Surface roughness and morphology of three nanocomposites after two different polishing treatments by a multitechnique approach.

OBJECTIVES

The purpose of this study was to assess the surface roughness and morphology of three nanocomposites polished with two different polishing systems.

METHODS

Specimens made of hybrid composite (Tetric Ceram [TC] as control) and nanocomposites: nanofilled (Filtek Supreme [FS]), nanofilled hybrid (Grandio [Gr]), complex nanofilled hybrid (Synergy D6 [Syn]) were polished with CompoSystem [CS] or Sof-Lex [SL] polishing discs. The average surface roughness (Ra) before and after polishing was measured using optical profilometry. Both AFM and SEM techniques were additionally used to analyze the surface morphology after polishing with the aim of relating the surface morphology and the surface roughness. Statistical analysis was done by ANOVA using a general linear model (alpha=0.05) with an adjustment for multiple comparisons.

RESULTS

Within the same polishing system, FS exhibited the smoothest surface, followed by Syn, TC and Gr (p<0.0001). Sof-Lex polishing discs produced the smoothest surface compared to CompoSystem (p<0.0001). AFM and SEM observations confirmed that the surface roughness was related to the surface morphology and to the average filler size.

SIGNIFICANCE

Positive correlation between the average filler size and the surface roughness suggest that using nanoparticles in the formulation does not necessary improve the surface texture. The nanofilled composite FS, which contains only nanofillers, showed the best results when associated to Sof-Lex polishing discs.