Gamma () = Ag3Sn
unreacted alloy strongest phase and
corrodes the least forms 30% of volume
of set amalgam Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
Mercury
Ag
AgAg
Sn
Sn
Sn
HgHg
Hg
AgAg33Sn + HgSn + Hg AgAg33Sn + AgSn + Ag22HgHg33 + Sn + Sn88HgHg
Phillip’s Science of Dental Materials 2003
1 2
Conventional Low-Copper Alloys Gamma 1 (1) = Ag2Hg3
matrix for unreacted alloyand 2nd strongest phase
10 micron grainsbinding gamma ()
60% of volume
AgAg33Sn + HgSn + Hg AgAg33Sn + AgSn + Ag22HgHg33 + Sn + Sn88HgHg
Phillip’s Science of Dental Materials 2003
1 2
1
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
Conventional Low-Copper Alloys
Gamma 2 (2) = Sn8Hg weakest and softest phase corrodes fast, voids form corrosion yields Hg which
reacts with more gamma () 10% of volume volume decreases with time
due to corrosion
AgAg33Sn + HgSn + Hg AgAg33Sn + AgSn + Ag22HgHg33 + Sn + Sn88HgHg
Phillip’s Science of Dental Materials 2003
1 2
2
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
AgAg33Sn + HgSn + Hg AgAg33Sn + AgSn + Ag22HgHg33 + Sn + Sn88HgHg 1 2
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
Mercury (Hg)
AgAgAg
Sn
SnSn
Hg Hg
1
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy 2
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
Conventional Low-Copper Alloys
(30%) (60%) (10%)
Admixed High-Copper Alloys
Ag enters Hg from Ag-Cu spherical eutectic particles eutectic
an alloy in which the elements are completely soluble in liquid solution but separate into distinct areas upon solidification
Both Ag and Sn enter Hg from Ag3Sn particles
Phillip’s Science of Dental Materials 2003
AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu + Cu66SnSn55 1
Ag-Sn Alloy
Ag-Sn Alloy
Mercury
Ag
AgAg
SnSn
Ag-Cu Alloy
AgHgHg
Admixed High-Copper Alloys
Sn diffuses to surface of Ag-Cu particles reacts with Cu to form
(eta) Cu6Sn5 () around unconsumed
Ag-Cu particlesAg-Sn Alloy
Ag-Cu Alloy
Ag-Sn Alloy
Phillip’s Science of Dental Materials 2003
AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu + Cu66SnSn55 1
Admixed High-Copper Alloys
Gamma 1 (1) (Ag2Hg3)
surrounds () eta phase (Cu6Sn5) and gamma ()
alloy particles (Ag3Sn)Ag-Sn Alloy
1
Ag-Cu Alloy
Ag-Sn Alloy
Phillip’s Science of Dental Materials 2003
AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu + Cu66SnSn55 1
AgAg33Sn + Ag-Cu + HgSn + Ag-Cu + Hg AgAg33Sn + Ag-Cu + AgSn + Ag-Cu + Ag22HgHg33 + Cu + Cu66SnSn55 1
Ag-Sn Alloy
Ag-Sn AlloyMercury
AgAgAg
SnSn
Ag-Cu Alloy
AgHgHg
Ag-Sn Alloy
Ag-Cu Alloy
Ag-Sn Alloy
Ag-Sn
Alloy 1
Ag-Cu Alloy
Ag-Sn
Alloy
Admixed High-Copper Alloys
Single Composition High-Copper Alloys
Gamma sphere () (Ag3Sn) with epsilon coating () (Cu3Sn)
Ag and Sn dissolve in Hg
Ag-Sn Alloy
Ag-Sn AlloyAg-Sn Alloy
Mercury (Hg)
Ag
SnAg
Sn
AgAg33Sn + CuSn + Cu33Sn + HgSn + Hg AgAg33Sn + CuSn + Cu33Sn + AgSn + Ag22HgHg33 + Cu + Cu66SnSn55
Phillip’s Science of Dental Materials 2003
1
Single Composition High-Copper Alloys
Gamma 1 (1) (Ag2Hg3) crystalsgrow binding together partially-dissolved gamma () alloyparticles (Ag3Sn)
Epsilon () (Cu3Sn) develops crystals on surface of gamma particle (Ag3Sn) in the form of eta () (Cu6Sn5) reduces creep prevents gamma-2 formation
Ag-Sn Alloy
Ag-Sn AlloyAg-Sn Alloy
1
AgAg33Sn + CuSn + Cu33Sn + HgSn + Hg AgAg33Sn + CuSn + Cu33Sn + AgSn + Ag22HgHg33 + Cu + Cu66SnSn55
Phillip’s Science of Dental Materials 2003
1
Material-Related Variables Dimensional change Strength Corrosion Creep
DIMENSIONAL STABILITY
DIMENSIONAL CHANGE
THEORY OF DIMENSIONAL CHANGE
EFFECT OF MOISTURE CONTAMINATION
Delayed Expansion
The gradual expansion of a zinc-containing amalgam over weeks to months, which is associated with hydrogen gas development caused by contamination of the plastic mass with moisture during its manipulation in a cavity preparation– Anusavice (2003)
DIMENSIONAL CHANGES DIMENSIONAL CHANGES
Dimensional changes on setting:Dimensional changes on setting:CONTRACTION during alloy dissolutionCONTRACTION during alloy dissolutionEXPANSION during impingement of reaction product crystalsEXPANSION during impingement of reaction product crystals(EXPANSION if side reactions due to H(EXPANSION if side reactions due to H22O contamination)O contamination)
EXP (+)EXP (+)
CONT (--)CONT (--)
TIMETIME
Dimensional changes depend on reaction variables:Dimensional changes depend on reaction variables:Particle size, Hg/alloy ratio, trituration time, condensation, ...Particle size, Hg/alloy ratio, trituration time, condensation, ...
ADA =ADA =± 20 ± 20 mm
Dimensional Change Most high-copper amalgams undergo a
net contraction Contraction leaves marginal gap
initial leakage post-operative sensitivity
reduced with corrosion over time
Phillip’s Science of Dental Materials 2003
Dimensional Change Net contraction
type of alloy spherical alloys have more
contraction less mercury
condensation technique greater condensation = higher contraction
trituration time overtrituration causes higher contraction
Phillip’s Science of Dental Materials 2003
STRENGTH Measurement of strength Effect of trituration Effect of mercury content Effect of condensation Effect of porosity Effect of amalgam hardening rate
Strength
Develops slowly 1 hr: 40 to 60% of maximum 24 hrs: 90% of maximum
Spherical alloys strengthen faster require less mercury
Higher compressive vs. tensile strength Weak in thin sections
unsupported edges fracture
Phillip’s Science of Dental Materials 2003
Amalgam Properties Compressive
Strength (MPa)% Creep Tensile
Strength(24 hrs) (MPa)
Amalgam Type 1 hr 7 days
Low Copper1 145 343 2.0 60
Admixture2 137 431 0.4 48
Single Composition3
262 510 0.13 64
Phillip’s Science of Dental Materials 2003
1Fine Cut, Caulk 2 Dispersalloy, Caulk 3Tytin, Kerr
CREEPCreep The time-dependent strain or deformation that is
produced by a stress. The creep process can cause an amalgam restoration to extend out of the cavity preparation, thereby increasing its susceptibility to marginal breakdown. – Anusavice (2003)
Marginal Breakdown
The gradual fracture of the perimeter of margin of a dental amalgam restoration that leads to the formation of gaps or ditching at the external interfacial region between the amalgam and the tooth. – Anusavice (2003)
Significance of creep on amalgam performance
Influence of microstructure on creep
Effect on manipulative variable on creep
Creep
Creep
Slow deformation of amalgam placed under a constant load load less than that necessary to produce fracture
Gamma 2 dramatically affects creep rate slow strain rates produces plastic deformation
allows gamma-1 grains to slide
Correlates with marginal breakdown
Phillip’s Science of Dental Materials 2003
Creep High-copper amalgams have creep
resistance prevention of gamma-2 phase
requires >12% Cu total single composition spherical
eta (Cu6Sn5) embedded in gamma-1 grains interlock
admixture eta (Cu6Sn5) around Ag-Cu particles
improves bonding to gamma 1
Amalgam Type % Creep
Low Copper1 2.0
Admixture2 0.4
Single Composition3 0.13
Phillip’s Science of Dental Materials 20031Fine Cut, Caulk
2 Dispersalloy, Caulk
3Tytin, Kerr
AMALGAM PROPERTIESAMALGAM PROPERTIES
2.2. Clinical PerformanceClinical Performancea.a. Longevity = 20-25 yrs ideally, 8-12 yrs practicallyLongevity = 20-25 yrs ideally, 8-12 yrs practicallyb.b. Modes of failure = caries, marginal fracture, bulkModes of failure = caries, marginal fracture, bulk
UNITEDSTATES
WORLD
ADA FDI
ISOANSI
B.B. Properties:Properties:
1.1. PhysicalPhysical2.2. MechanicalMechanical3.3. ChemicalChemical4.4. BiologicalBiological
AA.. Introduction:Introduction:
1.1. Specifications for Amalgam PropertiesSpecifications for Amalgam Propertiesa.a. ADA / ANSI and ISOADA / ANSI and ISO
Physical Properties Physical Properties
1.1. Thermal conductivity =Thermal conductivity = 2.2. Electrical conductivity = Electrical conductivity = 3.3. Coefficient of thermal expansion = Coefficient of thermal expansion = 4.4. Radiopacity =Radiopacity =5.5. Color =Color =
[>2 mm Aluminum][>2 mm Aluminum][Lustrous, shiny, white][Lustrous, shiny, white]
25 ppm/ºC25 ppm/ºC[High][High]
[High][High]
Mechanical Properties Mechanical Properties TYTIN (Kerr Dental Mfg) = “tie up the tin”TYTIN (Kerr Dental Mfg) = “tie up the tin”High-Copper, Spherical, 1 Particle, Zn-freeHigh-Copper, Spherical, 1 Particle, Zn-free42% Hg mixed with alloy42% Hg mixed with alloyFast-settingFast-settingHigh early strengthHigh early strength
PolishedPolishedSurfaceSurface
FractureFractureSurfaceSurface
Mechanical properties compressive strength is more for
high cu amalgam Its much more for single composition,when
compared to admixed alloys.
Chemical Properties Chemical Properties
Clean Surface,High O2 Potential
(CATHODIC)
Plaque Buildup,Low O2 Potential
(ANODIC)
(a)
(b)
(a) (b)
PlaqueBuildup
Clean Surface,High O2 Potential
(CATHODIC)
Plaque Buildup,Low O2 Potential
(ANODIC)
(a)
(b)
(a) (b)
PlaqueBuildup
ELECTROCHEMICAL CORROSION:ELECTROCHEMICAL CORROSION:
• Galvanic corrosionGalvanic corrosion• Local galvanic corrosion (structure selective)Local galvanic corrosion (structure selective)• Crevice corrosion (concentration cell)Crevice corrosion (concentration cell)• Stress corrosionStress corrosion
Sn-O-ClSn-O
CHEMICALCHEMICALCORROSION:CORROSION: AgS
Biological Properties Biological Properties Mercury Toxicity:Mercury Toxicity:
OSHA maximumOSHA maximum TLV = 50 TLV = 50 g/mg/m33 (vapor) per 40 hr work week(vapor) per 40 hr work weekTransient intraoral release (<35 Transient intraoral release (<35 g/mg/m33))
Mercury Hypersensitivity:Mercury Hypersensitivity:Low level allergic reactionLow level allergic reactionEstimated to beEstimated to be < 1 / 100,000,000< 1 / 100,000,000
Amalgam Tatoo:Amalgam Tatoo:Can occur during amalgam removal if no rubber damCan occur during amalgam removal if no rubber damEmbedded amalgam particles corrode and locally discolor gumEmbedded amalgam particles corrode and locally discolor gumNo known adverse reactionsNo known adverse reactions
Clinical Performance Clinical Performance
Reasons for Failure:Reasons for Failure:Secondary Secondary cariescaries -- principally with low-copper amalgam -- principally with low-copper amalgamMarginal fractureMarginal fracture -- prevalent with low-copper amalgam -- prevalent with low-copper amalgamBulk fractureBulk fracture -- most common with high-copper amalgam -- most common with high-copper amalgam
Jorgensen theory of mercuroscopic expansionJorgensen theory of mercuroscopic expansion
Corrosion at marginsCorrosion at margins
Sn-O-Cl and Sn-OSn-O-Cl and Sn-O
Internal corrosionInternal corrosion
PENETRATING versus SUPERFICIAL CORROSIONPENETRATING versus SUPERFICIAL CORROSION
Clinical EvaluationClinical Evaluation
Mahler scale:Mahler scale:
??????
Hi-CuHi-Cu Low-CuLow-Cu
CLINICAL PERFORMANCE OF AMALGAM RESTORATIONS
Tarnish & Corrosion
Compositional effects on the survival of amalgam restorations
Corrosion
Reduces strength Seals margins TYPES Dry corrosion/chemical corrosion Wet corrosion/electrochemical corrosion Galvanic corrosion Hetrogenous Stress corrosion Concentration cell corrosion [crevice corrosion]
Sutow J Dent Res 1991
Manufacturer controlled variables The composition of the alloy The heat treatment of the alloy The size, shape, & method of production of
the alloy particles The surface treatment of the particles The form in which the alloy is supplied
Dentist-Controlled Variables Alloy Selection
Manipulation Mercury/Alloy ratio trituration Condensation technique Marginal integrity Anatomic characteristics burnishing polishing
Alloy Selection
Handling characteristics Mechanical and physical
properties Clinical performance
Handling Characteristics Spherical
advantages easier to condense
around pins hardens rapidly smoother polish
disadvantages difficult to achieve tight contacts higher tendency for overhangs
Phillip’s Science of Dental Materials 2003
Handling Characteristics
Admixed advantages
easy to achieve tight contacts good polish
disadvantages hardens slowly
lower early strength
Overview of Manipulation Overview of Manipulation
Selection / Proportioning / Amalgamation / Manipulation / PolishingSelection / Proportioning / Amalgamation / Manipulation / Polishing
Placement andPlacement andCondensationCondensation
CarvingCarving BurnishingBurnishing PolishingPolishing
Onset ofOnset ofMIXINGMIXING
Onset ofOnset ofWORKINGWORKING
Onset ofOnset ofSETTINGSETTING
End ofEnd ofSETTINGSETTING
24 hours24 hours
TIMETIME
ALLOY MANIPULATIONALLOY MANIPULATION
Manual Trituration Procedures:Manual Trituration Procedures:Alloy + Hg Alloy + Hg mortar + pestle mortar + pestle manual mixing manual mixing
Mechanical Trituration Procedures:Mechanical Trituration Procedures:Powdered alloy + Hg Powdered alloy + Hg capsule + pestle capsule + pestle amalgamator amalgamatorPelleted alloy + Hg Pelleted alloy + Hg capsule + pestle capsule + pestle amalgamator amalgamator
Powdered alloy + Hg Powdered alloy + Hg pre-capsulated pre-capsulated amalgamator amalgamator
Amalgamators Amalgamators
SPEEDSPEED TIMETIME
ENERGY ENERGY == SpeedSpeed x x TimeTime
Trituration
Mixing time refer to manufacturer
recommendations
Overtrituration “hot” mix
sticks to capsule decreases working / setting time slight increase in setting contraction
Undertrituration grainy, crumbly mix
Phillip’s Science of Dental Materials 2003
Condensation Forces
lathe-cut alloys small condensers high force
spherical alloys large condensers less sensitive to amount of force vertical / lateral with vibratory motion
admixture alloys intermediate handling between lathe-cut and spherical
Burnishing
Pre-carve removes excess mercury improves margin adaptation
Post-carve improves smoothness
Combined less leakage
Ben-Amar Dent Mater 1987
Early Finishing
After initial set prophy cup with pumice provides initial smoothness to restorations recommended for spherical amalgams
Polishing
Increased smoothness Decreased plaque retention Decreased corrosion Clinically effective?
no improvement in marginal integrity Mayhew Oper Dent 1986 Collins J Dent 1992
ALTERNATIVES TO AMALGAM
1. Mercury-free direct –filling alloy: ADA-NIST (National Institute on Standards and
Technology) Patented this alloy Silver coated Silver-Tin particles that can be self-
welded by compaction (hand-consolidated) 2. Transitional Approaches:
Redesigning amalgam to have much less initial mercury
Alloy particles pack together well Reduce mercury for mixing to the 15%-25% range
PRIMM - Poly Rigid Inorganic Matrix Material - Porous Ceramic fibers. Condensable, curable, carvable, polishable. "White amalgam"
Restorations with >0.3% Zn and >12% Cu have minimal corrosion and the longest longevity. Zn and Cu act synergistically. (J. Dent Res, Nov 1997)
3. Gallium Alloys: Mercury controversy limits the use of Silver
Amalgam Toxic effects coupled with mercury hygiene led
the researchers think of mercury free alloys Suggested by PuttKammer -1928 PROPERTIES:
Wettability Sets in reasonable time and possesses strength Diametrical stability & corrosion resistance equal to
or greater than silver amalgam
COMPOSITION:
ALLOY LIQUID
Silver (Ag) – 60% Gallium (Ga) - 62%
Tin (Sn) -25% Iridium (Ir) - 25%
Copper (Cu) -13% Tin (Sn) -25%
Palladium ( Pd) - 20%
ALLOY CREEP % COMPRESSIVE STRENGTH (AFTER 6 HOURS)
SETTING(CONTRACTION/EXPANSION %)
Silver Alloy(High Copper)
1.04_0.06 370 MPa -0.05
Gallium Alloy
0.09_0.03 350 MPa +0.39
+
+
BONDED AMALGAM RESTORATIONS: Silver does not adhere properly to cavity walls Adhesive systems designed to bond amalgam to
enamel & dentin Improve adhesion, strengthen remaining tooth
structure, decreases the need for removal of health tooth structure
Pioneers were Sun Medical (Superbond), Kurrary (Panavia)
Superbond was based on 4-META/MMA resins Panavia was based on Bis GMAphosphonated
ester
Later dentin bonding agents have also been a subject of bonding amalgam to dentin
Various Agents are Amalgam Bond with HPA ( Parkell) All Bond 2 (Bisco) Optibond 2 (Kerr) Panavia 21(Kuraray) Clearfil Linear Bond 2 (Kuraray) Scothbond MP (3M)
a) etching the dental surface with acid,b) applying a treatment composition comprising an aromatic
sulfinate salt to the etched dental surface, c) applying a priming solution containing a film-former to the
treated dental surface, d) applying a chemically curable dental adhesive to the
primed dental surface, and e) applying amalgam to the adhesive-coated dental surface. The chemically curable adhesive comprises an oxidizing
agent and a reducing agent. The oxidizing agent is present in an amount sufficient to
interact with said aromatic sulfinate salt to achieve higher adhesion to the dental surface than a like method not comprising an aromatic sulfinate salt in the treatment composition.
- U.S Patent Issued on January 21, 1997
INDICATIONS: Auxillary retention Extensively carious posterior teeth Teeth with low Gingival-Occlusal height Temporary restorations Amalgam Sealants
ADVANTAGE: More conservative Reinforces tooth structure Eliminates the use of pins Decreases the incidence of marginal fracture Provides a bond at the tooth restoration interface Biologic sealing of the pulpo-dentinal complex Appointment time Cost effective
DISADVANTAGE: Technique sensitive Time to adapt to the new technique Clinical performance are not documented No sustained effects of amalgam bonding when
subjected to thermocycling Hydrolytic stability of the bond is questionable
"...amalgam bonding is an adjunct to and not a substitute for mechanical retentive form. The main advantage of conventional amalgam adhesives seems to be their ability to seal the tooth restorative interface, preventing microleakage into the dental tubules and pulp and reducing post-operative sensitivity.
- Cobb, et al, Am J Dent, Oct 1999 "Continuous microgaps were observed between
amalgam and dentin in the specimens using no lining material and Copal varnish compared to specimens using adhesive bonding system."
-Estafan, Gen Dent, March-April 2000
Criteria when considering amalgam substitutes: service life, radiopacity, wear properties, marginal adaptation, setting expansion/contraction, technique sensitivity, potential secondary caries risk. What materials are better than amalgam in
these areas? (Lutz and Krejc-2000)
CONCLUSION
SUMMARY “Dental alloys are manufactured for us.
Amalgams we make for ourselves and the strength and the stability of the hardened amalgam and the merit of the filling are only as good as the cause and the skill the dentist puts into it”.
- William E. Harper; J.Am.Dent.Assoc.13,119-125,1926.
“The tongue represents the best and the worst amongst things; amalgam restorations might be the most noble restorations but also the worst ignoble fillings”. - Aesop
REFERENCES Phillip’s Science of Dental Materials-
10th,11th Edition: Kenneth Anusavice Art & Science of Operative Dentistry-4th
Edition: Sturdevant. Restorative Dental Materials-11th Edition:
Robert G.Craig.
Jones DW: Putting dental mercury pollution into perspective. BDJ 2004;197:175-177.
Eichmiller FC: Research into Non-Mercury Containing Metallic Alternatives. Op Dent 2001;6:111-118.
Ronald K Harris: Dental Amalgam: Success Or Failure?. Op Dent 1992;17:243-252.
Dunne SM et al: Current materials and Techniques for direct restorations in posterior teeth. IDJ 1997;47:123-136.
MERCURY
TOXICITY
Mercury the Metal
Hg Facts & Uses
• Quicksilver• 13.6 times the weight of water• Evaporates at room temperature• Bacteria change to Methylmercury• Amalgam• Many Industrial uses
(thermometers, chemical reactions, gold mining)
Sources of Mercury Dental Schools Dental clinics Colleges & universities Hospitals, medical clinics & laboratories Home owners/communities Plumbers/electricians Junkyards/auto crushers & recyclers MSW incinerators Federal & other government facilities Farms
Mercury-Added Products Fever & lab thermometers Blood pressure devices Barometers, manometers, gauges Auto switches Elemental mercury from dental offices &
schools Appliances Fluorescent & other lamps
Mercury Collection Programs from Schools, Dental Offices & Households
Vapor Limits (TLV) = Vapor Limits (TLV) = 0.05 mg/m0.05 mg/m33 = 50 = 50 g/mg/m33 = 5 ppb = 5 ppb
Hg Liquid and VaporHg Liquid and VaporHg = odorless, colorless gasHg = odorless, colorless gasHg = penetrating liquidHg = penetrating liquid
Liquid
Gas
Vapor Toxicity CalculationsVapor Toxicity Calculations::
Sensitivity CalculationsSensitivity Calculations::
ADA ADA 1 / 100,000,000 1 / 100,000,000UNC UNC 1 / 180,000,0001 / 180,000,000
Current Controversy on Mercury (Types):1. Elemental - Least toxic. Very small contribution
to total body burden of Hg. Is the form found in dentistry. Lipid soluble, absorbed in lungs. Very short-lived due to rapid oxidation.
2. Inorganic - Moderate toxicity. Formed by oxidation of elemental. Limited lipid solubility. Becomes sequestered in kidney, excreted slowly in urine. Half life ~ 60 days.
3. Organic - Most toxic. High lipid solubility. Only from non-dental sources. 90% absorbed in gut. Accumulates in red blood cells, sequestered in CNS and liver. Not found in urine. Excreted in feces.
Elemental Mercury: Hg 0
InorganicMercury : Hg +1 or Hg +2
Organic Mercury;Compounds such as:Methyl mercury - HgCH3+Dimethyl mercury - Hg(CH3)2
PHYSIOLOGICAL Hg CYCLEPHYSIOLOGICAL Hg CYCLE
ElementalElementalHgHg
InorganicInorganicHgHg
OrganicOrganicHgHg
LUNGS
GITRACT
SKIN
BLOODBLOOD
Allothersites
Brain
Hair,Hair,NailsNails
URINE
FECES
EXFOLIATION ofSkin, Hair, Nails
BLOODBLOOD
Average Half-Life in Human Body = 55 DaysAverage Half-Life in Human Body = 55 Days
ABSORPTIONABSORPTIONROUTEROUTE
TRANSPORTION andTRANSPORTION andLOCALIZATIONLOCALIZATION
EXCRETIONEXCRETIONof Hgof Hg
HgHgFORMFORM
FF
MM
Chewing
MMFF
NoChewing
Hg Release from AmalgamsHg Release from Amalgams
TLV (40 hrs/wk)
1010
5050
4040
3030
2020
Me
rcu
ry R
ele
ase
(M
erc
ury
Rel
eas
e ( g
/mg
/m33 ))
FF
Time (minutes)Time (minutes)
3030 6060
Few
Many
No knownhealth effects.
Subtle changeson some tests.
Mild-to-moderatesymptoms.
Pronouncedsymptoms.
10001000
5050
100100
500500
1010
55
Hg Swallowed from AmalgamsHg Swallowed from Amalgams
10.010.0
1.01.0
Hg
Co
nce
ntr
aio
n in
Pla
sm
aH
g C
on
cen
tra
ion
in P
las
ma
(nm
ol /
L =
0.2
pp
b)
(nm
ol /
L =
0.2
pp
b)
TIME (days)TIME (days)
4040 80800.10.1
2020 6060
Af Geijersstam E, Sandborgh-Englund G, Jonsson F, Ekstrand J.Af Geijersstam E, Sandborgh-Englund G, Jonsson F, Ekstrand J.Mercury uptake and kinetics after ingestion of dental amalgam.Mercury uptake and kinetics after ingestion of dental amalgam. J Dent ResJ Dent Res 2001;80:1793-1796. 2001;80:1793-1796.
Controlled for baseline levels in volunteers.Controlled for baseline levels in volunteers. Pulverized fresh dental amalgam.Pulverized fresh dental amalgam. 1.0 gm amalgam powder placed in gelatin capsules.1.0 gm amalgam powder placed in gelatin capsules.Drew blood samples at 5, 24, 30 hrs and 2, 7, 14, 21, Drew blood samples at 5, 24, 30 hrs and 2, 7, 14, 21,
28, 56, 90 days.28, 56, 90 days.
Hg rapidly detected from GI track … but at very low levels.Hg rapidly detected from GI track … but at very low levels.No difference between 0 and 90 days. Hg half-life about 37 days.No difference between 0 and 90 days. Hg half-life about 37 days.
Body-Burden CalculationsBody-Burden CalculationsElementalElemental InorganicInorganic OrganicOrganic = TOTAL= TOTAL
AIR AIR 0.5 0.5 g/dayg/day …..….. …..….. = 0.5 = 0.5 g/dayg/dayWATERWATER …..….. 10 10 g/dayg/day …..….. = 10 = 10 g/dayg/dayFOODFOOD …..….. …..….. 100 100 g/dayg/day = 100 = 100 g/dayg/dayAmalgamsAmalgams 20 20 g/dayg/day …..….. …..….. = 20 = 20 g/dayg/day
TOTALTOTAL = 130.5 = 130.5 g/dayg/day
18 occlusal amalgams = all Hg release absorbed18 occlusal amalgams = all Hg release absorbed
Actual body burden due to amalgam estimated as <0.5% of totalActual body burden due to amalgam estimated as <0.5% of total
Environmental Impact of HgEnvironmental Impact of Hg
Humans are continually exposed to a variety of sources of Hg Humans are continually exposed to a variety of sources of Hg from the environment ----- Hg is omnipresent.from the environment ----- Hg is omnipresent.
AIRAIR supplysupply = natural sources, human pollution, …= natural sources, human pollution, …WATERWATER supplysupply = natural sources, human pollution, …= natural sources, human pollution, …FOODFOOD supplysupply = natural sources, human pollution, …= natural sources, human pollution, …DENTAL and MEDICALDENTAL and MEDICAL = amalgams, OTC ointments, ...= amalgams, OTC ointments, ...
AIRAIR Hg mine…………………....300 Hg mine…………………....300 g/mg/m33
Industrial emission…………3Industrial emission…………3Urban air……………………...0.05Urban air……………………...0.05Pure air………………………..0.002Pure air………………………..0.002
FOODFOOD Tunafish…………………..1000 Tunafish…………………..1000 g/kgg/kgCattle………………………..160Cattle………………………..160Humans………………………25Humans………………………25
MERCURY TOXICITYMERCURY TOXICITYHistorical Problems:Historical Problems:
TannersTannersThermometer techniciansThermometer techniciansHgS mine workersHgS mine workers
Recent Incidents:Recent Incidents:Almaden, Spain (Hg mine)Almaden, Spain (Hg mine)Minamata Bay, Kyushu, Japan (fish problem)Minamata Bay, Kyushu, Japan (fish problem)Iraq (grain problem)Iraq (grain problem)Alamogordo, NM (grain problem)Alamogordo, NM (grain problem)Sweden (environmental load problem)Sweden (environmental load problem)Michigan (redistillation problem)Michigan (redistillation problem)
Historical Awareness
SPAINSPAIN
ALMADEN, SPAINALMADEN, SPAINAlmaden Mercury MineAlmaden Mercury Mine2400 Years of Continuous Productions2400 Years of Continuous Productions
>300 >300 g/mg/m33
KYUSHU, JAPANKYUSHU, JAPAN1953, Minamata Bay, Chisso Corporation FactoryMethyl mercury waste dumped into bay.
CHISSO CORPORATIONCHISSO CORPORATIONProduced fertilizers, Produced fertilizers, chemcial, plasticschemcial, plastics
Minamata BayMinamata BayContaminationContamination
• Hg(CHHg(CH33))22 laden fish laden fish• Chronic Hg toxicityChronic Hg toxicity• 202 People Poisened202 People Poisened• 52 Deaths52 Deaths
SYMPTOMS ofSYMPTOMS ofchronic Hg poisoning:chronic Hg poisoning:
• Ataxic gait.Ataxic gait.• Convulsions.Convulsions.• Numbness in mouth and limbs.Numbness in mouth and limbs.• Constriction of visual field.Constriction of visual field.• Difficulty in speaking.Difficulty in speaking.
BANNED IN EUROPE ???BANNED IN EUROPE ???
Swedish National Board of Health and WelfareSwedish National Board of Health and Welfare(April 20th, 1992 --Report to the Government)(April 20th, 1992 --Report to the Government)
1.1. No amalgam restorations in deciduous teeth after No amalgam restorations in deciduous teeth after July 1, 1993.July 1, 1993.
2.2. No amalgam restorations in permanent teeth up to No amalgam restorations in permanent teeth up to age 10 after July 1, 1995.age 10 after July 1, 1995.
3.3. Evaluate in 1996 the possibility of discontinuing all Evaluate in 1996 the possibility of discontinuing all amalgam use after 1997.amalgam use after 1997.
Sweden
Minamata Bay, Japan 1953 startup of acetaldehyde production
at a coastal factory using mercuric oxide as a catalyst
Stray cats 1953- outbreak of polio-like disease among coastal fishing villages
went crazy after eating fish 1968-mercury diagnosed as cause of 2000
disease victims
Polluting with HG
Discharge in Minamata Bay
Minamata disease-infants Mental retardation in infants Abnormal reflexes, ataxia, involuntary
movements Cerebral palsy Developmental delays—some didn’t walk
until age 7
in Minamata disease adults Paresthesia-numbness “pins and needles” Cerebellar ataxia, tremors, convulsions Constriction of visual fields, loss of smell Loss of hearing, dizziness, insomnia Dysarthria -speech disorder. Speech was slow, weak, imprecise or
uncoordinated. Cognitive impairments, such as inattention,
excitement, hallucinosis, loss of intelligence
Life Long Effects of Methyl Hg
Ambient WaterSediments
Edible Fish
Inorganic Mercury
Methyl-Mercury
Methyl-MercuryIn Humans
Biomethylation
Bioaccumulation
Exposure
Discharge
Biotransformation of Mercury
Out Breaks of MeHg Poisoning
Place Year CasesMinamata 1953-60 1000
Negate 1964-65 646
Guatemala 1963-65 45
Ghana 1967 144
Pakistan 1969 100
Iraq 1956 100
Iraq 1960 1,002
Iraq 1971 40,000
On-going 2001 ???
Seed Grain Outbreaks
Mercury compounds applied as antifungal agent to seed grains
Iraq—made bread directly from treated seed grain
Planting Seed with Mercury
Iraq Mothers with Bread
Iraq Infant - Effects of Mercury
• Blindness - Deafness• Cerebral Palsy - Seizures• Abnormal reflexes & muscle tone• Retarded motor development• Visual and Auditory Deficits• Delayed motor development
Neurobehavioral Effects
• Decrease in Brain Size• Cell loss• Disorganization of cells• Cell migration failures
Effects On The Brain
Fetal Toxicity Birth defects may be due to a brief
exposure during critical periods of fetal development
Affected fetuses may spontaneously abort Relationship between exposure and
outcome is difficult to establish
• Natural Degassing of the earth• Combustion of fossil fuel• Industrial Discharges and Wastes• Incineration & Crematories• Dental amalgams
Hg0 Hg2+ CH3Hg+
Environmental Sources of Mercury
Mercury Release
50-75% mercury released in the environment related to human activities, but there is lots of mercury in the soil from millions of years ago
The Mercury Cycle
Mercury A Global Issue
Mercury distribution and exposure is a global problem
Hg and Heart Attacks 2002 case-control study showing higher
mercury in men who had heart attacks vs. controls
Hoping to start series of studies in Population Health Sciences on Hg and cardiovascular disease
Can Vaccines Containing Thimerosal (ethyl mercury)
Cause Autism? Parents say “yes” Science studies say “no” Hviid A, et al. Association between
thimerosal-containing vaccine and autism. (Denmark registry) JAMA October 1, 2003;290:1763-6 –totally negative
Inst. of Medicine: Immunization Safety Review: Vaccines and Autism Report: No Association, May 2004
Mercury in Dental Amalgams Dose is high in mouth, but low to the body Adult brain is developed Subtle changes in brain or kidney function
due to such a low dose? Alzheimer’s disease?
In one study, dentists with abnormally high concentrations of urinary mercury, attributable to their occupational exposure, showed no evidence of kidney impairment on several key measurements of renal function
Another study examined claims that dental amalgam interferes with immune function. The researchers found that subjects with dental fillings had the same number of disease fighting white blood cells as people who were amalgam-free.
A Swedish researcher found no differences between amalgam and non-amalgam groups in measures used to assess immune system health, liver and kidney function, and skeletal muscle status.
A Swedish study of 1024 women looked at the prevalence of 30 symptoms often claimed to reflect toxic effects of amalgam, including fatigue, dizziness, irritability, and back pain. Women with more than 20 amalgam fillings were no more likely to complain of these symptoms than women with few or no amalgams.
Another Swedish study examined mercury serum levels in a population of 1462 women in order to correlate the serum mercury level (from all sources including diet) to the vague symptoms often claimed to be due to mercury intoxication from amalgam.
The study correlated serum mercury levels with the incidence of Dizziness, Eye complaints.
Hearing defects, Headache, General fatigue, Sleep disturbances and 25 other symptoms over a period of 25 years.
This study found NO correlation between serum levels of mercury and the 31 symptoms studied.
(Note: In Sweden, serum mercury levels tend to be much higher than those found in North America or other non-Scandinavian parts of Europe because Scandinavians are more likely to eat large amounts of ocean caught fish which increases serum mercury levels much more than mercury from amalgam fillings.)
A study of 30,000 female dental assistants and the wives of 29,000 dentists, divided into high and low mercury exposure groups found no difference between the two groups in the incidence of miscarriage or of birth defects in their offspring.
Standards set by the Occupational Safety and Health Administration (OSHA) estimate the mercury-vapor concentration to which even the most sensitive workers can be chronically exposed without suffering adverse effects.
Under OSHA guidelines, the maximum safe occupational dose approximates roughly 300 to 500 micrograms of mercury vapor per day.
Current estimates predict that people with a moderate to large number of fillings are exposed to 1 to 4 micrograms of mercury per day, barely 1% of the dose considered safe.
INHALED MERCURY:
The results of one study in which patients with amalgam restorations were monitored with mercury vapor detectors over a 24-hour period showed that the amount of vapor inhaled was 1.7 µg/day.
Three other studies have confirmed that the magnitude of vapor exposure for a patient with 8 to 10 amalgam restorations is in the range of 1.1 to 4.4 µg/day.
The threshold value for workers in the mercury industry is 350 to 500 µg/day, depending on activity level, and is based on an exposure of 40 hours per week.
Blood Levels:
Mercury blood levels that were measured in one study indicated that the average level in patients with amalgam was 0.7 ng/mL compared with a value of 0.3 ng/mL for subjects with no amalgam.
This difference was found to be statistically significant (P 0.01).
However, one should be aware of a study in Sweden that demonstrated that one saltwater seafood meal per week raised average blood levels of mercury from 2.3 to 5.1 ng/mL, a sevenfold increase (2.8 ng/mL) compared with that (0.4 ng/mL) associated with amalgam restorations.
The normal daily intake of mercury is 15 µg from food, 1 µg from air, and 0.4 µg from water.
Total mercury vapor release was consistently found to be greater for admixed as compared to spherical amalgam.
Amalgam restorations prepared by an inexperienced operator demonstrated statistically less mercury vapor than a novice or experienced clinician for both spherical and admixed morphologies.
A statistically significant difference in mercury vapor using different condensation and carving techniques was found for the spherical amalgam but not for the admixed material.
Restoration design demonstrated significant differences in total mercury vapor dependent on volume and exposed surface area of the amalgam restoration.
Recommendations are changing – stay Recommendations are changing – stay current.current.
Understand recycling documentation. Understand recycling documentation. Look for similar recommendations for Look for similar recommendations for
other office materials.other office materials.
ADA Hg HYGIENEADA Hg HYGIENERecommendations
Dental mercury hygiene recommendationsDental mercury hygiene recommendations:: Sources of dental mercury in the office.Sources of dental mercury in the office. General mercury hygiene recommendations.General mercury hygiene recommendations.
Office emergencies.Office emergencies.
Hygiene recommendations during Hygiene recommendations during preparation and placement of dental preparation and placement of dental amalgam.amalgam.
Management of mercury spills.Management of mercury spills. Management of small mercury spills.Management of small mercury spills. Management of large mercury spills.Management of large mercury spills.
Residual Hg in CapsulesResidual Hg in Capsules
Stone ME, Pederson ED, Cohen ME, Ragain JC, Karaway RS, Auxer RA, Saluta AR. Stone ME, Pederson ED, Cohen ME, Ragain JC, Karaway RS, Auxer RA, Saluta AR. Residual mercury content and leaching of mercury and silver from used amalgam capsules. Residual mercury content and leaching of mercury and silver from used amalgam capsules. Dent MaterDent Mater 2002;18:289-294. 2002;18:289-294.
OBJECTIVE: Measure (1) residual Hg in capsules OBJECTIVE: Measure (1) residual Hg in capsules and (2) potential for leaching in landfill.and (2) potential for leaching in landfill.
METHODS: Residual Hg (USEPA Method 7471); METHODS: Residual Hg (USEPA Method 7471); Leaching Hg (USEPA Method 1311).Leaching Hg (USEPA Method 1311).
Capsule:Capsule: Residual HgResidual Hg Leached Hg – P/FLeached Hg – P/F(mg / capsule)(mg / capsule) (mg / L / capsule)(mg / L / capsule)
Dispersalloy Regular SetDispersalloy Regular Set 1.255 ± 0.7931.255 ± 0.793 0.0477 (P)0.0477 (P)Valliant PhDValliant PhD 0.770 ± 0.3300.770 ± 0.330 0.0261 (P)0.0261 (P)OptaloyOptaloy 0.650 ± 0.6440.650 ± 0.644 0.0340 (P)0.0340 (P)MegalloyMegalloy 0.590 ± 0.5040.590 ± 0.504 0.0399 (P)0.0399 (P)Valliant Snap SetValliant Snap Set 0.534 ± 0.3980.534 ± 0.398 0.0425 (P)0.0425 (P)Tytin Regular SetTytin Regular Set 0.266 ± 0.1840.266 ± 0.184 0.0104 (P)0.0104 (P)Tytin FCTytin FC 0.223 ± 0.1200.223 ± 0.120 0.1640 (P)0.1640 (P)Contour Self-ActivatingContour Self-Activating 0.181 ± 0.1210.181 ± 0.121 0.4120 (F)0.4120 (F)Sybraloy Regular SetSybraloy Regular Set 0.142 ± 0.1630.142 ± 0.163 0.2530 (F)0.2530 (F)Tytin Regular SetTytin Regular Set 0.125 ± 0.0630.125 ± 0.063 0.0110 (P)0.0110 (P)
Non-Contact AmalgamNon-Contact Amalgam
Spent fixer,Spent fixer,glycerine, glycerine, or wateror water
Unused amalgamUnused amalgamand mercury collectionand mercury collection
Pass-through Pass-through jar lidjar lid
Rubber damRubber damwith slitwith slit
Hg VaporHg Vapor
Hg Spill KitsHg Spill Kits
Spills = small; medium; largeSpills = small; medium; largeSpills = accidents; daily micro-spillsSpills = accidents; daily micro-spills
Hg-Spill KitHg-Spill Kit
AmalgamAmalgamStorageStorage
HG HYGIENEHG HYGIENE PLUMBINGPLUMBING
AmalgamAmalgamMixingMixing
• CapsulesCapsules• Non-Contact HgNon-Contact Hg
60%60% Large Particles Large Particles >100 >100 mm
30%30% Small ParticlesSmall Particles 10-100 10-100 mm
10%10% Very Small Particles,Very Small Particles, <10 <10 mmLiquid, and VaporLiquid, and Vapor
Sink TrapsSink Trapsand Plumbingand Plumbing SEWERSEWER
SeparatorSeparator
Vacuum PumpVacuum PumpFilter or TrapFilter or Trap
Vacuum PumpVacuum Pump
SEWERSEWER
SEWERSEWER
Suction / Mini-TrapSuction / Mini-Trap
Chairside FilterChairside Filter
Amalgam/Hg SeparatorsAmalgam/Hg Separators
Amalgam Separator:Amalgam Separator: EMPTY EMPTY FULLFULL Total Effluent HgTotal Effluent Hg(% Efficiency)(% Efficiency) (% Efficiency)(% Efficiency) (ppb, range)(ppb, range)
A1000A1000 96.09 ± 0.3996.09 ± 0.39 96.24 ± 0.4696.24 ± 0.46 30,200 - 34,89930,200 - 34,899Amalgam CollectorAmalgam Collector 99.89 ± 0.0699.89 ± 0.06 99.96 ± 0.0399.96 ± 0.03 1,180 - 3,350 1,180 - 3,350AsdexAsdex 99.10 ± 0.0999.10 ± 0.09 99.36 ± 0.1499.36 ± 0.14 9,930 - 15,750 9,930 - 15,750BullfroHgBullfroHg 98.88 ± 0.6498.88 ± 0.64 99.38 ± 0.4899.38 ± 0.48 5,850 - 16,270 5,850 - 16,270Durr 7800/7801Durr 7800/7801 98.06 ± 1.0898.06 ± 1.08 97.66 ± 0.3597.66 ± 0.35 970 4,070 970 4,070ECO IIECO II 98.17 ± 0.4398.17 ± 0.43 97.51 ± 0.7497.51 ± 0.74 16,310 - 26,34016,310 - 26,340HgSHgS 99.36 ± 0.1599.36 ± 0.15 99.28 ± 0.1099.28 ± 0.10 6,430 - 9,600 6,430 - 9,600Hg10Hg10 99.99 ± 0.0699.99 ± 0.06 (not tested)(not tested) 20 - 100 20 - 100MRUMRU 99.96 ± 0.0399.96 ± 0.03 99.95 ± 0.0499.95 ± 0.04 200 - 570 200 - 570MSS 2000MSS 2000 99.66 ± 0.3099.66 ± 0.30 98.94 ± 0.06 98.94 ± 0.06 730 - 4,040 730 - 4,040Rasch 890-4000Rasch 890-4000 99.93 ± 0.0399.93 ± 0.03 99.90 ± 0.0399.90 ± 0.03 600 - 1,250 600 - 1,250 RME 2000RME 2000 99.67 ± 0.1399.67 ± 0.13 99.66 ± 0.2499.66 ± 0.24 1,530 - 3,430 1,530 - 3,430
Fan PL, Batchu H, Chou HN, Gasparac W, Sandrik J, Meyer DM. Laboratory evaluation of amalgam Fan PL, Batchu H, Chou HN, Gasparac W, Sandrik J, Meyer DM. Laboratory evaluation of amalgam separators. separators. J Am Dent AssocJ Am Dent Assoc 2002; 133: 577-589. 2002; 133: 577-589.
OBJECTIVE: Remove amalgam and/or mercury OBJECTIVE: Remove amalgam and/or mercury from air/water stream in HVAC system.from air/water stream in HVAC system.
METHODS: ISO 11143 for Amalgam Separators.METHODS: ISO 11143 for Amalgam Separators.
Hg Release from AmalgamHg Release from AmalgamChemical and Electrochemical Corrosion Chemical and Electrochemical Corrosion NO Hg RELEASED NO Hg RELEASED
a.a. Low-copper dental amalgam:Low-copper dental amalgam:[Sn-Hg] [Sn-Hg] [Sn] + saliva [Sn] + saliva [Sn-O-Cl] [Sn-O-Cl] (soluble)(soluble)
[Sn] + saliva[Sn] + saliva [Sn-O] [Sn-O] (insoluble)(insoluble) [Hg] + [Sg-Sn][Hg] + [Sg-Sn] [Sg-Hg] + [Sn+Hg] [Sg-Hg] + [Sn+Hg] (more rx)(more rx)
b.b. High-copper dental amalgam:High-copper dental amalgam:[Cu-Sn][Cu-Sn] [Sn] + saliva [Sn] + saliva [Sn-O-Cl] [Sn-O-Cl] (soluble)(soluble)
[Sn] + saliva[Sn] + saliva [Sn-O] [Sn-O] (insoluble) (insoluble) [Cu] + saliva[Cu] + saliva [Cu-Cl] [Cu-Cl] (soluble)(soluble)
Company:Company: Location:Location: Telephone NumberTelephone Number
SOLMETEXSOLMETEX (Northburough, MA)(Northburough, MA) 978-262-9690978-262-9690DRNA DRNA (Hackensack,NJ)(Hackensack,NJ) 800-360-1001800-360-1001Max. Separ. Systems Max. Separ. Systems (Sanichton, BC)(Sanichton, BC) 800-799-7147800-799-7147AB Dental Trends AB Dental Trends (Lynden, WA) (Lynden, WA) 360-354-4722 360-354-4722 Rebec Rebec (Edmonds, WA) (Edmonds, WA) 800-569-1088 800-569-1088 Air Techniques Inc. Air Techniques Inc. (Hicksville, NY) (Hicksville, NY) 800-Air-Tech800-Air-Tech
Current Separator TechnologiesCurrent Separator Technologies
http://http://www.ncddental.orgwww.ncddental.org
P.O. Box 1069P.O. Box 1069Hackensack, NJ 07601Hackensack, NJ 076011-800-360-1001 (TEL)1-800-360-1001 (TEL)1-201-489-4740 (FAX)1-201-489-4740 (FAX)
SEWER 99+ %99+ %
SolmeteXSolmeteX29 Cook Street29 Cook StreetBillerica, MA 01821Billerica, MA 01821TEL = 978-262-9690TEL = 978-262-9690FAX = 978-262-9889FAX = 978-262-9889
$695 for installation$695 for installation$150 per cartridge exchange$150 per cartridge exchange
99.5% recovery is typical99.5% recovery is typical
SOLMETEXSOLMETEX
Air-Water SeparatorAir-Water Separator
Filter and Hg AbsorberFilter and Hg Absorber
DETECTION OF HgDETECTION OF Hg
DENTALDENTALOFFICEOFFICE
Work Place Monitoring:Work Place Monitoring:Air sampling -- 3M badgesAir sampling -- 3M badgesAir sampling -- Jerome Hg analyzerAir sampling -- Jerome Hg analyzer
Patient Monitoring:Patient Monitoring:Intraoral air measurementsIntraoral air measurementsPatch testing (by dermatologist or allergist)Patch testing (by dermatologist or allergist)Immune system testsImmune system tests
Dental Personnel Monitoring:Dental Personnel Monitoring:Air sampling -- 3M badgesAir sampling -- 3M badgesBlood testsBlood testsUrine testsUrine testsHair testsHair tests
HOMEHOMEENVIRONMENTENVIRONMENT
Hg ROAD MAPHg ROAD MAP
FDAFDA
Safety,Safety,EfficacyEfficacy• Patients• Personnel
TRASHTRASH
SanitarySanitaryLandfillLandfill(audits)(audits)
IncineratorIncinerator(audits)(audits)
RECYCLINGRECYCLINGPLANTPLANT(audits)(audits)
EPA / NCDENREPA / NCDENR
BMP’sBMP’s
• PurchasePurchase• StorageStorage• UsageUsage• Non-ContactNon-Contact• FiltersFilters• Training, SpillsTraining, Spills
OSHA / ADAOSHA / ADA
• Leach Field• Stream Dumping
• Burning• Land Spreading
WASTE-WATER
TREATMENTPLANT
CITY / EPACITY / EPA
HgHg
OFFICEOFFICEPLUMBINGPLUMBING
• [Chairside Filter]• [Vacuum SystemSystem and Trap]• Separators• Flushing Plumbing Lines
PR
OC
ED
UR
ES
/ 1
00
pts
200
1960 1970 1980 1990 2000 2010
0
50
100
150
DATE (year)
Total Amalgams
New Amalgams
PRESENT
The US Food and drug administration has this to say about international acceptance of dental amalgam:
"The safety of dental amalgams has been reviewed extensively over the past ten years, both nationally and internationally. In 1994, an international conference of health officials concluded there is no scientific evidence that dental amalgam presents a significant health hazard to the general population, although a small number of patients had mild, temporary allergic reactions. The World Health Organization (WHO), in its Consensus Statement on Dental Amalgam reached a similar conclusion. They wrote: "Amalgam restorations are safe and cost-effective. Components in dental restorative materials, including amalgam, may, in rare instances, result in local side-effects or allergic reactions. The risk of adverse side-effects is very low for all types of restorative materials, including amalgam and all resin-based materials.” Similar conclusions were reached by the United States Public Health Service, the European Commission, the National Board of Health and Welfare in Sweden, the New Zealand Ministry of Health, Health Canada and the province of Quebec."
Dental amalgam is NOT banned in any state in the US or in any Western country. However, legislation to ban it exists all over the map. The legislation is not the work of scientists. It is the work of anti-amalgamists pushing a political, not a scientific agenda, and the fact that it is not passed into law is because there is no scientific evidence that it is harmful to the general public and lots of evidence that
Making a amalgam restoration might be considered to be a chain process.
The strength of a chain depends upon its weakest link.
Misjudgment of its properties or the smallest neglect as to its manipulation might have unfavorable effects with regard to the restoration & even result in its total failure.
A.D.A & F.D.A state that use of amalgam is safe scientifically
Mercury and the American Dental Association
The American Dental Association (ADA) continues to remain in denial about the toxicity of mercury.
A news release by the American Dental Association (ADA) on June 13, 2001 contains a significantly erroneous statement. The American Dental Association (ADA) President Dr. Robert M. Anderton is reported as saying,
"There is no sound scientific evidence supporting a link between amalgam fillings and systemic diseases or chronic illness''. However, it is a well known fact in the published, peer-
reviewed dental journals that mercury leaks directly from amalgam into adjacent oral tissues causing periodontal disease (gum disease).
Dr. Murray Vimey is one of the top mercury researchers in the world and he has provided a detailed chronology documenting how mercury has been clearly established as a contributing factor for periodontal disease. Dr. Vimy is one of the leading mercury researchers and his rebuttal to the ADA press release is most informative:
Fact #1: In 1957, Zander (JADA, 55:11-15) reported "materials used in restorative dentistry may be a contributing factor in gingival disease. "Fact #2: In 1961, App (J Prosth Dent 11:522-532) suggested that there was greater chronic inflammation around amalgam sites than non-amalgam areas .Fact #3: In 1964, Trott and Sherkat (J CDA, 30:766-770) showed that the presence of mercury amalgam correlates with gingival disease. Such disease was not present at contralateral amalgam-free sites. Fact #4: In 1969, Sanches Sotres et al (J. Periodo. l40: 543-546) confirmed Trott and Sherkat findings .Fact #5: In 1972, Turgeon et al. (J CDA 37:255-256) reported the presence of very significant erythema around amalgam restorations which was not present at control non-amalgam sites.
Fact #6: In 1973, Trivedi and Talim (J. Prosth. Dentistry, 29:73-81) demonstrated that 62% of amalgam sites have inflammatory periodontal tissue reaction.
Thus, as early as 1973, a case can be made that the presence of dental mercury-amalgam results in chronic inflammation and bleeding in the gingival tissue adjacent to it; in other words, 'in situ' amalgamproduced chronic Gingivitis.
Fact #7: In 1974, Freden et al. (Odontol. Revy, 25: 207-210) showed that gingival biopsy material from sites not adjacent to amalgam had 1-10 µg mercury/gram of tissue (mean=3); whereas, gingival biopsy sites near amalgams contained 19-380 µg mercury/gram of tissue (mean=147).
Fact #8: In 1976, Goldschmidt et al (J. Perio. Res., 11:108-115) demonstrated that amalgam corrosion products were cytotoxic to gingival cells at concentrations of 10-6; that is, micrograms/gram of tissue.
Fact #9: In 1984, the year of the NIDR/ADA Workshop, Fisher et al (J Oral Rehab, 11:399-405) reported that at amalgam sites alveolar bone loss was very pronounced and statistically significant as compared to control non-amalgam sites. In other
Therefore, for the American Dental Association (ADA) to conclude "There is no sound scientific evidence supporting a link between amalgam fillings and systemic diseases or chronic illness'' is not correct.
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