## 3 Results and Discussion
### Bone Regeneration Characteristics of the Implanted Materials  
The individual histopathological evaluations are presented in Figures 6-9. At the 2-week observation, the process of new bone formation (ossification) was negative for every group (Figure 6). At the 4-week observation, the ossification was initialized in every group. The defects in the blank group were filled with fibrinous connective tissue with a very limited osseous fragment (Figure 7a). In the \(\alpha\)-CSH and control groups, the majority of tissue was branched, prosperous trabecular bone, and accompanied by fibrinous connective tissue and adipose tissues (Figure 7b,c). Figure 8 illustrates the 8-week observation of the defect. It was found that the ossification in the \(\alpha\)-CSH group was decreased (Figure 8c) but similar to the control group (Figure 8b). At this stage, the tissue remodeling was in progress, and the new bone was annealed to the lamellar bone with bone marrow and adipose tissue infiltration. Twelve weeks after implantation, original structure was not restored in the blank group (only a small amount of new bone formation) (Figure 9a). On the contrary, bone in the control and \(\alpha\)-CSH groups was repaired with intact lamellar bone and bone marrow tissues (Figure 9b,c), while the \(\alpha\)-CSH group exhibited more regenerated bone tissues than that of the control group. This feature demonstrated that \(\alpha\)-CSH may have a promising potential to promote bone healing and regeneration after implantation. Figure 5: Material volume was calculated by \(\mu\)-CT scanning in defects at 2, 4, 8, and 12 weeks after implantation of \(\alpha\)-CSH and control material. The degradation at 4 and 8 weeks was similar between control material and \(\alpha\)-CSH. At last observation, the \(\alpha\)-CSH reduced more than the control material. (\(p>0.05\)). Figure 6: Images of hematoxylin and eosin (H&E)-stained bone tissue 2 weeks after implantation: (a) blank, (b) control, and (c) \(\alpha\)-CSH samples. Calcium sulfate has been recommended for use in the management of osseous defects after curetttage of osteomyelitisitis, benign lesion, and trauma [45]. A high bone formation cloud has also been discovered in previous studies which found that calcium sulfate produces significantly more new bone formation and is completely effective in preserving alveolar bone in post-extraction ridge dimensions [46; 47]. The new bone mineralization rate of calcium sulfate is similar to the rate of autograft material leading to its promising application in clinical practice [49]. In our previous study [27], the innovative \(\alpha\)-CSH with uniform and specific crystal structure had more water absorption ability in a dehydrated state for setting [50]. The rapid setting causes the proteins and growth factors in blood to be quickly absorbed into the bone defect area with implanted \(\alpha\)-CSH [35], hence offering enough nutrition for the osteoblasts to promote the formation of angiogenesis. In addition, when calcium sulfate is resorbed, it serves as a concentrated source of calcium, which is needed during mineralization in active bone remodeling as calcium ions play an important role in offering osteoblasts for bone formation [45]. Therefore, the analysis results have proved the potential to enhance in vivo biocompatibility of the \(\alpha\)-CSH group in the rabbit model. As stated above, the microwave-synthesized innovative \(\alpha\)-CSH biocearamic is believed to possess superior bone healing and regeneration ability for clinical applications. However, future tests will require larger sample sizes as well as larger animals such as  
Figure 8: Images of H&E-stained bone tissue 8 weeks after implantation: (**a**) blank, (**b**) control, and (**c**) \(\alpha\)-CSH samples. Figure 7: Images of H&E-stained bone tissue 4 weeks after implantation: (**a**) blank, (**b**) control, and (**c**) \(\alpha\)-CSH samples. Figure 9: Images of H&E-stained bone tissue 12 weeks after implantation: (**a**) blank, (**b**) control, and (**c**) \(\alpha\)-CSH samples.