Use of Mercury in Dental Silver Amalgam: An Occupational and Environmental Assessment.

The objective of this study was to assess the occupational exposure to mercury in dentistry and associated environmental emission in wastewater of Lahore, Pakistan. A total of ninety-eight blood samples were collected comprising 37 dentists, 31 dental assistants, and 30 controls. Results demonstrate that the dentistry personnel contained significantly higher mean concentration of mercury in their blood samples (dentists: 29.835 µg/L and dental assistants: 22.798 µg/L) compared to that of the controls (3.2769 µg/L). The mean concentration of mercury was found maximum in the blood samples of older age group (62.8 µg/L) in dentists and (44.3 µg/L) in dental assistants. The comparison of mercury concentration among dentists, dental assistants, and controls (pairing based on their ages) revealed that the concentration increased with the age and experience among the dentists and dental assistants. Moreover, the mercury concentration in all the studied dental wastewater samples, collected from twenty-two dental clinics, was found to be exceeding the recommended discharge limit of 0.01 mg/L. Therefore, we recommend that immediate steps must be taken to ensure appropriate preventive measures to avoid mercury vapors in order to prevent potential health hazards to dentistry personnel. Strong regulatory and administrative measures are needed to deal with mercury pollution on emergency basis.

Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

Neuropsychological function in school-age children with low mercury exposures.

The EPA reference dose for methylmercury (MeHg) was established using data from populations with greater exposures than those typical of the US. Few data are available on potential adverse health effects at lower levels. We examined relationships between hair mercury (Hg) levels and neuropsychological outcomes in a population of US children. This study included data from 355 children ages 6-10 enrolled in the New England Children's Amalgam Trial. Data on total hair Hg levels, sociodemographic information and neuropsychological function were collected. We evaluated associations between hair Hg and neuropsychological test scores with linear regression methods and used generalized additive models to determine the shape of associations that departed from linearity. Models controlled for relevant covariates, including the potential beneficial effects of consuming fish. In adjusted models, we observed no significant linear relationships between hair Hg level and any test score. Significant departures from linearity were identified for WIAT Math Reasoning and WRAMVA Visual-Motor Composite scores. The association was positive for hair Hg levels below 0.5 microg/g and negative for levels between 0.5 and 1.0 microg/g. Overall, test scores of children with hair Hg levels 1.0 microg/g appeared to be lower than those of children with levels < 1.0 microg/g, but few children had levels in this upper range and these differences did not reach statistical significance. Hair Hg levels below 1.0 microg/g in US school-age children were not adversely related to neuropsychological function.

Assessment of some elements in human permanent healthy teeth, their dependence on number of metallic amalgam fillings, and interelements relationships.

In this study, 60 human permanent healthy teeth (without filling) were collected postmortem and analyzed using flame atomic absorption spectrometry (FAAS), cold vapor atomic absorption spectrometry (CVAAS), hydride generation atomic absorption spectrometry (HGAAS), and electrothermal atomic absorption spectrometry (ETAAS) for the determination of Ca, Hg, Se, Cu, and Ag. The concentration of these elements was assessed in carious and noncarious teeth, different tooth groups, with age and with number of amalgam fillings. A negative correlation was found between Ca and the number of amalgam fillings, and significant negative correlations were found between Ca and three other metals (Hg, Ag, and Cu) that indicate the possibility of substitutions of Ca by three other metals. Significant positive correlations were found among the number of amalgam fillings and Hg, Ag, Cu and Se showed metal concentration in permanent healthy teeth were affected by the presence of the number of amalgam filling. In addition, significant positive correlations between Hg and Ag, Hg and Cu, and Ag and Cu proved the suspicion that the Hg content in permanent healthy teeth was mainly found because of the influence of amalgam filling, not from other sources. Moreover, the significant positive correlation between Hg-Se and Ag-Se showed the formation of mercuric selenide and silver selenide complexes as part of a natural mechanism of detoxification. Consequently, the permanent healthy teeth would be considered as a bioindicator for the accumulation of long-term exposure of Hg and Ag.

Análise da qualidade microbiológica de materiais odontológicos / Microbiological quality assessment of dental materials

O objetivo foi avaliar a qualidade microbiológica de materiais odontológicos (Vitrebond- 3M, Z100 - 3M, Single Bond - 3M e Permite C - SDI) antes, durante e após serem usados. As amostras foram colocadas em Erlemayer contendo Calet (DIFCO) e incubadas a 32-35°C por 20 dias. Quando turvado, o meio foi semeado em MHa (Merck) e Alet (DIFCO), e incubado. Identificados os morfotipos, as bactérias foram transferidas para Agar Nutriente (Merck), para identificação. Verificou-se que os materiais testados vieram de fábrica sem contaminação, havendo pouca probabilidade de contaminação cruzada pelo uso desses materiais

Benefícios de um trinamento participativo no julgamento de restaurações de amálgama / Benefits of a participative training for amalgam restoration assessment

A variação no julgamento clínico das restaurações é um problema que afeta a maioria dos profissionais, resultando em prejuízos biológico e financeiro. Este trabalho teve como objetivo avaliar um programa de treinamento participativo para padronização de critérios na avaliação de restaurações de amálgama. Um grupo de cinco professores de Clínica Integrada de um Curso de Odontologia avaliou 28 dentes permanentes extraídos contendo restaurações de amálgama, antes e após a participação num programa de treinamento. Foram utilizados os exames visual e radiográfico e a avaliação final foi agrupada em quatro categorias de julgamento: satisfatória, necessita de substituição total, necessita de substituição parcial ou necessita de acabamento e polimento, com justificativa da opção feita. O programa de treinamento foi constituído de quatro sessões quinzenais: fundamentação teórica, calibração com slides, calibração com dentes extraídos e elaboração da tabela de critérios. Os resultados mostraram um aumento após o treinamento tanto no nível de concordância inter-examinadores (índice kappa) como no nível de acurária em relação ao padrão ouro (validade), e estes se mantiveram, mesmo decorridos cinco meses após o término do programa de trinamento. Estes resultados sinalizam a possibilidade da utilização desta metodologia para outras calibrações e outros grupos

Avaliação in vitro da rugosidade superficial do amálgama em função da liga, técnica e momento de polimento / In vitro assessment of surface roughness of different amalgam varying alloy, technique and polishing time

Análise in vitro da rugosidade superficial de diferentes ligas para amálgama, em função da técnica e período de polimento. utilizou-se três ligas para amálgama: M1 - Velvalloy, M2 - Permite e M3 - Dispersalloy, duas técnicas de polimento: T1 - multilaminadas + borrachas abrasivas + pedra pomes com água e T2 - borrachas abrasivas + pedra pomes com água em dois momentos: P1 - imediato (após 15 minutos da condensaçào) e P2 - após 24 horas. Para cada condição experimental foram confeccionados 5 corpos-de-prova, utilizando-se uma matriz de teflon com um orifício central de 5mm de diâmetro de 2mm de altura, sendo realizadas quatro leituras em cada um deles num rugosímetro (Prazis). os dados foram submetidos à análise de variância (pú0,05) e teste de Tukey. As médias obtidas em micrômetros foram: para o material - M1: 0,93; M2: 0,75 e M3: 0,81; para a técnica - T1: 0,99 e T2: 0,67, e para o momento de polimento - P1: 1,05 e P2: 0,61. Concluiu-se que é necessário esperar 24 horas para realizar o polimento, sendo mais indicado realizá-lo com borrachas abrasivas e pedar pomes com água. As ligas ricas em cobre apresentaram melhores resultados que a liga convencional