| Objective:To investigate the microstructure,biomechanical properties andosseointegration performance of new bones induced of ?-TCP combined with A-PRFby establishmentof bone defect models in rabbit.Furthermore,it provides a basic experimental basis for the clinical application with bone regeneration technique to increase bone mass.Method:36rabbits were randomly divided into the A-PRF group,?-TCP group and ?-TCP&A-PRF group(n=12),thoserabbits were used to prepare cylindrical bone defect with a diameter of 6.0mm and a depth of 10 mm in the lateral femoral condylea,the A-PRF group was implanted with A-PRF membrane,the ?-TCP groupwas implanted with ?-TCP and the ?-TCP&A-PRF groupwas implanted with ?-TCP&A-PRF(1:1).Postoperative 8 and 12 weeks later,3 rabbitswererandomly selected to be killed in A-PRF group,?-TCP group and ?-TCP&A-PRF group,removed the new bone samples,then detected the microstructure of new bone by Micro-CT and the mechanical properties of new bone by compression experiment.Besides postoperative 12 weeks,the remaining 6 rabbits in the A-PRF group,?-TCP group and ?-TCP& A-PRF group were implanted with the same size DIO implants(3.8mm*10mm)at the center of the new bone area.At the same time,the torque value after implantation of the implant was measured to detect the mechanical propertiesof the new bone against shearing.At 4 weeks and 12 weeks after implant implantation,three experimental rabbits were killed in each group,bone specimenswith implant were removed from the operation area,Micro-CT was used to detect the bone formation around the implants and pull-out testing of implants to detect biomechanical properties of the implant-bone interface.Results: 1.36 rabbits bone defect modelswere successfully and 36 implants were successfully implanted,the wound healed well without any obvious infection,no implantloosening or shedding occurred.2.New bone of Micro-CT measurement and analysis: Each group had a new-born bone formation at 8 weeks and 12 weeks.At 8 weeks after the GBR operation,A-PRF group,?-TCP group and ?-TCP&A-PRF group showed low-density newborn bone images and the low-density imaging range of the A-PRF group was the smallest.The low-density newborn bone images of the ?-TCP group and ?-TCP&A-PRF group were scattered in high-density tissue image.At 12 weeks,the low-density imaging range of each group was significantly increased,and the structure of bone-trabecula structure was orderly and interlaced,which was similar to normal bone tissue.The high-density shadow range was smaller than that at the 8week of the ?-TCP group and ?-TCP&A-PRF group,and the number of bonetrabecula in the ?-TCP& A-PRF group was numerous and closely related.Statistical analysis of new bone with BV/TV,Tb.Th,Tb.Sp and Tb.N index availablethat ?-TCP&A-PRF group is better than A-PRF and ?-TCP group,?-TCP&A-PRF group and?-TCP group at 8 weeks that Tb.Th andTb.Sp were no statistically significant difference(P>0.05),and other indicators at the same time points between two groups compare were statistically significant(P< 0.05).The same group of 8 weeks and 12 weeks were statistically significant(P<0.05)by t test analysis.3.New bone of compression test: At 8 weeks,the compression strength of A-PRFgroup,?-TCPgroup and?-TCP&A-PRFgroup were respectively7.123±0.641N/mm2,8.108±0.470N/mm2 and 8.940±0.618N/mm2.With the extension of bone repair time,the compressive strength of each group all increased at 12 weeks,the compression strength of A-PRFgroup,?-TCP group and?-TCP&A-PRF group were respectively 9.243±0.374N/mm2,10.632±0.784N/mm2 and11.905±1.141N/mm2.There were statisticallysignificant differences between the groups at the same time(P<0.05),and the t-test analysis of the same group in 8 weeks and 12 weeks were statistically significant(P<0.05).4.Implants implanted in torsion test:Postoperative 12 weeks,each implants implanted of experimental rabbits obtained good initial stability,the insertion torque value(ITV)of A-PRF group,?-TCP group and?-TCP&A-PRF group were respectively 16.85±2.24 N.cm,18.40±2.33 N.cm and 21.4±2.57 N.cm,there were statistically significant differences among the three groups(P<0.05).5.Micro-CT measurement of implant-bone interface: After 4 weeks of implants placement,the each group formed bone union with the surroundingimplants,and a small amount of new bone around the implants,and the bone trabecula was sparse and the numberwas small.After the implant was implanted with 12 weeks,the newly formed bone of the implant surface was closely combined with the implant,and the number of bone trabecula increase significantly.Statistical analysis of RIO area new bone around implant with BV/TV,Tb.N,Tb.Th and Tb.Sp indicators available that ?-TCPP&A-PRF group is superior to the A-PRF group and?-TCP group,the comparison among the three groups was statistically significant(P<0.05),The same group ofimplant implantationat 4 weeks and 12 weeks,therewere statistically significant(P<0.05)by t test analysis.5.Push-out testing of implant : The results showed that the maximum force of A-PRF group,?-TCP group and ?-TCP&A-PRF group were respectively 92.585±13.250 N,100.627±10.253 N and 113.98±11.251 N at 4 weeks after implant placement.As time went on,the maximum strength of each group was significantly increased at 12 weeks,A-PRF group,?-TCP group and ?-TCP& A-PRF group were respectively 354.469±36.403 N,398.047±18.480 N and 459.88±32.667 N.At the same time,the comparison among the three groups were statistically significant(P<0.05).The t-test analysis of the same group in 4 weeks and 12 weeks of implant placement were statistically significant(P<0.05).Conclusion:1.In this experiment,when the bone defect model was established in the femoral condyles of rabbits,the metatarsal line was used as the main reference marker,and the anatomicalsite was fixed.And successfully establish the rabbits femoral condylesof ?-TCPloaded withA-PRF bone inducted model.2.Bone substitution material of ?-TCP loaded with A-PRF,A-PRF and ?-TCP all can guide the formation of new bone,and the quality and mechanical properties of the new bone induced by ?-TCP&A-PRF composites are better than those induced by A-PRF or ?-TCP bonesubstitution materials alone.3.The new boneinduced by ?-TCP&A-PRF,A-PRF and ?-TCP that all can form good bone integration with implant,and it is more closely related to bone consolidation in the ?-TCP&A-PRFgroup.The combined strength of the implantbone interface of ?-TCP&A-PRF is superior to that of A-PRF or ?-TCP bone substitutionmaterials,which effectively promotes the densification of the bone around the implant. |
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