Surface Roughness and Gloss of Actual Composites as Polished With Different Polishing Systems.

OBJECTIVE: This in vitro study evaluated the effect of polishing with different polishing systems on the surface roughness and gloss of commercial composites. METHODS: One hundred disk-shaped specimens (10 mm in diameter × 2 mm thick) were made with Filtek P-90, Filtek Z350 XT, Opallis, and Grandio. The specimens were manually finished with #400 sandpaper and polished by a single operator using three multistep systems (Superfix, Diamond Pro, and Sof-lex), one two-step system (Polidores DFL), and one one-step system (Enhance), following the manufacturer's instructions. The average surface roughness (µm) was measured with a surface profilometer (TR 200 Surface Roughness Tester), and gloss was measured using a small-area glossmeter (Novo-Curve, Rhopoint Instrumentation, East Sussex, UK). Data were analyzed by two-way analysis of variance and Tukey's test (α=0.05). RESULTS: Statistically significant differences in surface roughness were identified by varying the polishing systems (p<0.0001) and by the interaction between polishing system and composite (p<0.0001). Pairwise comparisons revealed higher surface roughness for Grandio when polished with Sof-Lex and Filtek Z250 and Opallis when polished with Enhance. Gloss was influenced by the composites (p<0.0001), the polishing systems (p<0.0001), and the interaction between them (p<0.0001). The one-step system, Enhance, produced the lowest gloss for all composites. CONCLUSIONS: Surface roughness and gloss were affected by composites and polishing systems. The interaction between both also influenced these surface characteristics, meaning that a single polishing system will not behave similarly for all composites. The multistep systems produced higher gloss, while the one-step system produced the highest surface roughness and the lowest gloss of all.

Regulatory requirements for biocides on the market in the European Union according to Directive 98/8/EC.

In early 1998, the European Commission and Parliament adopted a new Directive concerning the placing on the market of biocidal products. The Directive is to be implemented in the member states by May 2000. The member states are currently concerned with the national implementation into legislation whereas the Commission is setting up the proposal for a review programme for the existing active substances and the products in which they are used. This paper describes the effort currently undertaken (up to the end of December 1998) to define the procedures to be used and characterise the substances covered.

[Critical study of electric activity of the small intestine in the dog]. / Etude critique de l'activité électrique de l'intestin grêle du chien.

Thanks to a cross-circulation, the authors caused to survive in the abdomen of a sacrificed dog, the whole of the small intestine, the motor activity of which was analysed by electro-enterography. This experimental preparation thus eliminates polygraphic recordings of all potential variations outside the small intestine, e.g. stomach, colon, diaphragm, muscle, myocardium. One thus obtains very pure tracings of the variations of potential originating in the small intestine, recorded from bipolar serous intestinal electrodes, they show the activity of the small intestine, consisting of a permanent basal electric rhythm on which are grafted spikes contemporary of motor phenomena. In the abdominal skin there were recorded only a cutaneous slow wave which was contemporary with the deep motor phenomena.