Influence of Finishing Procedures on the Color Stability and Surface Roughness of Lithium Disilicate and Monolithic Zirconia Oxide

Abstract

Aim: This study aimed at evaluating the impact of different adjustments and artificial aging on the color change (ΔE) and surface roughness (Ra) of monolithic zirconia (MLZ) and lithium disilicate (LD) ceramics. Materials and methods: Forty discs were prepared from two types of MLZs, including ceramill monolithic Zr (CM-Zr) and Prettau PSZ Zr (PP-Zr), and one LD (IPS e.max-LD, IPS-LD). After different clinical adjustments (performed with glazing, bur, bur + glazing, and bur + polishing) and artificial aging (in-vitro coffee immersion), the ΔE was assessed using a spectrophotometer. The roughness (Ra) was also evaluated after these adjustments. The ANOVA and multiple com-parisons test were used to compare the groups statisitcally and the level of significance was set at 5%. Results: In the CM-Zr group, the greatest ΔE was observed after bur adjustment (3.32, p < 0.05) while the lowest ΔE was seen after the glaze treatment (2.11, p < 0.05). In the PP-Zr group, the highest ΔE was observed after bur treatment (2.70, p < 0.05) while the lowest ΔE was seen after the glaze treatment (1.25, p < 0.05). Lastly, for the IPS-LD group, the highest ΔE was again observed after bur treatment (2.91, p < 0.05) while the lowest ΔE was seen after glaze treatment (1.0, p < 0.05). After coffee immersion, it was observed that the highest overall ΔE was observed for CM-Zr after the bur and polish treatment (3.45), while the lowest overall ΔE was observed in IPS-LD after the glaze treatment (2.10). All the ΔE values were within the clinical acceptable range. The highest overall Ra was witnessed for CM-Zr after bur adjustment (1.64), while the lowest overall Ra was seen for IPS-LD after glaze treatment (0.26). Different clinical adjustments and artificial aging influence the colour stability of different ceramic materials (CM-Zr, PP-Zr, and IPS-LD). Compared to the MLZ, IPS-LD ceramics were more stable as they presented with lower ΔE after surface adjustments and coffee immersion. Conclusions: The surface adjustment that minimally affected the colour of these ceramics was glaze treatment, while the ceramics were most affected by bur adjustments. Coffee aging affected colour stability of all ceramic materials. IPS-LD ceramics presented the lowest Ra values after different clinical adjustments.