This study investigated the effect of differences in granular size of coral granules (CG) derived from the exoskeleton of terrestrially cultivated Acropora coral on the bioresorption behavior in tooth extraction sockets. A group of small granules (600-1,000 µm in diameter) was used as the control group, and a group of large granules (1,000-2,000 µm in diameter) was used as the experimental group. CG was implanted into the tooth extraction sockets of 2-year-old female beagle dogs. Observation periods were 4 weeks and 12 weeks after implantation, and evaluation was performed using radiographic imaging and histopathological findings. The results showed that CG residue was observed in the tooth extraction sockets in both groups at 4 weeks after implantation. At 12 weeks after implantation, complete absorption of CG was observed in the small granule group, while some granular residue was confirmed in the large granule group by both radiographic imaging and histopathological findings. In summary, the bioabsorption behavior of bone graft material derived from the exoskeleton of artificially cultivated Acropora coral is influenced by differences in granule size, suggesting the possibility of controlling the role of the material in the tooth extraction socket healing process by adjusting the granule size.

This study aimed to clarify the in vivo behavior of coral granules (CG), a bone graft material derived from coral exoskeleton with calcium carbonate as its main component, during the healing process of tooth extraction sockets. CG (particle size: 600–1,000 µm) was implanted in tooth extraction sockets of beagle dogs, and histological and morphometric analyses were performed after 4 weeks. As a result, CG induced new bone formation within its porous structure, and the granule size significantly decreased from 911.3 µm before implantation to 378.8 µm after 4 weeks (p<0.05). Furthermore, the localization of TRAP-positive cells suggested the involvement of osteoclast-like cells, indicating the possibility that CG absorption and bone formation proceed in a coordinated manner. In conclusion, CG is suggested to be a useful bone graft material possessing both bone-inducing and bioresorbable properties.

To investigate the mechanism of structural reconstruction in demineralized bovine enamel interprismatic regions following the application of a calcium carbonate-based material (4D) and acidulated phosphate fluoride (APF) using scanning electron microscopy (SEM). Bovine enamel was demineralized using 5% EDTA for 30 minutes. Specimens were treated with 4D alone (4D group) or 4D followed by APF (4D+APF group). After ultrasonic cleaning, microstructures were observed via SEM. The 4D group exhibited structural reconstruction through the formation of plate-like crystal structures in the demineralized interprismatic regions. In the 4D+APF group, a layer of spherical crystals formed on the outermost surface; however, the plate-like crystals from the 4D treatment were preserved beneath this layer, demonstrating the formation of a stable bilayered structure. The application of 4D induced structural reconstruction via plate-like crystal precipitation, suggesting physiological epitaxial growth. The sequential application of 4D and APF formed a distinct bilayered structure, suggesting a potential role in novel hard-tissue barrier reconstruction.