Effect of intraoral polishing on the surface property, phase change, and color stainability of monolithic zirconia

Statement of problem

How glazing and polishing affects the phase change and color stainability of monolithic zirconia restorations is unclear.

Purpose

The purpose of this in vitro study was to investigate the phase changes and color stainability of monolithic zirconia after applying polishing systems and storage in different solutions.

Material and methods

Sixty Ø15×1.2 ±0.01-mm disks of 2 monolithic zirconia materials (Katana, GC Initial Zircon) were prepared, glazed, and assigned to 3 groups: A control group with no additional treatment after glaze; and 2 groups in which the glaze layer was removed and the surfaces polished using 2 different polishing systems (OptraFine and Ceramiste Shofu). One specimen from each group was examined under a scanning electron microscope. All specimens were kept in solution (coffee and cola) for 28 days. Color differences were calculated using CIEDE 2000 (ΔE₀₀), and phase change was analyzed with an X-ray diffractometer. Data were analyzed with ANOVA and Tukey post hoc tests (α=.05).

Results

Material type had a significant effect on phase change (P=.012), and the ΔE₀₀ values were significantly different between monolithic zirconia materials (P=.027). Katana had higher X_M values than GC, while GC had higher ΔE₀₀ values than Katana.

Conclusions

Cola and coffee changed the color of zirconia materials. Although glaze was the most successful process, intraoral zirconia polishing kits also provided acceptable surface properties.