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Objective: To measure the 5-year caries increment among high-risk children during their participation in the New England Children’s Amalgam Trial (NECAT), and to evaluate sociodemographic factors that may account for any observed disparities. Methods: NECAT recruited 534 children aged 6–10 with at least two decayed posterior occlusal surfaces from urban Boston and rural Maine. After restoration of baseline caries and application of sealants to sound surfaces, NECAT continued to provide free comprehensive semiannual dental care to participants. The net caries increment of children who completed the 5-year follow-up ( n = 429) was calculated and predictors of caries increment were investigated using multivariate negative binomial models. Results: The majority of children (89%) experienced new caries by the end of the 5-year follow-up. Almost half (45%) had at least one newly decayed surface by the first annual visit. At year 5, the mean number of new decayed teeth was 4.5 ± 3.6 (range 0–25) and surfaces was 6.9 ± 6.5 (range 0–48). Time trends showed a noticeably higher increment rate among older children and young teenagers. Multivariate models showed that age ( P < 0.001), number of baseline carious surfaces ( P < 0.001), and toothbrushing frequency (<1/day versus ≥2/day, P = 0.04) were associated with caries increment. Only 48 children (11%) did not develop new caries. Conclusions: Despite the receipt of comprehensive semiannual dental care, the vast majority of these high-risk children continued to develop new caries within 5 years. While disparities were observed by age, extent of prior decay, and toothbrushing frequency, no other sociodemographic factors were associated with caries increment, suggesting that the dental care provided during the trial reduced sociodemographic disparities in prior caries experience that were observed at baseline. [ABSTRACT FROM AUTHOR]

BACKGROUND: Urinary mercury (U-Hg) excretion is a commonly used biomarker for mercury exposure from dental amalgam restorations. OBJECTIVES: Our goal was to determine the most efficient measure of dental amalgam exposure for use in analyses concerning U-Hg in children. METHODS: We 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. RESULTS: At 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). CONCLUSIONS: One 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. [ABSTRACT FROM AUTHOR]