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The Children's Amalgam Trial

This study has been completed.
Information provided by:
New England Research Institutes Identifier:
First received: August 1, 2003
Last updated: April 27, 2010
Last verified: August 2005

August 1, 2003
April 27, 2010
September 1997
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IQ as measured by the WISC III Test
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Complete list of historical versions of study NCT00065988 on Archive Site
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The Children's Amalgam Trial
Health Effects of Dental Amalgams in Children

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.

Phase 3
Allocation: Randomized
Endpoint Classification: Safety Study
Intervention Model: Single Group Assignment
Masking: Single Blind
Primary Purpose: Treatment
Dental Caries
Device: Dispersed phase amalgam restoration /composite restoration
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*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
March 2005
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  • 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.
6 Years to 10 Years
Contact information is only displayed when the study is recruiting subjects
United States
NIDCR-11886, U01DE011886
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New England Research Institutes
National Institute of Dental and Craniofacial Research (NIDCR)
Principal Investigator: Sonja M McKinlay New England Research Institutes, Inc
New England Research Institutes
August 2005

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP