An Experiment Study On Reconstruction Of Ribbit Bone Defect With Strontium-containing Brushite Bone Cements

Objectives To evaluate the ability of repairing bone defect with strontium-containing brushite and observing the expression and distribution of basic fibroblast growth factor(b-FGF)in the new osseous tissue.Discussing whether strontium-containing brushite can be used in clinic as bone substitute.Methods To make 5% and 10% strontium-containing brushite by adding strontium chloride according to the Sr/(Sr+Ca).To test and analysis the property,surface morphology and compressive strength of materials by X-ray diffraction,scanning electron microscopy,Cone beam computed tomography.To detect the biocompatibility and safety of materials with acute hemolytic test and skin irritation reaction test.90 healthy male rabbits were randomly divided osteoporosis group(n=36),Castration method + injections of glucocorticoid(a hormone steroid)method is used to quickly establish a rabbit model of osteoporosis in three mouths,osteoporotic castration control group(n=9),osteoporotic blank control group(n=9).Another 36 male rabbits are divided into four groups randomly: blank control group(blank group);brushite bone cement group(DCPD group);doped 5% strontium brushite bone cement group(doped strontium 5% group);doped 10% strontium brushite bone cement group(doped strontium 10% group).To make 5% and 10% strontium-containing brushite by adding strontium Rabbits are defected 10mm×3mm×4mm in bilateral mandibular and implanted materials corresponding,except the blank group.To observe the status of bone defect with images of x ray image and expression and distribution of basic fibroblast growth factor(b-FGF)in fourth,eighth,and twelfth week.To measure the average optical density(MOD)of bFGF positive expression in the same multiples with Image-Pro-Plus 6.0 software,comparing each group at the same and statistics processing.Results 1 Making 5% and 10% strontium-containing brushite successfully;X-ray diffraction results prove strontium form hydrogen phosphate strontium in bone cement and No other impurities;Scanning electron microscopy showed that brushite was composed by a lot of short bar crystal structure and strontium-containing brushite was composed by clusters of crystal structure.The compressive strength of both 5% and 10% strontiumcontaining brushite are lower than brushite,and the 10% strontium-containing brushite is more lower than the 5% strontium-containing brushite.2 The rates of hemolysis below the national standard,then prove three of samples all safety and non-toxic both in vitro and vivo test.3 After both strontium-containing brushite have implanted into the rabbits,its dissolution rate was faster than brushite,and the repair time of bone defect was shorter than brushite group;There was still a large area of defects in the blank group of normal rabbits and osteoporotic rabbits in 12 weeks;The bone defects of strontium-doped brushite group of osteoporosis rabbits have been basically repaired in 8 week,while the brushite group repaired until after 12week;The bone defects of strontium-doped brushite group of osteoporosis rabbits have been basically repaired in 8 week,while the brushite group repaired until after 12week;The bone defects of strontium-doped brushite group of osteoporosis rabbits have been basically repaired in 12 week,while partial defect of brushite group repaired,unfinishing the renovation of bone defects,the defect was concave and the bone defect was obviously delayed.4 Immunohistochemical results: The expression level of b-FGF was the highest in 4 week,lowest in 12 week.Comparing the MOD of b-FGF each group at 4 week we will see significant difference in every two groups(P<0.05),the smallest is blank group and the most is doped 10% strontium group;The difference between the normal group and the osteoporosis group was statistically significant(P<0.05),the MOD of normal group is higher than the osteoporosis group.At 8 week,there are significant differences in every two groups(P<0.05),blank group is the smallest,group with strontium higher than DCPD group;The difference between the normal group and the osteoporosis group was statistically significant,the MOD of normal group is higher than the osteoporosis group.There was no significant different among normal groups at 12 week,but the different among osteoporosis group was statistically significant.Group with strontium higher than DCPD group.That all prove strontium can increase the expression of b-FGF,promoting osteogenesis.Conclusions 1 Making brushite and strontium-containing brushite successfully and the compressive strength close to the strength of the cancellous bone.2 Brushite bone cement and strontium brushite bone cement are safety and non-toxic material.3 Three groups of bone cement has good biocompatibility,and doped strontium brushite degradation speed,osteogenesis effect is good.4 Strontium brushite bone cement can repair bone defect in the condition of osteoporosis,and the effect of doped 10% strontium is more obvious than doped 5% strontium.