Quantitative analysis of potentially toxic metals in alginates for dental use

Alginate is one the materials most employed in practice to make dental impressions. Substances like zinc, cadmium and lead silicate, which are included in several alginate brands with the aim of improving their physical, chemical and mechanical properties, are a source of serious concern as regards their toxicity. The most serious chronic effect of oral exposure to cadmium is renal toxicity. Assimilation of lead has deleterious effects on the gastrointestinal tract, hematopoietic system, cardiovascular system, central and peripheral nervous systems, kidneys, immune system, and reproductive system. Chronic oral exposures to zinc have resulted in hypochromic and microcyte anemia in some individuals. The aim of the present study was to measure the cadmium, lead and zinc contents of seven brands of alginate for dental use on sale in Brazil. The samples were weighed and placed in the Teflon cups of a closed-system microwave oven. Aqua regia (4mL concentrated HCI:HNO3, 3:1 v/v) and hydrofluoric acid (2mL concentrated HF) were added to the samples, which were then subjected to heating. The samples were then cooled to room temperature and diluted to 25 mL in deionized water in a volumetric glass flask. The samples were diluted in duplicate and analyzed against a reagent blank. The analyses were performed in an atomic absorption flame spectrophotometer. Neither lead nor cadmium was detected. Zinc contents ranged from 0.001% to 1.36% by weight. The alginates exhibited low contents of the metals under study and gave no cause for concern regarding toxicity; even so, it is advisable to monitor potentially toxic materials continually and to analyze their plasmatic levels in the professionals working with them.

Educação a distância: um estudo analítico das políticas governamentais com foco no projeto da Universidade Aberta do Brasil

The present study at the doctoral level, is in the initial phase of the Program Graduate School of Education UNESP, SP-Araraquara campus. That makes an analysis of government policies in distance education system through the Open University of Brazil (UAB). We present in this moment, the historical background of the creation and expansion of the system of the Open University of Brazil with emphasis on policies of expansion of higher education and also the degree in pedagogy courses offered by the partner universities of the University System in Brazil Open southeast. Among the main objectives of the study is to compare the Brazilian government policies of expansion of higher education with the management and characteristics of undergraduate courses in pedagogy. Partial results indicate a total 51 universities that offer degree courses in pedagogy at UAB system in Brazil, including 12 institutions in the Southeast.