Dissertations / Theses on the topic 'Calvaria de rat'

A reconstrução de defeitos ósseos críticos é alvo de inúmeras pesquisas em cirurgia bucomaxilofacial. Tais pesquisas visam, de maneira geral, a optimização da neoformação óssea e a eliminação dos procedimentos de remoção de osso autógeno para reconstrução. Os modelos animais têm sido a metodologia mais utilizada para avaliar a eficácia de novas substâncias e biomateriais na reparação óssea. O objetivo desta pesquisa foi avaliar a influência de um flavonóide, o icariin, na reparação óssea de defeitos críticos confeccionados na calvária de ratos Wistar. Um defeito ósseo crítico circular foi confeccionado em 40 calvarias de ratos por meio de uma broca trefina de 8 mm de diâmetro sob irrigação salina constante. Ao final dos procedimentos cirúrgicos, os animais foram divididos, aleatoriamente, em grupo teste (n=20), que recebeu o icariin, na dose de 125 mg/kg de peso e grupo controle (n=20), que recebeu soro fisiológico. Ambas as substâncias foram administradas por meio de gavagem até o dia da eutanásia. Ao final de cada período observacional de 7, 14, 21 e 42 dias, 5 animais de cada grupo foram eutanasiados e as amostras da calvária foram removidas e mantidas em formol 10% por 48 horas. As calvárias foram radiografadas e, após descalcificação, foram submetidas à avaliação histológica com coloração hematoxilina-eosina sob microscópio de luz. Os defeitos foram analisados considerando a diminuição da área do defeito na imagem radiográfica, as características de reparo ósseo e a osteogênese na região da ferida. Os resultados da análise radiográfica mostraram que a área do defeito ósseo no grupo teste foi significativamente menor que no grupo controle em todos os períodos observacionais. A avaliação histológica mostrou um aumento na neoformação óssea do grupo teste (p=0,02). A histomorfometria demonstrou osteogênese significante no grupo teste com 7 dias (p=0,021), 14 dias (p=0,014), 21 dias (p=0,021) e 42 dias (p=0,009). Foi possível concluir que o icariin sistêmico induziu uma maior neoformação óssea em defeitos críticos.
Bone critical defect reconstruction is an important target in current oral surgery research. Contemporary research has been searching for osteogenesis optimization to minimize the necessity of using autogenous bone grafts procedures. Animal models have been the widespread methodology to evaluate the effect of different new substances and biomaterials in bone healing. The aim of this study was to assess the influence of systemic daily flavonoid, icariin, in the repair of calvaria critical size defects induced in Wistar rats. A round critical size defect was performed centrally in 40 rats calvaria using an 8mm trephine under sterile saline solution irrigation. After surgery, half the animals, randomly, received by gavage daily doses of 125mg/Kg-icariin (Test Group) till the euthanasia. The other half (Control Group) received the same volume of saline solution. Five animals of each group were euthanized after 7, 14, 21 and 42 days postoperatively. The rats calvaria were removed, fixed in 10% formalin for 48 hours. Calvarias were X-rayed and after decalcification they underwent histological examination with hematoxylin eosin stain under a light microscope. Defects were analyzed considering area diminishing in X-ray image, bone healing characteristics and osteogenesis in the defect region. Results showed that bone defect area in Test Group was significant smaller in all observational periods. Histological evaluation showed an increased expression in bone trabeculae neoformation in Test Group (p=0,02). Histomorphometry demonstrated significant osteogenesis in Test Group at 7 days (p=0,021), 14 days (p=0,014), 21 days (p=0,021) and 42 days (p=0,009). It was concluded that systemic icariin induced a more expressive bone healing in critical size defects in rats.

The objective of the present study was to synthesize porous, biodegradable poly (D, l- lactide-co-glycolide) PLGA-B-HA (Bovine hydroxyapatite) composite and evaluate the effect of ceramic content on bone marrow cell differentiation in vitro. A macroporous biodegradable PLGA-B-HA composite with the pore size varying from 0.1 to 1000?? and a highly interconnected structure was fabricated using the freeze-drying/lyophilization technique. A pilot study was done to determine the effects of B-HA on to the osteoblast function. The main study was done to determine the effect of the increase in B-HA concentration on to the mesenchymal stem cell differentiation. Morphological characteristics of the composites were analyzed using FTIR and SEM/EDX analysis. The composites were seeded with neonatal rat calvarial osteoblasts (NRCO). The polymer: ceramic ratio in this study was 35%:65%. For comparison parallel experiments involving pure HA-200 discs were performed. SEM results indicated a higher proliferation and mineralization on PLGA-B-HA composites than pure HA discs. In addition, we evaluated the in vitro characteristics of PLGA-B-HA composites with varying ratios, i.e., 1:1, 1:2 and 1:3, seeded with rat marrow cells. FTIR indicated an increase in the area under the ceramic peak as ceramic concentration was increased. In addition, the average roughness values increased in the order of 1:3 andgt; 1:2 andgt; 1:1. Both compressive strength and modulus of 1:1 were significantly higher than 1:2 and 1:3 PLGA-B-HA composites. No significant difference in compressive modulli and strengths could be observed for 1:2 and 1:3 PLGA-B-HA composites. Cellular activity was determined by measuring AP activity, total protein analysis and osteocalcin concentration. Evaluation of alkaline phosphatase activity showed bone cells attached to 1:3 (PLGA-B-HA) expressed significantly higher alkaline phosphatase as compared to 1:1 and 1:2 PLGA-B-HA composites. In addition, cells seeded on to 1:3 composites secreted significantly higher osteocalcin and at a relatively short time period as compared to the other samples. Corrosion studies (ICP) and pH values indicate minimal difference in the concentration of Ca and P and pH in tissue culture media for all the samples at the end of all time periods. Hence we conclude that an increase in the ceramic concentration stimulated mesenchymal stem cell differentiation thereby promoting osteogenesis.

Orientador: Jose Ricardo de Albergaria-Barbosa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-07-21T20:50:26Z (GMT). No. of bitstreams: 1 Silva_ClaudiaJordao_M.pdf: 4090867 bytes, checksum: bfd1ff3ed0e4830528fe82ad6f674596 (MD5) Previous issue date: 1996
Resumo: O propósito deste trabalho foi avaliar histologicamente o processo de reparo de defeitos ósseos, criados cirurgicamente em calvária de coelho, com ou sem enxerto ósseo e submetidos ou não a eletroestimulação. Foram utilizados 18 coelhos, sendo que cada um deles recebeu duas osteotomias na calvária. Na osteotomia do osso parietal direito o fragmento removido foi imediatamente reposicionado, sendo que no parietal esquerdo o fragmento foi desprezado. Os animais dos grupos tratados receberam a eletroestimulação por uma hora, durante 21 dias. Já os animais do grupo controle foram submetidos as mesmas condições de stress, porém com o aparelho desligado. Os períodos de sacrifício foram as quatro, oito e quinze semanas, compreendendo seis animais sacrificados em cada período. A análise dos espécimes sob a microscopia óptica revelou neoformação óssea em todos os animais. Nos animais com enxerto ósseo houve uma reparação mais acentuada quando comparados com o grupo sem enxerto. A eletroestimulação parece ter alterado o processo de reparo ósseo de maneira discreta
Abstract: The purpose of this research was to histologicalIy evaluate the healing process in bone defects surgically created in calvaria of rabbits, with or without bone grafts under the action of eletrotherapy or not. It were utilized 18 rabbits with 2 perfurations in each calvaria. In the right parietal bone perforation the fragment removed was immediately grafted in its place. lu the left parietal bone the fragment was thrown away. The animais in the treated group received 1 hour of eletrotherapy dayly, during 21 days. The animals in the control group were submitted to the same stress conditions, but the stimulator was turned off. The sacrifice periods were 4, 7 and 15 weeks, with 6 sacrificed animais in each group. The analysis of the specimens under optical microscopy revealed bone formation in all animals. In the animals with the bone grafted there was a more noticeable healing when compared to the animais in the control group. With regard the electrotherapy it seems to affect the bone healing mildly
Mestrado
Cirurgia e Traumatologia Buco-Maxilo-Faciais
Mestre em Clínica Odontológica

O elevado número de cirurgias de enxertia óssea impulsiona o desenvolvimento de novos biomateriais de preenchimento. Materiais a base de hidroxiapatita sintética e tendão bovino mineralizado foram preparados para servirem de arcabouço para regeneração óssea. Este estudo teve como objetivo avaliar a osteocondutibilidade desses materiais, comparando-os ao Bio-Oss/Geistlich. Foram criados defeitos de tamanho crítico (circular / 8 mm) na calvária de ratos Wistar, preenchidos com os biomateriais e, após 30 dias, ocorreu o sacrifício, análise não invasiva por microtomografia computadorizada (micro-CT/ microtomógrafo SkyScan 100kV - 100\'mü\'A) com reconstituição de imagem em três dimensões (3D) e análise histológica convencional para avaliar a neoformação óssea e comparar os métodos. Os resultados da micro-CT mostraram que o Bio-Oss apresentou maior volume, densidade e porcentagem de tecido ósseo que os demais grupos. Nas imagens reconstituídas em 3D notou-se no grupo Bio-Oss as menores taxas de reabsorção, permanecendo em maior quantidade no interior do defeito aos trinta dias. No grupo da hidroxiapatita sintética notou-se uma intensa reabsorção do material e uma leve neoformação óssea nas margens do defeito, deixando-o com um contorno irregular. O grupo do tendão bovino mineralizado apresentou discretíssima neoformação óssea e o material foi totalmente reabsorvido. Já na avaliação da presença do material, de vasos sanguíneos e das células osteoblásticas no interior do defeito obtidos através da análise histológica, os grupos Bio-Oss e hidroxiapatita sintética obtiveram resultados semelhantes e maiores que o tendão bovino mineralizado. Constatou-se através da análise histológica que a hidroxiapatita sintética mostrou-se presente no interior do defeito exibindo propriedades osteocondutoras semelhantes a marca comercial Bio-Oss. Já o tendão bovino mineralizado não teve boa osteocondução, sendo contra-indicado na manutenção do espaço ósseo. Na comparação dos dois métodos, constatou-se que a micro-CT apresenta baixa especificidade, ou seja, não foi capaz de distinguir o tecido ósseo do Bio-Oss e alta sensibilidade, pois quantifica de uma forma muito precisa os valores com alta resolução. Já a análise histológica consegue distinguir com precisão os materiais e o tecido adjacente, porém não consegue quantificá-los de maneira fácil e precisa. Portanto, conclui-se que a hidroxiapatita sintética tem grande potencial de ser utilizada no preenchimento de defeitos ósseos, diferentemente do tendão bovino mineralizado. Quanto aos métodos de avaliação, eles são complementares e novos aprimoramentos devem ser feitos na técnica de micro-CT para melhorar sua capacidade de distinguir diferentes materiais.
Biodegradable bone grafts have been widely employed on bone regeneration. The purpose of this study was to evaluate the osteoconductive potential of hydroxyapatite, mineralized bovine tendon and Bio-Oss/Geistlich in a rat critical-size calvaria defect model through non-destructive three-dimensional (3D) micro-tomographic (\'mü\'CT) imaging and histological evaluation. Two experimental biomaterials were developed: synthetic hydroxyapatite (particles size < 0,2 mm) and mineralized bovine tendon. Bio-Oss/Geistlich was employed as a control group. A critical size defect (8 mm) was created in the skull of Wistar rats (weight 200 - 300 g) and treated with the biomaterials and one group was left untreated in the control group (n = 5). After 30 days, the animals were killed and the calvaria removed for \'mü\'CT and histological analysis. No adverse reactions were noted. No bone repair was observed in untreated surgical defects. The results of micro-CT showed that BioOss showed higher volume, density and percentage of bone tissue than the other groups. In the images reconstructed in 3-D was noted in the group Bio-Oss the lowest rates of resorption, staying in larger quantities within thirty days of the defect. In the group of synthetic hydroxyapatite noticed an intense resorption of the material and a slight bone formation at the margins of the defect, leaving him with an irregular contour. The bovine tendon mineralized group presented discreet bone formation and the material was completely resorbed. In the evaluation of the presence of the material, blood vessels and osteoblastic cells within the defect obtained by histological analysis, the groups Bio-Oss and synthetic hydroxyapatite showed similar results and larger than the mineralized bovine tendon. We verified by histological analysis that the synthetic hydroxyapatite is present within the defect displaying osteoconductive properties similar to trademark BioOss. Already the mineralized bovine tendon, again, did not have good osteoconduction and is contraindicated in maintaining the bone. When comparing the two methods observed that the micro-CT has low specificity, ie, was not able to distinguish the bone tissue to Bio-Oss and high sensitivity, as quantified in a very accurate values with high resolution. Already histological analysis can accurately distinguish materials and tissues, but can not quantify them easily and accurately. Therefore, we conclude that the synthetic hydroxyapatite has great potential to be used to fill bone defects, unlike mineralized bovine tendon. When comparing the methods, we found that still are complementary and new enhancements must be made in micro-CT technique to improve their ability to distinguish different materials.

Orientadores: Paulo Kharmandayan, Ivan Felizardo Contrera Toro
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-26T14:18:09Z (GMT). No. of bitstreams: 1 Calderoni_DaviReis_D.pdf: 2411163 bytes, checksum: f124b9aeaf19c6f4e86c382fef12ffeb (MD5) Previous issue date: 2014
Resumo: Introdução: A reparação de um defeito craniano é um procedimento desafiador, que requer não somente o preenchimento da falha óssea mas também estabilidade a longo prazo do material empregado e restabelecimento do contorno e simetria. Diversos tipos de materiais com diferentes características bem como diferentes métodos de produção dos implantes vêm sendo testados, sem que ainda haja um substituto ósseo considerado ideal. No presente estudo foram investigadas as propriedades de osteointegração de implantes da liga Ti6Al4V construídos por prototipagem com poros tridimensionalmente conectados considerando a influência do recobrimento dos mesmos com uma camada delgada de ?-fosfato tricálcico nestas propriedades. Método: Trinta ratos foram submetidos à criação de defeitos ósseos bilaterais na calvária, que foram preenchidos com implantes, recobertos ou não com ?-fosfato tricálcico, de modo aleatório. Os animais foram distribuídos em grupos e sacrificados 15, 45 e 90 dias após o procedimento. A integração dos implantes foi inicialmente avaliada por ensaio de compressão. A interface osso-implante foi analisada por meio de microscopia eletrônica de varredura. Resultados: A força máxima para produzir o deslocamento inicial dos implantes foi aumentando durante o período estudado, alcançando valores da ordem de 100N para ambos os tipos de implante. Foi observada integração entre o osso e a superfície dos implantes, com crescimento ósseo progressivo no interior dos poros. Não foram observadas diferenças significativas entre implantes recobertos e não recobertos por ?-fosfato tricálcico. Conclusão: Foi alcançada uma adequada osteointegração nas reconstruções cranianas utilizando implantes prototipados da liga Ti6Al4V com as características de porosidade e superfície descritas, sem influência do recobrimento cerâmico adotado. Os resultados sugerem que as características de construção utilizadas podem ser incorporadas aos implantes para reconstrução craniana para melhorar os resultados cirúrgicos
Abstract: Background: The repair of a calvarial defect is a challenging procedure, requiring not only filling of the bone gap but long term stability of the employed material and satisfactory contour and symmetry. Several types of materials with different characteristics have been studied, as well as various methods of implant production. However, to date no ideal bone substitute has been found. The osseointegration properties of porous prototyped implants with tridimensionally interconnected pores made of the Ti6Al4V alloy and the influence of a thin layer of calcium phosphate coating were investigated. Methods: Bilateral critical size calvarial defects were produced in thirty rats and filled with coated and uncoated implants in a randomized fashion. The animals were distributed in groups and kept for 15, 45 and 90 days before sacrifice. Implant mechanical integration to bone was evaluated with a push-out test. Bone-implant interface was analyzed using scanning electron microscopy. Results: The maximum force to produce initial displacement of the implants increased during the study period, reaching values around 100N for both types of implants. Intimate contact between bone and implant surface was present, with progressive bone growth into the pores. No significant differences were seen between coated and uncoated implants. Conclusion: Adequate osseointegration can be achieved in calvarial reconstructions using prototyped Ti6Al4V scaffolds with the described physical characteristics of surface and porosity. The results suggest that the proposed implant design characteristics can be incorporated into calvarial implants to improve reconstructive results.
Doutorado
Fisiopatologia Cirúrgica
Doutor em Ciências

碩士
國防醫學院
牙醫科學研究所
106
Background: In guiding bone formation, creating an adequate space is critical due to defect complexity.  In this study, a polycaprolactones (PCL) scaffold, computer designed and 3D-printed, was implanted into the critical-sized calvaria defect in rat, whereas the effect of plasma-rich fibrin (PRF) on the bone formation was also tested. Methods:  Two round defects, 6 mm in diameter, were surgically created in parietal bones of 32 rats, then 4 defect groups, including defect control, PRF, PCL, and PCL-plus-PRF (PRF+PCL), were divided according to scaffold implantation and PRF delivery.  Four and eight weeks after, half of the rats were sacrificed, respectively. Bone formation was assessed by dental radiography, micro-computed tomography (µ-CT), and histology. Results: By dental radiography and µ-CT, the radio-opaque row-by-row squares were observed in the defects of PCL and PCL+PRF groups. The opaque areas/volumes, as well as their relative values (areas/volumes), in defects were similar among 4 groups; however, significantly greater values were noted in central, but not peripheral zone in the groups with PCL (PCL and PRF+PCL groups) than those without PCL (defect control and PRF groups). By histology, the bones formed in the spaces between PCL struts; however, there was no bones-struts contact observed. Histometry showed that the tissue areas were significant greater in the groups with PCL than that without, particularly in central zone, in spite of the intervals. In week 8, similar findings were observed, including the bone and connective tissue areas. Similar areas for PCL residuals were observed in the PCL and the PRF+PCL groups. (太長) Conclusions: In the critical-sized calvarial defect of rat, our results showed the bones formed within the spaces supported by the computer-designed 3D-printed PCL scaffold but no contact with PCL struts. Strategy of using the customized scaffold for supporting spaces in augmenting bone formation is therefore suggested.