The Effect Of Force And Inflammatory Factors On The Expression Of Osteogenesis Regulators In HPDLCs

It is known that, in bone tissue, osteocyte is the direct responder to force. But compared with other bone tissue, tooth-PDL-alveolar bone construct a more complicated structure. Without the PDL, force can not lead to alveolar bone remodeling. And in the orthodontic treatment process, PDL which is a unique structure is capable of responding orthodontic force stimulus independently, starting alveolar bone osteogenesis and osteoclastogenesis. Alveolar bone remodeling leaded by orthodontic force brings no loss of bone mass. However, inflammation may cause alveolar bone loss. This implies that force and inflammation induce differentiations of neoblasts via different pathways. The strength of force affects the differentiation of periodontal ligament cells, and takes antagonistic or synergistic effects with inflammatory cytokines by complex autocrine and paracrine regulation. The complicated process leads to local bone resorption and bone deposition in bone remodeling. We will observe the effect by force signals and inflammatory cytokines (IL-1 β,TNF α,IL-6,IL-23) on the expressions of functional proteins (OPG,RANKL,OPN) during differentiation of periodontal ligament cells to osteoblasts and osteoclasts.Method:In this study, human PDLCs were exposed to inflammatory cytokines and cyclic mechanical tension with a maximum 5% elongation for different durations. We then examined the expression of signaling molecules related to osteogenesis and osteoclastogenesis at protein level.Result:Inflammatory cytokines reduce the expression of osteogenesis regulators in hPDLCs, while cyclic-tension force can improve its expression. But the result of combined effect is suppression, force cannot resist the role of inflammatory cytokines to the expressions of functional proteins during differentiation of periodontal ligament cells to osteoblasts.Conclusion:Inflammatory cytokines have inhibitory effect on the expression of the osteogenic factors, and cyclic-tension which promote the osteogenetic process unable to offset this inhibitory effect...