Orientadores: Marcio Zaffalon Casati, Karina Gonzales Silverio Ruiz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-14T23:45:21Z (GMT). No. of bitstreams: 1 Ribeiro_FernandaVieira_D.pdf: 8018060 bytes, checksum: 8fc3b530db926d929facce5cfd30fb4e (MD5) Previous issue date: 2009 / Resumo: O objetivo deste estudo foi avaliar histometricamente o reparo ósseo em defeitos periimplantares do tipo deiscência, criados cirurgicamente em cães, tratados com a associação de células derivadas da medula óssea (CMs) e regeneração óssea guiada (ROG). A medula óssea foi obtida a partir da crista ilíaca de oito cães beagle adultos machos. Células derivadas da medula óssea (CMs) foram isoladas, cultivadas in vitro e fenotipicamente caracterizadas com relação as suas propriedades osteogênicas. Os mesmos animais foram submetidos à extração bilateral dos primeiros molares e terceiro e quarto pré-molares inferiores. Após três meses, três leitos para a colocação de implantes foram confeccionados em cada lado da mandíbula, deiscências ósseas vestibulares foram criadas e, então, implantes de titânio de superfície usinada foram colocados. As deiscências ósseas foram tratadas aleatoriamente, de acordo com um dos seguintes grupos: 1) ROG+CMs+C: membrana de PTFE-e com reforço de titânio associada às células derivadas da medula óssea semeadas no carreador, 2) ROG+C: membrana de PTFE-e com reforço de titânio associada ao uso do carreador sem células, 3) CMs+C: células derivadas da medula semeadas no carreador, 4) ROG: membrana de PTFE-e com reforço de titânio, 5) C: carreador sem células e 6) Controle: nenhum tratamento. Após três meses, os animais foram sacrificados e os implantes em conjunto com os tecidos adjacentes foram processados laboratorialmente para obtenção de secções não descalcificadas. Os parâmetros avaliados foram: Contato direto osso-implante (CO), Preenchimento ósseo dentro das roscas do implante (PR) e Área de tecido ósseo fora das roscas (AF). In vitro, a caracterização fenotípica demonstrou que células derivadas da medula óssea apresentaram potencial osteogênico identificado pela formação de nódulos minerais e expressão de marcadores ósseos (fosfatase alcalina, sialoproteína óssea e colágeno tipo I). As análises histométricas revelaram que todos os defeitos tratados com membrana (ROG+CMs+C, ROG+C e ROG) demonstraram resultados estatisticamente similares (p>0,05) com relação à área de novo osso formado fora das roscas do implante, apresentando, no entanto, maior quantidade de osso neoformado fora dos limites das roscas, quando comparados aos demais grupos (CMs+C, C e Controle) (p<0,05). Adicionalmente, foi observado que o preenchimento ósseo dentro das roscas foi estatisticamente semelhante entre os grupos que utilizaram membrana (ROG+CMs+C, ROG+C, ROG) e o grupo tratado com células sem barreira (CMs+C) (p>0,05), enquanto todos estes grupos mostraram um preenchimento ósseo significativamente superior ao grupo Controle (p<0,05). Com relação à porcentagem de contato osso-implante, embora os defeitos tratados com membrana (ROG+CMs+C, ROG+C e ROG) tenham apresentado valores estatisticamente maiores quando comparados aos defeitos dos grupos C e Controle (p<0,05), uma tendência para aumento da extensão de contato osso-implante foi observada nos defeitos tratados com células sem a associação da ROG (grupo CMs+C). Dentro dos limites do presente estudo, pôde-se concluir que embora as células derivadas da medula óssea, utilizadas isoladamente, tenham promovido bons resultados em relação à formação óssea dentro das roscas do implante, o seu uso, associado à ROG, não promoveu benefícios adicionais na formação óssea em defeitos peri-implantares de deiscência. / Abstract: The purpose of this investigation was to histometrically evaluate the bone healing in surgically created dehiscence-type defects around titanium implants treated with an association of bone marrow-derived cells (BMCs) and guided bone regeneration (GBR). Bone marrow cells were harvested from eight male adult beagle dogs, cultured in vitro and phenotypically characterized with regard to their osteogenic properties. Following, the same animals were subjected to bilaterally teeth extraction (lower premolars and the first molar) and three months later, three implant sites were drilled in each side of mandible, buccal bone dehiscences were created and titanium dental implants with machined surface were placed. Dehiscences were randomly assigned to one of the following groups: 1) GBR+BMCs+C: PTFE-e barrier placement associated with BMCs into the carrier, 2) GBR+C: PTFE-e barrier placement associated with carrier, 3) GBR: PTFE-e barrier placement, 4) BMCs+C: BMCs into the carrier, 5) C: carrier without cells e 6) Control: no treatment. After 3 months, the animals were sacrificed and the implants in conjunction with adjacent hard tissues were processed for undecalcified sections. Bone-to-implant contact (BIC), bone filling within the limits of implant threads (BF) and new bone area (BA) in a zone lateral to the implant surface were obtained. Results: In vitro, phenotypic characterization demonstrated that BMCs presented osteogenic potential identified by the mineral nodule formation and the expression of bone markers. Histometrically, inter-group analysis demonstrated that all defects treated with GBR (GBR+BMCs+C, GBR+C and GBR) were statistically similar in terms of BA (p>0.05), presenting significantly higher BA as compared with other groups (BMCs+C, C and Control) (p<0.05). With respect the BF, no differences were observed among GBR+BMCs+C, GBR+C, GBR and BMCs+C groups (p>0.05), whereas all these groups showed statistically superior BF as compared to Control group (p<0.05). Additionally, although the percentage of BIC has been significantly higher in the defects treated by barrier membrane (GBR+BMCs+C, GBR+C and GBR) as compared to C and Control groups (p<0.05), a trend towards to a greater extension of BIC has been observed for the defects treated with BMCs+C. Within the limits of this study, it was concluded that although the use of bone marrowderived cells has provided promising outcomes in terms of bone formation within the limits of implant threads, their use, in combination with GBR, has not promoted additional benefits on the bone regeneration in peri-implantar dehiscence type bone defects. / Doutorado / Periodontia / Doutor em Clínica Odontológica

Orientador: Altair Antoninha Del Bel Cury / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-14T23:43:34Z (GMT). No. of bitstreams: 1 RicominiFilho_AntonioPedro_M.pdf: 1929547 bytes, checksum: 3218196794c582fbd092c07948036e16 (MD5) Previous issue date: 2009 / Resumo: A presença de microrganismos na interface implante e pilar é um dos fatores associado ao insucesso de implantes osseointegrados. Sistemas de implantes de encaixe cônico visam precisa adaptação entre o implante e o pilar, entretanto não se sabe o comportamento desses sistemas frente a condições de estresse da cavidade oral quanto à manutenção da pré-carga e capacidade de selamento bacteriano. Assim, o objetivo deste estudo foi avaliar a perda de précarga e a infiltração bacteriana na interface implante e pilar de sistemas de encaixe cônico e hexágono externo, submetidos à ciclagem térmica e fadiga mecânica (CF). Foram utilizados 48 implantes de quatro sistemas de implante-pilar divididos em 8 grupos (n=6): (1) hexágono externo e munhão universal; (2) hexágono externo e munhão universal com CF; (3) cone morse e munhão universal; (4) cone morse e munhão universal com CF; (5) cone morse e munhão universal parafuso passante; (6) cone morse e munhão universal parafuso passante com CF; (7) cônica justaposição e pilar padrão; (8) cônica justaposição e pilar padrão com CF. Os implantes foram fixados em resina epóxica e os pilares acoplados, realizando a pré-carga. Os espécimes (implante-pilar) foram submetidos à ciclagem térmica de 1.000 ciclos a 5°C e 55°C, com permanência de 60 s em cada banho, e à fadiga mecânica de 1,0 milhão de ciclos, 1,0 Hz e 120 N. O ensaio de infiltração bacteriana foi realizado com o microrganismo Streptococcus sanguinis (NCTC 10904). Os espécimes foram imersos em meio Tryptic Soy + Yeast Extract (TY) contendo S. sanguinis e incubados a 37°C e 10% CO2 por 72 h. Os valores de destorque foram registrados e os pilares foram desacoplados. Cone de papel estéril foi esfregado na parte interna do implante, inserido em um tubo contendo meio TY estéril e incubado. A presença de infiltração bacteriana foi avaliada por meio da turbidez do caldo. Implantes e pilares foram avaliados por meio de MEV. Os dados de perda de pré-carga foram submetidos à análise de variância a 2 critérios e ao teste de Tukey. Todos os sistemas apresentaram maiores valores de destorque quando submetidos à CF (p<0,05). O sistema cone morse com munhão universal apresentou os maiores valores de destorque quando comparado aos demais sistemas (p<0,01). Todos os sistemas cônicos apresentaram infiltração bacteriana. Dentro das condições experimentais, o sistema cone morse com munhão universal apresentou os maiores valores de destorque e não foi observado relação entre a perda da précarga e infiltração bacteriana. / Abstract: The presence of microorganisms in the implant and abutment interface is one of the factors associated to the osseointegrated implant failures. Conical junction implant systems have aimed a precise fit between implant and abutment, however, the behavior of these systems it is not known when submitted to the stress environment as found in the oral cavity, related to the preload maintenance and bacterial seal ability. Thus, the aim of this study was to evaluate the preload loss and the bacterial penetration through the implant-abutment interface of conical and external hexagon connection systems, submitted to thermal cycling and mechanical fatigue (TM). Forty eight implants of four different implant-abutment systems were divided in 8 groups (n=6): (1) external hexagon and universal post; (2) external hexagon and universal post with TM; (3) morse taper and universal post; (4) morse taper and universal post with TM; (5) morse taper and universal post two pieces; (6) morse taper and universal post two pieces with TM; (7) locking taper and standard abutment; (8) locking taper and standard abutment with TM. The implants were embedded in epoxy resin and the abutments were connected, setting the preload. The assemblies (implant-abutment) were submitted to thermal cycling of 1.000 cycles at 5°C and 55°C, with a dwell time of 60 s each and to mechanical fatigue, 1.0 million cycles, 1.0 Hz, 120 N. Bacterial penetration assay was performed with Streptococcus sanguinis (NCTC 10904). The assemblies were immersed in Tryptic Soy + Yeast Extract (TY) broth containing S. sanguinis and incubated at 37°C and 10% CO2 for 72 h. Detorque values were recorded and the abutments were disconnected. Sterile paper points were rubbed on the inner part of the implant and inserted in a tube with sterile TY broth and incubated. The presence or absence of bacterial penetration was assessed by the broth turbidity. Implants and abutments were observed by SEM. The preload loss data was analyzed by two-way ANOVA, followed by Tukey test. All the screw systems showed higher detorque values when submitted to TM(p<0,05). The morse taper system with universal post showed the highest detorque values when compared with the other systems (p<0,01). All the conical systems showed bacteria penetration. Within these experimental conditions, the morse taper system with universal post showed the higher detorque values and no relation between the preload loss and the bacterial penetration was observed. / Mestrado / Protese Dental / Mestre em Clínica Odontológica

Orientadores: Marcio Zaffalon Casati, João Batista Cesar Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-15T00:47:10Z (GMT). No. of bitstreams: 1 Lima_LianaLinhares_D.pdf: 1779418 bytes, checksum: 5170e97149f324c7dae9d9edd2c763fb (MD5) Previous issue date: 2009 / Resumo: O objetivo do presente estudo foi avaliar histometricamente a influência do PTH (1-34) sobre o reparo ósseo e osseointegração de implantes de titânio instalados em tíbias de ratas expostas ou não à inalação da fumaça de cigarro. Foram utilizadas 61 ratas Wistar adultas aleatoriamente divididas em: grupo 1 (n=15) : animais que receberam a aplicação do veículo necessário para a dissolução do hormônio após a instalação do implante; grupo 2 (n=16) : inalação de fumaça de cigarro (IFC) por 60 dias no pré e pós-operatório da colocação do implante; grupo 3 (n = 17): tratamento do grupo 2 associado à injeções subcutâneas de 40 fxg/kg de PTH sintético (1-34) três vezes por semana, após a colocação do implante e grupo 4 (n=13) : injeções subcutâneas de 40 Hg/kg de PTH sintético (1-34) três vezes por semana após a instalação dos implantes. Os animais foram sacrificados sessenta dias após a colocação dos implantes, secções não descalcificadas foram obtidas e avaliadas histometricamente, segundo os seguintes parâmetros: porcentagem de tecido ósseo em contato direto com a superfície do implante (CD), porcentagem de preenchimento ósseo das roscas do implante (AO) e porcentagem de tecido mineralizado numa zona de 500 um, adjacente à superfície do implante (PTM). Os parâmetros foram obtidos separadamente para região cortical e região medular. Não foram detectadas diferenças entre os grupos que receberam aplicação de PTH (1-34) (Grupos 3 e 4) em todos os parâmetros avaliados (p>0,05). Além disso, o PTH promoveu um aumento significativo no CD, AO e PTM em ambas as regiões, mesmo na presença de IFC (p<0.05) (exceto para AO na região cortical). Uma influência negativa da IFC foi observada para o parâmetro CD na região cortical, uma vez que o grupo 2 apresentou os menores valores de CD, seguidos do grupo 1. Resultados semelhantes foram observados para PTM em ambas as regiões analisadas. Dentro dos limites deste estudo pode-se concluir que a aplicação intermitente de PTH (1-34) é capaz de minimizar os impactos negativos da inalação da fumaça de cigarro na osseointegração de implantes de titânio inseridos em tíbias de ratas. / Abstract: The aim of this study was to investigate the synthetic parathyroid hormone, PTH (1-34), can mitigate the effect of cigarette smoke inhalation (CSI) on the bone healing around titanium implants inserted in rats. 61 female Wistar rats were randomly assigned to one of four groups: group l(n = 15): animals that received the application of the necessary vehicle for the dissolution of the hormone after installation of the implant; group 2 (n = 16): cigarette smoke inhalation (CSI) for 60 days preoperatively and sixty days after implant placement group 3(n = 17), treatment group 2, associated with subcutaneous injections of 40 u-g / kg of synthetic PTH (1-34) three times a week after implant placement and group 4 (n = 13): subcutaneous injections of 40 ug / kg of synthetic PTH (1-34) three times a week after placement of implants. The animals were sacrificed sixty days after the placement of implants, not decalcified sections were obtained and evaluated histometrically, according to the following parameters: percentage of bone tissue in direct contact with the implant surface (BIC), percentage of bone filling the threads of the implant (BF) and percentage of mineralized tissue in an area of 500 urn adjacent to the implant surface (BA). The parameters were obtained separately for the cortical and cancellous bone. No differences were found between the groups that received PTH (1-34) (Groups 3 and 4) in all evaluations (p> 0.05). In addition, PTH (1-34) caused a significant increase in BIC, BF and BA in both regions, even in the presence of CSI (p <0.05) (except for BF in the cortical region). A negative influence of the IFC was observed for the parameter BIC in the cortical region, as group 2 had the lowest values of BIC, followed by group 1. Similar results were observed for BA in both regions analyzed. Within the limits of this study can conclude that the intermittent application of PTH (1-34) is able to reversing the negative effects of cigarette smoke inhalation on osseointegration of titanium implants inserted in rats. / Doutorado / Periodontia / Doutor em Clínica Odontológica

Orientador: Solange Maria de Almeida / Tese (doutorado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-15T20:48:17Z (GMT). No. of bitstreams: 1 Menezes_AlynneVieirade_D.pdf: 1911461 bytes, checksum: 9eed499fb3fe7db23a7c4de2811423d3 (MD5) Previous issue date: 2010 / Resumo: A utilização de implantes dentários para a reabilitação de regiões edêntulas é uma das atividades mais crescentes da Odontologia e a utilização de imagens é um fator essencial para se alcançar o almejado sucesso. Vários métodos de imagem vêm sendo utilizados com esse propósito e a tomografia computadorizada de feixe cônico (TCFC) vem se estabelecendo como um dos métodos promissores nesse sentido, pois se trata de um método confiável, capaz de produzir imagens em tamanho real, sem sobreposição e com dose de radiação menor que a tomografia computadorizada fan beam. Neste trabalho teve-se como objetivo avaliar a influência da posição da mandíbula na realização de medidas da altura e da espessura de sítios implantares em cortes ortorradiais de TCFC. Para tanto, foram utilizadas 10 mandíbulas maceradas, sendo obtidas imagens utilizando-se o tomógrafo de feixe cônico i-CAT. Foi realizada uma única imagem de cada mandíbula e a partir dessa imagem, os cortes ortorradiais foram obtidos considerando-se 3 diferentes posições: 1: base da mandíbula paralela ao plano horizontal (Posição Normal - PN); 2: base com inclinação de +10° (Posição Superior - PS) e 3: com inclinação de -10° (Posição Inferior - PI). A altura e a espessura óssea de cada região foram mensuradas por um único examinador e os dados obtidos nos grupos experimentais (PS e PI) foram comparados com os dados obtidos do grupo controle (PN) usando a análise de variância two-way (a=0,05). Os valores médios de altura e de espessura ósseas não variaram significativamente entre as posições inclinadas (PS e PI) e a posição padrão (PN), o que permite concluir que nas inclinações avaliadas, a direção do plano axial não influenciou nas medidas obtidas / Abstract: Dental implants have became part of routine treatment plans in many cases of edentulous patients and an important part of preimplant examination is provided by images of the existing bone structures in addition to the clinical findings. Several imaging modalities have been used for preimplant assessment and the cone-beam computed tomography may indeed be the next major advancement, since provides clinicians with accurate images of high diagnostic quality with relatively short scanning times and a reported radiation dose lower than fan beam computed tomography. The aim of this present study was to investigate the influence of mandibular inclination on the measured height and width of the cortical bone in reformatted cross-sectional cone beam computed tomography. Ten human dry mandibles were scanned with dental CBCT (i-CAT). It was performed only one scan of any mandible and reformatted cross-sectional scans were obtained at three different positions: (1) parallel to the lower border of the mandible (standard position); (2) with a inclination of +10° (Upper Position) and (3) with a n inclination of -10°(Lower Position). The alveolar bone height and width were measured for one examiner and data subjected to two-way analysis of variance and to compare the means obtained for the experimental groups (UP and LP) with the control group (standard position) (a=0,05). Mean values of bone height and width did not varied significantly between the inclined (UP and LP) and the standard positions. It could be concluded that in the positions analyzed, the direction of the axial planes did not influence the measurements obtained / Doutorado / Radiologia Odontologica / Doutor em Radiologia Odontológica

Orientadores: Rafael Leonardo Xediek Consani, Mateus Bertolini Fernandes dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-24T21:15:14Z (GMT). No. of bitstreams: 1 Nogueira_MoisesdaCostaFerraz_M.pdf: 1749031 bytes, checksum: 8fa4481a045e127aabb629294129a5b0 (MD5) Previous issue date: 2014 / Resumo: O objetivo neste estudo foi avaliar por meio da análise por elemento finito 3-D, as tensões ocorridas em overdentures com sistemas de retenção barra-clipe, quando diferentes formas da seção transversal (circular, ovóide ou Hader) apresentam diferentes níveis de desajuste vertical (50, 100 e 200 µm) e são confeccionadas com diferentes ligas metálicas (Au tipo IV, Ag-Pd, Co-Cr e Ti cp). Modelos tridimensionais foram feitos utilizando software para modelagem 3-D (SolidWorks 2010) e importados para o software de simulação mecânica (ANSYS Workbench 11). Aperto simulado do parafuso foi realizado até obter assentamento adequado entre infraestrutura e plataforma protética. As análises foram realizadas com o objetivo de obter as tensões Máxima Principal e de von Mises (MPa). Os valores da tensão aumentaram com o aumento do desajuste vertical, assim como a barra Hader proporcionou os maiores valores. Barras circulares feitas com Au tipo IV causaram os menores valores na barra e no parafuso protético. Ligas resilientes mostraram melhores resultados que as rígidas, enquanto a maior complexidade da seção transversal da barra e o maior nível de desajuste vertical aumentaram a concentração das tensões na barra, parafuso protético e tecido ósseo cortical. Conclui-se que as tensões induzidas na barra, parafuso protético e tecido ósseo peri-implantar foram influenciadas pelo aumento do desajuste vertical, complexidade da seção transversal e liga da barra / Abstract: The objective of this study was to evaluate by 3-D finite element analysis tensions occurred in overdentures with bar-clip retention systems, when different cross-sectional geometries (circular, oval or Hader) have different levels of vertical misfit (50, 100 and 200 µm) and were maded from different metallic alloys (type IV Au , Ag-Pd , Co-Cr and Ti cp). Three-dimensional models were maded using 3-D modeling software (SolidWorks 2010) and imported into the software of mechanical simulation (ANSYS Workbench 11). A displacement simulating screw tightening was done until proper fitting of the prosthetic platform infrastructure. The analyzes were performed in order to obtain the Maximum Principal Stress and von Mises (MPa). The stress values increased proportionally with the level of vertical misfit and Hader bar showed the highest values. Circular bars made with Au type IV showed the lowest values on the bar and prosthetic screw. Resilient alloys performed better than hard, while the greater complexity of the cross section of the bar and the highest levels of vertical misfit increased stress concentration on the infrastructure of the bar, prosthetic screw and cortical bone tissue. The stress induced on the bar, prosthetic screw and peri-implant bone tissue were influenced by increased vertical misfit, complexity of cross section and different alloys of the bar / Mestrado / Protese Dental / Mestre em Clínica Odontológica

Longtemps sous-estimées, les complications (douleurs, infections) en chirurgie viscérale par pose d’implants pariétaux s’avère critique par leur implication sur le retour à une activité normale du patient. Les techniques actuelles (ex. infiltration cicatricielle) ne parviennent à assurer qu’une analgésie de courte durée, voir des effets indésirables. La solution proposée a consisté à modifier deux implants pariétaux, l’un biostable (PET) et l’autre résorbable (PLA), par un polymère de cyclodextrine (polyCD), molécule cage connue pour sa capacité à former des complexes d'inclusions réversibles avec des médicaments. L'étude a d'abord porté sur la fonctionnalisation des supports en faisant varier les paramètres afin de maîtriser le degré de polyCD présent sur le textile, ensuite caractérisé par diverses techniques. Une étude de cytocompatibilité in vitro a été réalisée afin de détecter l'impact du polyCD sur la vitalité cellulaire. Les supports ont été imprégnés de ciprofloxacine. Après avoir mesuré leur capacité de chargement, des études de libération in vitro ont été menées, suivies de tests microbiologiques sur E. coli et S. aureus. Ces derniers ont montré la contribution du polyCD à augmenter la durée de l'activité antibactérienne. Puis deux molécules anesthésiques (lidocaïne et ropivacaine) ont été étudiées. D'abord, leur inclusion dans la cavité de la CD a été observée en solution par RMN et électrophorèse capillaire. Leurs isothermes d'adsorption ont été réalisées pour évaluer leur taux de chargement respectif sur le textile modifié. Ce taux s’est avéré correspondre aux doses thérapeutiques couramment appliquées localement dans les thérapies existantes. / For a long time underestimated, complications (pain, infection) in visceral surgery with implants, are critical in their impact on the return to normal activity of the patient. Current techniques (scar infiltration, ...) fail to ensure a short analgesia with sometimes side effects. The proposed solution is to confer bioactivity to the prosthesis. To this end, two textiles, a biostable (PET) and an absorbable (PLA), were modified by coating fibers with a cyclodextrin polymer (polyCD). Cyclodextrins are cage molecules known for their ability to form reversible inclusion complexes with bioactive molecules. The study initially focused on the functionalization of materials by varying the parameters to control the degree of polyCD, then characterized by various techniques. Cytocompatibility study was performed to detect the polyCDs impact on the vitality of cells. Concerning the biological activation of the materials, a series of tests was performed with ciprofloxacin. After measuring their loading capacity, release studies were conducted in vitro, followed by microbiological tests on E. coli and S. aureus. The latter showed the contribution of polyCD on the duration of the antibacterial activity. Then two local anesthetics (lidocaine and ropivacaine) were studied. First, their inclusion in the cyclodextrin was observed in solution by NMR and capillary electrophoresis. Their sorption isotherms were conducted to evaluate their respective loading rate, which corresponded to therapeutic doses commonly used in usual therapeutics.

Magister Chirurgiae Dentium - MChD / The purpose of this study was to investigate the stress produced around the angled distal implants under simulated occlusal loading in the All-on-Four&ordf; concept by means of two-dimensional photoelastic stress models. / South Africa

archives@tulane.edu / Prostheses have enabled many people with bone injuries to achieve a quality of life that would be difficult without the advances in biomedical engineering and materials sciences. Exploration of alternatives to current methods of prosthetic bone development will result in more options from both the physician and patient perspective for the replacement of bone and the use of bone substitutes. Thus, new bone prostheses can be customized to a patient’s needs. To address rising healthcare costs, 3D printed bone substitutes are enabling affordable and customizable bone replacements. In this study, we designed a strong yet lightweight structural matrix to substitute bone grafts in cases of comminuted fracture of tibial bone. The artificial matrix is inspired by structural components called voxels that have been demonstrated to be feasible in the areas of aerospace for fixed and morphing wing flight. The basis of this voxel matrix is derived from units of hollow eight-sided faces formed from 12 connected struts. In this study, we have produced and simulated a lattice that can resemble natural bone performance. This bone facsimile has been evaluated using finite element analysis to suggest an optimal voxel density and beam width at which the internal structure has a high elastic modulus to relative density ratio for use as a scaffold during bone reconstruction. A lattice-based implant was designed and evaluated using finite-element analysis for osteosarcoma-afflicted long bones such as the tibia. This study should pave the way for bone implants made of strong but lightweight structures can help patients regain the faculties of natural bone. Ultimately, this structure would be constructed from biocompatible materials that provide nutrients for natural bone regeneration processes. With this, the structure would reabsorb completely into the healing bone, after providing a matrix upon which osteoblasts can form new bone. / 1 / Afsheen Sajjadi

Cochlear implants have successfully been used to enable hundreds of thousands of profoundly deaf people to regain some perception of hearing. Hearing performance does, however, vary greatly among individual implant users. In order to gain a better understanding of the underlying factors that cause these inter-user performance differences, insight into the functioning of individual implant users’ hearing systems is required. Some of the parameters unique to an implanted user’s hearing system may be measured non-invasively using psychoacoustics or the measurement of electrically evoked compound action potentials. While these methods provide information of the macro response of a user’s hearing system to stimulation, individual parameters, for example the individual neurons that are excited cannot be measured. Some individual parameters are difficult or even impossible to measure in a living human as it is not technically feasible or invasive surgery is required. When obtaining measurements inside the inner ear of a living human is not an option, an alternative that mimics the human hearing system is required from which measurements can be predicted: models. This study describes the development of a method to construct an electrical computational three-dimensional finite element model of the implanted cochlea of a specific living individual. This method is presented as a tool for researchers to probe the cochleae of specific implanted users non-invasively. Data from a low resolution computer tomography scan is used to construct a geometric representation of the bony outer cochlear structures and augmented with histologic data to construct the smaller inner cochlear structures. A detailed skull geometry with brain and scalp volumes that includes the user’s return electrode is also constructed. The user’s electrode array is modelled in its intra-cochlear location and stimulation is simulated using finite element modelling. The cochleae of five individual ears were modelled and intra-cochlear and neural node potentials were predicted along with neural excitation patterns. Having models that can predict user-specific outcomes, predictions that include the variability between implanted ears are obtained. This allowed the comparison of modelled data to common trends found in literature and enabled the investigation of questions frequently asked by modellers. These include the effect that bone resistivity, head volume shape, return electrode implementation and return electrode position have on modelled results. These findings were incorporated and contributed to higher detailed models being produced than are currently described in literature. The models were then practically applied in two areas. The first was in the quantification of potential decay in the cochlea where a simple model is derived to predict decay at the neuron level based on the location of an electrode. The second was in the translation of the model into the clinical domain where the mismatch between the perceived pitch and mapped frequencies of specific implanted individuals were predicted. Along with these predictions it was found that neural excitation and intra-cochlear potential spread are highly dependent on individual cochlear morphology. This warrants the inclusion of user-specific morphology in volume conduction models of the implanted cochlea where user-specific outcomes are predicted. / Thesis (PhD (Electronic Engineering))--University of Pretoria, 2015. / Electrical, Electronic and Computer Engineering / PhD (Electronic Engineering) / Unrestricted

Les implants dentaires sont maintenant largement utilisés pour remplacer les dents manquantes chez les patients partiellement ou complètement édentés. Plusieurs facteurs de risque qui peuvent contribuer à des maladies péri-implantaires sont désormais identifiés tels que la mauvaise hygiène buccodentaire ou des habitudes tabagiques. Cependant, il n'y a toujours pas de consensus sur plusieurs facteurs systémiques qui peuvent interférer avec l'obtention ou le maintien d'une ostéointégration de l'implant. L'objectif de cette étude était d'examiner systématiquement la survie des implants et la perte osseuse marginale radiographique autour de ces implants chez les patients souffrant de différentes maladies ou conditions osseuses. Une recherche bibliographique de différentes bases de données a été réalisée en incluant des études publiées entre janvier 1990 et décembre 2019. La revue systématique et la méta-analyse ont été effectuées conformément aux lignes directrices recommandées par la directive du "Preferred Reporting Items for Systematic Review and Meta-Analyses". Suivant les critères d'inclusion et d'exclusion établis, cette revue systématique a retenu six articles sur le diabète avec 661 implants au total et deux études sur des patients ostéoporotiques avec 274 implants au total. Dans la population diabétique, les paramètres péri-implantaires étaient généralement pires en particulier lorsque leur niveau glycémique n'était pas contrôlé. Quatre des études ont été incluses dans la méta-analyse. Il y avait moins de perte osseuse chez la population non diabétique (différence moyenne 0,46 mm; intervalle de confiance 95% (0,06-0,86), z=2,28, p=0,02) par rapport aux patients ayant un diabète non contrôlé. Il n'y avait aucune différence dans les taux de survie des implants entre les deux populations à l'étude. Chez les patients ostéoporotiques, il n'y avait pas de différence de survie des implants ou de perte osseuse marginale par rapport aux patients sains. Cette revue systématique et méta-analyse ont démontré que les patients diabétiques non contrôlés doivent être traités avec prudence mais aucune conclusion n'a pu être tirée sur d'autres maladies et conditions osseuses. Des études à long terme bien menées sont nécessaires afin d'établir des lignes directrices pour traiter les patients ayant des maladies systémiques de façon adéquate. / Dental implants are now widely used to replace missing teeth in partially or fully edentulous patients. Several risk factors associated to peri-implant diseases are now recognized such as poor oral health or smoking habits. However there is no consensus on several systemic factors that may interfere with gaining or maintaining osteointegration. The objective of this study was to systematically review the survival of implants and radiographic marginal bone loss around those implants in patients that have bone diseases or conditions that affect bone metabolism. A literature search of different databases was conducted for studies published between January 1990 and December 2019. The systematic review and meta-analysis were done according to the guidelines recommended by the "Preferred Reporting Items for Systematic Review and Meta-Analyses statement". Following the established inclusion and exclusion criteria, we selected six published articles on diabetic patients with 661 implants in total and two published studies on osteoporotic patients with 274 implants in total. In the diabetic population, peri-implant parameters were generally worse particularly when their diabetes was not controlled. Four of the studies were included in the meta-analysis. There was less bone loss in the non-diabetic population (mean difference 0.46 mm; 95% confidence interval (0.06-0.86), z=2.28, p=0.02) as compared to patients that have poorly controlled diabetes. There was no difference in implant survival rates in the two studied populations. As for osteoporotic patients there was no difference in implant survival or marginal bone loss when compared to healthy patients. This systematic review and meta-analysis showed that uncontrolled diabetic patients need to be treated with caution. No conclusions were drawn on any other bone diseases and conditions. More long-term studies are needed to establish guidelines to provide better patient care in the presence of systemic disease.