Exploring The Preparation Of A New Jaw Bone Scaffold Material And The Association Of Its Biomechanical Properties With Bone Repair

Jaw defects could result in loss of functions in stomatognathic system,which would severely compromise people’s quality of life and daily work.The most effective way to treat this is to repair the bone defects through implanting bone scaffold material.In recent years,the incidence of jaw defects showed a stable upward trend,due to the fact that the prevalence of trauma and diseases including tumors were increasing and also the world’s population was aging.This led to the increasing need for the bone scaffold material.Currently,the imported bone scaffold material in powder form was predominant in the domestic markets.Whereas this type of material was costly.Also it could not be applied on the relatively large bone defect surfaces(beyond 8mm)and failed to promote osteogenesis.Therefore,there is impending need to develop a new kind of bone scaffold material with independent intellectual property rights,which could promote osteogenesis,and also be used to repair the large bone defect surfaces.The current evidence from the studies on biomechanics of bone scaffold material have demonstrated that the superior biomechanical properties of bone scaffold material and its internal microstructure exerted a positive influence on bone defect repair(e.g.promoting bone and blood vessel regeneration and osteoblast factor expression).At present,however,related studies remained in the stage of trial-and-error testing.This was not only for the complexity of bone defect repair procedure,but also because of the insufficient evidence associated with microstructure and biomechanical properties of the ideal scaffold material.In addition,the bone scaffold material was a key scientific issue.However,the related researches were very weak and need to be improved.Therefore,this study performed the following experiments and related analysis by using calcined natural cancellous bone from adult cattle and foetal calf.1.Improve calcination technology for natural cancellous bone from cattle by using ammonium dihydrogen phosphate calcination method and assess its biocompatibility;conduct zinc and chitosan compound surface modification for calcined cancellous bone of cattle,and systematically evaluate its biosecurity and osteogenic capability.2.Test geometric structure and biomechanical properties of pores in these two kinds of calcined bone scaffold material through the present experiments combined with three-dimensional finite element modeling;from the perspective of cell,molecular and animal experiments,compare the effectiveness of these two kinds of materials in bone defect repair at initial,medium and later stages,respectively,through in vitro and in vivo experiments;analyze the association between their biomechanical properties and bone defect repair.3.Compare the microbial community structure colonized on these two different materials at initial stage by using high-throughput genome sequencing technology;analyze the impact of pore size and porosity on microbial community structures colonized on bone scaffold materials.The main innovative conclusions and related significance were listed as following.1.The preparation method of calcined natural cattle bone was proposed,which could be used to prepare the β-tricalcium phosphate scaffold in high purity.A new kind of bone scaffold material composed of natural cattle bone,calcined ammonium dihydrogen phosphate,zinc and chitosan,was developed and prepared.This material was characteristic of good biocompatibility,strong osteogenic capability,which may be widely employed in clinic practice.2.The biomechanical properties in bone scaffold material prepared from calcined natural cancellous bone of cattle were revealed as following:(1)Pore size followed normal distribution;(2)By stimulating the condition of scaffold structure under force inhuman body,the average stress was found to be randomly distributed in internal structure and the stress concentration areas were situated at the joint area of bone trabecula and bone lamella.At the same time,it was found that the degradation process and characteristics in this new material were similar to the forced degradation and absorption process in cancellous bone of human body.Based on the above-mentioned characteristics,this study may provide some guidance and reference for artificially synthesizing the new bone scaffold material.3.This study proposed that pore size and porosity of scaffold material exerted a significant impact on the initially colonized microbial community structure.The larger pores may benefit the initial colonization of facultative anaerobe,while the smaller ones may be related with the initial colonization of anaerobicbacteria.The porous scaffold material was more likely to be infected than the material in powder form.This may provide a support for further studying on the infection of bone scaffold material and also offer some guidance for the usage of antibiotics to treat or prevent the infection in scaffold.