## 4 Results
### Scanning Electron Microscopy, Coupled with Energy-Dispersive Spectroscopy  
SEM images of the C and M sides of the samples that exhibited the most significant microstructural modifications, namely, 2_P1, 2_P2, 4_P1, and 4_P2, are shown in Tables 7 and 8, along with the chemical composition, as determined by EDS. Table 8 also includes the results of SEM-EDS for the as-3-D-printed Co-Cr-W alloy. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **AFM Micrograph** & **Histogram of Height Distribution** & **Sq** & **Sy** \\  & & **(nm)** & **(nm)** \\ \hline
3\_P1\_M & & 16.0 & 88.16 \\
3\_P2\_M & & 11.5 & 12.64 & 83.67 \\
4\_P2\_M & & 11.2 & 16.8 & 103.04 \\ \hline
4\_P2\_M & & 11.85 & 103.04 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: _Cont._ \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline Sample & SEM Image & Si & Al & K & Na & Zr & Ti & V \\  & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** \\ \hline
2\_P1\_C & 28.90 & 11.17 & 11.19 & 10.47 & 38.27 & - & - \\ \hline
2\_P2\_C & 28.90 & 11.17 & 11.19 & 10.47 & 38.27 & - & - \\ \hline
35.20 & 11.31 & 13.42 & 8.74 & 18.65 & 9.60 & 3.08 \\ \hline
4\_P1\_C & 28.90 & 11.17 & 11.19 & 10.47 & 38.27 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 7: SEM (\(\times\)3000 magnification) and EDS images of 2_P1_C, 2_P2_C, 4_P1_C, and 4_P2_C. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **SEM Image** & **Si** & **AI** & **K** & **Na** & **Zr** & **Ti** & **V** \\  & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** & **wt \%** \\ \hline
4_P2_C & & 58.19 & 15.35 & 14.69 & 11.77 & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 7: _Cont._According to the SEM image, the surface of the 2_P1_C sample, layered with the opaquer and followed by firing at 930 \({}^{\circ}\)C, is characterized by high roughness and numerous defects, including the discontinuities and pores highlighted in the image. The observed porosity is probably related to opaquer condensation issues. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **SEM Image** & **Co** & **Cr** & **W** & **Si** \\  & **wt \%** & **wt \%** & **wt \%** & **wt \%** \\ \hline
2\_P2\_M & & 42.58 & 34.93 & 9.87 & 12.62 \\ \hline
4\_P1\_M & & 51.5 & 34 & 9.45 & 5.05 \\ \hline
4\_P2\_M & & 42.35 & 38.12 & 8.91 & 10.54 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: _Cont._The SEM image of the 2_P2_C sample, layered with the opaqueer following firing at 940 \({}^{\circ}\)C, reveals an improved surface roughness and texture, combined with a smaller volume fraction of surface defects, compared to the 2_P1_C sample fired at a lower temperature. The SEM image of the surface of the 4_P1_C sample, with a multi-layered ceramic coating consisting of opaqueer, dentin, and enamel, the subsequent firing at different temperatures (930 \({}^{\circ}\)C, 910 \({}^{\circ}\)C, and 900 \({}^{\circ}\)C) reveals a relatively smooth texture; no significant porosity can be observed. The SEM image of the 4_P2_C sample with a multi-layered ceramic coating, consisting of opaqueer, dentin, and enamel, followed by firing at different temperatures (940 \({}^{\circ}\)C, 930 \({}^{\circ}\)C, and 920 \({}^{\circ}\)C), exhibits a very smooth and homogeneous surface texture as a result of higher firing temperatures, while no significant surface defects, i.e., voids and microcracks, are detected. The EDS analysis of the 2_P1_C sample revealed contents of Si, Al, K, Na, and Zr specific to the ceramic opaqueer. In the case of the 2_P2_C sample, additional Ti and V contents were found, with the Zr content being much lower compared to that in the 2_P1_C sample, corresponding to the chemical composition of the opaqueer as given by the manufacturer. The EDS chemical analysis of the 4_P1_C and 4_P2_C samples revealed contents of Si, Al, K, and Na that are specific for feldspathic ceramics.