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Dental Amalgam PowerPoint Presentation

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Description : Check out this medical presentation on Dental Amalgam, which is titled "Dental Amalgam", to know about amalgam, a common filling material used to repair dental cavities. The material contains mercury in combination with silver, tin, copper, and sometimes zinc.

Tags : Dental Amalgam, Dental Amalgam, filling material, repair, dental cavities

Published on : Jul 01, 2021 | Views : 3783 | Downloads : 24

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Slide 1-

Dental Amalgam Col Kraig S. Vandewalle USAF Dental Evaluation & Consultation Service
Slide 2-

Official Disclaimer The opinions expressed in this presentation are those of the author and do not necessarily reflect the official position of the US Air Force or the Department of Defense (DOD) Devices or materials appearing in this presentation are used as examples of currently available products/technologies and do not imply an endorsement by the author and/or the USAF/DOD
Slide 3-

Overview History Basic composition Basic setting reactions Classifications Manufacturing Variables in amalgam performance Click here for briefing on dental amalgam (PDF)
Slide 4-

History 1833 Crawcour brothers introduce amalgam to US powdered silver coins mixed with mercury expanded on setting 1895 G.V. Black develops formula for modern amalgam alloy 67% silver, 27% tin, 5% copper, 1% zinc overcame expansion problems
Slide 5-

History 1960’s conventional low-copper lathe-cut alloys smaller particles first generation high-copper alloys Dispersalloy (Caulk) admixture of spherical Ag-Cu eutectic particles with conventional lathe-cut eliminated gamma-2 phase Mahler J Dent Res 1997
Slide 6-

History 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
Slide 7-

Amalgam An alloy of mercury with another metal.
Slide 8-

Why Amalgam? Inexpensive Ease of use Proven track record >100 years Familiarity Resin-free less allergies than composite Click here for Talking Paper on Amalgam Safety (PDF)
Slide 9-

Constituents in Amalgam Basic Silver Tin Copper Mercury Other Zinc Indium Palladium
Slide 10-

Basic Constituents Silver (Ag) increases strength increases expansion Tin (Sn) decreases expansion decreased strength increases setting time Phillip’s Science of Dental Materials 2003
Slide 11-

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
Slide 12-

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 Click here for ADA Mercury Hygiene Recommendations Phillip’s Science of Dental Materials 2003
Slide 13-

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 Þ
Slide 14-

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
Slide 15-

Other Constituents Palladium (Pd) reduced corrosion greater luster example Valiant PhD (Ivoclar Vivadent) 0.5% palladium Mahler J Dent Res 1990
Slide 16-

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
Slide 17-

Basic Setting Reactions Conventional low-copper alloys Admixed high-copper alloys Single composition high-copper alloys
Slide 18-

Dissolution and precipitation Hg dissolves Ag and Sn from alloy Intermetallic compounds formed Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury (Hg) Ag Ag Ag Sn Sn Sn Conventional Low-Copper Alloys Hg Hg Ag3Sn + Hg Þ Ag3Sn + Ag2Hg3 + Sn8Hg Phillip’s Science of Dental Materials 2003   1 2
Slide 19-

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 Ag Ag Sn Sn Sn Hg Hg Hg Ag3Sn + Hg Þ Ag3Sn + Ag2Hg3 + Sn8Hg Phillip’s Science of Dental Materials 2003   1 2
Slide 20-

Conventional Low-Copper Alloys Gamma 1 (1) = Ag2Hg3 matrix for unreacted alloy and 2nd strongest phase 10 micron grains binding gamma () 60% of volume 1 Ag3Sn + Hg Þ Ag3Sn + Ag2Hg3 + Sn8Hg Phillip’s Science of Dental Materials 2003   1 2 Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy
Slide 21-

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 Ag3Sn + Hg Þ Ag3Sn + Ag2Hg3 + Sn8Hg Phillip’s Science of Dental Materials 2003   1 2 2 Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy
Slide 22-

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 Ag3Sn + Ag-Cu + Hg Þ Ag3Sn + Ag-Cu + Ag2Hg3 + Cu6Sn5   1  Ag-Sn Alloy Ag-Sn Alloy Mercury Ag Ag Ag Sn Sn Ag-Cu Alloy Ag Hg Hg
Slide 23-

Admixed High-Copper Alloys Sn diffuses to surface of Ag-Cu particles reacts with Cu to form (eta) Cu6Sn5 () around unconsumed Ag-Cu particles Ag-Sn Alloy Ag-Cu Alloy  Ag-Sn Alloy Phillip’s Science of Dental Materials 2003 Ag3Sn + Ag-Cu + Hg Þ Ag3Sn + Ag-Cu + Ag2Hg3 + Cu6Sn5   1 
Slide 24-

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 Ag3Sn + Ag-Cu + Hg Þ Ag3Sn + Ag-Cu + Ag2Hg3 + Cu6Sn5   1 
Slide 25-

Single Composition High-Copper Alloys Gamma sphere () (Ag3Sn) with epsilon coating () (Cu3Sn) Ag and Sn dissolve in Hg Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury (Hg)  Ag Sn Ag Sn Ag3Sn + Cu3Sn + Hg Þ Ag3Sn + Cu3Sn + Ag2Hg3 + Cu6Sn5 Phillip’s Science of Dental Materials 2003   1   
Slide 26-

Single Composition High-Copper Alloys Gamma 1 (1) (Ag2Hg3) crystals grow binding together partially- dissolved gamma () alloy particles (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 Alloy Ag-Sn Alloy 1  Ag3Sn + Cu3Sn + Hg Þ Ag3Sn + Cu3Sn + Ag2Hg3 + Cu6Sn5 Phillip’s Science of Dental Materials 2003   1   
Slide 27-

Classifications Based on copper content Based on particle shape Based on method of adding copper
Slide 28-

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
Slide 29-

Particle Shape Lathe cut low Cu New True Dentalloy high Cu ANA 2000 Admixture high Cu Dispersalloy, Valiant PhD Spherical low Cu Cavex SF high Cu Tytin, Valiant
Slide 30-

Method of Adding Copper Single Composition Lathe-Cut (SCL) Single Composition Spherical (SCS) Admixture: Lathe-cut + Spherical Eutectic (ALE) Admixture: Lathe-cut + Single Composition Spherical (ALSCS)
Slide 31-

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)
Slide 32-

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)
Slide 33-

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)
Slide 34-

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)
Slide 35-

Manufacturing Process Lathe-cut alloys Ag & Sn melted together alloy cooled phases solidify heat treat 400 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
Slide 36-

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
Slide 37-

Material-Related Variables Dimensional change Strength Corrosion Creep
Slide 38-

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
Slide 39-

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
Slide 40-

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
Slide 41-

Corrosion Reduces strength Seals margins low copper 6 months SnO2, SnCl gamma-2 phase high copper 6 - 24 months SnO2 , SnCl, CuCl eta-phase (Cu6Sn5) Sutow J Dent Res 1991
Slide 42-

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
Slide 43-

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 Click here for table of creep values
Slide 44-

Dentist-Controlled Variables Manipulation trituration condensation burnishing polishing
Slide 45-

Trituration Mixing time refer to manufacturer recommendations Click here for details 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
Slide 46-

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
Slide 47-

Burnishing Pre-carve removes excess mercury improves margin adaptation Post-carve improves smoothness Combined less leakage Ben-Amar Dent Mater 1987
Slide 48-

Early Finishing After initial set prophy cup with pumice provides initial smoothness to restorations recommended for spherical amalgams
Slide 49-

Polishing Increased smoothness Decreased plaque retention Decreased corrosion Clinically effective? no improvement in marginal integrity Mayhew Oper Dent 1986 Collins J Dent 1992 Click here for abstract
Slide 50-

Alloy Selection Handling characteristics Mechanical and physical properties Clinical performance Click here for more details
Slide 51-

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
Slide 52-

Handling Characteristics Admixed advantages easy to achieve tight contacts good polish disadvantages hardens slowly lower early strength
Slide 53-

Amalgam Properties Phillip’s Science of Dental Materials 2003 1Fine Cut, Caulk 2 Dispersalloy, Caulk 3Tytin, Kerr
Slide 54-

Survey of Practice Types Civilian General Dentists Amalgam Users Amalgam Free Haj-Ali Gen Dent 2005
Slide 55-

Frequency of Posterior Materials by Practice Type Amalgam Users Amalgam Free Haj-Ali Gen Dent 2005
Slide 56-

Profile of Amalgam Users Civilian Practitioners Do you use amalgam in your practice? Yes No DPR 2005 Do you place fewer amalgams than 5 years ago? Yes No
Slide 57-

Review of Clinical Studies (Failure Rates in Posterior Permanent Teeth) Hickel J Adhes Dent 2001 % Annual Failure
Slide 58-

% Annual Failure Manhart Oper Dent 2004 Click here for abstract Standard Deviation Longitudinal and Cross-Sectional Data Review of Clinical Studies (Failure Rates in Posterior Permanent Teeth)
Slide 59-

Acknowledgements Dr. David Charlton Dr. Charles Hermesch Col Salvador Flores Questions/Comments Col Kraig Vandewalle DSN 792-7670 ksvandewalle@nidbr.med.navy.mil