1.Research On The Volue Change Of Bone Graft After Lateral Window Sinus Floor Elevation Based On Three-Dimensional Reconstruction 2.Preparation Of ACP-CCS-PVA Composite Membrane And Preliminary Research On Bone Formation

Part 1:Research on the volume change of bone graft after lateral window sinus floor elevation based on three-dimensional reconstructionObjectivesIn this study,the three-dimensional reconstruction of bone graft after lateral window sinus floor elevation was performed to analyze the changes of bone graft volume after surgery and to study the related influencing factors,so as to provide reference for the preoperative evaluation and prognosis of lateral window sinus floor elevation.MethodsA total of 30 subjects were included in this retrospective study.Cone-beam computed tomography（CBCT）was selected before surgery,immediately after surgery,and 6 months after surgery.According to the preoperative imaging results,the patients were divided into groups according to residual alveolar bone height,the width of the maxillary sinus and the presence or absence of chronic inflammation or cysts in the maxillary sinus.The DICOM format file obtained by CBCT was imported into Mimics20.0 software to perform 3D modeling of the maxillary sinus cavity.Import the 3D modeling file into the Geomagic Wrap 2017 software in STL format and perform the fitting.The difference in sinus volume obtained by subtraction is the volume of the bone graft immediately after the operation（T₀）and 6 months after the operation（T₆）.The rate of bone graft volume change between 6 months and immediately after surgery was△T（%）=（T₀-T₆）/T₀*100%.Statistical analysis of the data using SPSS software,P<0.05is statistically significant.ResultsThe retrospective research included 30 patients and 53 implant sites.The bone graft volume decreased significantly at 6 months after the operation,and the rate of change was（20.05±12.94）%.There was no statistical significance in the change rate of the bone graft volume between the groups of the residual alveolar bone height by one-way ANOVA（P>0.05）.One-way ANOVA showed no significant difference between SW<12mm and SW=12-15mm（P>0.05）.SW<12mm and SW>15mm had significant difference（P<0.05）.There was significant difference between SW=12-15mm and SW>15mm（P<0.05）.Pearson analysis showed that the width of maxillary sinus was positively correlated with the volume change rate of bone graft,that is,the wider the cavity of maxillary sinus,the greater the volume change rate of bone graft.There was no significant difference in the volume change rate between bone graft and maxillary sinus with/without chronic inflammation or cyst by independent sample t-test（p>0.05）.ConclusionsDuring the healing process of maxillary sinus floor lift with sidewall fenestration,the volume of bone graft decreased significantly.The main factor affecting the volume change rate of the bone graft is the width of the maxillary sinus,which is positively correlated;it is not statistically significant with residual alveolar bone height,presence or absence of chronic inflammation or cysts in the maxillary sinus.Part 2: Preparation of ACP-CCS-PVA composite membrane and preliminary research on bone formationObjectivesThe purpose of this experiment is to study the preparation of amorphous calcium phosphate nanoparticles and amorphous calcium phosphate（ACP）-carboxylated chitosan（CCS）-polyvinyl alcohol（PVA）composite membranes,and to evaluate the physical and chemical properties and biological properties of ACP-CCS-PVA composite membrane,so as to explore its potential to promote osteogenesis in bone defect areas.MethodsACP nanoparticles were prepared with calcium chloride,sodium dihydrogen phosphate and adenosine 5’-triphosphate.ACP nanoparticles were added to the CCS-PVA blend system,and ACP-CCS-PVA composite membranes with different ACP contents were prepared by chemical copolymerization and freeze-thaw cycles.The surface morphology of the synthesized ACP nanoparticles and ACP-CCS-PVA composite membrane was observed by transmission electron microscope and scanning electron microscope. Its elemental composition was analyzed by energy spectrometer,its mineral phase characteristics were analyzed by x-ray diffraction,and its group composition was analyzed by fourier transform infrared spectroscopy.The mineral content,swelling property,degradation property,mechanical properties and the release of calcium and phosphorus ions of CCS-PVA composite membrane,10wt%ACP-CCS-PVA and 20wt%ACP-CCS-PVA composite membrane were characterized.CCK8 experiment was used to detect proliferation of the composite membranes in each group on day 1.3.5.7,and alkaline phosphatase（ALP）staining and quantitative experiments were used to detect the initial osteoinductive ability of composite membranes in each group on day 7.14.The experiment was repeated independently for 3 times in each group.SPSS software was used for statistical analysis of the data,and P < 0.05 was statistically significant.Results1.Transmission electron microscopy shows that ACP nanoparticles are round,with a particle size distribution within 5nm.Scanning electron microscopy showed interconnected pores in each group of composite membranes.Energy spectrum analysis shows that ACP nanoparticles are uniformly distributed in the entire ACP-CCS-PVA composite membrane.2.X ray diffraction results show that ACP nanoparticles,CCS-PVA and ACP-CCS-PVA composite membrane are amorphous materials.In the fourier transform infrared spectroscopy spectrum,the characteristic peaks of phosphate in ACP and the interaction between ACP and CCS-PVA composite film can be seen.3.Thermogravimetric analysis shows that the mineral content of 20wt% ACP-CCS-PVA composite membrane is higher than that of 10wt% ACP-CCS-PVA composite membrane.The composite membranes have good swelling performance,suitable degradation performance and mechanical strength,and the higher the ACP content,the smaller the swelling percentage,the faster the degradation rate,and the greater the tensile modulus and deformability.4.The trend of Ca and P ions release curve of 20wt% ACP-CCS-PVA composite membranes is similar to that of 10wt% ACP-CCS-PVA composite membranes,and the release concentration of Ca and P ions are higher than 10wt% ACP-CCS-PVA composite membrane.5.The proliferation ability of MC3T3-E1 cells on the composite membranes of each group is good.There is no statistical significance between 20wt% ACP-CCS-PVA and 10wt% ACP-CCS-PVA composite membranes,but the cell viability of both is better than that of CCS-PVA composite membrane.6.The ALP staining and quantitative results on the composite membranes of each group showed that the 10wt% ACP-CCS-PVA composite membrane had the highest activity,followed by the 20wt% ACP-CCS-PVA and CCS-PVA composite membranes.And there was statistical significance among all groups on the 14 th day.ConclusionsThe porous ACP-CCS-PVA composite membrane has good mechanical properties,transports calcium and orthophosphate ions in a continuous manner,promotes cell proliferation and osteogenic differentiation,proving that it has the potential to guide bone regeneration.