Dental Amalgam and Mercury Hygiene Quiz

Introduction to Dental Amalgam Restorations

• Dental amalgam is an alloy made by mixing mercury with silver tin dental amalgam alloy, to which varying amounts of copper and zinc are added.

• Amalgam alloy particles mixed with mercury produce a matrix of mercury reaction products surrounding residual dental amalgam alloy particles before and after reaction.

• Dental amalgam is classified according to copper content, particle geometry, and zinc content.

• The principal considerations for any amalgam are the amount of mercury in the final restoration and the type of reaction products formed.

• Most contemporary mixtures are made with 45-55% initial mercury and end up with about 42% after the reaction and condensation steps are complete.

• The setting reaction of dental amalgam involves silver, tin, copper, zinc, and mercury, which creates solubility, fluidity, and increases strength and hardness.

• Low-copper dental amalgam undergoes penetrating corrosion, while high-copper dental amalgam replaces tin-mercury phase with copper-tin, which is much less corrosion-prone.

• Amalgam contraction and expansion depend on reaction variables such as particle size, Hg/alloy ratio, trituration time, and condensation.

• Amalgam has high thermal and electrical conductivity, high compressive strength, low tensile strength, high wear resistance, and is non-adhesive.

• Dental amalgam restorations undergo both chemical and electrochemical corrosion, with electrochemical corrosion leading to amalgam creep or mercurioscopic expansion.

• Mercury toxicity and hypersensitivity are minimal, and amalgam restorations have low biocompatibility with the pulp.

• Mercury vapor can be hazardous if not managed properly, and sources of mercury in the clinic include amalgam raw materials, mixed but unhardened amalgam, amalgam scrap, amalgam undergoing finishing and polishing, and amalgam restorations being removed.Mercury and Dental Mercury Hygiene Recommendations

• Mercury is a naturally occurring element that can exist in various forms, including organic and inorganic.

• Dental amalgam, a mixture of metals that includes mercury, has been used for more than 150 years to fill cavities.

• Dental amalgam releases a small amount of mercury vapor, which can be inhaled and potentially cause health problems.

• The amount of mercury vapor released from dental amalgam varies depending on factors such as the age of the filling and the temperature of the filling.

• Organic mercury is readily absorbed in the GI tract, while inorganic mercury is not practically absorbed in the lungs.

• Mercury does not collect irreversibly in human tissues, and on average, the half-life of circulating mercury in the body is 55 days.

• Dental professionals should be aware of the potential sources of mercury vapor and work in well-ventilated spaces with outside exhaust.

• Periodic checks of the dental operatory atmosphere for mercury vapor should be conducted.

• Non-absorbent floor coverings should be used, and only pre-capsulated alloys should be used.

• Skin contact should be avoided, and high-volume evacuation should be used when finishing or removing amalgam.

• Scrap amalgam should be stored in a tightly closed container with radiographic fixer solution and recycled.

• Mercury-contaminated materials should not be placed in medical waste bags as they will be burned, potentially vaporizing mercury.