Indiana University-Purdue University Indianapolis (IUPUI) / Orthodontic closing loops offer an efficient way to control the moment to force ratios (M/F) delivered during space closure. The triangular loop is often used in the Graduate Orthodontic Clinic at the Indiana University School of Dentistry. Previous studies on the triangular loop were concerned with various loop geometries. The present project was designed to study the triangular loop in a clinically realistic experimental set up. Compared to the previous studies, three major changes were implemented: instead of two coplanar brackets, the current study employed a bracketed typodont arch (1) the effects of loop locations (2) and different interbracket distances were considered (3). The measured moment and forces reflect considerable differences in the systems due to the new experimental set up. As in previous studies, the triangular loops were fabricated from 0.016 X 0.022- inch stainless steel wire. The loops were equilateral triangles with 8 mm sides, ligated to the arch wire by elastomeric rings. There were 4 loop locations: location 1 was at 1.2 mm away from the mesial bracket; location 2 was at 3 .2 mm away from the distal bracket; location 3 was centered in the middle of the original interbracket distance; location 4 was located 2.6 mm away from the mesial bracket. There were three interbracket distances (IB). The original IB (IBl) of 12.6 mm was decreased by 3 mm (IB 2) and by 6 mm (IB 3). The loops were activated by 1.6 mm and 3.3 mm. Force and moment components were measured along three mutual perpendicular axes (x, y, and z) corresponding to the buccolingual, mesiodistal, occlusogingival axes respectively. Comparisons of Mx/Fy and Mz/Fy at the mesial and distal, by three activation levels, three interbracket distances, and four locations, and all interaction effects, were performed using a mixed design repeated measures ANOV A procedure. The General Linear Model (GLM) procedure for unbalanced designs was used because not all interbracket distances could be accommodated with all loop locations. Activation distance was the within specimen repeated factor. Loop location and interbracket distance were the between specimen factor. It was theorized that the location of the triangular loop, as well as the interbracket distance, have a considerable effect on the generated M/F. The Null Hypothesis was that there are no significant differences (p > 0.05) in the M/F ratios generated by the triangular loop as the loop position changes relative to the brackets, and there are no significant differences (p>0.05) in the M/F ratios generated by the triangular loop as the interbracket distance becomes shorter with space closure. Statistical significant interactions were found for Mx/Fy and Mz/Fy at location 2, for all activations, at both the mesial and distal measures. Therefore we rejected the first part of the Null Hypothesis (no differences as the loop location changes), and accept the second part (no differences as the interbracket distance shortens). We were able to see clear trends at all loop locations, as well as interbracket distances, and draw useful clinical implications. We found that the mesial closing forces are quite small when compared to those at the distal. We attributed this discrepancy to the U shape geometry of the continuous arch wire technique. We observed that if closing loops are delivered with no activation, then counterproductive M/F ratios are produced. Our data also indicated that anchorage becomes more critical as the interbracket distance shortens. Finally, we determined that wire tie ligation for prevention of rotation along the long axis of the tooth is especially important for the lateral incisor.

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No. of bitstreams: 1 pinotti_kf_dr_bot.pdf: 7020764 bytes, checksum: fa87243e46f8244edc33c33d3eea6530 (MD5) Previous issue date: 2016-08-08 / Introdução: A técnica de fechamento convencional, após esternotomia mediana, para unir as duas partes do esterno, é realizada com fios de aço aplicando-se sutura simples ou sutura em forma de oito, no entanto, esta técnica tem sido associada a várias complicações pós-operatórias graves, tais como: deiscência da ferida, infecção esternal profunda, instabilidade esternal e mediastinite, principalmente em pacientes com fatores de risco, tais como portadores de osteoporose, diabetes, obesidade, entre outros. Novas estratégias para o fechamento de esternotomias medianas estão sendo propostas para tentar minimizar a incidência dessas complicações. Objetivos: Avaliar a eficácia de técnicas de fechamento esternal não convencional para a prevenção de complicações da ferida esternal após esternotomia mediana, comparando com o fechamento convencional. Métodos: A última pesquisa foi realizada nodia 15 de Setembro de 2015. Não houve restrições de linguagem. Os trabalhos foram obtidos a partir das seguintes fontes: Wounds Cochrane Grupo Especializada Register, Cochrane Central Register de Ensaios Controlados (CENTRAL), Ovid MEDLINE (1946 até o dia 15 de Setembro de 2015), Ovid EMBASE (1974 até o dia 15 de Setembro de 2015), EBSCO CINAHL (1982 até o dia 15 de Setembro de 2015) e LILACS (1982 até o dia 15 de Setembro de 2015). Foram pesquisados os registros de ensaios clínicos. Foram também rastreadas as listas de referências e contactados os autores necessários. Critério de seleção: dois revisores independentes identificaram os estudos para a inclusão. Foram incluídos estudos randomizados controlados de técnicas de fixação esternal após esternotomias, comparando métodos convencionais com métodos alternativos realizados com pessoas de qualquer idade, sexo e raça. Coleta e análise de dados: dois revisores extraíram independentemente os dados, avaliaram seu risco de viés e os desfechos para cada artigo. Para desfechos dicotômicos foi utilizada a razão de risco (RR) com intervalos de confiança (IC) de 95%. Para desfechos contínuos foram apresentados os resultados como diferenças de médias (MD) com intervalo de confiança (IC) de 95%. Resultados: Foram incluídos 23 estudos que envolveram 8741 pacientes. O maior risco de viés foi do mascaramento de participantes e pessoal, devido à natureza cirúrgica da intervenção. Houve uma diferença estatisticamente significativa favorecendo o fechamento não convencional, mas com uma baixa qualidade de evidência, quando analisados os desfechos: infecção profunda da ferida esternal (RR 0,24, IC95% 0,06-0,93; 16 estudos, 7559 participantes); instabilidade do esterno (RR 0,20, IC95% 0,07-0,56; 15 estudos, 5467 participantes); e tempo de ventilação mecânica (diferença média de -1,93 dias, IC 95% -3,77 a -0,10; 5 estudos, 1800 participantes). Não houve diferença nos desfechos: deiscência da ferida (RR 1,07, IC95% 0,60-1,89; 12 estudos, 6758 participantes); morte (RR 0,96, IC95% 0,64 a 1,45; 13 estudos, 4506 participantes); tempo de internação hospitalar (diferença média - 1,16 dias, IC 95% -3,15 a 0,83; 11 estudos, 4859 participantes); re-operação (RR 0,60, IC95% 0,23-1,60; 9 estudos, 5124 participantes); permanência na UTI (diferença média - 0,15 dias, IC 95% -0,37 a 0,07; 8 estudos, 5240 participantes); e mediastinite (RR 0,65, IC95% 0,18 a 2,39; 7 estudos, 3011 participantes). Houve diferença estatisticamente significante favorecendo a utilização de colete torácico pós-operatório, mas também com baixa qualidade de evidência, quando analisados os desfechos: infecção profunda da ferida esternal (RR 0,44, IC95% 0,25- 0,77; 3 estudos, 3510 participantes); tempo de internação hospitalar (diferença média - 5,16 dias, IC 95% -6,65 a -3,67; 2 estudos, 971 participantes); e reoperação (RR 0,43, IC95% 0,23 a 0,80; 2 estudos, 3289 participantes). Não houve diferença nos desfechos: deiscência da ferida (RR 1,07, IC95% 0,59-1,91; 3 estudos, 3510 participantes); instabilidade do esterno (RR 0,13, IC95% 0,01-1,22; 2 estudos, 971 participantes); e morte (RR 0,14, IC95% 0,02 a 1,16; 2 estudos, 971 participantes). Conclusões: Há alguma evidência, de baixa qualidade, de que o uso de métodos não convencionais, em pacientes de alto risco, pode reduzir a infecção profunda da ferida esternal, a instabilidade esternal e o tempo de ventilação mecânica no pós-operatório de esternotomia mediana, mas não há diferença quando se comparam as taxas de: morte, deiscência da ferida, mediastinite, reoperação, tempo de internação hospitalar ou internação em UTI. Existe uma baixa evidência de que o uso de colete torácico no pós-operatório pode reduzir a infecção profunda da ferida esternal, a reoperação e o tempo de internação hospitalar, mas não há diferença quando comparamos deiscência, instabilidade esternal e mortalidade. / Background: The standard closure technique after median sternotomy is to join the two parts of the sternum using steel wires with simple suture or figure-of-eight fashion wiring, however this tecnique has been associated with several serious postoperative complications, such as: wound dehiscence, deep sternal wound infection, sternal instability, mediastinitis, specially in patients with risk factors such as osteoporosis, diabetis, obesity, and others. New strategies for the closure of median sternotomies are being sought to try minimize the incidence of these complications. Objectives: Evaluate the efficacy and safety of non-conventional sternal closure techniques for preventing sternal wound complications following sternotomy, compared to the conventional closure. Methods: We ran the search on the 15 September 2015. There were no language restrictions. Trials were obtained from the following sources: the Cochrane Wounds Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE (1946 to present), Ovid EMBASE (1974 to present), EBSCO CINAHL (1982 to present) and LILACS (1982 to present). We searched clinical trials registers. We also screened reference lists and contacted experts. Selection criteria: Two review authors independently identified studies for inclusion. We included randomized controlled trials of sternal fixation techniques following sternotomies, comparing standard methods with alternative methods conducted with people of any age, gender and race. Data collection and analysis: Two review authors, independently extracted data, assessed their risk of bias in the trials and outcomes for each trial. For dichotomous data we used the risk ratio (RR) with 95% confidence intervals (CI). For continuous data we presented the results as mean differences (MD) with 95% confidence intervals (CI). Results: We included 23 studies that involved 8741 people. The increased risk of bias was the blinding of participants and personnel, due to the surgical nature of the intervention. There were low quality of the evidence favoring non standard closure, when we analised the outcomes: deep sternal wound infection (DSWI) (RR 0.14, 95% CI 0.04 to 0.43; 16 studies, 7559 participants); sternal instability (RR 0.20, 95% CI 0.07 to 0.56; 15 studies, 5467 participants); and mechanical ventilation time (Mean difference 1.93 fewer days, 95% CI -3.77 to -0.10; 5 studies, 1800 participants). There was no difference in outcomes: wound dehiscence (RR 1.07, 95% CI 0.60 to 1.89; 12 studies, 6758 participants); death (RR 0.96, 95% CI 0.64 to 1.45; 13 studies, 4506 participants); hospital stay (Mean difference - 1.16 days, 95% CI -3.15 to 0.83; 11 studies, 4859 participants); reoperation (RR 0.60, 95% CI 0.23 to 1.60; 9 studies, 5124 participants); ICU stay (Mean difference - 0.15 days, 95% CI -0.37 to 0.07; 8 studies, 5240 participants); and mediastinitis (RR 0.65, 95% CI 0.18 to 2.39; 7 studies, 3011 participants). There were low quality of evidence favoring the use of post operative thoracic vest (corset), when we analised the outcomes: deep sternal wound infection (DSWI) (RR 0.44, 95% CI 0.25 to 0.77; 3 studies, 3510 participants); hospital stay (Mean difference 5.16 fewer days, 95% CI -6.65 to -3.67; 2 studies, 971 participants); and reoperation (RR 0.43, 95% CI 0.23 to 0.80; 2 studies, 3289 participants). There was no difference in outcomes: wound dehiscence (RR 1.07, 95% CI 0.59 to 1.91; 3 studies, 3510 participants); sternal instability (RR 0.13, 95% CI 0.01 to 1.22; 2 studies, 971 participants); and death (RR 0.14, 95% CI 0.02 to 1.16; 2 studies, 971 participants). Conclusions: There is low quality of the evidence that the use of non standard methods, in high risk patients, can reduce deep sternal wond infection, sternal instability and mechanical ventilation time on post operative median sternotomy, but there is no difference when we compare rates of: death, wound dehiscence, mediastinites, reoperation, hospital stay or ICU stay. There is low quality of the evidence that the use of post operative Thorax Vest (Corset) can reduce deep sternal wound infection, reoperation and hospital stay, but there is no difference when we compare wound dehiscence, sternal instability and death.

Les propriétés magnétiques détaillées des solides peuvent être vu comme le résultat de l'interaction de plusieurs sous-systèmes: celui des spins effectifs, portant l'aimantation, celui des électrons et celui du réseau crystallin. Différents processus permettent à ces sous-systèmes d'échanger de l'énergie. Parmis ceux-ci, les phénomènes de relaxation jouent un rôle prépondérants. Cependant, la complexité de ces processus en rend leur modélisation ardue. Afin de prendre en compte ces interactions de façon abordable aux calculs, l'approche de Langevin est depuis longtemps appliquée à la dynamique d'aimantation, qui peut être vue comme la réponse collective des spins. Elle consiste à modéliser les interactions entre les trois sous-systèmes par des interactions effectives entre le sous-système d'intérêt, les spins, et un bain thermique, dont seulement la densité de probabilité constituerait une quantité pertinente. Après avoir présenté cette approche, nous verrons en quoi elle permet de bâtir une dynamique atomique de spin. Une fois son implémentation détaillée, cette méthodologie sera appliquée à un exemple tiré de la littérature et basé sur le superparamagnétisme de nanoaimants de fer. / Detailed magnetic properties of solids can be regarded as the result of the interaction between three subsystems: the effective spins, that will be our focus in this thesis, the electrons and the crystalline lattice. These three subsystems exchange energy, in many ways, in particular, through relaxation processes. The nature of these processes remains extremely hard to understand, and even harder to simulate. A practical approach, for performing such simulations, involves adapting the description of random processes by Langevin to the collective dynamics of the spins, usually called the magnetization dynamics. It consists in describing the, complicated, interactions between the subsystems, by the effective interactions of the subsystem of interest, the spins, and a thermal bath, whose probability density is only of relevance. This approach allows us to interpret the results of atomistic spin dynamics simulations in appropriate macroscopic terms. After presenting the numerical implementation of this methodology, a typical study of a magnetic device based on superparamagnetic iron monolayers is presented, as an example. The results are compared to experimental data and allow us to validate the atomistic spin dynamics simulations.