This study was aimed at investigating the in vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT). Osteoblastic cells were obtained from human alveolar bone fragments and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured on P(VDF-TrFE)/BT and expanded polytetrafluoroethylene (e-PTFE--control) membranes in 24-well plates. Cell adhesion and spreading were evaluated at 30 min, and 4 and 24 h. For proliferation assay, cells were cultured for 1, 7, and 10 days. Cell viability was detected by trypan blue at 7 and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 7, 14, and 21 days. Cultures were stained with Alizarin red at 21 days, for detection of mineralized matrix. Data were compared by ANOVA and Student t test. Cell attachment (p = 0.001), cell number (p = 0.001), and ALP activity (p = 0.0001) were greater on P(VDF-TrFE)/BT. Additionally, doubling time was greater on P(VDF-TrFE)/BT (p = 0.03), indicating a decreased proliferation rate. Bone-like nodule formation took place only on P(VDF-TrFE)/BT. The present results showed that both membranes are biocompatible. However, P(VDF-TrFE)/BT presented a better in vitro biocompatibility and allowed bone-like nodule formation. Therefore, P(VDF-TrFE)/BT could be an alternative membrane to be used in guided tissue regeneration.

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The present work seeks to evaluate the biocompatibility of experimental glass ionomer cements (GIC) prepared from niobium-calcium fl uoro-alumino-silicate glass powder and two commercial GICs. The GICs were implanted into the subcutaneous connective tissue of sixty rats. The rats were sacrifi ced during four varying time periods: 7, 15, 30, and 60 days and histopathological examinations were then performed. The Kruskal-Wallis test was performed to evaluate any signifi cant differences between the materials. Additionally, multiple comparisons of the mean rank were also carried out using the Dunn test (p<0.05). No signifi cant differences were observed that one GIC was superior to the other. The tissue response for all of the GICs tested was similar in all the periods examined.

. Glass ionomer cements are glass and polymer composite materials. These materials currently find use in dentistry. The purpose of this work is to obtain glass powders based on the composition 4.5SiO 2 -3Al 2 O 3 -2CaO to be used in dentistry. The powders were prepared by a chemical route at 700 0 C. The properties of glass ionomer cements obtained from powders prepared at 700 ºC were studied. Diametral tensile strength and microhardness were evaluated for the experimental glass ionomer cements and a commercial material. It was concluded that the properties of experimental cements were similar to those of the commercial ones.Keywords: cements; dental; glass. INTRODUÇÃOCimento de ionômero de vidro (CIV) é um material compósito vidro/polímero, no qual as partículas de vidro têm função de material de preenchimento e são fonte de cátions para formação de ligações cruzadas com as cadeias poliméricas. Os cimentos são formados pela mistura de partículas vítreas com solução aquosa de áci-dos poliméricos orgânicos (geralmente ácido poliacrílico) 1,2 . Quando as partículas de vidro do tipo cálcioaluminosilicato são misturadas com solução aquosa de ácido poliacrílico forma-se uma pasta, que pode ser facilmente manipulada pelo dentista e usada em várias aplicações odontológicas, como cimentação de dispositivos protéticos, forração de cavidades e nas restaurações 3 . Os CIV adquirem presa inicial via reação de neutralização do tipo ácido/base entre os seus componentes. O processo envolve a hidrólise ácida das ligações Si -O -Al da rede vítrea, resultando na liberação dos cátions Ca 2+ e Al 3+ e na formação de ácido ortosilícico, o qual se polimeriza formando sílica gel 4,5 . Os cátions extraídos da rede vítrea Ca 2+ e Al 3+ são quelados pelos grupos carboxílicos, presentes na estrutura polimérica do ácido orgânico, formando sais de poliacrilato e iniciando a "pega" da pasta vidro/ ácido por geleificação 1 . Dessa maneira, o cimento obtido é constituído de partículas vítreas, com superfície revestida por sílica gel, e que estão presentes em uma matriz formada pelos sais de poliacrilato, os quais são responsáveis pelo endurecimento dos cimentos.Os CIV apresentam certas propriedades, tais como adesão à estrutura dentária, valor do coeficiente de expansão térmico linear similar ao do dente e biocompatibilidade com os tecidos dentários [6][7][8] . Essas propriedades propiciam o uso desses cimentos em Dentística Restauradora como agentes cimentantes, para forramento de cavidades, preenchimento de dentes anteriores e, também, como cimentos ósseos 9 . Os sistemas vítreos mais utilizados em Odontologia como formadores de cimentos de ionômero de vidro são os baseados no sistema ternário SiO 2 -Al 2 O 3 -CaO 2,4,5 e apresentam razão molar Al:Si igual ou superior a 1:2. A partir desse sistema originaram-se outros mais complexos, pela inclusão de novos componentes para conferir ao cimento odontológico propriedades melhores. Por ex., a maioria dos pós contêm em suas formulações óxidos de BaO ou SrO, modificadores ópticos, que conferem ao ...

The aim of this paper is to compare the fluoride-releasing and mechanical properties of an experimental luting glass ionomer cement, which has a modified composition and a commercial luting cement. The experimental powder was obtained by sol-gel process and then, it was used to prepare the experimental cements. The properties of cement pastes, such as setting time and working time, microhardness and diametral tensile strength were determined. Fluoride release from GICs was evaluated at time intervals of 1, 7, 14, 21 and 28 days in deionized water. Atomic force microscopy (AFM) analyses showed that the surface of the experimental cements is more homogeneous than commercial GICs. The mechanical properties and the measure of liberation of fluoride of the two cements were influenced by ratio powder:liquid and chemical composition of the precursor powders. Experimental cements released less fluoride than commercial cements. However, this liberation was more constant during the analyzed period. Thus, the results obtained in this study indicated that the composition of the experimental powder modified by the niobium can lead the formation of the polysalt matrix with good mechanical properties. In other words, we can say that experimental powder offered considerable promise for exploitation in dental field.