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Philip W Davidson - One of the best experts on this subject based on the ideXlab platform.

  • neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal Dental Amalgam the seychelles child development nutrition study
    Neurotoxicology and Teratology, 2013
    Co-Authors: Gene E Watson, Edwin Van Wijngaarden, Tanzy Love, Emeir M Mcsorley, Maxine P Bonham, Maria S Mulhern, Alison J Yeates, Philip W Davidson, Conrad F Shamlaye, J J Strain
    Abstract:

    Limited human data are available to assess the association between prenatal mercury vapor (Hg⁰)) exposure from maternal Dental Amalgam restorations and neurodevelopment of children. We evaluated the association between maternal Dental Amalgam status during gestation and children's neurodevelopmental outcomes at 5 years in the Seychelles Child Development Nutrition Study (SCDNS). Maternal Amalgam status was determined prospectively in a longitudinal cohort study examining the associations of prenatal exposure to nutrients and methylmercury (MeHg) with neurodevelopment. A total of 236 mother-child pairs initially enrolled in the SCDNS in 2001 were eligible to participate. Maternal Amalgam status was measured as number of Amalgam surfaces (the primary metric) and number of occlusal points. The neurodevelopmental assessment battery was comprised of age-appropriate tests of cognitive, language, and perceptual functions, and scholastic achievement. Linear regression analysis controlled for MeHg exposure, maternal fatty acid status, and other covariates relevant to child development. Maternal Amalgam status evaluation yielded an average of 7.0 surfaces (range 0-28) and 11.0 occlusal points (range 0-40) during pregnancy. Neither the number of maternal Amalgam surfaces nor occlusal points were associated with any outcome. Our findings do not provide evidence to support a relationship between prenatal exposure to Hg⁰ from maternal Dental Amalgam and neurodevelopmental outcomes in children at 5 years of age.

  • prenatal exposure to Dental Amalgam in the seychelles child development nutrition study associations with neurodevelopmental outcomes at 9 and 30 months
    Neurotoxicology, 2012
    Co-Authors: Gene E Watson, Edwin Van Wijngaarden, Emeir M Mcsorley, Maxine P Bonham, Maria S Mulhern, Katie Evans, Sally W Thurston, Julie M W Wallace, Alison J Mcafee, Philip W Davidson
    Abstract:

    Background Dental Amalgam is approximately 50% metallic mercury and releases mercury vapor into the oral cavity, where it is inhaled and absorbed. Maternal Amalgams expose the developing fetus to mercury vapor. Mercury vapor can be toxic, but uncertainty remains whether prenatal Amalgam exposure is associated with neurodevelopmental consequences in offspring.

  • prenatal exposure to Dental Amalgam evidence from the seychelles child development study main cohort
    Journal of the American Dental Association, 2011
    Co-Authors: Gene E Watson, Conrad F Shamlaye, Sally W Thurston, Miranda L Lynch, Gary J Myers, Grazyna Zareba, Thomas W Clarkson, Philip W Davidson
    Abstract:

    ABSTRACT Background Dental Amalgams contain approximately 50 percent metallic mercury and emit mercury vapor during the life of the restoration. Controversy surrounds whether fetal exposure to mercury vapor resulting from maternal Dental Amalgam restorations has neurodevelopmental consequences. Methods The authors determined maternal Amalgam restoration status during gestation (prenatal exposure to mercury vapor [Hg 0 ]) retrospectively in 587 mother-child pairs enrolled in the Seychelles Child Development Study, a prospective longitudinal cohort study of the effects of prenatal and recent postnatal methylmercury (MeHg) exposure on neurodevelopment. They examined covariate-adjusted associations between prenatal maternal Amalgam restoration status and the results of six age-appropriate neurodevelopmental tests administered at age 66 months. The authors fit the models without and with adjustment for prenatal and recent postnatal MeHg exposure metrics. Results The mean number of maternal Amalgam restorations present during gestation was 5.1 surfaces (range, 1–22) in the 42.4 percent of mothers who had Amalgam restorations. The authors found no significant adverse associations between the number of Amalgam surfaces present during gestation and any of the six outcomes, with or without adjustment for prenatal and postnatal MeHg exposure. Results of analyses with the secondary metric, prenatal Amalgam occlusal point scores, showed an adverse association in boys only on a letter- and word-identification subtest of a frequently used test of scholastic achievement, whereas girls scored better on several other tests with increasing exposure. Conclusions This study’s results provide no support for the hypothesis that prenatal Hg 0 exposure arising from maternal Dental Amalgam restorations results in neurobehavioral consequences in the child. These findings require confirmation from a prospective study of coexposure to MeHg and Hg 0 .

Gene E Watson - One of the best experts on this subject based on the ideXlab platform.

  • neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal Dental Amalgam the seychelles child development nutrition study
    Neurotoxicology and Teratology, 2013
    Co-Authors: Gene E Watson, Edwin Van Wijngaarden, Tanzy Love, Emeir M Mcsorley, Maxine P Bonham, Maria S Mulhern, Alison J Yeates, Philip W Davidson, Conrad F Shamlaye, J J Strain
    Abstract:

    Limited human data are available to assess the association between prenatal mercury vapor (Hg⁰)) exposure from maternal Dental Amalgam restorations and neurodevelopment of children. We evaluated the association between maternal Dental Amalgam status during gestation and children's neurodevelopmental outcomes at 5 years in the Seychelles Child Development Nutrition Study (SCDNS). Maternal Amalgam status was determined prospectively in a longitudinal cohort study examining the associations of prenatal exposure to nutrients and methylmercury (MeHg) with neurodevelopment. A total of 236 mother-child pairs initially enrolled in the SCDNS in 2001 were eligible to participate. Maternal Amalgam status was measured as number of Amalgam surfaces (the primary metric) and number of occlusal points. The neurodevelopmental assessment battery was comprised of age-appropriate tests of cognitive, language, and perceptual functions, and scholastic achievement. Linear regression analysis controlled for MeHg exposure, maternal fatty acid status, and other covariates relevant to child development. Maternal Amalgam status evaluation yielded an average of 7.0 surfaces (range 0-28) and 11.0 occlusal points (range 0-40) during pregnancy. Neither the number of maternal Amalgam surfaces nor occlusal points were associated with any outcome. Our findings do not provide evidence to support a relationship between prenatal exposure to Hg⁰ from maternal Dental Amalgam and neurodevelopmental outcomes in children at 5 years of age.

  • prenatal exposure to Dental Amalgam in the seychelles child development nutrition study associations with neurodevelopmental outcomes at 9 and 30 months
    Neurotoxicology, 2012
    Co-Authors: Gene E Watson, Edwin Van Wijngaarden, Emeir M Mcsorley, Maxine P Bonham, Maria S Mulhern, Katie Evans, Sally W Thurston, Julie M W Wallace, Alison J Mcafee, Philip W Davidson
    Abstract:

    Background Dental Amalgam is approximately 50% metallic mercury and releases mercury vapor into the oral cavity, where it is inhaled and absorbed. Maternal Amalgams expose the developing fetus to mercury vapor. Mercury vapor can be toxic, but uncertainty remains whether prenatal Amalgam exposure is associated with neurodevelopmental consequences in offspring.

  • prenatal exposure to Dental Amalgam evidence from the seychelles child development study main cohort
    Journal of the American Dental Association, 2011
    Co-Authors: Gene E Watson, Conrad F Shamlaye, Sally W Thurston, Miranda L Lynch, Gary J Myers, Grazyna Zareba, Thomas W Clarkson, Philip W Davidson
    Abstract:

    ABSTRACT Background Dental Amalgams contain approximately 50 percent metallic mercury and emit mercury vapor during the life of the restoration. Controversy surrounds whether fetal exposure to mercury vapor resulting from maternal Dental Amalgam restorations has neurodevelopmental consequences. Methods The authors determined maternal Amalgam restoration status during gestation (prenatal exposure to mercury vapor [Hg 0 ]) retrospectively in 587 mother-child pairs enrolled in the Seychelles Child Development Study, a prospective longitudinal cohort study of the effects of prenatal and recent postnatal methylmercury (MeHg) exposure on neurodevelopment. They examined covariate-adjusted associations between prenatal maternal Amalgam restoration status and the results of six age-appropriate neurodevelopmental tests administered at age 66 months. The authors fit the models without and with adjustment for prenatal and recent postnatal MeHg exposure metrics. Results The mean number of maternal Amalgam restorations present during gestation was 5.1 surfaces (range, 1–22) in the 42.4 percent of mothers who had Amalgam restorations. The authors found no significant adverse associations between the number of Amalgam surfaces present during gestation and any of the six outcomes, with or without adjustment for prenatal and postnatal MeHg exposure. Results of analyses with the secondary metric, prenatal Amalgam occlusal point scores, showed an adverse association in boys only on a letter- and word-identification subtest of a frequently used test of scholastic achievement, whereas girls scored better on several other tests with increasing exposure. Conclusions This study’s results provide no support for the hypothesis that prenatal Hg 0 exposure arising from maternal Dental Amalgam restorations results in neurobehavioral consequences in the child. These findings require confirmation from a prospective study of coexposure to MeHg and Hg 0 .

James S Woods - One of the best experts on this subject based on the ideXlab platform.

  • critique of reanalysis of casa pia data on associations of porphyrins and glutathione s transferases with Dental Amalgam exposure
    Human & Experimental Toxicology, 2015
    Co-Authors: Timothy A Derouen, James S Woods, Brian G Leroux
    Abstract:

    In their 2013 article in Human and Experimental Toxicology, Geier et al. presented reanalyses of data from the ‘‘Casa Pia Study of the Health Effects of Dental Amalgam in Children,’’ in particular, the results described in Woods et al. regarding the association of exposure to Dental Amalgam with glutathione-S-transferase (GST)-a and GST. In a similar manner, in their 2011 article in ‘‘Biometals,’’ Geier et al. also presented reanalyses of data from the Casa Pia study regarding the association of exposure to Dental Amalgam with urinary porphyrins, as presented in Woods et al. In both the articles, Geier et al. imply that their analyses, which they claim show significant associations of urinary porphyrins and GSTs with Dental Amalgam exposure, contradict our published findings on porphyrins and GSTs (which indicate no associations with Amalgam exposure) because they used a more sensitive statistical analysis. This letter is in response to those claims. There are two major points we would like to make regarding this issue. The first issue is the major difference and discrepancy in statistical approach. The Casa Pia study was a randomized clinical trial, and porphyrins and GSTs were secondary measures in that clinical trial. Even with secondary measures, the appropriate analytic approach in testing whether the exposure of one of the treatment groups to Dental Amalgam caused an increase in porphyrins or GSTs compared to the nonexposed (Dental composite) group was a comparison of the two randomized treatment groups. By taking advantage of the randomized design and using the treatment assignment that was designated by the randomization, our analyses allowed inferences to be made about the potential cause–effect relationships between Amalgam exposure and outcomes. In contrast, analyses that examine associations between outcomes and observed urinary mercury levels or weighted Amalgam exposure scores are prone to biases due to confounding. In order to make our analyses as robust and precise as possible we adjusted for covariates that either explained some of the error variance (and therefore increased precision) or that adjusted for group differences that might have occurred by chance despite the random group assignment. Such a procedure in hypothesis testing using a prespecified model and hypothesis offers the most objective evaluation of whether the observed data provide sufficient evidence to conclude that there is an association, while at the same time protecting the overall probability of reaching false positive conclusions. This is the approach advocated in the clinical trial literature. The approach used by Geier et al. is an exploratory method that uses the data to suggest how to best configure the model and the hypothesis so that ‘‘statistical significance’’ is more likely to be declared. This approach is basically the same as in a clinical trial in which intervention and control are compared and declared with no overall difference. Advocates for the intervention, not satisfied with the result, sometimes then delve into the data to try to find subgroups of patients in which a ‘‘statistically significant’’ difference could be declared. This is a wellknown pitfall in clinical trials, which Friedman et al., in their book Fundamentals of Clinical Trials (p. 372), call

  • urinary porphyrin excretion in children with mercury Amalgam treatment findings from the casa pia children s Dental Amalgam trial
    Journal of Toxicology and Environmental Health, 2009
    Co-Authors: James S Woods, Michael D Martin, Brian G Leroux, Timothy A Derouen, Mario Bernardo, Henrique Luis, Jorge Leitao, Lynne P Simmonds, Diana Echeverria, Tessa Rue
    Abstract:

    Increases in the urinary concentrations of pentacarboxyl- and coproporphyrins and the appearance of the atypical precoproporphyrin have been defined in relation to mercury (Hg) body burden in animal studies, and this change in the porphyrin excretion pattern has been described as a biomarker of occupational Hg exposure and toxicity in adult human subjects. In the present studies, urinary porphyrins were determined in relation to Hg exposure in children and adolescents, 8–18 yr of age, over the 7-yr course of a clinical trial designed to evaluate the neurobehavioral and renal effects of Dental Amalgam in children. Subjects were randomized to either Dental Amalgam or composite resin treatments. Urinary porphyrins and creatinine concentrations were measured at baseline and annually in all subjects. Results were evaluated using linear regression analysis. No significant differences between treatment groups (Amalgam versus composite) were found when comparing all subjects for any of the porphyrins of interest....

  • biomarkers of kidney integrity in children and adolescents with Dental Amalgam mercury exposure findings from the casa pia children s Amalgam trial
    Environmental Research, 2008
    Co-Authors: James S Woods, Michael D Martin, Brian G Leroux, Timothy A Derouen, Mario Bernardo, Henrique Luis, Jorge Leitao, John V Kushleika, Tessa Rue, Anna Korpak
    Abstract:

    Abstract Mercury is toxic to the kidney, and Dental Amalgam is a source of mercury exposure. Few studies have evaluated the effects of Dental Amalgam on kidney function in a longitudinal context in children. Here, we evaluated urinary concentrations of glutathione S -transferases (GSTs) α and π as biomarkers of renal proximal and distal tubular integrity, respectively, and albumin as a biomarker of glomerular integrity in children and adolescents 8–18 years of age over a 7-year course of Dental Amalgam treatment. Five hundred seven children, 8–12 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral and renal effects of Dental Amalgam in children. Subjects were randomized to either Dental Amalgam or resin composite treatments. Urinary GSTs α and π, albumin, and creatinine concentrations were measured at baseline and annually in all subjects. Results were evaluated using linear regression analysis. GST-α concentrations were similar between treatment groups and in each sex and race (white vs. non-white) group in each follow-up year. GST-π levels tended upward over the course of follow-up by four- to six-fold. This increase was seen in all groups irrespective of the treatment, race, or gender. Females had GST-π levels approximately twice those of males at all ages. Albumin concentrations were constant throughout the follow-up period and did not differ by treatment, although females had 39% higher albumin levels than males. Additionally, we found no significant effects of Amalgam treatment on the proportion of children with microalbuminuria (>30 mg/g creatinine). These findings are relevant within the context of children's health risk assessment as relates to the safety of mercury exposure from Dental Amalgam on kidney function. These data also provide normative values for sensitive indices of renal functional integrity that may serve in the evaluation of children and adolescents with renal disorders.

  • the contribution of Dental Amalgam to urinary mercury excretion in children
    Environmental Health Perspectives, 2007
    Co-Authors: James S Woods, Michael D Martin, Brian G Leroux, Timothy A Derouen, Mario Bernardo, Henrique Luis, Jorge Leitao, John V Kushleika, Lynne P Simmonds, Ying Huang
    Abstract:

    Much attention has focused on potential adverse health effects associated with exposure to mercury and mercury compounds. Of particular public health concern has been possible neurologic impairment associated with prolonged exposure to elemental mercury (Hg0) vapor (Clarkson 2003; Echeverria et al. 1998; Goering et al. 1992). Children are known to be particularly vulnerable to Hg0, prolonged exposure to which may cause impairment of the developing central nervous system, along with attendant personality, motor function, and behavioral disorders (Counter and Buchanan 2004; Davidson et al. 2004; Levy et al. 2004). A principal source of Hg0 exposure in children is through Dental Amalgam fillings, which are approximately 50% metallic mercury by weight. Hg0 vapors released from Amalgam fillings in tooth surfaces are readily absorbed into the systemic circulation by inhalation (Berglund et al. 1988; Mackert and Berglund 1997; Svare et al. 1981; Vimy and Lorscheider 1985). Once absorbed, Hg0 undergoes biotransformation predominantly in erythrocytes, to mercuric ion (Hg2+), the ultimate mediator of mercury toxicity (Halbach and Clarkson 1978; Magos et al. 1978). Debate continues as to the potential adverse effects of low-level Hg0 exposure from Dental Amalgam, particularly in children (Brownawell et al. 2005; Clarkson and Magos 2006). Findings from two concurrently conducted clinical trials that were designed to evaluate the potential neurologic and neurobehavioral consequences of prolonged Hg0 exposure from Dental Amalgam fillings in children have been recently reported (Bellinger et al. 2006; DeRouen et al. 2006). As part of one of those clinical trials (DeRouen et al. 2006), we performed annual measurements of urinary mercury concentrations in children between 8 and 18 years of age as an assessment of longitudinal exposure to Hg0 from Amalgam fillings. Here we describe changes in urinary mercury levels in children with and without Amalgam fillings over the course of the trial. We also report age-, race-, and sex-related changes in urinary mercury concentrations associated with Amalgam exposure.

  • neurobehavioral effects of Dental Amalgam in children a randomized clinical trial
    JAMA, 2006
    Co-Authors: Timothy A Derouen, James S Woods, Michael D Martin, Brian G Leroux, Mario Bernardo, Henrique Luis, Jorge Leitao, Brenda D Townes, Alexandre Castrocaldas, Gail Rosenbaum
    Abstract:

    ContextDental (silver) Amalgam is a widely used restorative material containing 50% elemental mercury that emits small amounts of mercury vapor. No randomized clinical trials have determined whether there are significant health risks associated with this low-level mercury exposure.ObjectiveTo assess the safety of Dental Amalgam restorations in children.DesignA randomized clinical trial in which children requiring Dental restorative treatment were randomized to either Amalgam for posterior restorations or resin composite instead of Amalgam. Enrollment commenced February 1997, with annual follow-up for 7 years concluding in July 2005.Setting and ParticipantsA total of 507 children in Lisbon, Portugal, aged 8 to 10 years with at least 1 carious lesion on a permanent tooth, no previous exposure to Amalgam, urinary mercury level <10 μg/L, blood lead level <15 μg/dL, Comprehensive Test of Nonverbal Intelligence IQ ≥67, and with no interfering health conditions.InterventionRoutine, standard-of-care Dental treatment, with one group receiving Amalgam restorations for posterior lesions (n = 253) and the other group receiving resin composite restorations instead of Amalgam (n = 254).Main Outcome MeasuresNeurobehavioral assessments of memory, attention/concentration, and motor/visuomotor domains, as well as nerve conduction velocities.ResultsDuring the 7-year trial period, children had a mean of 18.7 tooth surfaces (median, 16) restored in the Amalgam group and 21.3 (median, 18) restored in the composite group. Baseline mean creatinine-adjusted urinary mercury levels were 1.8 μg/g in the Amalgam group and 1.9 μg/g in the composite group, but during follow-up were 1.0 to 1.5 μg/g higher in the Amalgam group than in the composite group (P<.001). There were no statistically significant differences in measures of memory, attention, visuomotor function, or nerve conduction velocities (average z scores were very similar, near zero) for the Amalgam and composite groups over all 7 years of follow-up, with no statistically significant differences observed at any time point (P values from .29 to .91). Starting at 5 years after initial treatment, the need for additional restorative treatment was approximately 50% higher in the composite group.ConclusionsIn this study, children who received Dental restorative treatment with Amalgam did not, on average, have statistically significant differences in neurobehavioral assessments or in nerve conduction velocity when compared with children who received resin composite materials without Amalgam. These findings, combined with the trend of higher treatment need later among those receiving composite, suggest that Amalgam should remain a viable Dental restorative option for children.Trial Registrationclinicaltrials.gov Identifier: NCT00066118

Mark R. Geier - One of the best experts on this subject based on the ideXlab platform.

  • New science challenges old notion that mercury Dental Amalgam is safe
    BioMetals, 2014
    Co-Authors: Kristin G. Homme, Paul G King, Janet K Kern, David A. Geier, Boyd E. Haley, Lisa K. Sykes, Mark R. Geier
    Abstract:

    Mercury Dental Amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children’s Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from Dental Amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury Dental Amalgam.

  • a significant dose dependent relationship between mercury exposure from Dental Amalgams and kidney integrity biomarkers a further assessment of the casa pia children s Dental Amalgam trial
    Human & Experimental Toxicology, 2013
    Co-Authors: David A. Geier, Paul G King, Thomas J Carmody, Janet K Kern, Mark R. Geier
    Abstract:

    Dental Amalgams are a commonly used Dental restorative material. Amalgams are about 50% mercury (Hg), and Hg is known to significantly accumulate in the kidney. It was hypothesized that because Hg accumulates in the proximal tubules (PTs), glutathione-S-transferases (GST)-α (suggestive of kidney damage at the level of PT) would be expected to be more related to Hg exposure than GST-π (suggestive of kidney damage at the level of the distal tubules). Urinary biomarkers of kidney integrity were examined in children of 8–18 years old, with and without Dental Amalgam fillings, from a completed clinical trial (parent study). Our study determined whether there was a significant dose-dependent correlation between increasing Hg exposure from Dental Amalgams and GST-α and GST-π as biomarkers of kidney integrity. Overall, the present study, using a different and more sensitive statistical model than the parent study, revealed a statistically significant dose-dependent correlation between cumulative exposure to Hg fr...

  • a dose dependent relationship between mercury exposure from Dental Amalgams and urinary mercury levels a further assessment of the casa pia children s Dental Amalgam trial
    Human & Experimental Toxicology, 2012
    Co-Authors: David A. Geier, Paul G King, Thomas J Carmody, Janet K Kern, Mark R. Geier
    Abstract:

    Dental Amalgams are a commonly used Dental restorative material, and Amalgams are about 50% mercury (Hg). In our study, urinary Hg levels was examined in children of age 8–18 years, with and without Dental Amalgam fillings, from a completed clinical trial (parent study) that was designed to evaluate the potential health consequences of prolonged exposure to Hg from Dental Amalgam fillings. Our study was designed to determine whether there was a significant dose-dependent correlation between increasing Hg exposure from Dental Amalgams and urinary Hg levels. Hg exposure depends on the size and number of teeth with Dental Amalgams. Overall, consistent with the results observed in the parent study, there was a statistically significant dose-dependent correlation between cumulative exposure to Hg from Dental Amalgams and urinary Hg levels, after covariate adjustment. Further, it was observed that urinary Hg levels increased by 18% to 52% among 8 to 18 year old individuals, respectively, with an average exposur...

  • a dose dependent relationship between mercury exposure from Dental Amalgams and urinary mercury levels a further assessment of the casa pia children s Dental Amalgam trial
    Human & Experimental Toxicology, 2012
    Co-Authors: David A. Geier, Paul G King, Thomas J Carmody, Janet K Kern, Mark R. Geier
    Abstract:

    Dental Amalgams are a commonly used Dental restorative material, and Amalgams are about 50% mercury (Hg). In our study, urinary Hg levels was examined in children of age 8-18 years, with and without Dental Amalgam fillings, from a completed clinical trial (parent study) that was designed to evaluate the potential health consequences of prolonged exposure to Hg from Dental Amalgam fillings. Our study was designed to determine whether there was a significant dose-dependent correlation between increasing Hg exposure from Dental Amalgams and urinary Hg levels. Hg exposure depends on the size and number of teeth with Dental Amalgams. Overall, consistent with the results observed in the parent study, there was a statistically significant dose-dependent correlation between cumulative exposure to Hg from Dental Amalgams and urinary Hg levels, after covariate adjustment. Further, it was observed that urinary Hg levels increased by 18% to 52% among 8 to 18 year old individuals, respectively, with an average exposure to Amalgams, in comparison to study subjects with no exposure to Amalgams. The results of our study suggest that Dental Amalgams contribute to ongoing Hg exposure in a dose-dependent fashion.

  • A significant relationship between mercury exposure from Dental Amalgams and urinary porphyrins: a further assessment of the Casa Pia children’s Dental Amalgam trial
    BioMetals, 2011
    Co-Authors: David A. Geier, Paul G King, Thomas J Carmody, Janet K Kern, Mark R. Geier
    Abstract:

    Previous studies noted specific changes in urinary porphyrin excretion patterns associated with exposure to mercury (Hg) in animals and humans. In our study, urinary porphyrin concentrations were examined in normal children 8–18 years-old from a reanalysis of data provided from a randomized, prospective clinical trial that was designed to evaluate the potential health consequences of prolonged exposure to Hg from Dental Amalgam fillings (the parent study). Our analysis examined dose-dependent correlations between increasing Hg exposure from Dental Amalgams and urinary porphyrins utilizing statistical models with adjustments for the baseline level (i.e. study year 1) of the following variables: urinary Hg, each urinary porphyrin measure, gender, race, and the level of lead (Pb) in each subject’s blood. Significant dose-dependent correlations between cumulative exposure to Hg from Dental Amalgams and urinary porphyrins associated with Hg body-burden (pentacarboxyporphyrin, precoproporphyrin, and coproporphyrin) were observed. Overall, 5–10% increases in Hg-associated porphyrins for subjects receiving an average number of Dental Amalgam fillings in comparison to subjects receiving only composite fillings were observed over the 8-year course of the study. In contrast, no significant correlations were observed between cumulative exposure to Hg from Dental Amalgams and urinary porphyrins not associated with Hg body-burden (uroporphyrin, heptacarboxyporphyrin, and hexacarboxyporphyrin). In conclusion, our study, in contrast to the no-effect results published from the parent study, further establishes the sensitivity and specificity of specific urinary porphyrins as a biomarker for low-level Hg body-burden, and also reveals that Dental Amalgams are a significant chronic contributor to Hg body-burden.

Sonja M Mckinlay - One of the best experts on this subject based on the ideXlab platform.

  • immune function effects of Dental Amalgam in children a randomized clinical trial
    Journal of the American Dental Association, 2008
    Co-Authors: Bruce J Shenker, A Zhang, Nancy N Maserejian, Sonja M Mckinlay
    Abstract:

    ABSTRACT Background Dental Amalgam is a widely used restorative material containing 50 percent elemental mercury that emits mercury vapor. No randomized clinical trials have determined whether there are adverse immunological effects associated with this low-level mercury exposure in children. The objective of this study was to evaluate a subpopulation of the participants in the New England Children's Amalgam Trial for in vitro manifestations of immunotoxic effects of Dental Amalgam. Methods The authors conducted a randomized clinical trial in which children requiring Dental restorative treatment were randomly assigned to receive either Amalgam for posterior restorations or resin-based composite restorations. They assessed 66 children, aged 6 to 10 years, for total white blood cell counts, specific lymphocyte (T-cell and B-cell) counts and lymphocyte, neutrophil and monocyte responsiveness across a five-year period. Because of the small number of participants, the authors acknowledge that the study is exploratory in nature and has limited statistical power. Results The mean number of tooth surfaces restored during the five-year period was 7.8 for the Amalgam group and 10.1 for the composite group. In the Amalgam group, there was a slight, but not statistically significant, decline in responsiveness of T cells and monocytes at five to seven days after treatment; the authors consistently observed no differences at six, 12 or 60 months. Conclusions The findings of this study confirm that treatment of children with Amalgam restorations leads to increased, albeit low-level, exposure to mercury. In this exploratory analysis of immune function, Amalgam exposure did not cause overt immune deficits, although small transient effects were observed five to seven days after restoration placement. Clinical Implications These findings suggest that immunotoxic effects of Amalgam restorations are minimal and transient in children and most likely do not need to be of concern to practitioners considering the use of this restorative Dental material.

  • Dental Amalgam and psychosocial status the new england children s Amalgam trial
    Journal of Dental Research, 2008
    Co-Authors: David C Bellinger, Felicia L Trachtenberg, A Zhang, Mary Tavares, David B Daniel, Sonja M Mckinlay
    Abstract:

    High-dose exposures to elemental mercury vapor cause emotional dysfunction, but it is uncertain whether the levels of exposure that result from having Dental Amalgam restorations do so. As part of the New England Children's Amalgam Trial, a randomized trial involving 6- to 10-year-old children, we evaluated the hypothesis that restoration of caries using Dental Amalgam resulted in worse psychosocial outcomes than restoration using mercury-free composite resin. The primary outcome was the parent-completed Child Behavior Checklist. The secondary outcome was children's self-reports using the Behavior Assessment System for Children. Children's psychosocial status was evaluated in relation to three indices of mercury exposure: treatment assignment, surface-years of Amalgam, and urinary mercury excretion. All significant associations favored the Amalgam group. No evidence was found that exposure to mercury from Dental Amalgams was associated with adverse psychosocial outcomes over the five-year period following initial placement of Amalgams.

  • renal effects of Dental Amalgam in children the new england children s Amalgam trial
    Environmental Health Perspectives, 2007
    Co-Authors: Lars Barregard, Felicia L Trachtenberg, Sonja M Mckinlay
    Abstract:

    BackgroundMercury is nephrotoxic and Dental Amalgam is a source of mercury exposure.MethodsChildren 6–10 years of age (n = 534) with two or more posterior teeth with caries but no prior Amalgam res...

  • a dose effect analysis of children s exposure to Dental Amalgam and neuropsychological function the new england children s Amalgam trial
    Journal of the American Dental Association, 2007
    Co-Authors: David C Bellinger, Felicia L Trachtenberg, A Zhang, Mary Tavares, David B Daniel, Sonja M Mckinlay
    Abstract:

    ABSTRACT Background The New England Children's Amalgam Trial (NECAT) was a five-year randomized trial of 534 6- to 10-year-old children that compared the neuropsychological outcomes of those whose caries were restored using Dental Amalgam with the outcomes of those those whose caries were restored using mercury-free resin-based composite. The primary intention-to-treat analyses did not reveal significant differences between the treatment groups on the primary or secondary outcomes of the administered psychological tests: Full-Scale IQ score on the Wechsler Intelligence Scale for Children-Third Edition, General Memory Index of the Wide Range Assessment of Memory and Learning, and Visual-Motor Composite of the Wide Range Assessment of Visual Motor Abilities. Methods To determine whether treatment group assignment, a dichotomous measure of exposure, was sufficiently sensitive to detect associations between mercury exposure and these outcomes, the authors conducted analyses to evaluate the associations between the primary and secondary outcomes and two continuously distributed indexes of potential exposure, surface-years of Amalgam and urinary mercury excretion. Results Neither index of mercury exposure was significantly associated with any of the three outcomes. Conclusions The authors found no evidence that exposure to mercury from Dental Amalgam was associated with any adverse neuropsychological effects over the five-year period after placement of Amalgam restorations. Clinical Implications Analyses of the outcomes of the NECAT study indicate that use of Dental Amalgam was not associated with an increase in children's risk of experiencing neuropsychological dysfunction.

  • Dental Amalgam restorations and children s neuropsychological function the new england children s Amalgam trial
    Environmental Health Perspectives, 2006
    Co-Authors: David C Bellinger, Felicia L Trachtenberg, Mary Tavares, David B Daniel, Sonja M Mckinlay
    Abstract:

    We previously reported on a randomized clinical trial, the New England Children’s Amalgam Trial (NECAT), in which no significant differences were found, over a 5-year follow-up interval, between the neuropsychological scores of children for whom Dental Amalgam was used to repair caries and the scores of children for whom mercury-free composite materials were used (Bellinger et al. 2006). The Full-Scale IQ score on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler 1991) was the primary end point, and the General Memory Index (GMI) on the Wide Range Assessment of Memory and Learning (WRAML; Sheslow and Adams 1990), and the Visual Motor Composite (VMC) on the Wide Range Assessment of Visual–Motor Ability (WRAVMA; Adams and Sheslow 1995) were the two secondary end points. Each of these is a global score, derived by combining a child’s performance on tasks that assess somewhat different abilities. The additional analyses reported in this article address three issues. First, if mercury vapor liberated from Dental Amalgams produces specific rather than general neuropsychological effects and are most likely to be evident on tests that assess specific cognitive domains, global scores such as Full-Scale IQ, GMI, and VMC might be relatively insensitive to important treatment-group differences. Even in the absence of treatment-group differences on global test scores, differences in specific cognitive domains could, depending on their nature and severity, represent morbidities with important consequences for children’s health and well-being. Therefore, here we report comparisons of the scores of the Amalgam and composite groups on the sub-scales that contribute to Full-Scale IQ, the GMI, and the VMC, as well as scores on a battery of additional, domain-focused, neuropsychological and educational tests. Second, the exposure index used in the primary analyses of the trial was treatment-group assignment. This could have introduced a form of exposure misclassification insofar as the variability in the treatment needs of the children in the Amalgam group resulted in the receipt of variable amounts of Amalgam and thus in their potential exposure to mercury. Therefore, we repeated the analyses replacing treatment-group assignment with two continuously distributed indices of exposure: surface-years of Amalgam and urinary mercury concentration. Third, it is possible that only a subset of children experienced adverse neuropsychological effects as the result of exposure to Amalgam, either because of behaviors, such as bruxism or frequent gum chewing, that cause enhanced release of mercury (Barregard 2005; Barregard et al. 1995) or because of enhanced sensitivity to mercury. Two recent studies of Dental professionals suggest that polymorphisms for brain-derived neurotrophic factor (Echeverria et al. 2005; Heyer et al. 2004) and the coproporphyrinogen oxidase gene (Echeverria et al. 2006) modify the neurotoxicity of elemental mercury. If the prevalence of such enhanced vulnerability to elemental mercury is low or the associated increase in neuropsychological toxicity is modest in magnitude, its impact on the mean scores of children in the Amalgam group might not have been sufficiently large to produce significant treatment-group differences. In an attempt to identify the presence of a subgroup of children who are particularly sensitive to Amalgam, we compared the distributional characteristics of the scores within the treatment groups.