The ingredients inside a silver-amalgam filling are no secret. The most common combination is ~50% mercury, ~25% silver, ~14% tin, ~8% copper, and a few other trace metals (Kerr Material Safety Data Sheet, 2009).
Fillings can be made out of a wide range of materials, from Bis-phenol A, Bis-GMA, dimethacrylate monomers (UDMA, HDDMA, TEGMA), dimethylglyoxime, and silica. Research is suggesting that some of these materials are cytotoxic (toxic to cells). The European Union has made statements about the safety of some of these materials, but more research and longitudinal data are necessary.
There are different types of crowns: Porcelain fused to metal, full cast gold, stainless steel, all porcelain, and zirconium. And each of them can be made out of various materials.
Porcelain fused to metal –These crowns have a substructure made out of metal with porcelain baked on top. The metal can be made out of:
- Non-Precious or Base Metals — Noble metal content is less than 25% and they often contain nickel, chromium, and/or beryllium.
- Semi-Precious or Noble Alloys –At least 25% noble metal content.
- High Noble Metal or Precious Metals – Contain over 60% noble metal (gold, platinum, and/or palladium), and more than 40% must be gold.
Gold crowns – The high noble metals have a high, but not universal acceptance rate. According to Clifford Research Lab, a testing facility for dental materials, 3% of the population is sensitive/allergic to gold.
Stainless Steel Crowns – These crowns are made of chromium, nickel, and iron. The nickel may cause a reaction for those with a nickel sensitivity (~11-28 percent of women and ~6% men).
All porcelain – Porcelain contains silicon dioxide, lithium oxide, potassium oxide, aluminum oxide, and other materials (Glidewell Dental, 2015). Some researchers and practitioners believe that those with an aluminum allergy should not have aluminum oxide in their mouth.
Zirconium – Zirconium is 100% ceramic and is the strongest material we use in dentistry. Because it’s harder than tooth structure, it can even wear away the opposing tooth. Many consider zirconium to be the most biocompatible material.
So which is the best material to use?
Customizing materials is a big part of holistic dentistry. And the best material is the one that works with your unique body’s chemistry. A biocompatibility test is the best method to determine which materials your body works best with. So if you or your patient has sensitivities to foods or the environment, using a biocompatibility test prior to dental procedures would ensure that the right materials are used.
Nickel in dentistry
About 6% of men and 11-28% of women have a contact dermatitis nickel allergy. Nickel is widespread in dentistry, especially for kids. Most stainless-steel appliances such as braces, crowns, and wire retainers contain nickel. This means that kids are exposed to nickel at a young age. Even when kids react to the nickel, doctors identify the mouth as a source of the problem. Testing for nickel and other metal allergies may be beneficial prior to beginning dental work. Working with a dentist who limits the use of metals can minimize harmful effects on the body.
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