Determination of bisphenol A and related aromatic compounds released from bis-GMA-based composites and sealants by high performance liquid chromatography

'Reproduced with permission from Environmental Health Perspectives'Most of the composites and sealants used in dentistry are based on bisphenol A diglycidylether methacrylate (Bis-GMA). Reports revealed that in situ polymerization is not complete and that free monomers can be detected by different analytic methods. Concerns about the estrogenicity of bisphenol A (BPA) and other aromatic components leached from commercial products have been expressed. We studied biphenolic components eluted from seven composites and one sealant before and after in vitro polymerization using HPLC and gas chromatography/mass spectrometry and we investigated how pH modifications affect the leaching of these components. We found BPA (maximal amount 1.8 microg/mg dental material), its dimethacrylate derivative (Bis-DMA, 1.15 microg/mg), bisphenol A diglycidylether (6. 1 microg/mg), Bis-GMA (2.0 microg/mg), and ethoxylate and propoxylate of bisphenol A in media in which samples of different commercial products were maintained under controlled pH and temperature conditions. Our results confirm the leaching of estrogenic monomers into the environment by Bis-GMA-based composites and sealants in concentrations at which biologic effects have been demonstrated in in vivo experimental models. The main issue with implications for patient care and dentist responsibility is to further determine the clinical relevance of this estrogenic exposure.This research was supported by grants from the Spanish Ministry of Health (FIS, 95/1959) and Education (CICYT, AMB97-1194-CE) and the Andalusian Regional Government, Department of Health (Consejeria de Salud, JA, 231/97)

Estrogenicity of resin-based composites and sealants used in dentistry.

We tested some resin-based composites used in dentistry for their estrogenic activity. A sealant based on bisphenol-A diglycidylether methacrylate (bis-GMA) increased cell yields, progesterone receptor expression, and pS2 secretion in human estrogen-target, serum-sensitive MCF7 breast cancer cells. Estrogenicity was due to bisphenol-A and bisphenol-A dimethacrylate, monomers found in the base paste of the dental sealant and identified by mass spectrometry. Samples of saliva from 18 subjects treated with 50 mg of a bis-GMA-based sealant applied on their molars were collected 1 hr before and after treatment. Bisphenol-A (range 90-931 micrograms) was identified only in saliva collected during a 1-hr period after treatment. The use of bis-GMA-based resins in dentistry, and particularly the use of sealants in children, appears to contribute to human exposure to xenoestrogens

Determination of bisphenol A and related aromatic compounds released from bis-GMA-based composites and sealants by high performance liquid chromatography

'Reproduced with permission from Environmental Health Perspectives'Most of the composites and sealants used in dentistry are based on bisphenol A diglycidylether methacrylate (Bis-GMA). Reports revealed that in situ polymerization is not complete and that free monomers can be detected by different analytic methods. Concerns about the estrogenicity of bisphenol A (BPA) and other aromatic components leached from commercial products have been expressed. We studied biphenolic components eluted from seven composites and one sealant before and after in vitro polymerization using HPLC and gas chromatography/mass spectrometry and we investigated how pH modifications affect the leaching of these components. We found BPA (maximal amount 1.8 microg/mg dental material), its dimethacrylate derivative (Bis-DMA, 1.15 microg/mg), bisphenol A diglycidylether (6. 1 microg/mg), Bis-GMA (2.0 microg/mg), and ethoxylate and propoxylate of bisphenol A in media in which samples of different commercial products were maintained under controlled pH and temperature conditions. Our results confirm the leaching of estrogenic monomers into the environment by Bis-GMA-based composites and sealants in concentrations at which biologic effects have been demonstrated in in vivo experimental models. The main issue with implications for patient care and dentist responsibility is to further determine the clinical relevance of this estrogenic exposure.This research was supported by grants from the Spanish Ministry of Health (FIS, 95/1959) and Education (CICYT, AMB97-1194-CE) and the Andalusian Regional Government, Department of Health (Consejeria de Salud, JA, 231/97)

Método activo en Química de COU

Cambiar la metodología de la enseñanza de la Química, pretendiendo conseguir la formación y participación del alumno. Dar al alumno la oportunidad de que haga suyos los fundamentos de la Química, participando, poniendo a prueba sus hipótesis y defendiendo sus observaciones, analizando datos y discutiendo resultados. De esta forma, el alumno 'aprende a aprender' y en definitiva hace Ciencia. Todos los grupos de Química de COU de los siguientes centros de Bachillerato: I.B. Donoso Cortés de Don Benito, I.B. Luis Chamizo de Don Benito-Villanueva de la Serena, I.B. Pedro de Valdivia de Villanueva de la Serena, I.B. Manuel Godoy de Castuera y el Centro Municipal Homologado de Orellana la Vieja. En total 127 alumnos. El método activo en Química de COU ha sido elaborado por el Seminario Permanente de Física y Química Vegas Altas del Guadiana. El material base del proyecto lo constituyen los apuntes y un cuaderno de prácticas de laboratorio. Cada tema se desarrolla en 5 etapas, cuya evaluación se realiza mediante pruebas orales, escritas y prácticas, siendo evaluables todas las actividades y actitudes del alumno. En el plan de trabajo se elabora a principios de curso, un banco de datos sobre los estudiantes de los distintos centros (nivel económico-cultural familiar, expediente), asimismo, se pasan pruebas conjuntas, a fin de verificar y controlar el grado de asimilación, así como poder detectar aquellos aspectos que deben ser revisados, con todo ello, más las observaciones directas, trabajo diario de clase y pruebas específicas, se realiza la evaluación y calificación final. Pruebas de control, problemas, cuestiones. Porcentajes. El número de aprobados en el primer control (25) es bastante inferior al obtenido en el segundo control (46). Además de las dificultades normales en una nueva asignatura, pues el grupo de control pasa del 0 al 26, piensan que muy bien pudiera deberse a que el alumnado llega acostumbrado a una enseñanza tradicional, donde es un mero receptor de conocimientos y, en consecuencia, poco habituado a una enseñanza más activa y participativa, por lo que una posible solución sería un cambio en el currículum del BUP, comenzando en segundo de BUP con una nueva metodología que guíe al alumno en los aspectos experimentales de esta materia. Otro problema es el exceso número de alumnos por aula. Por último, hay una falta de correlación entre las notas de junio y las notas de Selectividad en la asignatura de Química. En junio aprobaron la asignatura 75 alumnos (59), de los cuales 53 se presentaron a Selectividad. De los 53, sólo aprobaron la Química en Selectividad 21, es decir, el 40 por ciento de los presentados. Comparando los resultados del grupo con los del resto del tribunal son bastante parecidos. Por lo tanto el método es bueno.ExtremaduraBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; Fax +34917748026; [email protected]