## 3 Results and Discussion  
The present study comprehensively compared the microstructure, flexural strength, and fracture toughness differences between Y-TZP ceramics fabricated by SLA and traditional SM. The SM process is considered the gold standard in fabricating ceramics [15]. The microstructures of the two different ceramics were studied using various analytical methods, including micro-CT, SEM, XRD, EDS, and EBSD. The mechanical properties were evaluated by a three-point flexural strength test, and the values were subjected to Weibull analysis. The fracture toughness of the materials was calculated by the indentation fracture method. The micro-CT images of the Y-TZP ceramic specimens produced by the two different approaches were similar. Both ceramic specimens exhibited a relatively pore-free dense body. The difference in density between the two ceramics was not clearly visible, and density analysis showed only a slight difference in value between the SM (6.077 g/cm\({}^{3}\)) and SLA (6.043 g/cm\({}^{3}\)) ceramics. This finding may be attributable to the difference in the final sintering temperature and potentially in the Al\({}_{2}\)O\({}_{3}\) content between the two ceramics [23]. The electron channeling contrast images of the SM and SLA Y-TZP ceramics are shown in Figure 1. The images with a magnification of 10,000\(\times\) reveal that the small pores were more frequently detected in the SLA specimen than in the SM specimen. The grains of the two Y-TZP ceramics were uniform and tightly arranged. The SM specimen was composed of larger grains than the SLA specimen. This finding may be due to the higher sintering temperature of the SM specimen inducing more grain growth [24]. Figure 2 is the XRD spectra of the two different Y-TZP ceramics. The patterns show a mixture of structures with tetragonal and monoclinic ZrO\({}_{2}\) as the major and minor phases, respectively. In addition, Al\({}_{2}\)O\({}_{3}\) content was detected in the spectra of both materials. Overall, this XRD analysis reveals that the ceramics shared a similar phase composition to each other, in accordance with previous XRD studies by [PERSON] et al. [5] and [PERSON] et al. [25]. The results of EDS analysis of the two different Y-TZP ceramics are illustrated in Figure 3. Although the pores and Al\({}_{2}\)O\({}_{3}\) were not clearly distinguished in the ECC images (Figure 1), the presence of Al\({}_{2}\)O\({}_{3}\) within the ceramics was revealed by EDS elemental mapping. In the EDS images, the presence of pores was more frequently detected in the SLA specimens than in the SM specimens. Figure 1: Electron channeling contrast images of the SM- (**a**) and SLA-fabricated (**b**) Y-TZP ceramics (magnification = 10,000\(\times\); scale bar = 1 \(\upmu\)m). Figure 2: XRD patterns of the SM (**a**) and SLA (**b**) Y-TZP ceramics. Peaks of monoclinic and tetragonal phases were identified by ICDD card no. 01-078-0047 and 01-088-1007, respectively. Al\({}_{2}\)O\({}_{3}\) was also identified by ICDD card no. 04-013-1687. The EBSD maps of the SM and SLA ceramic specimens are presented in Figure 4. The grain size and phase fraction of the ceramics derived from the EBSD images are also summarized in Table 1. In general, the findings are in accordance with those of the XRD test (Figure 2). The BC and IPF maps showed that the SLA ceramic was composed of finer grains (0.4 \(\upmu\)m) than the SM ceramic (0.7 \(\upmu\)m). [PERSON] [24] reported that a longer time and higher temperature of sintering increase the grain size of the sintered zirconia body. In addition, the grain sizes (0.68 and 0.33 \(\upmu\)m at 1600 \({}^{\circ}\)C and 1450 \({}^{\circ}\)C, respectively) obtained in a previous study [24] resemble those in the current study. The Y-TZP ceramic surface is highly stress-sensitive, thus easily causing tetragonal-to-monoclinic (t-m) phase transformation [26]. Therefore, extreme care should be taken in preparing and polishing zirconia samples for EBSD analysis to prevent such phase transformation on the surface [27].