The effect of different polishing systems on the surface roughness of a nanocomposite and a microhybrid composite

Abstract

Objectives: To evaluate the surface roughness of a nanocomposite and a microhybrid composite after polishing the composites with different polishing systems. Key words: Polishing, surface roughness, microhybrid composite, nanocomposite, Sof-Lex XT, Spiral Wheels, Enhance, Intensiv UniglossCellbrush, Zircon-Brite, Dura-White stones, Mylar strips Methods: The composites used in this study were Filtek Supreme XTE (3M ESPE, St Paul, USA) and Z100 (3M ESPE, St Paul, USA). Thirty-five composite samples were made from each of the two composites. Uncured composite was placed into an aluminium ring mould, 10mm X 2mm. Both the upper and lower surfaces of the composite were covered with Mylar strips and glass plates, before the specimens were cured for 40 seconds from both sides. Samples were randomly divided into seven groups. The groups were: 1. Mylar polyester strip (control) 2. Sof-Lex XT finishing and polishing discs (3M ESPE, St Paul, USA) 3. Sof-Lex Spiral Wheels (3M ESPE, St Paul, USA) 4. Dura-White stones (Shofu Inc, Kyoto, Japan) 5. Intensiv UniglossCellbrush (Intensiv SA, Montagnola, Switzerland) 6. Enhance finishing and polishing system (Dentsply, Milford, USA) 7. Sof-Lex Spiral Wheels combined with Zircon-Brite (Dental Ventures of America, Corona, USA) The polishing of the specimens was performed by a single operator according to manufacturer s instructions. The mean surface roughness of each specimen was determined using a profilometer (Surftest SJ 210, Mitutoyo, Tokyo, Japan). Three readings were collected from each specimen. Data was statistically analysed using ANOVA. Scanning Electron Microscope (JEOL JSM-5800 LV, Tokyo, Japan) photos were taken of the representative samples. Results: Statistically significant differences in surface roughness were observed between the following groups: Z100 and Filtek Supreme XTE with the polishing systems combined (p=0.005); Control group vs all the polishing systems; Sof-Lex XT finishing and polishing discs vs Dura-White stones, Intensiv UniglossCellbrush, Enhance finishing and polishing system (p < 0.0001); Sof-Lex Spiral Wheels vs Dura-White stones, Intensiv Unigloss Cellbrush, Enhance finishing and polishing system (p <0.0001); Dura-White stones vs Intensiv UniglossCellbrush, Enhance finishing and polishing system, Sof-Lex Spiral Wheels/Zircon-Brite (p <0.0001); Intensiv UniglossCellbrush vs. Spiral Wheels/Zircon-Brite (p<0.0001); Enhance finishing and polishing system vs. Spiral Wheels/Zircon-Brite (p <0.0001). Conclusion: Filtek Supreme XTE displayed significantly better polishability and lower surface roughness values after polishing than Z100. The composite samples cured against the Mylar polyester strip produced significantly smoother surface roughness values than all the polishing systems tested in this study. The following polishing systems led to the smoothest surfaces after polishing: Sof-lex Spiral Wheels in combination with Zircon-Brite, as well as the Sof-Lex Spiral Wheels and Sof-Lex finishing and polishing discs. These systems were significantly smoother than the Enhance system used in combination with Prisma Gloss polishing paste, and also the one-step polishing system Intensiv UniglossCellbrush. There was no statistically significant difference between Sof-Lex Spiral Wheels in combination with Zircon-Brite, the Sof-Lex Spiral Wheels and the Sof-Lex finishing and polishing discs.