Orientador: Frab Norberto Boscolo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T19:08:05Z (GMT). No. of bitstreams: 1 Vasconcelos_KarladeFaria_D.pdf: 5688492 bytes, checksum: d9b11160adfcddce4c94ac1cd818c1e3 (MD5) Previous issue date: 2015 / Resumo: O conhecimento da microarquitetura óssea desempenha importante papel no sucesso das reconstruções ósseas e posterior reabilitação com implantes dentários. Os objetivos dessa pesquisa foram: 1. Avaliar a microarquitetura óssea de sítios da maxila, que foram reconstruídos com enxertos ósseos, autógeno e xenógeno e 2. Avaliar tridimensional e bidimensionalmente a formação óssea na superfície dos parafusos de fixação (BIC-Bone-to-implant contact). Doze amostras contendo parafusos de fixação recobertos por 0,5 a 1mm de osso humano foram removidas com auxílio de uma broca trefina, após seis meses da colocação de blocos de enxerto em maxila de 8 pacientes, cinco mulheres e três homens, com média de idade entre 50 anos. Sete de sítios xenógenos e cinco de autógenos. As amostras foram avaliadas por meio de imagens obtidas pelo microtomógrafo SkyScan 1173 e por meio da técnica histológica de Stevenels blue e Van Giesen red. Para caracterizar a microarquitetura foram avaliados: a razão volume ósseo/volume tecidual, espessura das trabéculas, distância trabecular, número de trabéculas e densidade de conectividade, em três áreas distintas (enxerto/transição/osso nativo). O cálculo do BIC 2D foi realizado em imagens histológicas e microtomográficas. O BIC 3D foi viabilizado em áreas selecionadas em 17 amostras, entretanto, apenas em imagens adquiridas por microtomografia. Quando os parâmetros da microarquitetura foram comparados entre as áreas, foram observadas diferenças estatísticas (p<0,05) na espessura e distância das trabéculas, entre a área de osso nativo e do enxerto, apenas nas amostras autógenas. As amostras xenógenas não apresentaram diferenças entre as áreas. Quando os dois tipos de enxerto foram comparados entre si, diferenças estatísticas (p<0,05) foram encontradas entre o volume de tecido ósseo, espessura entre as trabéculas e a distância entre as trabéculas. O cálculo do BIC 2D revelou semelhança entre as técnicas (p=0,802) e também entre os tipos de enxerto (p=0,097). Avaliando os valores do BIC 3D, observou-se diferença estatística significante nos valores do BIC entre as diferentes áreas, osso e enxerto, com valores mais altos nas áreas de osso nativo. Esses dados estruturais e observações obtidas a partir de imagens microtomográficas proporcionam valiosa caracterização desses sítios e oportunidade de futuras correlações com estudos de elementos finitos e resultados clínicos / Abstract: The knowledge of bone microarchitecture is an important role in the success of bone reconstructions and following rehabilitation with dental implants. Thus, the main objectives of this study were: 1) To characterize the microarchitecture of implant bone sites reconstructed with bone grafts and 2) To assess in two and three-dimensions the percentage of bone in contact with bone graft fixing screws (BIC-Bone-implant contact). Six months after graft placement of blocks in the maxilla of eight patients (five women and three men, with a mean of 50 years of age) twelve samples containing fixing screws covered by 0.5 to 1 mm of human bone were removed using a trephine drill. Five were from sites that had received autogenous grafts and seven from sites that had received xenogeneic grafts. Samples were evaluated by micro tomography images obtained by the SkyScan 1173 (Bruker, Kontich, Belgium) device and by histological technique with Stevenels blue e Van Giesen red solutions. To characterize the bone microarchitecture, bone volume, trabecular thickness, trabecular distance, trabecular number and connectivity in three distinct areas (graft / transition / native bone) were evaluated. The 2D BIC was performed in histological and microtomography images. The 3D BIC was performed only in images acquired by microtomography in whole sample. When the microtomography bone parameters were compared between areas, statistical differences were noted only in the thickness and distance of the trabecular area between the native bone and autogenous graft (p<0.05). No statistically significant differences were observed between these areas in the xenogenous sample. When the parameters were compared between two types of grafts, statistical differences were found between the bone volume (p<0.05), the trabecular thickness (p<0.05) and trabecular separation (p<0.05).While calculating the BIC 2D revealed similarity when comparing values obtained by both techniques (p=0.802), and both grafts (p=0.097). It was observed statistically significant difference in values of BIC 3D in different areas (bone and graft) (p=0.0021) with the highest values in areas of native bone. The structural data and observations obtained from micro-computed tomography images provided valuable characterization of sites that received bone grafts and the opportunity for future correlations with finite element studies and clinical outcomes / Doutorado / Radiologia Odontologica / Doutora em Radiologia Odontológica

Os equipamentos dispóníveis para acompanhamento clínico de implantes dentários monitoram mudanças de estabilidade, mas não são capazes de quantificar o nível de osseointegração. A literatura mostra que a aplicação de ultra-som pulsado de baixa intensidade estimula o reparo de fraturas ósseas e o crescimento de tecido ósseo nos poros de implantes, indicando que um guia de onda ultra-sônico poderia ser usado tanto para monitorar o processo de osseointegração como também para diminuir o período de recuperação. Diversas dimensões e geometrias foram consideradas nas simulações dos guias ultra-sônicos, e o guia com formato degrau apresentou maior sensibilidade a mudanças na composição do meio que envolve o implante. Resultados obtidos por simulação sugerem que há uma relação linear entre a energia do sinal detectado e o grau de osseointegração. Foram realizados experimentos com guias de onda de titânio e alumínio, sendo necessário realizar mais testes com guias de dimensões reduzidas para a obtenção de um dispositivo adequado para uso clínico. / Available equipments for clinical assessment of dental implants monitor changes in stiffness but are not able to quantify the osseointegration level. Literature shows that the application of low-intensity pulsed ultrasound stimulates the healing of bone fractures and the bone ingrowth into implants pores, indicating that an ultrasonic waveguide could be used to monitor the osseointegration process as well as to shorten the healing period. Several dimensions and geometries were considered in the waveguides simulations, and the step-shaped waveguide showed more sensibility to changes in the surrounding media of the implant. Results obtained by simulation suggest there is a linear relation between the energy of the detected signal and the osseointegration level. Experiments with titanium and aluminum waveguides were conducted, being necessary to carry out more studies with reduced size waveguides in order to obtain a suitable device for clinical use.

A união estrutural entre o tecido ósseo e a superfície do implante é definida como osseointegração. O sucesso deste processo depende tanto de fatores relacionados à característica física do implante, bem como de fatores sistêmicos e biológicos responsáveis pela formação e manutenção do tecido perimplantar. O processo de osseointegração pode ser comprometido por inúmeros fatores de risco: fumo, baixa qualidade e quantidade de tecido ósseo e morbidades sistêmicas, como o diabetes. Contudo, mesmo em condições excelentes, por vezes, não há a formação de tecido ósseo em plenitude ao redor da superfície implantar. A falha na osseointegração pode ocorrer precoce ou tardiamente ocasionando a perda do implante. A fotofuncionalização por irradiação de luz ultravioleta (UV) tem sido reportada recentemente como um método capaz de modificar a superfície do titânio e aumentar sua capacidade osteocondutora. A irradiação com luz ultravioleta (UV) tem sido proposta como método para reverter o processo de envelhecimento do titânio. Contudo a intensidade, tempo de exposição e comprimento de onda que proporcionam os melhores resultados ainda não foram esclarecidos. Objetivo: O objetivo deste estudo foi avaliar os efeitos da fotocatálise por luz UVC sobre o envelhecimento do titânio e analisar alterações de estrutura e de capacidade biológica in vitro do titânio irradiado em diferentes tempos de exposição. Metodologia: Foi desenvolvida uma câmara para fotofuncionalização de titânio com características distintas das apresentadas no mercado. A amostra foi composta por discos de titânio irradiados em diferentes tempos de exposição à luz ultravioleta (0, 15, 30, 60 minutos). Os discos foram testados quanto à molhabilidade de superfície (ângulo de contato com água), a topografia (microscopia eletrônica de varredura- MEV) e composição química (espectroscopia de fotoelétrons excitados por raio-x – XPS), adesão celular (cultura celular e MEV) e viabilidade por SRB. Resultados: O tratamento por luz UVC promoveu alterações nas características de superfície do titânio, como aumento da molhabilidade e remoção de hidrocarbonetos da superfície após 15 minutos de exposição na câmara desenvolvida. As características biológicas do material também parecem ter sofrido alterações, com melhora na capacidade de adesão e viabilidade. Conclusões: A fotofuncionalização do titânio provou ser eficaz para o tratamento de superfícies envelhecidas neste estudo, com significativas modificações na estrutura química superficial e na capacidade biológica do material. / The structural union between the bone tissue and the implant surface is defined as osseointegration. The success of this process depends both on factors related to the physical characteristics of the implant, as well as the systemic and biological factors responsible for the formation and maintenance of perimplant tissue. The process of osseointegration can be compromised by numerous risk factors: smoking, poor quality and quantity of bone tissue and systemic morbidities, such as diabetes. However, even in excellent conditions, sometimes there is no formation of bone tissue in fullness around the implant surface. Failure to osseointegration may occur early or late leading to implant loss. Photofunctionalisation by ultraviolet (UV) light irradiation has recently been reported as a method capable of modifying the titanium surface and increasing its osteoconductive capacity. Ultraviolet (UV) irradiation has been proposed as a method to reverse the aging process of titanium. However the intensity, time of exposure and wavelength that provide the best results have not yet been clarified. The Aim: of this study was to evaluate the effects of photocatalysis by UVC light on aging of titanium and to analyze changes in structure and in vitro biological capacity of irradiated titanium at different exposure times. Methodology: A titanium photofunctioning chamber has been developed with characteristics different from those presented in the market. The sample was composed of titanium disks irradiated in different times of exposure to ultraviolet light (0, 15, 30, 60 minutes). The discs were tested for surface wettability (water contact angle), topography (SEM-scanning electron microscopy) and chemical composition (x-ray excitation photoelectron spectroscopy), cell adhesion (cell culture and SEM) and viability by SRB. Results: UVC treatment promoted changes in titanium surface characteristics, such as increased wettability and removal of hydrocarbons from the surface after 15 minutes of exposure in the developed chamber. The biological characteristics of the material also appear to have changed, with improved adhesion and viability. Conclusions: Photofunctional titanium has proved to be effective for the treatment of surfaces aged in this study, with significant modifications in the surface chemical structure and biological capacity of the material.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22370号 / 医博第4611号 / 新制||医||1043(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 別所 和久, 教授 戸口田 淳也, 教授 妻木 範行 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Orientador: Maria Aparecida Neves [Unesp] Jardini / Resumo: A utilização de estimulação biofísica através da modalidade de campo eletromagnético pulsado (CEMP) para o tratamento de diversas condições no tecido ósseo tem despertado o interesse científico há décadas. Entretanto, a grande variedade nos parâmetros e protocolos utilizados e a divergência de resultados na literatura dificultam o estabelecimento de uma metodologia que seja eficaz no contexto da terapia com implantes osseointegrados. Dessa forma, torna-se importante avaliar o efeito de diferentes tempos de aplicação do CEMP padronizado em diferentes momentos no processo de osseointegração de implantes de titânio inseridos em tíbias de ratos. Para isso, foram utilizados 60 animais (Rattus norvegicus, variação albinus, Wistar), randomizados em três grupos experimentais: controle, teste A (GTA) submetidos por 3 horas de CEMP, e teste B (GTB) com 1 hora de CEMP, sendo que, a exposição ocorreu em 5 dias semanalmente durante o período experimental. Todos os animais receberam implantes em ambas as tíbias, e a aplicação do CEMP ocorreu apenas nos grupos teste com parâmetros fixos de ± 1 mT, 15 Hz, com 25 ciclos repetidos por 200 microssegundos. Após a eutanásia as peças foram separadas e preparadas para o teste mecânico, análises histomorfométricas, microtomografia computadorizada (µCT) e ensaios biológicos in vitro. Os dados foram tabulados e a análise de variância ANOVA foi aplicada, com nível de significância de 5%. Os resultados obtidos revelaram que, GTB apresentou melhores resu... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of biophysical stimulation through the pulsed electromagnetic field modality (PEMF) for the treatment of various conditions in bone tissue has aroused scientific interest for decades. However, the wide variety of parameters and protocols used and the divergence of results in the literature make it difficult to establish a methodology that is effective in the context of therapy with osseointegrated implants. Thus, it is important to evaluate the effect of different application times of the standardized PEMF at different times in the osseointegration process of titanium implants inserted in tibiae of rats. For this, 60 animals (Rattus norvegicus, variation albinus, Wistar) were used, randomized in three experimental groups: control, test A (GTA) submitted for 3 hours of CEMP, and test B (GTB) with 1 hour of PEMF, and the exposure occurred in 5 days weekly during the trial period. All animals received implants in both tibiae, and the application of PEMF only occurred in the test groups with fixed parameters ± 1 mT, 15 Hz, with 25 cycles repeated for 200 microseconds. After euthanasia, the pieces were separated and prepared for mechanical testing, histomorphometric analysis, computed microtomography (µCT) and in vitro biological tests. Data were tabulated and ANOVA analysis of variance was applied, with a significance level of 5%. The results obtained revealed that, GTB presented better results in comparison to GTA in the removal torque tests in 07 days; in bone volume an... (Complete abstract click electronic access below) / Doutor

Titanium has been used in bio-medical implants for decades due to its superior biocompatibility. To improve the osseointegration of dental and orthopaedic implants, various surface modification techniques have been used including laser surface texturing. In particular, short-pulsed lasers, such as femtosecond and picosecond lasers, are widely used for surface modification. In this thesis, commercially pure Ti surfaces are modified by a femtosecond laser to explore the relationship between surface topography, surface chemistry, surface wettability, and biocompatibility with the goal of improving the osseointegration of implants. The laser textured surfaces consist of 1μm wide grooves spaced 10 μm, 4.8 μm, 2.4 μm and 1.2 μm apart. Gradient configurations where the groove spacing varies are also investigated. Surface morphology was characterized using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). A custom-build contact angle measurement apparatus is used to investigate the wettability of the laser textured surfaces using the sessile drop method. Freshly laser-treated commercially pure Ti surfaces are found to be super-hydrophilic and become hydrophobic over time when exposed to air. The presence of grooves can accelerate the evolution of the contact angle over time, and introduces anisotropy in the wetting behavior (along vs. across the grooves). The hydrophilicity of laser treated surfaces can be retained by storing samples in ethanol. X-ray Photoelectron Spectroscopy (XPS) shows that the relative carbon content increases over time when Ti samples are exposed to air, which results in the subsequent evolution of the contact angle and cell response to laser textured Ti surfaces. Besides, laser treatment promotes the oxidation of pure Ti, and the product, TiO2, is responsible for the better biocompatibility. In vitro experiments using MG 63s osteoblast-like cells are implemented on laser-treated Ti surfaces and polished surfaces (control) with 1 day, 3 days and 7 days of cell culture. The best cell outcome was obtained by storing samples in air for 1 week, where storing for shorter or longer times resulted in the worst outcome, especially in the early stages of cell adhesion. There does not appear to be a direct link between wettability and the fate of cells on Ti surfaces. Indeed, while samples stored in air and ethanol have drastically different contact angle measurements (the former being hydrophobic and the latter hydrophilic), the cell behavior was unaffected. In addition, while wettability and laser treatment can affect the early stages of cell adhesion, they do not have a strong effect on the number of cells at longer incubation times (3 and 7 days). Laser machining does however affect the cell morphology and alignment, where cells preferentially align themselves parallel to the direction of the laser machined grooves with an elongated morphology.

No description available.

Titanium has been widely used for dental implants, and in particular, roughened titanium surfaces have provided a means for increasing bone apposition and strengthening the implant-to-bone interface. Finding a way to further increase osseointegration is important because there is a significant clinical benefit to patients if a stable anchor can be established instead of anchoring orthodontic hardware to the molars. In this study, the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the ability of temporary anchorage devices (TADs) to osseointegrate was investigated. The temporary anchorage devices (TADs) used in this study were manufactured from commercially pure titanium and divided into 2 types of treatments: (1) sandblasted and acid-etched (i.e. the control) and (2) sandblasted and acid-etched treated with Medtronic INFUSE® Bone Graft (recombinant human bone morphogenetic protein-2 placed on an absorbable collagen sponge). The implants were placed on the cranial bones of 10 adult male Sprague-Dawley rats. The rats were euthanized by carbon dioxide asphyxiation 6 weeks following surgery for histological examination and biomechanical testing. The results from visual inspection and biomechanical testing showed that the sandblasted and acid-etched TADs treated with rhBMP-2 promoted better osseointegration than TADs that were only sandblasted and acid-etched. Specifically, surface modified TADs treated with rhBMP-2 on bottom showed an increased surface coverage by bone and an increase in the adhesion strength at the TAD-to-bone interface.

The current gold standard treatment for bone defects is autologous cancellous bone graft, which involves increased surgery time and donor site morbidity, and limited supply of bone and cells for regeneration. Bioreactors may aid in the generation of mechanically conditioned bone grafts with more cells compared to traditional grafts. However, the specific parameters of fluid flow and mechanical loading which contribute to osteogenesis and cell viability in bioreactors are not fully characterized. Here, a perfusion-compression bioreactor system was developed to study osteogenesis in porcine trabecular bone explants. Loading accuracy was over 88% across six bioreactors at a 0.1 s-1 strain rate and 20 N target force, akin to running. A flow rate of 0.2 mL/min appeared to be more favorable for cell viability than 1 mL/min. Overall, this work offers a foundation for future efforts to enhance cell viability and osteogenesis in bone explants.

Syfte. Syftet med denna systematiska litteraturöversikt var att undersöka det vetenskapliga underlaget avseende långsiktig stabilitet hos olika typer av benersättningsmaterial i kombination med implantatinstallation.Material och metod. En elektronisk sökning gjordes med hjälp av PubMed och Web of Science. Block med sökord konstruerades och skrevs in i sökmotorerna för att hitta studier med implantatbehandling i kombination med benaugmentation, med en radiologisk uppföljning efter minst 2 år. Funna artiklar granskades i förhållande till förutbestämda inklusions- och exklusionskriterier. Data från inkluderade studier registrerades. Risken för bias i de inkluderade studierna bedömdes enligt modifierade protokoll.Resultat. Den elektroniska sökningen resulterade i 1183 studier, varav 14 studier med antingen autogent, allogent, xenogent eller alloplastiskt benersättningsmaterial inkluderades i denna litteraturöversikt. Resultatet från studierna visade en stor skillnad i både tekniker och material.Slutsats. Den generella slutsatsen i denna studie är att den marginella benförlusten vid dentala implantat som placerats i augmenterat ben inte överstiger 1 mm inom två år. En mer exakt slutsats om den marginella bennivåns stabilitet kunde inte dras på grund av de stora skillnaderna mellan de inkluderade studierna. Det finns ett behov av fler högkvalitativa studier med långtidsuppföljning som undersöker och jämför den marginella bennivåns stabilitet för olika benersättningsmaterial. / Aim. The purpose of this systematic review was to investigate the literature available regarding long-term stability of different bone augmentation materials in combination with dental implant treatment.Material and methods. An electronic search was done using PubMed and Web of Science. Blocks with keywords were constructed and inserted into the search engines to find studies involving implant treatment in combination with bone augmentation, with a radiographic follow-up of at least 2 years. Found articles were reviewed in relation to predetermined inclusion- and exclusion criteria. Data from included studies was extracted. Included studies were assessed of risk of bias according to modified protocols. Results. The electronic search yielded 1183 studies. 14 studies using either autogenous, allogeneic, xenogeneic or alloplastic augmentation materials was included in this review. The results from the data extraction process showed a wide variation in both materials and techniques used.Conclusion. The general conclusion drawn from this study is that marginal bone loss around dental implants placed in augmented bone does not exceed 1 mm within two years post-operatively. A more precise conclusion regarding marginal bone level stability could not be drawn due to the heterogeneity of the included studies. There is a need for additional high-quality studies with long-term follow-up, investigating and comparing marginal bone level stability for different bone augmentation materials.