DLA 1201, exam 3

1. Dental Amalgam
Part Two

2. Manipulation of Amalgam
• Selection of alloy
• Dispensing of alloy and mercury
• Trituration
• Placement and condensation
• Burnishing and carving
• Finishing and polishing
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3. Manipulation of Amalgam
• The dentist selects the dental alloy on the basis of his or her personal preference
for its handling characteristics.
• High-copper alloys are used almost universally because they have superior
properties to low-copper alloys.
• The amalgam must be handled properly from the start through the entire
placement process if the restoration is to be successful.
• Use of premeasured capsules is the most hygienic way to work with these
materials.
• Chances for contamination of material or for spills are fewer. 3

4. Manipulation of Amalgam
• Powder and mercury are mixed together in a mechanical device called a
triturator, or amalgamator.
• Triturator has settings that allow adjustment in the speed and time of mixing
process
• Each manufacturer of amalgam materials provides specific time and speed
specifications regarding the mixing of a particular material.
• https://www.youtube.com/watch?feature=player_detailpage&v=3SgOMC
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5. Amalgamator
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6. Manipulation of Amalgam
• Under-triturated amalgam appears dry and crumbly and sets too quickly.
• Resulting in weaker restoration
• Occurs because components have not completely mixed, leaving a higher level of
unreacted mercury and alloy particles
• Over-triturated amalgam appears wet and sets quickly, producing heat.
• Results in weaker restoration that will corrode more readily because it forms too many
reaction products
• Properly triturated amalgam has a satin-like appearance.

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8. Manipulation of Amalgam
• After mixing, the amalgam is removed from the capsule and is placed into an
amalgam well.
• The amalgam is picked up in small increments with the use of an amalgam carrier.
• https://www.youtube.com/watch?feature=player_detailpage&v=VpoRXQgSsNQ
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9. Amalgam Well, Amalgam Carrier
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10. Manipulation of Dental Amalgam
• Condensers are used to work the material into all areas of the
preparation.
• The cavity preparation is slightly overfilled during placement and
condensation of amalgam to allow enough material to carve to
contours and remove excess mercury that has been forced to the
surface during the condensation process.
• If excess mercury is left, the physical properties will be poorer.

11. Amalgam placement
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12. Manipulation of Amalgam
• Burnishing before carving produces a much smoother and denser surface.
• Burnishing also helps to seal margins and enhances the longevity of the restoration.
• Carving removes extra material from the cavosurface margins and allows the missing
anatomy to be reformed.
• Once the amalgam is hard, attempts at carving may damage the amalgam margins or
cause fracture of portions of the amalgam mass.
• https://www.youtube.com/watch?feature=player_detailpage&v=_mZpUNueNRU
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13. • Patient’s should be advised to avoid chewing on a newly placed amalgam for at least 8 hours.
• Most amalgams will gain about 80% of their strength by then.
• Finishing is best done 24 hours or longer after initial placement, to allow crystallization within the
amalgam to go to completion.
• Polishing should be wet with a light touch
• This avoids generating heat that can bring mercury to the surface and potentially irritate the pulp.
• Polishing agents used are Silux or a surry mix of fine pumice or abrasive-impregnated rubber polishers are used
• Do not generate heat
• Do not polish dry
• Because a second visit is involved for finishing and polishing amalgam restorations, many clinicians do
not polish them.
• High-copper amalgams have a smoother surface after carving than low-copper amalgams, and tend to tarnish
less.
• Polishing is not as critical to their longevity as with low-copper amalgams.

14. Burnishing with indirect vision
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15. Carving using indirect vision
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16. Condensing using direct vision
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17. Before carving final anatomy
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18. After checking occlusion
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19. Amalgam instruments and steps…..
• https://www.youtube.com/watch?feature=player_detailpage&v=q8-
l5SBMpSc
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20. Bonding Amalgam
• Amalgam is retained in the cavity preparation by parallel walls or undercut walls and
through its adaptation to irregularities in the tooth created during preparation.
• It is not bonded to the tooth surface but is retained mechanically.
• Recently, many dentists have begun bonding amalgam with resin bonding agents this
is called the wet resin technique.
• After etching and application of bonding agent, a dual-cure bonding resin is applied to the cavity
preparation; and while it is still wet, the amalgam is placed.
• The wet resin mechanically intermixes with the amalgam during condensation; and when the
resin sets, it mechanically locks the amalgam in place and the resin bonds to the tooth.
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21. Mercury Safety Procedures
• Mercury: Toxic metal
• Concerns about the safety of amalgam and the mercury it
contains should be considered from three aspects:
• Safety of the patient
• Safety of the dentist and staff
• Safety of the environment
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22. Mercury Safety Procedures
• The amount of mercury that is released from a set amalgam is minimal.
• No substantiated research has proved otherwise.
• When old restorations are removed, it is important to use a water spray to minimize
vapor.
• When one is disposing of amalgam waste, it is important to do so properly.
• Commercial containers can be purchased for scrap amalgam disposal and recycling.
• Although some offices do so, scrap amalgam should never be thrown into the trash
can. 22

23. Mercury Safety Procedures
• Studies have shown mercury levels in most dental offices to be far below OSHA’s
recommended minimum.
• The elemental mercury used in amalgam is less toxic than organic mercury
• Although dental offices do not contribute as much mercury to the environment as
large companies, there contribution is not insignificant
• Mercury-free amalgam was developed that had an appearance and handling characteristics similar
to amalgam
• It used gallium as a substitute for mercury
• These are still used in some countries, but not in the United States.

24. Sources of Office Staff
Exposure to Mercury
• Placing or removing amalgam
• Leaking amalgam capsules (less frequent with factory-sealed capsules)
• Mercury droplets collecting on triturator surfaces
• Sterilizing instruments contaminated with amalgam
• Improper disposal of amalgam capsules and waste
• Improper storage of amalgam scrap
• Amalgam particles in traps within high-volume evacuation system
• Carpeted operatories or floors with tile or linoleum seams that can collect spilled
mercury 24

25. Sources of Office Staff
Exposure to Mercury
• Several measures can be taken by the office staff to minimize mercury exposure:
• (1) sterilization rooms must have adequate ventilation to disperse any mercury vapor
that may come from the sterilizer during the sterilization process;
• (2) operatory floors should have surfaces that are nonporous and easy to clean; and
• (3) gloves, masks, and eye protection should be worn when working around amalgam
and mercury.
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26. Summary
• Dental amalgam plays a large role in restorative dentistry
• Patients should be educated about the pros and cons of a material so that
they can make informed decisions
• Dental amalgam is an economical, durable, and versatile material.
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