Methods: One hundred and twenty plexiglass molds were filled with Tetric EvoCeram and light cured. The surface of the samples was roughened in a standardized manner. Twelve dentists polished the samples with five different finishing techniques: method 1 (40μm diamond (40D), 15μm diamond (15D), Brownie silicon polisher (B), Greenie silicon polisher (G) and Occlubrush (O)), method 2 (40D, B, G, O), method 3 (40D, B, G and PoGo), method 4 (40D, B, PoGo) and method 5 (40D, B, O). The polishing quality was measured with a surface roughness meter (Ra). Statistical differences between the methods were analyzed with nonparametrical ANOVA and pairwise Wilcoxon signed rank tests. The statistical significance level was set at α=0.05. A qualitative evaluation of the polished restorations was done with SEM.
Results: Methods 3 and 4 showed the best polishing results. Method 1 was slightly worse (p>0.05) than method 4 but still showed a smooth surface with Ra=0.1μm. No differences could be shown between method 1 and method 2 where the rougher diamond was not followed by a finer one. Method 5 resulted in a significantly poorer finishing of the composite sample.
Conclusions: All tested procedures reached a sufficient surface polishing with Ra≤0.2μm. Finishing procedures can be shortened by integrating an universal polisher in a multi step procedure which is of interest in dental practice. Optimized polishing procedures result in a predictable surface finishing for different operators.