Evaluation of the effect of different polishing systems on the surface roughness of dental ceramics

Statement of problem. How the finishing and polishing of ceramic restorations may affect their surface properties is unclear. Purpose. The purpose of this in vitro study was to evaluate the effect of different polishing systems on the surface roughness of dental ceramics by using a profilometer, an environmental scanning electron microscope (ESEM), and an atomic force microscope (AFM). Material and methods. Sixty square specimens (2x14x14 mm) of 3 popular ceramic systems (monolithic zirconia and feldspathic-based ceramic containing feldspar and fluorapatite) were prepared, glazed, and assigned to 1 of the 5 groups: a control group with no additional treatment after the glaze; in the other groups, the glaze layer was removed, and the surfaces were polished by using 4 different ceramic polishing systems (OptraFine, Shofu, Meisinger, or Komet). The surface roughness was evaluated numerically by using a profilometer and visually by using an ESEM and an AFM. The data were interpreted by using 2-way ANOVA. A multiple comparison of averages was conducted by using the Tukey HSD (alpha=.05). Results. The smoothest surface was obtained in the glazed group polished with the OptraFine kit, with no statistically significant difference (P=.95). The other groups showed a significant difference from the glazed one (P<.05); however, the difference among the other groups was not significantly different (P=.59). Conclusions. After the adjustment of dental ceramics and upon removal of the glaze, the OptraFine polishing kit and paste application can be used as an alternative to glazing for the 3 ceramic types tested. It was not possible to adequately polish the ceramic surface by using the Komet polishing kit.