| Objective:Oral and maxillofacial bone defects are often caused by tumor,trauma,infection,long-term non-repair after missing teeth,gasification of maxillary sinus and so on.Sufficient bone mass is beneficial to the ideal three-dimensional position of the implant,as well as the stability and long-term survival rate of the implant.The application of bone increment technique can improve the problem of local bone deficiency and expand the indications of implant surgery.the commonly used surgical techniques include bone splitting,bone compression,guided bone tissue regeneration,maxillary sinus lifting,onlay bone grafting and so on.The application of these bone increment techniques often requires the use of bone graft materials,such as autogenous bone,xenogeneic bone,synthetic bone and so on.All kinds of bone graft materials have their own advantages and disadvantages.As xenogeneic bone,Bio-oss particles are widely used in the field of bone increment.In recent years,as a new type of bone graft material,dentin particles have achieved satisfactory results in basic research and clinical application.Tricalcium phosphate / collagen composite simulates a three-dimensional environment suitable for the growth of osteocytes and is a bioactive synthetic material.Many experiments have confirmed its good effect of bone regeneration.In this experiment,the animal model of mandibular defect in Beagle dogs was established,and the osteogenic properties of three kinds of bone graft materials were compared,so as to provide reference for the selection of clinical bone transplantation materials.Materials and methods:1.Preparation of dentin granules: clean the teeth collected in clinic,quickly remove enamel,cementum,dental pulp and periodontal tissue by bone grinding and sieve into particles about 0.5-1mm in diameter,degrease with isopropanol for 2 hours,boil for 2 hours,sterilize at high temperature and high pressure,and set aside.2.Tricalcium phosphate / collagen composite(β-TCP/Col): in this experiment,bulk tricalcium phosphate / collagen bone filler was selected,which was made from the mixture of human absorbable collagen and β-TCP.The two materials were cross-linked together after dehydration,ultraviolet radiation sterilization and freeze-drying.3.Bio-oss particles: natural calf bone is a bone incremental material produced by Geiger in Switzerland after a series of chemical treatments,which removes all organic components and is similar to the inorganic structure in human bones.4.Experimental animal grouping: eight healthy Beagle dogs were randomly divided into four groups: group A(n = 4),group B(n = 4),group B(n = 4)and group D(n = 4).Dentin particles were implanted in group A,tricalcium phosphate / collagen composite was implanted in group B,Bio-oss particles were implanted in group C,and group D was used as blank control.5.During the operation,a trapezoidal incision was made at the bilateral mandibular external oblique line,the mucoperiosteal flap was opened,and 10 × 8 × 2mm boxed bone defect areas were prepared on both sides of the external oblique line.Tricalcium phosphate / collagen composites,dentin particles and Bio-oss particles were implanted,close suture,and postoperative intramuscular injection of penicillin to prevent infection.6.Observation index: general observation of wound healing in the bone graft area,infection and empyema,graft probing texture and mobility,paraffin decalcification section to observe new bone formation,histological measurement and analysis of new bone formation rate.SPSS22 statistical software was used to compare the rate of new bone formation in each group by single factor analysis of variance(P<0.05).Result:1.General observation: at 3 months,the mucous membrane of the bone graft area healed well,and no suppuration or infection was found.In group A,the boundary of bone defect was blurred,the boundary was smooth,the dentin particles were wrapped by fibrous connective tissue,the texture of the connection between probing and basal bone was slightly hard,and the texture in the center of group A was soft;The boundary of group B is clear,the texture of bone graft is softer than that of dentin granule group,and the coating of fibrous connective tissue can be seen on the surface of the material;In group C,the boundary is clear,a lot of fibrous connective tissue can be seen on the surface of the material,and the texture of probing is slightly hard;In group D,the boundary was clear,there was an obvious depression,a lot of fibrous connective tissue grew into the group D,and the texture of exploration was soft.2.Histological observation: at 3 months after operation,the histological sections showed that the dentin particles in group A were slightly absorbed,surrounded by new bone tissue,new bone trabeculae and capillaries were formed,and there were a large number of active osteoblasts between the bone trabecules.in the central area of the bone graft area,dentin particles were surrounded by a large number of fibrous connective tissue.In group B,a small number of new bone trabeculae and osteoblasts could be seen,a large number of powdered β-TCP particles and a small amount of inflammatory cells could be seen in the fibrous connective tissue,some β-TCP particles were surrounded by new bone tissue,and the bone marrow cavity could be seen in the new bone.In group C,some Bio-oss particles were surrounded by new bone tissue,some Bio-oss particles were wrapped by surrounding fibrous connective tissue,and fibers,particles and new bone were intertwined.In group D,fibrous connective tissue grew into the bone defect,no new bone formation was found,and many capillaries could be seen in a large number of fibrous connective tissue.3.Histological measurement and analysis: at 3 months after operation,the new bone formation rates of groups A,B,C and D were 43.92%,30.10%,42.76% and 7.40%,respectively.There was a significant difference in the rate of new bone formation between group A,group B,group C and group D(P < 0.05),indicating that the osteogenic effect of the three kinds of bone transplantation materials was better than that of the blank control group;There was significant difference between group A and group B(P < 0.05),and the osteogenic effect of group A was better than that of group B;There was no significant difference between group A and group C(P>0.05),The osteogenic effect of group A was similar to that of group C;There was significant difference between group B and group C(P < 0.05),The osteogenic effect of group C was better than that of group B.Conclusion:1.Through this study,it is found that undecalcified heterogeneous dentin particles,tricalcium phosphate / collagen composite and Bio-oss particles can promote the formation of new bone in the repair of mandibular box defects.2.Three months after bone transplantation,there was no significant difference in osteogenic effect between undecalcified xenogeneic dentin particles and Bio-oss particles,but the osteogenic effects of undecalcified xenogeneic dentin particles and Bio-oss particles were better than tricalcium phosphate / collagen composites,but the long-term effect needs further observation. |
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