Surface Roughness and Filler Particles Characterization of Composite Resins

Objectives: The aim of this study was to evaluate the surface roughness (SR) after finishing/polishing and the characteristics of filler particles of four restorative systems. 

Methods: Two low shrinkage resin composites (Filtek P-90, 3MESPE and Aelite LS, Bisco Inc.), two traditional resin composites (Heliomolar and Tetric N-Ceram, Ivoclar-Vivadent) and finishing and polishing systems of their respective manufacturers (Sof-Lex Disks, 3M ESPE; Finishing Discs Kit, Bisco Inc. and Astropol F, P, AH, Ivoclar-Vivadent) were evaluated. The resin composites were applied into Teflon molds to create discs (2mm thick and 15mm in diameter), light-activated and finished/polished according to the manufacturers’ instructions (n=5). The polished surfaces were evaluated with a profilometer (Surfcorder SE 1700, Kosaka Corp.) after storage in water for one week or one year. The data were obtained (Ra, µm) and statistically analyzed by 2-way ANOVA and Tukey test (α=0.05). To characterize the inorganic components and morphology of filler particles of composites it was used the Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX). The composites were immersed in organic solvents (alcohol and acetone) to eliminate the organic phase, mounted in stubs and coated with gold for SEM and coated with carbon for EDX analysis.

Results: Filtek P-90 composite resin presented the smoothest surfaces among the materials, which did not alter after water storage for one year. SEM analysis showed different shapes for the filler particles of composites and the size of particles varied from 0.28µm (Aelite LS) to 0.15µm (Filtek P-90). Although there were differences in the chemical compositions of filler particles observed among the materials, the EDX showed the presence of silicon for all composites.

Conclusions: Results suggested that SR is influenced by characteristics of the particles; however, it did not increase after one year of storage in water. All resin cements contain silicon, however, other components varied among them.

Acknowledgments-FAPESP 2009/51454-6 and 2009/52328-4