**3. Results**

## *3.1. Surface Roughness*

Mean and standard deviation for Ra scores of CoCr specimens after using different fabrication techniques are presented in Table 1. SLM fabricated copings displayed the highest mean values (2.251 ± 0.310 μm). Cast/LWT specimens presented the lowest mean Ra score (1.055 ± 0.184 μm). Ra values among all investigated groups were statistically significant (*p* < 0.05). SLM specimens showed significantly higher Ra than DLP cast copings (1.590 ± 0.167 μm) (*p* = 0.001). Mean Ra of Cast/LWT copings was lower than CAD-CAM (1.840 ± 0.236 μm) (*p* = 0.001), SLM (*p* = 0.001), and DLP cast (*p* < 0.05) specimens respectively. The micrographs obtained for surface roughness assessment are presented in Figure 2. The uniform high roughness was observed in SLM samples (2 D) and the DLP-Cast specimen displayed a smoother surface with minimal localized craters (2 C).

**Table 1.** Comparison of surface micro-roughness of the CoCr copings.


\* Statistical significant difference using Tukey Kramer post hoc test; \$ Statistical significant difference using ANOVA.

**Figure 2.** Surface roughness (Ra) micrographs for groups (**A**) Cast/LWT, (**B**) CAD-CAM, (**C**) DLP-Cast, and (**D**) SLM.
