The Children's Amalgam Trial is one of only two randomized trials of its kind, and the only such trial in the United States, to address the potential impact of mercury exposure from amalgam restorations on neuropsychological and renal function in children.

The safety of silver amalgam as a dental restorative material has been controversial since its introduction 150 years ago, but until recently it has been assumed that the exposure to mercury from dental amalgam is limited to the acute placement phase. However, some recent studies have raised safety concerns by demonstrating chronic release of mercury vapor from amalgam fillings during chewing and brushing. The Children's Amalgam Trial (CAT) is a two-arm randomized trial of safety, comparing amalgam with a mercury-free restorative material. A single masking procedure is used to ensure that all investigators and staff measuring outcomes are unaware of assigned trial arm. The study follows 534 New England children, aged 6-10 years at enrollment, for 5 years. The children were recruited from two northeastern U.S. communities, one in rural Maine, and one in urban Massachusetts. No trial subjects received prior amalgam restorations, and all were in need of at least two posterior occlusal fillings. Participants were randomized to receive either amalgam or composite material for all posterior restorations at baseline and at subsequent visits. The primary endpoint will be 5-year change in IQ scores. Secondary endpoints will include measures of other neuropsychological assessments and renal functioning.

• Bellinger DC, Trachtenberg F, Barregard L, Tavares M, Cernichiari E, Daniel D, McKinlay S. Neuropsychological and renal effects of dental amalgam in children: a randomized clinical trial. JAMA. 2006 Apr 19;295(15):1775-83.
• Trachtenberg F, Maserejian NN, Soncini JA, Hayes C, Tavares M. Does fluoride in compomers prevent future caries in children? J Dent Res. 2009 Mar;88(3):276-9.
• Maserejian NN, Trachtenberg F, Link C, Tavares M. Underutilization of dental care when it is freely available: a prospective study of the New England Children's Amalgam Trial. J Public Health Dent. 2008 Summer;68(3):139-48.
• Soncini JA, Maserejian NN, Trachtenberg F, Tavares M, Hayes C. The longevity of amalgam versus compomer/composite restorations in posterior primary and permanent teeth: findings From the New England Children's Amalgam Trial. J Am Dent Assoc. 2007 Jun;138(6):763-72.

• 6 - 10 years of age at last birthday
• Fluent in English
• No prior or existing amalgam restorations
• Two or more posterior teeth with dental caries such that restoration would include the occlusal surfaces
• No clinical evidence of existing psychological, behavioral, neurologic, immunosuppressive, or renal disorders.