Amalgam Research Today is a free monthly online journal that collates and summarizes the latest research about Amalgam, including details on dental fillings, dentistry, side-effects.

Design and evaluation of a filter-based chairside amalgam separation system.

Stone ME, Cohen ME, Berry DL, Ragain JC

Naval Institute for Dental and Biomedical Research, 310A B Street, Great Lakes, Illinois 60088, USA.

This study evaluated the ability of a chairside filtration system to remove particulate-based mercury (Hg) from dental-unit wastewater. Prototypes of the chairside filtration system were designed and fabricated using reusable filter chambers with disposable filter elements. The system was installed in five dental operatories utilizing filter elements with nominal pore sizes of 50mum, 15mum, 1mum, 0.5mum, or with no system installed (control). Daily chairside wastewater samples were collected on ten consecutive days from each room and brought to the laboratory for processing. After processing the wastewater samples, Hg concentrations were determined with cold vapor atomic absorption spectrometry (USEPA method 7470A). Filter systems were exchanged after ten samples were collected so that all five of the configurations were evaluated in each room (with assignment order balanced by a Latin Square). The numbers of surfaces of amalgam placed and removed per day were tracked in each room. In part two, new filter systems with the 0.5mum filter elements were installed in the five dental operatories and vacuum levels at the high-velocity evacuation cannula tip were measured with a vacuum gauge. In part three of the study, the chairside filtration system utilizing 0.5mum and 15mum filter elements was evaluated utilizing the ISO 11143 testing protocol, a laboratory test of amalgam separator efficiency utilizing amalgam samples of known particle size distribution. Mean Hg per chair per day (no filter installed) was 1087.38mg (SD = 993.92mg). Mean Hg per chair per day for the 50mum, 15mum, 1mum, 0.5mum filter configurations was 79.13mg (SD = 71.40mg), 23.55mg (SD = 23.25mg), 17.68mg (SD = 17.35mg), and 4.25mg (SD = 6.35mg), respectively (n = 50 for all groups). Calculated removal efficiencies from the clinical samples were 92.7%, 97.8%, 98.4%, and 99.6%, respectively. ANCOVA on data from the four filter groups, with amalgam-surfaces-removed included as a significant covariate, was statistically significant (P < 0.0001). Tukey post-hoc comparisons (P </= 0.05) indicated that the 50mum filter removed less mercury than all other filters and the 0.5mum removed more mercury than the 50mum and 15mum filters. Chairside vacuum measured on chairs with the 0.5mum filters installed were minimally affected at the time of installation, and then gradually diminished as the filters became loaded with debris. The 0.5mum configuration passed the ISO 11143 testing protocol at 96.8% efficiency.

Published 6 May 2008 in Sci Total Environ, 396(1): 28-33.
Full-text of this article is available online (may require subscription).

Articles on Amalgam published 30 April 2008:

Correlation of parenting style and pediatric behavior guidance strategies in the dental setting: preliminary findings.   Acta Odontol Scand, 66(2): 99-104.

OBJECTIVE: The aim of this study was to investigate the influence of parenting style on the choice of proper behavior guidance strategies in pedodontics. MATERIAL AND METHODS: Seventy-two children aged between 4 and 6 years (mean 5.12 years) with carious primary mandibular molars were selected. The Primary Caregivers' Practices Report (PCPR) was used to quantify authoritarian, permissive and authoritative aspects of the caregivers' parenting style. After inferior alveolar nerve block, carious ... [Abstract] [Full-text]

Articles on Amalgam published 29 April 2008:

Homoleptic 2-mercapto benzothiazolate uranium and lanthanide complexes.   Inorg Chem, 47(9): 3863-8.

Treatment of [Ln(BH 4) 3(THF) 3] (Ln = Ce, Nd) with 3 and 4 mol equiv of KSBT in tetrahydrofuran (THF) led to the formation of [Ln(SBT) 3(THF)] and [K(THF)Ln(SBT) 4], respectively. The uranium(IV) compound [U(SBT) 4(THF) 2] was obtained from U(BH 4) 4 and was reversibly reduced by sodium amalgam into the corresponding anionic uranium(III) complex. The crystal structures of [Ln(SBT) 3(THF) 2] (Ln = Ce, Nd), [K(15-crown-5) 2][Nd(SBT) 4], [U(SBT) 4(THF)], and [K(15-crown-5) 2][U(SBT) 4(py)] show ... [Abstract] [Full-text]

Multimodal multidisciplinary standardization of perioperative care: still a long way to go.   Curr Opin Anaesthesiol, 21(2): 187-90.

PURPOSE OF REVIEW: The complexity of the perioperative care process has resulted in a suboptimal use of resources, quality problems and a relatively high incidence of errors. In an attempt to optimize resources, patient safety, and quality, multimodal, multidisciplinary standardization of the care process has become an increasingly recognized goal. RECENT FINDINGS: The anaesthesiologist as perioperative clinician plays a pivotal role in the development and implementation of standardized ... [Abstract] [Full-text]

Articles on Amalgam published 18 April 2008:

Blood and urine mercury levels in adult amalgam patients of a randomized controlled trial: Interaction of Hg species in erythrocytes.   Environ Res, 107(1): 69-78.

Parts of the population are permanently exposed to low levels of Hg degrees and Hg(II) from dental amalgam. It was the aim (1) to investigate the internal exposure to amalgam-related mercury from the kinetics of inorganic Hg in plasma and erythrocytes after amalgam removal, and (2) to estimate the amalgam-related absorbed dose. Dietary coexposure was monitored by determination of blood organic-Hg. Postremoval steady-state Hg concentrations were measured for 18 months. Eighty-two patients had ... [Abstract] [Full-text]

Maternal amalgam dental fillings as the source of mercury exposure in developing fetus and newborn.   J Expo Sci Environ Epidemiol, 18(3): 326-31.

Dental amalgam is a mercury-based filling containing approximately 50% of metallic mercury (Hg(0)). Human placenta does not represent a real barrier to the transport of Hg(0); hence, fetal exposure occurs as a result of maternal exposure to Hg, with possible subsequent neurodevelopmental disabilities in infants. This study represents a substudy of the international NIH-funded project "Early Childhood Development and polychlorinated biphenyls Exposure in Slovakia". The main aim of this ... [Abstract] [Full-text]

Scalp hair and urine mercury content of children in the Northeast United States: The New England Children's Amalgam Trial.   Environ Res, 107(1): 79-88.

Children may be at particular risk from toxic effects of mercury (Hg). Previous studies of hair (organic) and urine (inorganic) Hg levels in US children were unable to assess Hg levels while accounting for exposure to amalgam dental restorations. This analysis describes, over a 5-year period, levels and correlates/predictors of scalp hair (H-Hg) and urinary (U-Hg) mercury in 534 New England Children's Amalgam Trial (NECAT) participants, aged 6-10 years and without exposure to dental amalgam at ... [Abstract] [Full-text]

Mercury as a serious health hazard for children in gold mining areas.   Environ Res, 107(1): 89-97.

In many developing countries, mercury is used to extract gold from ore in small-scale mining areas. Exposure through mercury in these small-scale mining communities is a serious health hazard, especially to the children living and working there. Many children begin working with immediate contact to mercury from the very early age of seven. In Indonesia and Zimbabwe, 166 children were clinically examined for mercury. The mercury concentration in the blood, urine, and hair was analyzed. Compared ... [Abstract] [Full-text]

Articles on Amalgam published 8 April 2008:

Association between oral lichenoid reactions and amalgam restorations.   J Eur Acad Dermatol Venereol.

Background The aim of this study was to perform a clinical assessment of the association between oral lichenoid reactions (OLR) and amalgam restorations and to determine the salivary concentrations of interleukin-6 (IL-6) and IL-8 before and after replacement of the amalgam restorations. Methods The study included 20 patients with OLR and 20 healthy volunteers, who were examined between 2001 and 2005 at the Oral Medicine Unit of the Medical Faculty University of Rijeka. All patients were skin ... [Abstract] [Full-text]

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