Search

Summary Objectives To evaluate the antibacterial activity of four endodontic sealers: one epoxy resin sealer (AH Plus), two zinc oxide eugenol (ZOE)-based sealers (Endomethasone, Pulp Canal Sealer), and one sealer containing both ZOE and orthophenilphenol (Vcanalare). Methods A direct contact test (DCT) was performed. A 10 μl suspension of Enterococcus faecalis was placed on the test material 20 min, 24 h and 7 days after mixing. Bacteria were allowed to directly contact the sealers for 1 h at 37 °C. Bacterial growth was then spectrophotometrically measured every 30 min for 7 h, and again after 24 h as well. Results All freshly mixed sealers showed complete inhibition of bacterial growth. Similar results were obtained with the 24-h-old samples, with the exception of AH Plus. Vcanalare was the only sealer still inhibiting bacterial growth 7 days after mixing. Conclusions The antimicrobial activity of the tested sealers depends on the time interval between mixing and testing. All sealers exhibit bactericidal effect when freshly mixed, but only Vcanalare extended this effect until 7 days after setting.

The feasibility of very long-span suspension bridges is analysed. The relation between the geometrical parameters, the load and the material characteristics is first discussed in order to find out the limit value of the span length. An iteration procedure is then proposed to study the main aspects of the structural behaviour in the deflection theory. The results of a numerical investigation allow to state that the behaviour of a very long-span suspension bridge, both in terms of stresses and deflection, is similar to the behaviour of an unstiffened cable, the contribution of the girder being negligible. © 2000 Elsevier Science Ltd.