Neurological Effects of Dental Amalgam Tooth Restorations

The research, conducted by researchers from the University of Lisbon, Portugal, and the University of Washington, Seattle, studied the possible neurological effects of dental amalgam tooth restorations.

Dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc to form a safe, stable alloy. For generations, it has been used to fill decayed teeth that might otherwise have been lost.

In the seven-year long study, the researchers studied 507 children aged 8 through 12 years who received either amalgam or resin-based composite fillings.

The research team conducted routine clinical neurological examinations to assess two types of neurological signs: hard (indicating damage to specific neural structures) and soft (subtle signs of central nervous system dysfunction that likely point to immature sensory-motor skills rather than to any structural damage in the brain).

They also evaluated the children for presence of tremor.

In the end of the study, the two groups of children did not differ in terms of the presence or absence of hard signs or tremor. They also didn't differ in terms of the presence or absence or severity of soft signs at any point. Also, as expected in healthy children, the severity of any neurological soft signs diminished as the children aged.

"Even at the levels of amalgam exposure in this study (a mean of 7.7-10.7 amalgam surfaces per subject across the seven years of follow-up, we conclude that exposure to mercury from dental amalgam does not adversely affect neurological status,” the researchers said.

"These data indicate the absence of a generalized negative effect on children's nervous system functions stemming from the presence of dental amalgam, and while we cannot rule out potential adverse reactions in individual children, we found no indications of any,” they added.

The study is published in The Journal of the American Dental Association.