Effect of filler particles on surface roughness of experimental composite series

OBJECTIVE The 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 METHODS Thirty-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/cm(2) 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 (R(a)), maximum roughness depth (R(max)) and horizontal roughness parameter (S(m)) were recorded using a contact profilometer. The data were analyzed by one-way ANOVA and the means were compared by Scheffé post-hoc test (alpha=0.05). RESULTS The lowest surface roughness (R(a)) 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 (R(a)) values increased as the filler size increased yielding a linear relation (r(2)=0.82). On the contrary, the horizontal parameter (S(m)) was not significantly affected by the filler size (r(2)=0.24) as well as the filler shape. CONCLUSIONS Filler particle's size and shape have a great effect on the surface roughness parameters of these composite series.