1.preparation And Characterization Of Biphasic Ceramic Scaffolds With Core-shell Structure 2.guided Tissue Regeneration Combined With Connective Tissue Graft In The Treatment Of Periodontal Hard And Soft Tissue Defects

Background:Non-contained bone defect is a difficult problem in clinical alveolar bone repair.Bioceramics scaffolds with precisely tuned morphology and good supporting capacity can be a candidate in clinical non-contained alveolar bone defects repair.Unfortunately,pure bioceramic scaffolds such as beta-tricalcium phosphate(?-TCP)or wollastonite(CaSiO3;CSi)scaffolds may not achieve optimal mechanical strength,biodegradation and osteostimulative effect simultaneously.Composite bioceramics scaffolds can solve some of the problems above,but still cannot precisely tune the composition distribution and biological activity of the materials.The newly studied core-shell bioceramics scaffolds with a designed custom shape,fabricated by the core-shell structural design based on 3D printing technology,can distribute the different components in core or shell layer of the scaffolds for tailoring physiochemical and biological performance.Objective:To fabricate core-shell structure bioceramics scaffolds based on TCP and 5%Mg-doped CSi(CSi-Mg5).To evaluated the effects of core-shell structure design on the physicochemical properties and biological activities of scaffolds in vitro and in vivo,and investigate scaffolds' osteogenic capability in beagle dog alveolar bone defect model.Method:Three groups of bioceramic core-shell scaffolds(TCP@CSi-Mg5,TCP@TCP and CSi-Mg5@CSi-Mg5)were prepared by coaxially aligned 3D writing bi-nozzle method.The fracture morphologies of the sintered scaffolds and the ability of apatite-forming on the surface in simulated body fluid(SBF)were characterized using scanning electron microscopy(SEM)while chemical analyses were performed by energy-dispersive spectroscopy(EDX).The mechanical strength of the bioceramic scaffolds were performed using a static mechanical test machine.After the scaffolds were immersed in a Tris buffer with an initial pH 7.4,the ion release of the scaffolds was measured by inductively coupled plasma-optical emission spectrometry(ICP-OES)to evaluated the biodissolution patterns in vitro.The one-well intrabony defects in six male beagle dogs(?18 months old)were used to compare the osteogenic efficacy of different materials.The scaffolds(CSi-Mg5@CSi-Mg5,TCP@CSi-Mg5)and Bio-Oss(?)granules(control group)were then randomly implanted into the defects,and defects without implantation were used as blank group.After 4 and 8 weeks,micro-CT and 3D reconstructed image were used to measure the osteogenesis capacity of scaffolds in vivo;.HE staining and Masson's trichrome staining were used to observe the new bone formation and bone maturity in the defect.The number of osteoclasts was analyzed by tartrate resistant acid phosphatase(TRAP)staining to quantify the resorption behavior of materials.Result:The clear core-shell-type structure of TCP@CSi-Mg5 scaffolds can be easily observed from the fracture surface by SEM,and the difference of ceramic components in inner and outer layers of the scaffolds was confirmed by EDS.Three groups of bioceramic scaffolds showed good re-mineralization ability in SBF.In vitro degradation and mechanical strength tests showed that the degradation rate of TCP@CSi-Mg5 scaffolds was similar to CSi-Mg5@CSi-Mg5 scaffolds,and higher than that of TCP@TCP scaffolds.And the compressive resistance of the TCP@CSi-Mg5 fell in between the scaffolds of TCP@TCP and CSi-Mg5@CSi-Mg5.? CT reconstruction analysis showed that the new bone tissues and trabecular number data were significantly higher in the TCP@CSi-Mg5 group than the other groups,implying an appreciable new bone ingrowth and high-efficient bone repair at 4 weeks postoperatively.HE and Masson trichrome staining observed that both scaffolds were replaced by new bone tissues with mature collagen fibers in a short period of time.However,Bio-Oss granules were still retained at 8 weeks postoperatively,the newly formed bone was limited and the bone tissue is less matured.TRAP staining showed that the peak of osteoclasts density appeared at 4 weeks in scaffolds groups,and more osteoclasts were observed in the CSi-Mg5@CSi-Mg5 group compared with TCP@CSi-Mg5 group.Then at 8 weeks,the degradation rate of the Bio-Oss group was accelerated when the degradation in scaffold groups was basically stopped.Conclusion:Coaxially aligned printing bi-nozzles can fabricate core-shell-strut scaffolds with adjustable mechanical,biodegradable and biological properties.In addition to appropriate compressive strength and biodegradation,TCP@CSi-Mg5 scaffolds performed effective early-stage bone tissue regeneration in the one-wall bone defects in beagle dogs which is promising for clinical alveolar bone repair.Background:Periodontitis can cause complex alveolar bone defects.The combination of guided tissue regeneration(GTR)and periodontal bone grafting is the main treatment of intraosseous defects.Though promising clinical results can be obtained in this combination therapy,post-surgery gingival recession should be limited;especially in intrabony defects associated with gingival recession,where the risk of gingival recession can be further increased.Connective tissue graft(CTG),a common surgical procedure for treatment of gingival recession,can effectively obtain root coverage,augment of keratinized tissue,as well as reducing the post-operative shrinkage of gingival.Objective:To evaluating the clinical efficacy of CTG combined GTR and periodontal bone grafting in treating intrabony defects associated with Miller Class ? gingival recession,in order to provide a new strategy for regenerative treatment of loss of bone and soft tissues in periodontitis.Methods:Five patients diagnosed as periodontitis in Department of Periodontology in the hospital from July 2015 to March 2018 were included.The patients suffered from periodontitis with bone defects combined with gingival recessions.The degree of gingival recession was classified as class ? according to Miller's classification published in 1985.All the patients were informed and signed the informed consents.After periodontal examinations were performed to evaluating gingival recession,the intrabony defects were examined by teeth X-ray or cone-beam CT(CBCT).Then CTG and GTR combined with periodontal bone grafting were used for the treatment of intrabony defects and Miller ? gingival recession.Changes of probing the depth(PD),attachment loss(AL),distance from gingival margin(GM)to cementum-enamel junction(CEJ),keratinized tissue height(KTH)and intrabony component(IC)etc.were measured followed by the defect fill(DF)was calculated to evaluate the outcome of the therapy.Results:After the surgery,attachment gain and probing depth reduction can be observed in addition to more root coverage,decreased GM-CEJ and increased KTH.In the meantime,bone fill can be observed in the defects and intrabony component decreased.Conclusion:Adjunctive use of CTG in GTR combined with bone graft are effective in treating periodontal bone defects associated with gingival recession.The patients showed improved appearance of gingiva with decreased IC and increased KTH.However,this study needs to be further confirmed by randomized controlled clinical trials with a large sample.