Experimental Study On Restoration Of Bone Defects Around Dental Implants By Platelet-rich Fibrin

Objective:This study through the establishment of dog tooth model,by the platelet-rich fibrin (platelet-rich fibrin,PRF) and β-tricalcium phosphate (β-tricalcium phosphate, P-TCP) joint used in dental implants surrounding bone defect, is to explore the feasibility of the PRF and β-TCP joint repair bone defects around dental implants and its osteogenesis effectiveness evaluation,for looking for repair bone defects around dental implants to provide the basis.Methods:Six heathy adult dogs were chosen (15-20kg),no teeth missing column,clean level,male and female unlimited.According to the conventional breeding conditions raising two weeks after divide remove six dogs bilateral mandibular premolar1,2,3,4.Three months after extraction,4star3mm×10mm implants were separately implanted in each side of the mandibule.At the same time,a3.5mm×3.5mm×3.5mm size bone defect were created in the mesial aspect of each implant. The same period Prepared the PRF,the three bone Defects around Dental implants were divided into three groups(group A,group B and group C):group A filled β-TCP/PRF compounds,group B filled β-TCP, and group C do not make any deal (blank control).All in the bone defect area covered collagen membrane.Every2dogs were sacrificed at4,8and12weeks after the implantation,and gross observation,X-rays,histopathology and ESEM were examined.Result:1.gross observation the36implants without fall off, general observation area wound healing was good, did not happen wound infection, soft tissue form color normal, no crack, and suture already fall off. At4weeks, β-TCP/PRF group bone defect area can see a little sag in the surface, the surface sag of β-TCP group more depression than β-TCP/PRF group, and the surface of the blank control can be obviously sag. At8weeks, bone defect area surface sag of the three groups were less than4weeks, but the β-TCP/PRF group less than the depression of other two groups, β-TCP/PRF group sag area are covered callus, bone harder, visible P-TCP particles residue. At12weeks, the surface depression of the three groups are not obvious, but P-TCP/PRF group than other two groups more surface level off, and the surface has more callus growth, qualitative hard, and the surrounding bone tissue mass boundary is not clear, the surface has not seen the P-TCP particles, blank control group also visible several needle size absorption sag.2.X-rays observationX-ray image shows:At4weeks, blank control group bone defect area can be obviously low density shadow,P-TCP/PRF group bone defect area of low density minimum, X-ray resistance strong shot. At8weeks, three groups of bone defect area of low density are reduced, β-TCP/PRF group bone defect area of low density density and evenness tend to natural bone. At12weeks, the blank control group bone defect area still can see low density shadow, bone absorption also is more apparent, there were no significant difference in the β-TCP/PRF group and P-TCP group bone defect area density and evenness, only a very small bone absorption.3.environmental scanning electron microscopy(ESEM) observationAt4weeks, in the β-TCP/PRF group bone defect area,the material part was reduced significantly, β-TCP group bone defect area can see lots of the β-TCP particles. At8weeks, in the β-TCP/PRF group new bone trabeculae and residual material mixed. osseointegration of new bone tissue and implant more closed.The β-TCP group and control group blank bone defect area showed a small amount of bone trabeculae. At12weeks, the β-TCP/PRF group bone defect area showed new bone density trabecular, material degradation more fully, osseointegration of new bone tissue and implant more closed.The P-TCP group and control group blank bone defect area bone defect area new bone trabeculae loomed in the residual material, material degradation less, osseointegration of new bone tissue and implant less closed than β-TCP/PRF group.4.histopathology observationEach period biopsy observation showed:in the β-TCP/PRF group aroundding dental implants have lots of visible osteoblasts, bone cells and new bone trabeculae, the new bone tissue are more mature, and in the P-TCP group aroundding dental implants have visible osteoblasts, bone cells and new bone trabeculae, the new bone tissue are mature, and in the blank control group there was less osteoblast,fine and less bone trabeculae and more connective tissue.Conclusion:PRF plays a signifcant role in the Restoration of Bone Defects around Dental Implants. β-TCP/PRF is a better bone repair material with the promotion of new bone formation and the elevation of healing quality.