Although dental amalgam has been used for at least 150 years to fill dental cavities, because it is made up of 50% mercury there have been on-going concerns over the potential side effects to health.
Mercury is a known neurotoxin and there has been widespread concern about exposure to the chemical for some time.
Queries over the safety of amalgam dental fillings have prompted many to have them removed and replaced, which in itself is not without risk and is of course expensive.
Mercury is a highly reactive metal with commonly recognized toxic properties in high dosage, and can affect the nervous system.
Very little medical research has been done to investigate if the trace amounts of mercury that fillings slowly release could produce any negative cognitive effects, especially when used in children's mouths.
Several newly released studies may help dispel some of the disquiet and offer reassurance that amalgam fillings are safe.
In one New England study, 534 children were given either amalgam or mercury-free fillings after a cavity was detected and it was found that after five years, there was no statistically significant difference between the two groups when it came to measuring IQ, memory or visual-motor abilities.
The only noticeable difference appears to be that the children in the amalgam group showed higher levels of mercury in their urine.
In a Portuguese study of 507 children in Lisbon, a similar pattern was seen and no notable differences in measurements of intelligence were found.
The American Dental Association says the studies support the continued use of dental amalgam as an important treatment option.
In general amalgam fillings are less common than they were 20 or so years ago, mainly because of their unsightly, metallic appearance and composite fillings are more popular as they resemble natural teeth.
Nevertheless an estimated 70 million amalgam fillings are done each year in the United States.
Experts in the dental field say the results are very positive but more research is needed before amalgam fillings can be safely said to be completely without risks.
The studies are published in the current issue of the Journal of the American Medical Association.