A study of the healing mechanisms of destructive periapical lesions and regenerative medicine for periapical bone defect

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It has been reported that there are three key factors, such as cells, scaffolds and signaling molecules (growth factors), in the regenerative medicine. However, regenerative mechanisms of large-size defects in periapical lesions are not yet well understood. This study presented herein was therefore undertaken to define the progression and healing mechanisms in periapical lesions, and the effects of regenerative materials was investigated. It was showed that transplanted proliferating tissue produced by GTR membrane promoted the formation of new periodontal ligament(PDL) around the tooth. We have established three immortal human PDL fibroblast line by transfecting SV40T-Ag and hTERT into primary PDL fibroblasts.These immortalized cells was useful models for elucidating the biological features and regenerative mechanisms of human PDL. Mineral Trioxide Aggregate could up-regulated osteopontin and osteocalcin mRNA in human PDL to induce their differentiation. FGF-2 enhanced hyaluronan prod … More uction by both human dental pulp cell and human PDL cell and hyaluronan synthase (HAS)1 and HAS2mRNA expression in both cells. Immune and nervous systems play key roles in periapical pathosis, and functional interactions between antigen-presenting cells and nerve fibers may play some roles in the development of self-defense reactions in periapical lesions. In addition, expression of RANKL is correlated with periapical lesion expansion, and followed by the expressions of RANK and OPG. Platelet-rich plasma (PRP) and washed platelets were potent inhibitors of RANKL-induced osteoclast differentiation in RAW264.7 cells. After application of Emdogain containing enamel matrix protein to the root surface, the formation of new cementum and more remarkable recovery of the bone tissue were observed. Although the expression of cytokines, such as IL-1β, RANKL, and RANK were hardly seen, BMP-2and BMP-4 expressing macrophages were increased. It was suggested that wound healing macrophages may express BMP and play an important role in the regeneration of periodontal tissue at the apex in EMD application. Less