Macrophages have been found to regulate the effects of biomaterials throughout the entire tissue repair process as an antigen-presenting cell. As a well-defined osteoconductive biomaterial for bone defect regeneration, tricalcium phosphate (TCP) has been found to facilitate a favourable osteoimmunomodulatory response that can shift macrophage polarization towards the M2 phenotype. In the present study, our group discovered that a histone methyltransferase enhancer of zeste1 (EZH1) was drastically downregulated in Thp1 cells stimulated by TCP, indicating that EZH1 may participate in the macrophage phenotype shifting. Furthermore, the NF-κB pathway in macrophages was significantly downregulated through stimulation of TCP, suggesting a potential interaction between EZH1 and the NF-κB pathway. Utilizing gene knock-down therapy in macrophages, it was found that depletion of EZH1 induced M2 macrophage polarization but did not downregulate NF-κB. When the NF-κB pathway was inhibited, the expression of EZH1 was significantly downregulated, suggesting that the inhibition of EZH1 may be regulated by the NF-κB pathway. These novel findings provide valuable insights into a potential gene target system that controls M2 macrophage polarization which ultimately favours a microenvironment suitable for bone repair.

Backgroud: Regardless of application scenarios, proper mechanical characteristics and degradation properties are prerequisites for horizontal platelet rich fibrin (H-PRF) to manifest its ability. Among the methods used to modify PRF, thermal manipulation is promising as it is easy to handle without adding extra additives. Yet there is no consensus on optimal temperature treatment. This study aimed to investigate the effects of heating on the biological and mechanical characteristics of H-PRF and explore the optimum heating temperature for H-PRF thermal treatment. Methods: We employed a series of temperature gradients, room temperature, 50℃, 75℃, 90℃, 105℃. The microstructure and the mechanical properties were recorded by Scanning Electron Microscope (SEM) and tensile strength tests respectively. The degradation rate of H-PRF membranes was examined by digestion assay with plasmin and trypsin. The viability of cells within H-PRF membranes and the proliferation of osteoblasts cultured with extracts from different H-PRF groups was evaluated using CCK-8 assays. Results: Compared with the nonheated group, overheated manipulation beyond 90℃ can significantly prolong the degradation properties for up to 3 to 4 weeks and enhance the mass stress of H-PRF membranes. A high-temperature treatment of 105℃ accompanied by the cell activity beneath H-PRF reduced more than half, and thus, the biological effect on human osteoblasts (hFOBs) also reduced dramatically. Conclusions: High thermal manipulation can prolong the degradation properties and enhance the mechanical properties of PRF membranes accompanied by the loss of biological effect.

BACKGROUND The history of allogenic tooth transplantation can be traced back to the 16th century. Although there have been many successful cases, much needs to be better understood and researched prior to the technique being translated to everyday clinical practice. CASE SUMMARY In the present report, we describe a case of allogenic tooth transplantation between a mother and her daughter. The first left maxillary molar of the mother was diagnosed with residual root resorption and needed to be extracted. The 3rd molar of the daughter was used as a donor tooth. Prior to transplantation, a 3D printing system was introduced to fabricate an individualized reamer drill specifically designed utilizing the donor's tooth as a template. The specific design of our 3D printed bur allowed for the recipient site to better match the donor tooth. With the ability to 3D print in layers, even the protuberance of the root can be matched and 3D printed, thereby minimizing unnecessary bone loss. CONCLUSION Our study is a pioneering case combining 3D printing with allogenic tooth transplantation, which could be able to minimize unnecessary bone loss and improve the implant stability. This article aims to enhance our understanding of allogenic tooth transplantation and 3D printing, and may potentially lead to tooth transplantation being utilized more frequently - especially since transplantations are so commonly utilized in many other fields of medicine with high success rates.

Aims: Inflammation is a key process involved in the early stages of periodontal regeneration, where immune cells are responsible for the recruitment of osteoblast to facilitate periodontal regeneration. The aim of the present study was to explore the effect of platelet‐rich fibrin (PRF) on macrophage polarization, and thereafter to investigate its effect on osteoblast recruitment to enhance early‐stage periodontal regeneration. Materials and Methods: The extracted liquids of PRF, produced using fixed‐angled and horizontal centrifugation protocols, were utilized to stimulate Thp1 to study macrophage proliferation and polarization. Thereafter, the supernatants of Thp1 were collected and utilized to stimulate the migration of human bone marrow osteoblasts, to investigate the recruitment of osteoblast via macrophage polarization. Results: PRF stimulated the proliferation and recruitment of macrophages, with horizontal centrifugation protocols demonstrating significantly greater potential when compared to fixed‐angled. Furthermore, PRF was able to enhance the recruitment of osteoblast via macrophage polarization, with horizontal platelet‐rich fibrin (H‐PRF) demonstrating the most significant increase. Conclusion: The present study explored a promising mechanism of the periodontal regeneration function of PRF, by inducing macrophage polarization, thereby enhancing osteoblast recruitment, with horizontal centrifugation significantly improving these findings.