Comparative Evaluation of Micro-hardness and Surface Roughness of Different Composites Resins and Polishing System (In-Vitro Study)

     Objectives: The purpose of this study was to evaluate the microhardness and surface roughness of Nano hybrid and Nano-fill composites with and without polishing technique (in-vitro study). Materials and Methods: sixty-four samples were prepared in disc-shaped stainless-steel molds with a uniform size of 6 mm in diameter and 4 mm in thickness. The samples were divided according to the materials used into two groups of 32 samples for each material, and each group was then subdivided into subgroups according to the polishing instruments with 16 samples in each subgroup: Group I (control group) (Mylar’s strip) with no finishing and polishing. Group II, the specimens’ surfaces were finished with an ultrafine diamond finishing bur and polished with Sof-lex discs. Each subgroup was divided into two groups according to measurements of surface roughness and microhardness (n=8). The surface roughness was measured by using Mitutoyo Japan Surftest SJ-210 Tester and surface microhardness was measured using Vickers microhardness tester (Wilson TukonTM1102, Germany). The data were analyzed using two-way ANOVA for both the surface roughness and microhardness tests, followed by pairwise test for multiple comparisons Results: the Mylar’s strips (control group) exhibited significantly lower roughness values (smoothest surface) than the polishing systems (p <0.0001). Nano-fill composite showed statistically significantly lower surface roughness. Nanohybrid composite showed statistically significantly higher microhardness value. Conclusions: The control group had the lowest surface roughness and microhardness values compared to the polishing group. Nano-fill composite showed lower surface roughness compared to nanohybrid composite. Nanohybrid composite had a higher microhardness value when compared with nano-fill composite.