Influence of Polishing Protocols on Surface Roughness and Color Properties of a Zirconia-Based Nano-Hybrid Resin Composite.

BACKGROUND

This study evaluated the impact of polishing procedures on the surface texture and color stability of two nano-hybrid resin composites, with or without zirconia filler.

MATERIAL AND

METHODS

Cylindrical specimens (6 × 2 mm) were fabricated using a nano-hybrid resin composite containing zirconia (Forma, Ultradent) or a composite without zirconia (Empress Direct, Ivoclar Vivadent). Specimens were subjected to two finishing and polishing protocols (n = 12): aluminum oxide abrasive disks (Sof-Lex, 3M) or disk-shaped abrasive rubbers (Jiffy, Ultradent). Roughness (Ra, µm) and color (CIEL*a*b* system, CIEDE2000, Vita shade guide units [SGU]) were measured at baseline, after polishing protocol, and after immersion in coffee solution.

RESULTS

were evaluated using linear mixed-effects models for repeated measures, along with Tukey-Kramer, Mann-Whitney, Friedman, and Nemenyi tests ( = 0.05).

Results

All groups exhibited an increase in Ra after polishing, with the highest values observed in specimens polished with abrasive rubbers (p < 0.05). SGU values significantly increased for both resin composites following coffee exposure, although the zirconia-based composite showed lower overall SGU changes (p < 0.05). After staining, Eab and E00 values were greater for the abrasive rubber groups compared to the aluminum oxide disk groups and were also higher for the non-zirconia resin composite compared to the zirconia-based material (p < 0.0001).

CONCLUSIONS

Polishing with aluminum oxide abrasive disks resulted in smoother surfaces and reduced susceptibility to staining. Nevertheless, the zirconia-containing resin composite demonstrated superior color stability regardless of the polishing method.