The Effect And Mechanism Of Diabetes On Osseointegration Of Dental Implants

Objective:The aim of this study is to investigate the effect of high glucose levels on proliferation and osteogenic ability in MC3T3-E1 osteoblastic cell line, and to explore the regulatory mechanism of PI3K/Akt signalling pathway in vitro. By animal experiments, this project tries to investigate the impact of diabetes mellitus (DM) and different glycemic control times on early osseointegration of dental implants, and to explore possible mechanism by expression and significance of integrinα5β1 and fibronectin (FN) in osseous tissue around implant in vivo.Materials and Methods:In vitro experiment:Different concentrations of glucose regulate proliferation and osteogenic differentiation of osteoblasts via the PI3-kinase/Akt pathway.The cultures were divided into 8 treatment groups:four concentrations of glucose (5.5, 15.5,25.5 and 35.5 mM) with or without LY294002. The cell proliferation, alkaline phosphatase (ALP) assay, alizarin red staining of mineralized nodule, osteogenic genes and P-AKT expression were analyzed.In vivo experiment:Potential Mechanism for Osseointegration of Dental Implants in ZDF Rats.33 Male Zucker Diabetic Fatty (ZDF) Rats 3 months old were divided into three groups:Group A, diabetic rats with dental implants (controls); Group B, diabetic rats treated with insulin and implants placed simultaneously; Group C, diabetic rats treated with insulin until serum glucose at a constant level and then implants be placed. Rats were sacrificed at 7,14,30,60 days after implant surgery in batches. Immunohistochemistry analysis was used to detect the expression of integrin α5β1 and FN in osseous tissue around the implants in each group.Results:Cell proliferation、ALP activity、mineralization、osteogenic genes(RUNX2, OSX, OPN, OCN) and P-AKT expression in MC3T3-E1 cells were increased while the glucose concentration changed from 5.5 mM to 15.5 mM. However, when the glucose concentrations continue to increase from 25.5 mM to 35.5 mM, the proliferation and osteogenic ability in MC3T3-E1 cells were gradually declined. Furthermore, these effects were significantly inhibited by PI3K/Akt inhibitor LY294002 at a glucose concentration of 15.5 mM which was the optimum.Fibronectin and integrin α5β1 were detected in osseous tissue around the implants. The expression of integrin α5β1 and FN in Group C were stronger than the other two groups.14 days after implantation, expression of integrin α5β1 in group B was stronger than that in group A.60 days after implantation, the expression of FN in group B was stronger than that in group A, and there were statistically significant.Conclusions:Appropriate high glucose concentration (15.5 mM) can increase osteogenic differentiation by activating PI3K/Akt pathway in MC3T3-E1 cells, but exorbitant high glucose concentrations (25.5 mM and 35.5 mM) inhibited the biomineralization process. Findings indicated that PI3K/Akt pathway plays an important role in the physiological process of MC3T3-E1 cells. Both Fibronectin and integrin α5β1 participate in adhesion of osteoblasts and act as positive signal of bone implant interface. Diabetes interfere implant osseointegration by way of deferring expression of Fibronectin and integrin α5β1.