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Lido di Ostia, Italy

Salerno M.,Italian Institute of Technology | Derchi G.,Tirrenian Stomatologic Institute | Thorat S.,Italian Institute of Technology | Thorat S.,University of Genoa | And 3 more authors.
Dental Materials | Year: 2011

Objectives: The purpose of this study was to characterize the surface morphology and the elastic properties of four dental restorative flowable composites currently on the market (Venus Diamond Flow, Vertise Flow, Filtex Supreme XT Flow, Surefil SDR Flow). Additionally, one adhesive system (Adhese One F) and one non-flowable composite (Venus Diamond) have also been characterized as the control materials. Methods: Surface morphology was studied by both scanning electron and atomic force microscopy, and the elastic modulus and the hardness measured by instrumented indentation. Grain analysis was performed on the microscopic images, and statistical analysis was carried out on the results of the nanoindentation measurements. Results: It was observed that Vertise, Filtek XT and Surefil SDR exhibit stiffness similar to the non-flowable Venus Diamond, whereas Venus Diamond Flow presents itself as the more compliant flowable composite, with Adhese showing intermediate stiffness. Grain analysis of the images confirmed the general rule that the mechanical properties improve with increasing filler loading, with the notable exception of Vertise Flow that shows modulus and hardness as high as 9.1 ± 0.6 and 0.43 ± 0.03 GPa, respectively, for an estimated loading of only ∼40% by volume. Significance: Whereas generally flowable composites are confirmed not to possess sufficiently strong mechanical properties for bulk restorations, exceptions can eventually be found upon appropriate laboratory screening, as presently seems to be the case for Vertise Flow. However, real practice in actual restorations and respective clinical evaluation are required for final assessment of the suggested results. © 2011 Academy of Dental Materials.

Salerno M.,Italian Institute of Technology | Patra N.,Italian Institute of Technology | Patra N.,University of Genoa | Thorat S.,Italian Institute of Technology | And 3 more authors.
Science of Advanced Materials | Year: 2012

We have investigated the effect of polishing with two different systems, namely Venus Supra and Enhance, on the properties of a resin composite currently in use for dental restorations, namely Venus Diamond. On both the non-polished and polished specimens, first the material surfaces have been imaged by scanning electron microscopy and atomic force microscopy, and quantitative information on the surface roughness has been extracted. Then the elastic properties of the composite have been measured in compression by instrumented indentation. The measured reduced modulus and hardness of the non-polished material were (12.7±2.0) GPa and (435±105) MPa, respectively. The polishing affected the elastic properties only in the case of Venus Supra system, which apparently decreased both modulus and hardness of ~10% and ~20%, respectively, when measured at a maximum indentation depth of ~2 μm. However, at higher indentation depth of ~5 μm this difference disappears. We tentatively assign the apparent decrease observed in the elastic properties to the material smear distributed on the surface by the polishing. © 2012 by American Scientific Publishers.

Salerno M.,Italian Institute of Technology | Giacomelli L.,Tirrenian Stomatologic Institute | Derchi G.,Tirrenian Stomatologic Institute | Patra N.,Italian Institute of Technology | And 2 more authors.
BioMedical Engineering Online | Year: 2010

Background: Surface roughness is the main factor determining bacterial adhesion, biofilm growth and plaque formation on the dental surfaces in vivo. Air-polishing of dental surfaces removes biofilm but can also damage the surface by increasing its roughness. The purpose of this study was to investigate the surface damage of different conditions of air-polishing performed in vitro on a recently introduced dental restorative composite.Methods: Abrasive powders of sodium bicarbonate and glycine, combined at different treatment times (5, 10 and 30 s) and distances (2 and 7 mm), have been tested. The resulting root mean square roughness of the surfaces has been measured by means of atomic force microscopy, and the data have been analyzed statistically to assess the significance. Additionally, a fractal analysis of the samples surfaces has been carried out.Results: The minimum surface roughening was obtained by air-polishing with glycine powder for 5 s, at either of the considered distances, which resulted in a mean roughness of ~300 nm on a 30 × 30 μm2surface area, whereas in the other cases it was in the range of 400-750 nm. Both untreated surfaces and surfaces treated with the maximum roughening conditions exhibited a fractal character, with comparable dimension in the 2.4-2.7 range, whereas this was not the case for the surfaces treated with the minimum roughening conditions.Conclusions: For the dental practitioner it is of interest to learn that use of glycine in air polishing generates the least surface roughening on the considered restorative material, and thus is expected to provide the lowest rate of bacterial biofilm growth and dental plaque formation. Furthermore, the least roughening behaviour identified has been correlated with the disappearance of the surface fractal character, which could represent an integrative method for screening the air polishing treatment efficacy. © 2010 Salerno et al; licensee BioMed Central Ltd.

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