IMPACT OF AN ADDITIONAL POLISHING METHOD ON PHYSICAL, MICROMORPHOLOGIC AND MICROTOPOGRAPHIC PROPERTIES OF BULK FILL COMPOSITES
Dental polishing. Composite resins. Scanning electron microscopy. Atomic force microscopy. Wettability.
The aim of this study was to evaluate the surface roughness, wettability, compactness, mapping of chemical elements, 3D microtopography and micromorphology of bulk fill composites after additional polishing. The specimens were prepared from bulk fill (Filtek Bulk Fill Tetric N-Ceram Bulk Fill Opus Bulk Fill X-tra Fil) and conventional composites (Filtek Z250 XT, Grandioso, Tetric N-Ceram, Vittra APS), and randomly distributed in 3 groups (n = 10): without finishing and polishing, finishing and polishing with Astropol, additional polishing with Astrobrush (Astropol + Astrobrush). The surface roughness (Ra) and contact angles were measured using a profilometer and adapted goniometer, respectively. The 3D microtopography was evaluated using atomic force microscopy (AFM), while the micromorphology and the compactness, through scanning electron microscopy (SEM). The mapping of chemical elements was evaluated using (SEM / EDS - X-ray Dispersive Energy Detector). The roughness and the contact angle were analyzed by 2-way ANOVA and Tukey's test (p <0.05); other variables were descriptively analyzed. All the composites involved in this study had a superficial layer rich in dilute organic matrix, a subsurface layer rich in particles of smaller dimensions. Additional polishing step reduced surface roughness of Filtek Bulk Fill resins, Vittra APS, Tetric N-ceram Bulk Fill and X-trafil resins, increased the contact angle value of the X-tra Fil and decreased the Filtek Z250 XT. In the analyzes for 3D microtopography and micromorphology, smoother and uniform surfaces were observed in all a composites. The elements: Carbon (C), Oxygen (O), Silicon (Si) were present in all composite resins. Fluorine (F) was detected only in the Tetric N-ceram, Tetric N-ceram Bulk Fill. Only X-tra Fil did not present zirconia (Zr). Barium (Ba) was detected in Filtek Bulk Fill, TetricN-ceram Tetric N-ceram Bulk Fill, X-tra Fil, but absent in Vittra APS, Opus Bulk Fill and Grandiose. Titanium was found only in Opus Bulk Fill and tungsten only in Filtek Bulk Fill. Additional polishing step improved the surface properties of the composites studied.