Avaliação do reparo ósseo no levantamento do seio maxilar de coelhos após implantação de esferas de hidroxiapatita carbonatada nanoestruturada contendo 5% de estrôncio / Evaluation of bone repair after maxillary sinus grafting with 5% strontium, nanostructured, carbonated hydroxyapatite microspheres in a rabbit model

A hidroxiapatita (HA) tem sido amplamente utilizada como um importante substituto ósseo. Quando em dimensão nanométrica, assemelha-se em tamanho e morfologia à apatita biológica, podendo ser considerada um biomaterial promissor para aplicação clínica. O estrôncio contribui por atuar na redução da reabsorção óssea e indução na atividade osteoblástica, enquanto os carbonatos favorecem a bioabsorção. Objetivos: caracterizar físico-quimicamente e analisar histologicamente, e de forma comparativa, a hidroxiapatita carbonatada contendo 5% de estrôncio com a hidroxiapatita estequiométrica. Material e métodos: foram utilizados 12 coelhos brancos Nova Zelândia, divididos em: hidroxiapatita carbonatada nanoestruturada contendo 5% de estrôncio (nSrcHA-experimental) e hidroxiapatita carbonatada nanoestruturada (ncHA-controle). Após a confecção dos sítios cirúrgicos, foram implantadas nas cavidades dos seios maxilares microesferas de ncSrHA e ncHA, nos lados esquerdo e direito, respectivamente. Os animais foram eutanasiados para análise histológica após quatro e 12 semanas. Resultados: após quatro semanas, o grupo ncHA apresentou osso neoformado e pavimentação osteoblástica próximo da parede do defeito. No grupo nSrcHA, o biomaterial apresentou-se de forma difusa com uma maior deposição de matriz osteogênica em torno do biomaterial, tecido ósseo neoformado próximo das paredes e no interior dos defeitos. No período de 12 semanas o grupo ncHA exibiu biomaterial no interior do defeito e osso neoformado, enquanto no grupo nSrcHA observou-se uma intensa formação óssea no interior do defeito com presença de osteócitos. Conclusão: ambos os materiais foram biocompatíveis e osteocondutores.

Hydroxyapatite (HA) has been widely used as an important bone substitute. Its nanometer scale is similar in size and morphology of biological apatite, which can be considered a promising biomaterial for clinical application. Strontium contributes to reduce bone resorption and induces osteoblast activity, whereas the carbonates favor bio-absorption. Objectives: to perform physico-chemical and histological characterization of nanostructured carbonated hydroxyapatite containing 5% strontium and the stoichiometric hydroxyapatite. Material and methods: twelve white New Zealand rabbits were used in this study and divided into nanostructured carbonated hydroxyapatite containing 5% strontium (ncSrHA-experimental) and nanostructured carbonated hydroxyapatite (ncHA-control). Two surgical defects were created in the maxillary sinus cavities and received microspheres of ncSrHA and ncHA in the left and right sides, respectively. After the experimental periods of 4 and 12 weeks, the animals were euthanized for histological analysis. Results: after four weeks, the ncHA group showed new bone formation and osteoblastic layer near the defect wall. For ncSrHA, a diffuse, increased osteogenic matrix deposition was seen around the biomaterial, with newly formed bone near the walls and inside the defects. At 12 weeks, the ncHA group exhibited biomaterial inside the defect and new bone formation, while in the ncSrHA group an intense bone formation within the defect with presence of osteocytes was observed. Conclusion: both materials are biocompatible and osteoconductive.

Porosity study of the carbonated hydroxyapatite cement / 中国矫形外科杂志

[Objective] To compose carbonated hydroxyapatite cement with chemica l materials,and by adding the pore agent to develop a new bone substitute,which can be solidified in situ to form porous carbonated hydroxyapatite.[Method](1)A new type of carbonated hydroxyapatite cement(CHC)was prepared.The powder of cement was composed of calcium carbonate,tricalcium phosphate and calcium phosphate dibasic.The liquids were prepared by 0.2mol/L sodium phosphate buffer,solide phase to liquid phase was 1g to 0.4 ml;(2)To prepare an in situ setting porous carbonated hydroxyapatite cement,add the pore agent into the powder of cement,pore generate CO2 during situ setting of cement;(3)The chemcial composition,chemcial constitution mechanical property,setting time,interval porosity of the PCHA were tested.and then the physio-chemical character,manipulatity,histocompatibility were evaluated.[Result]Addition of pore agent could succeed to prepare a new bone substitute which could set in situ and transform into porous carbonated hydroxyapatite.The setting time was 13~15 minutes which was suitable to clinical application.The pore size and porosity character could be controlled by adjustment of the component.The checking results demonstrated that the self-setting composition of this cement was carbonated hydroxyapatite which was similar with the mineral phase of natural cancellous bone,the carbonic acid radical was 5.6% in the solidify production.Contain of the porosity was 36% with interconnect pore,the compressive strength was 5.6?2.2 MPa which was equal to strength of cancellous bone,and the cytotoxicity tests showed an exellent biocompatibility.[Conclusion]The porous carbonated hydroxyapatite cement is a good bone substitute which seems to be the cancellous bone with good porosities,exellent biocompatibility.

Vertebral augmentation for the treatment of vertebral compression fractures subsequent to osteoporosis / 解放军医学杂志

Objective To determine the efficacy of vertebroplasty and kyphoplasty with polymethylmethacrylate (PMMA) and carbonated hydroxyapatite cement (CHC) as augmenting biomaterials in the treatment of osteoporosis vertebral compression fractures subsequent to osteoporosis. Methods 58 patients of osteoporosis with vertebral compression fractures were treated with the following methods: vertebroplasty+PMMA (11 cases, 13 vertebra), vertebroplasty+CHC (23 cases, 26 vertebrae), kyphoplasty+PMMA (8 cases, 8 vertebrae), and kyphoplasty+ CHC (16 cases, 19 vertebrae). The height loss and kyphotic angle of vertebral compression fractures were respectively measured from preoperative and postoperative lateral X-ray films, and with them the restored height ratio and kyphosis angle ratio were calculated. Both preoperation and postoperation pain scores were evaluated by Visual Analog Scale (VAS). Results No complication was found in all the patients. The restored ratio of both vertebra heights and kyphotic angles by kyphoplasty was better than that by vertebroplasty. There was no difference of filling volume in all the groups. The operation time of vertebroplasty was significantly shorter than that of kyphoplasty. There was no difference in preoperative VAS scores. The VAS scores of PMMA groups were better than that of CHC groups, but the difference was not obvious 4 weeks after operation. Conclusion Vertebral augmentation was a minimally invasive, safe and effective method for the treatment of osteoporosis vertebral compression fractures in patients with osteoporosis. The treatment modality and filling biomaterials should be selected according to the patients' condition.