Objectives: Composite restorations with complex anatomy are difficult to polish; rigidity of rubber points can alter surface texture. The purpose of this study was to investigate the surface roughness of a microhybrid composite polished with abrasive pastes or rubber points, with or without superficial light-cured resin.
Materials and methods: Forty discs (diameter 7 mm × 1.5 mm) of composite (Filtek Z250, 3M ESPE) were light cured and randomly divided into four groups (n = 10): group 1 (G1), rubber points (70, 40, and 5 m, Identoflex AG); group 2 (G2), abrasive pastes (80, 35, and 4 m, FGM); group 3 (G3), rubber points (=G1) and Seal Coat Fast resin (DEI Italia); group 4 (G4), abrasive pastes (=G2) and Seal Coat Fast resin. The specimens were analyzed using a rugosimeter (Talysurf CLI 1000, Taylor Hobson) considering a linear parameter (Ra); nine standardized 0.5 mm long measurements were made for each specimen. A 0.2m roughness value was assumed as clinically acceptable threshold. Collected data were statisti- cally analyzed with Kruskal–Wallis and Mann–Whitney tests (p < 0.05). Samples were then observed with SEM, running in low vacuum mode, without any sample preparation and by means of backscattered electron detector.
Results: Roughness values were lower than 0.2m in all groups. Mean Ra values ± SD (m) were: G1 = 0.07 ± 0.02, G2 = 0.06 ± 0.01; G3 = 0.06 ± 0.04; G4 = 0.03 ± 0.01. Significant differences among groups were found: G1 vs. G2 (p < 0.05); G1, G2 and G3 vs. G4 (p < 0.01). Grooves and loss of superficial filler were found in G1 and G2; grooves in G1 were parallel. Specimens treated with surface resin coat presented smoother aspect than untreated specimens.
Conclusions: All tested techniques offered roughness values under clinically acceptable threshold on flat surfaces. Abrasive pastes seem to be a valid alternative to rubber points when used on restoration with complex anatomy. Best results were obtained in G4; resin coating improves surface smoothness obtained with pastes.
