Study recommends no more than eight dental fillings to keep mercury levels down

Researchers in the USA have investigated the potential health risks associated with certain dental amalgams, used for filling tooth cavities. After studying data from some 15,000 people, they found that exposure to mercury could become toxic for the body in individuals with more than eight dental fillings.

Metals such as mercury, silver, copper and tin are frequently used in dental amalgams. As well as being relatively cheap, mercury is highly effective when it comes to plugging dental cavities. Researchers in the USA analyzed the effects of mercury exposure in nearly 15,000 patients with dental fillings to establish the level at which the substance could become toxic for the body. 

Blood test data showed that methyl mercury, the most toxic form of mercury, was present at higher than normal levels in these patients.

What’s more, people with more than eight dental fillings were found to have 150% more mercury in their blood than those with none. The study therefore suggests that individuals with more than eight fillings could be at higher potential risk of adverse effects. The US average is three fillings per adult but 25% of American adults have 11 or more fillings.

In 1991, The World Health Organization concluded that the biggest source of mercury for the general population, not exposed to the substance industrially (environment, food), came from dental amalgams. At high levels, this heavy metal is known to be toxic for the brain, the heart, the kidneys, the lungs and the immune system. 

A blood test combined with hair and urine samples can give a relatively accurate analysis of mercury levels in the body and the effectiveness of the elimination processes.

Unconvincing alternatives

With amalgam considered by dentists to be the best filler, relatively safe, antibacterial and offering 30-to 40-year lifespans, the development of new compounds remains rare. Possible alternatives include dental composite resins. However, these can release tiny qualities of bisphenol A (BPA), an endocrinal disruptor known for its negative effects on the body. The study’s authors consider that more advanced research is necessary to better understand the effects of BPA exposure from resin-based materials.

The study is published in the journal Ecotoxicology and Environmental Safety and is available here: http://www.sciencedirect.com/science/article/pii/S0147651316303475