Dental Amalgam Exposure and Urinary Mercury Levels in Children: The New England Children’s Amalgam Trial

Abstract

BackgroundUrinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations.ObjectivesOur goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children.MethodsWe analyzed time-sensitive longitudinal amalgam exposure data in children randomized to amalgam restorations (n = 267) during the 5-year New England Children’s Amalgam Trial. We calculated 8 measures of amalgam, evaluating current versus cumulative exposure, teeth versus surfaces, and total versus posterior occlusal amalgams. Urine samples collected during follow-up years 3–5 were analyzed for mercury excretion. Multivariate models for current and cumulative U-Hg excretion estimated associations between exposures and U-Hg.ResultsAt the end of follow-up, the average (± SD) cumulative exposure was 10.3 ± 6.1 surfaces and 5.7 ± 2.9 teeth ever filled with amalgam, corresponding to 30 ± 21 surface-years. Amalgam measures and U-Hg were moderately correlated. Of amalgam exposure measures, the current total of amalgam surfaces was the most robust predictor of current U-Hg, whereas posterior occlusal surface-years was best for cumulative U-Hg. In multivariate models, each additional amalgam surface present was associated with a 9% increase in current U-Hg, and each additional posterior occlusal surface-year was associated with a 3% increase in cumulative U-Hg excretion (p < 0.001).ConclusionsOne single measure of amalgam exposure is insufficient. Studies of cumulative effects of mercury from amalgam exposure in children are likely to have improved validity and precision if time-sensitive amalgam exposure measures are used. In contrast, simple counts of current amalgam fillings are adequate to capture amalgam-related current U-Hg.

Prenatal exposure to dental amalgam

“…This metric takes into account all surfaces of amalgam available for Hg 0 release and has been extensively used as a measure of exposure. 10,24-30 We also used a secondary exposure metric modified from the “amalgam points” scoring of Olstad et al 31 For this metric we considered only the occlusal surfaces of amalgams on premolars and molars, and assigned a score of 1 for small size occlusal amalgams such as pits, 2 for medium size occlusal amalgams on premolars, and 3 for large size occlusal amalgams on molars. Significant release of Hg 0 from amalgams during chewing has been well documented and likely occurs primarily from the occlusal amalgam surfaces.…”

“…32 Maserejian and coworkers studied various amalgam exposure measures in children and found the metric that included posterior occlusal surfaces to be the best predictor of cumulative urinary Hg excretion, the common biomarker of Hg 0 exposure. 30 The summed scores constitute our “occlusal points” score and are more representative of the surface area available to actively release Hg 0 from amalgams during chewing.…”

Mercúrio em clínica odontológica: concentrações semanais no ambiente de trabalho e suas relações com procedimentos dentários em São Gonçalo, Estado do Rio de Janeiro, Brasil

“…Na cavidade oral há evaporação do Hg que, após ser inalado, é absorvido pelo sangue e levado aos tecidos e órgãos diversos, podendo causar alterações, principalmente em rins e no sistema nervoso central 7 .…”

Dental Composite Restorations and Psychosocial Function in Children

“…Furthermore, BPA effects are observed in experimental studies at chronic low doses, 9 similar to concentrations observed in saliva or urine after dental material placement. 5,6,18,19 Although dental amalgam has been scrutinized given its mercury content, [20][21][22] the safety of its most common alternatives, composites, remains an unresolved issue.…”