ObjectiveThe purpose of this study was to evaluate the effect of different filler sizes and shapes on the surface roughness of experimental resin-composite series.Material and MethodsThirty-three disc-shaped specimens of the series (Spherical-RZD 102, 105, 106, 107, 114 and Irregular-RZD 103, 108, 109, 110, 111, 112) were prepared in a split Teflon mold and irradiated with an halogen light-curing unit (450 mW/cm2 for 40 s) at both top and bottom surfaces. The specimens were stored for 3 months in distilled water. The surface roughness values in form of surface finish-vertical parameter (Ra), maximum roughness depth (Rmax) and horizontal roughness parameter (Sm) were recorded using a contact profilometer. The data were analyzed by one-way ANOVA and the means were compared by Scheffé post-hoc test (α=0.05).ResultsThe lowest surface roughness (Ra) was observed in S-100 (0.079±0.013), while the roughest surface was noted in I-450/ 700/1000 (0.125±0.011) and I-450/1000 (0.124±0.004). The spherical-shape series showed the smoothest surface finish compared to the irregular-shape ones with higher significant difference (p>0.05). The vertical surface roughness parameter (Ra) values increased as the filler size increased yielding a linear relation (r2=0.82). On the contrary, the horizontal parameter (Sm) was not significantly affected by the filler size (r2=0.24) as well as the filler shape.ConclusionsFiller particle’s size and shape have a great effect on the surface roughness parameters of these composite series.

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Analysis of variance revealed highly significant differences between the materials for the Ra roughness parameter at each finishing and polishing system used (p < 0.05). On the one hand, Filtek P90 (3M ESPE Dental Products, Seefeld, Germany) and Definite (Degussa, Dental Centrum, Hanau, Germany) provided the smoothest surface finish (Ra) when they were finished and polished with a series of Sof-Lex pop-on disks (3M ESPE Dental Products) and Astropol (Ivoclar Vivadent, Schaan, Liechtenstein), respectively. On the other hand, Filtek P60 (3M ESPE Dental Products) presented the roughest surface when it was finished with Fini disks (Jeneric/Pentron Clinical Technologies, Wallingford, CT, USA). Scanning electron microscope images indicated a uniform surface topography for Filtek P90 with most finishing/polishing systems. Contrary to CompoSite polishers (Shofu Inc., Kyoto, Japan), Astropol showed the smoothest surface finish with most of the investigated composites. CLINICAL SIGNIFICANCE The smoothest surface finish was achieved by most of the finishing/polishing systems investigated specifically on cationic (Filtek P90) and organically modified ceramics (Definite) composites compared with dimethacrylate-based composites, suggesting their successful clinical use.

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The aim of this study was to evaluate the effect of post-irradiation dry aging at different periods of time on Vickers microhardness of some dental composites based on various resin matrices. Sixty four disc-shaped specimens of the resin composites were prepared in a split Teflon mold (8 × 2 mm) and irradiated by Optilux 501 light cure (500 mW.cm -2 for 40 seconds) on their top side. The specimens were aged-dry in dark at 23 and 37 °C for the following storage periods; immediate, 1/2 an hour, 1, 6, 12, 24, 48 and 168 hours. The microhardness values were recorded using a Vickers Hardness Tester at 300 g load for 15 seconds. Results showed that Filtek ® P90 and Definite expressed the highest hardness value followed by Tetric Evoceram and then Premise Enamel. At each aging period, all materials demonstrated significant differences between hardness values of top and base surfaces as well as both temperatures examined (P < 0.05). In conclusion, surface hardness developed gradually in most of the materials reaching optimum after 168 hours post-irradiation aging. Dental composites based on silorane and ormocer resin matrices achieved higher Vickers microhardness than those based on dimethacrylates resin.