The Effect of Finishing and Polishing Techniques on the Surface Roughness and the Color of Nanocomposite Resin Restorative Materials

Abstract

Background. Rough, poorly polished surfaces contribute to staining, plaque accumulation, gingival irritation and recurrent caries. Finishing and polishing techniques are critical factors contributing to the longevity of the direct composite resin restorations. Objectives. The aim of this in vitro study was to evaluate the effects of finishing and polishing systems on surface roughness of six nanocomposite restorative resins. Material and Methods. Thirty specimens of each restorative material (n = 180) were placed in a teflon mould (6 mm in diameter and 3 mm in depth) and cured with a LED curing unit. Six specimens from each of restorative material were randomly assigned to four groups for finishing and polishing (carbide burs, diamond burs, aluminium oxide discs, silicon rubber polisher) techniques. Mylar strip formed specimens were served as control group. After finishing and polishing procedures surface roughness was evaluated by a profilometer. The data was analyzed by 2-way analysis of variance and the Tukey HSD test (alpha = 0.05). Results. Significant differences were found between the groups in terms roughness (p < 0.001). The control group and aluminium oxide discs group had the lowest Ra values and were significantly different from other groups (p < 0.001). The roughest surface was obtained with diamond burs followed by silicon rubbers and carbide burs. Overall, the smoothest surfaces were obtained with the use the complete sequence of aluminum oxide discs. Conclusions. In areas that could not be reached by the aluminum oxide discs, the carbide burs produced satisfactory surface smoothness for the nanocomposite restorative materials. Although mylar matrix strip formed surfaces presents lower surface roughness values, recountouring and polishing of resin restorations are often required in clinical situations. Aluminium oxide discs and carbide finishing burs are suitable for finishing and polishing procedures for nanocomposite restorative resins