Effect of Different Veneering Techniques on Mechanical Properties and Translucency of Zirconia Framework-veneer Ceramic Crowns.

Aim: The aim of this study is to assess the effect of veneering techniques on bond strength, fracture resistance (FR), and translucency of zirconia framework-veneer ceramic crowns.

Materials and methods: Four commercially available glass ceramic materials were used in this study: IPS e.max CAD (Ivoclar Vivadent), IPS e.max Zirpress (Ivoclar Vivadent), IPS e.max Ceram powder (Ivoclar Vivadent), and IPS e.max Zir CAD Prime (Ivoclar Vivadent). The first three materials were used to fabricate veneering layer over the fourth material (zirconia frameworks) to create samples in the forms of crowns (core veneered with superstructure) to study the FR (n = 30) and plates veneered with ceramic discs to study shear bond strength (SBS) and translucency parameter (TP) (n = 60). A total of 90 samples were constructed. The samples were divided into three equal groups: Group A: CAD-ON Technique (n = 30); group B: Press-over technique (n = 30); and group C: Ttraditional layering technique (n = 30). Each group is divided into three subgroups according to the type of test. Subgroup (1): Shear bond strength (n = 10). Subgroup (2): Fracture resistance and subgroup (3) translucency (n = 10). A universal testing machine (5ST; Tinius Olsen, England) was used to measure FR and SBS. A spectrophotometer was used to measure color parameters (L*, a*, b*) and total luminous transmittance (τ) of the specimens for calculation of TP. One-way analysis of variance (ANOVA) test combined with a post hoc test was used to analyze the data (α = 0.05).

Results: The mean FR was high for the CAD-ON technique (N ± SD) (1723.80 ± 110.96) followed by the layering technique (1092.70 ± 181.35), and lowest for the press-over technique (820.80 ± 75.95). The difference between the groups was statistically significant (p-value < 0.05). The mean SBS values were also highest for the CAD-ON technique (MPa ± SD) (28.00 ± 1.96), followed by the layering technique (25.71 ± 0.79), and lowest for the press-over technique (20.80 ± 1.46). For TP, the press-over technique had the highest mean value (6.05 ± 0.32), followed by the layering technique (5.56 ± 0.27), and then CAD-ON technique (5.15 ± 0.33). A statistically significant difference was observed among the three techniques (p < 0.05).

Conclusion: The file-splitting (CAD-ON) veneering technique shows higher FR and bonding strength. In contrast, veneering zirconia using the layering and press-over techniques resulted in samples with higher translucency compared to those veneered with the CAD-ON technique.

Clinical significance: The clinical significance lies in the potential to enhance the longevity, esthetics, and overall performance of dental restorations. By understanding how various veneering techniques impact these factors, dental professionals can improve durability, enhance esthetic outcomes, and guide treatment planning. How to cite this article: Sanad AG, Mohsen CA, Mohamed ME. Effect of Different Veneering Techniques on Mechanical Properties and Translucency of Zirconia Framework-veneer Ceramic Crowns. J Contemp Dent Pract 2025;26(3):294-302.