This study compared the linear leakage patterns shown by 5% aqueous solution of methylene blue (MB) and India ink (II). One-hundred and twenty-five roots with single canals from extracted human teeth were used. The canals were cleaned and shaped using the step-back technique under copious irrigation. Three groups were arranged to receive root fillings of gutta-percha and one of three proprietary sealers using standard lateral condensation techniques: Sealapex (40 roots), Tubli-Seal (40 roots) and Ketac-Endo (20 roots). The remaining roots were used as controls: positive with gutta-percha and no sealer and negative with the apices sealed with nail varnish. The roots were randomly selected for 7-day immersion in either MB or II, then sectioned longitudinally; dye penetration was assessed using a Wild Leitz stereomicroscope. In all groups MB showed more penetration than II. The results were statistically significant at the P = 0.01 level, with the exception of the positive control groups. Negative controls showed no penetration. It is concluded that MB, which has a low molecular weight penetrated more deeply along root canal fillings than II, which has a large particle size.

In this study, a methacrylate-based orthopaedic bone cement was modified for use as a root canal sealer by changing the monomer from n-butyl methacrylate to tetrahydrofurfuryl methacrylate. The sealing and bonding capabilities, solubility and handling properties of the resin were evaluated. Seventy-three extracted mature human teeth with single canals were used. The teeth were randomly divided into two experimental groups each of 30 teeth; three control teeth were set aside for the leakage tests. Ten teeth were reserved for the scanning electron microscope studies. All the experimental teeth were root filled with gutta-percha and the resin sealer. The particle size of the polymer was limited in Group 1 to 75 microns or less and in Group 2 to 45 microns or less. The controls were filled with gutta-percha only. Silver nitrate solution was used as the leakage indicator. In Group 1 the mean linear penetration of the indicator was 1.10 mm +/- 1.04; four roots showed no leakage. In Group 2 the mean linear penetration of the indicator was 0.57 mm +/- 0.65; 12 roots showed no leakage. The test bodies showed no weight change after 1 and 3 months' storage in saline at 37 degrees C. The scanning electron microscope examination revealed a bond both between the resin and the dentine and between the resin and the gutta-percha. The working time of the new resin composition was normally about 50 min, and handling was found to be easy.

The Vaxholm (or Laval) case concerns an industrial action undertaken on a building site in Vaxholm, a town not far from Stockholm, Sweden. The work was performed by Latvian workers employed by a Latvian company. In order to put pressure on the company to conclude a collective agreement the Swedish Building workers' union initiated industrial action, including a ban on all building and installation. This blockade was supported by the Electricians' Union through a secondary action. Both the primary and the secondary actions were lawful under Swedish law. The case raises the question whether the industrial action or Swedish law is contrary to Community law on the free movement of services or the Posted Workers Directive. The case is now pending before the European Court of Justice (ECJ). The aim of this article is to present the background and context of the Vaxholm case for a non-Swedish audience and to outline the main issues of legal interpretation at stake, as well as their background in the Swedish industrial relations system and in Swedish and European law. The authors also point to some probable solutions in the light of earlier case-law of the ECJ.

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