Amalgam Filling Composite Filling
Click on the following link to see how we remove amalgam (mercury) fillings:
Dental materials are becoming more of a concern especially to health conscious Charlotte NC area patients. The material of most concern for my patients is dental amalgam which contains mercury (Hg).We have not used amalgam fillings for 20 years.
Fillings, crowns and bridges come in a variety of materials and some are less reactive with the body than others. Patients are also concerned about root canal material, implant material, dental cement and dental adhesive, whitening solution, denture material and even the various materials and chemicals used at cleaning appointments. In our practice we have made special efforts to ensure our materials are as biocompatible as possible. Like any conscientious dentist we want to our materials to react minimally with our patients bodies. All dentists should be knowledgeable about dental materials.
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum. A heavy, silvery d-block element, mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, and metals such as caesium, francium, gallium, and rubidium melt just above room temperature. With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water-soluble forms of Hg (such as mercuric chloride or methylmercury), inhalation of hg vapor, or eating seafood contaminated with mercury.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, some electrical switches, and other scientific apparatus, though concerns about the element's toxicity have led to Hg thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through Hg vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.
Mercury is a heavy, silvery-white metal. As compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity. Mercury has an exceptionally low melting temperature for a d-block metal. A complete explanation of this fact requires a deep excursion into quantum physics, but it can be summarized as follows: Mercury has a unique electronic configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d and 6s subshells. As such configuration strongly resists removal of an electron, mercury behaves similarly to noble gas elements, which form weak bonds and thus easily melting solids. The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus (see lanthanide contraction). The absence of a filled inner f shell is the reason for the somewhat higher melting temperature of cadmium and zinc, although both these metals still melt easily and, in addition, have unusually low boiling points. Metals such as gold have atoms with one less 6s electron than mercury. Those electrons are more easily removed and are shared between the gold atoms forming relatively strong metallic bonds. At its freezing point (−38.86 °C), the density of mercury is 13.534 g/cm3.
Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate[disambiguation needed ], nitrate[disambiguation needed ], and chloride[disambiguation needed ] salts. Like silver, Hg reacts with atmospheric hydrogen sulfide. Mercury even reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury vapors (spill kits also use activated carbon and powdered zinc).
Mercury dissolves to form amalgams with gold, zinc and many other metals. Because iron is an exception, iron flasks have been traditionally used to trade Mercury. Other metals that do not form amalgams with Hg include tantalum, tungsten and platinum. Sodium amalgam is a common reducing agent in organic synthesis.
Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam reacts with air to give aluminium oxide, small amounts of hg corrode aluminium. For this reason, Hg is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.
There are seven stable isotopes of mercury with 202mercury being the most abundant (29.86%). The longest-lived radioisotopes are 194Hg with a half-life of 444 years, and 203mercury with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. 199Hg and 201mercury are the most often studied NMR-active nuclei, having spins of 1⁄2 and 3⁄2 respectively.
Mercury exists in two main oxidation states, I and II. Higher oxidation states are unimportant, but have been detected, e.g., mercury(IV) fluoride (HgF4) but only under extraordinary conditions.
Different from its lighter neighbors, cadmium and zinc, mercury forms simple stable compounds with metal-metal bonds. The Hg(I) compounds are diamagnetic and feature the dimeric cation, Hg2+2. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg2+ and elemental Hg. Hg(I) chloride, a colorless solid also known as calomel, is really the compound with the formula Hg2Cl2, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation.
Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg32+(AsF6–)2.
More on mercury:
Mercury is a heavy metal. Heavy metals is a topic that many of my Charlotte North Carolina NC area patients are concerned about. I continuously have patients presenting to my office who have been told they have high levels of heavy metals. We do not test for heavy metals in my office but apparently a lot of other healthcare providers are. Being that dentists deal with metals in various forms in our dental materials, it makes sense to understand this topic.
A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides.