Osteogenic Properties Of Demineralized Dentin Matrix-fibrin Glue Composites

Objective: Insufficient bone volume is a problem facing implant repair.Numerous studies have confirmed that demineralized dentin matrix(DDM)has osteoinductive and osteoconductive abilities as a scaffold material for bone tissue engineering,but the particulated bone graft material of DDM is quite loose,resulting in a suboptimal effect of bone augmentation surgery.sticky bone(SB),which is composed of bone powder,growth factors and fibrin,is plastic and structurally stable,which facilitates repair of bone defects.Fibrin glue(FG)mainly acts as a hemostat,sealant and adhesive.In this study,we fabricated DDM-FG composites by mixing the homemade DDM with FG in different ratios,compared their porosity and pore size changes,and performed in vivo experiments to compare their abilities to repair calvarial bone defects in rabbits,which may provide an experimental basis for the clinical study of ddm-fg mixture in repairing bone defectsMethods: 1.Mix self-made DDM and FG according to the ratio of1g:0.1ml(DDM-FG1)and 1g:0.5ml(DDM-FG2)to make DDM-FG composites,observe DDM,DDM-FG1 and DDM-FG2 by scanning electron microscope Surface morphological characteristics,porosity and pore diameter were measured by Image J;2.Four 6mm-diameter bone defects were made on the skulls of 24 adult Japanese big-eared rabbits,and DDM-FG1,DDM-FG2,and autologous bone tissue were respectively implanted,leaving one Without any treatment for bone defect as blank control,6 rabbits were sacrificed at 2w,4w,8w and 12 w,and the skull specimens were collected.The skull specimens of the three rabbits were fixed with 4% paraformaldehyde,and Micro-CT measure bone volume/tissue volume(BV/TV)and trabecular bone thickness(Tb.Th);3.The skull specimens of the three rabbits were stored in a-80°C refrigerator,and the expression levels of ALP,RUNX2,OPN,and OCN in different periods were detected by Western Blot.Results: 1.FG can bind DDM,and DDM in DDM-FG2 is more tightly bound than DDM-FG1;2.DDM pore size: 2.51±0.49μm,porosity 12.77%,the porosity of DDM-FG1 is 10.32%,and DDM-FG2 is 5.27%;after DDM and FG are mixed,FG partially covers the surface of DDM,and porosity of DDM become smaller;3.Bone volume fraction(BV/TV)was found by Micro-CT examination,showing the trend of autologous bone>DDM-FG2 > DDM-FG1 >blank control,and the trabecular bone thickness(Tb.Th)of DDM-FG2 and DDM-FG1 were shown at higher levels at various stages of healing.4.The expression of bone formation related proteins ALP,RUNX2,OPN and OCN detected by western blot showed that the expression of ALP protein in DDM-FG1 and DDM-FG2 was lower in early healing,but showed the same trend as BV/TV in late healing,and the expression of RUNX2 and OPN in the whole bone healing period was consistent with that of BV/TV.The expression concentration of OCN was low in 2w of healing time,and could not be shown in the amount of 20ug/ml,but the expression in autogenous bone group was higher in 4w,8w and 12 w.Conclusions: 1.DDM and FG can be mixed to make sticky bone.2.DDM-FG composites can promote bone healing,and when DDM-FG2(DDM:FG=1g:0.5ml)the bone healing ability is stronger,but the bone repair ability is lower than that of autologous bone.The expression of RUNX2 and OPN protein was consistent with the new bone volume(BV/TV)during the healing process.