[Comparison of surface roughness of nanofilled and microhybrid composite resins after curing and polishing].

OBJECTIVE: To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing. METHODS: A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mmx8 mmx5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing. RESULTS: P60 had the lowest Ra (0.125-/+0.030 microm) followed by Z250 and Spectrum. The Ra of Z350 (0.205-/+0.052 microm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen. CONCLUSION: The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.