Dissertations / Theses on the topic 'Air abrasion'

Objectives: This research aimed to characterise the physico-chemical interaction of bioactive glass 45S5 (BAG) air-abrasion with human enamel including the controlled and selective removal of substrates and the remineralisation of enamel white spot lesions (WSLs). Materials and methods: The effect of six operating parameters on air-abrasion dynamic cutting efficiency/patterns was assessed using an enamel analogue material (MacorTM) and white light profilometry. Standardised resin composite restorations created within MacorTM blocks, were removed in simulated clinical conditions and scanned using triangulation laser profilometry to investigate the effect of operating parameters on the selective resin composite removal using BAG air-abrasion. The remineralisation of artificial enamel WSLs treated using BAG mixtures were evaluated using Raman micro-spectroscopy, microhardness and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). The physical and optical changes in WSLs pre-conditioned using air-abrasion with BAG-polyacrylic acid (PAA-BAG) powder were detected using non-contact profilometry and optical coherence tomography (OCT). All comparisons were considered statistically significant if p < 0.05. Results: Significant differences in air-abrasion cutting efficiency / pattern were observed according to the tested parameters. BAG air-abrasion removed resin composite more selectively than conventional alumina air-abrasion and the effect of altering the unit’s operating parameters was significant. Enamel WSLs treated with BAG mixtures exhibited a significantly higher Knoop microhardness compared to the negative control. Raman micro-spectroscopy detected significantly higher phosphate content and the SEM images revealed mineral depositions on the surface of treated lesions. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion increased WSL surface area. This pre-treatment increased Knoop microhardness and the mineral content of remineralised WSLs. Conclusions: The ultraconservative clinical applications of BAG air-abrasion can be improved by altering the operating parameters. BAG and PAA-BAG can remineralise enamel WSLs. Pre-conditioning the lesion surface with PAA-BAG air-abrasion modifies the lesion surface physically and consequently enhances remineralisation using BAG 45S5 therapy.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Pouco se sabe sobre o efeito do jateamento pré-sinterização da zircônia na sua resistência mecânica, sob condições de envelhecimento. Este estudo avaliou a influência do tamanho da partícula, do momento do jateamento e do envelhecimento na resistência mecânica de uma zircônia estabilizada por ítria. Quatrocentos discos de uma zircônia estabilizada por ítria pré-sinterizados foram alocados como segue: sem jateamento; jateamento com partículas de óxido de alumínio (Al2O3) de 50 µm ou 120 µm antes (50/PRÉ ou 120/PRÉ) ou após (50/PÓS ou 120/PÓS) sua sinterização. Os discos foram não envelhecidos (24h) ou envelhecidos por: ciclagem mecânica (CM); envelhecimento hidrotérmico (EH) ou CM+EH, totalizando 20 grupos (n=20). Os espécimes foram submetidos ao teste de resistência à flexão biaxial (RFB) e, posteriormente, foram analisados fractograficamente. A análise de difração de raios-X (DRX) foi realizada em determinadas condições para caracterizar cristalograficamente o efeito do jateamento na zircônia. Os dados de RFB (MPa) foram analisados por ANOVA a 3 fatores e pós teste de Games Howell (α=0,05). Também foi realizada análise de Weibull. A RFB e a resistência característica (σ0) dos grupos 120/PÓS, envelhecidos ou não, foram significativamente maiores que as dos demais grupos jateados, e estatisticamente similares ou maiores que as dos respectivos grupos sem jateamento. Em contrapartida, o grupo 120/PRÉ/não envelhecido e todos os grupos 50/PRÉ apresentaram os menores valores. Em todos os grupos, o defeito inicial se originou na superfície submetida à tração. Nem o jateamento, nem o envelhecimento (exceto o grupo 50/PÓS/CM+EH) reduziram a confiabilidade da zircônia em relação à dos respectivos grupos controles. O jateamento promoveu um aumento do conteúdo de fase monoclínica, enquanto a sinterização zerou essa fase. O jateamento da zircônia antes da sinterização teve pior desempenho para RFB em comparação ao realizado após sua sinterização, sob os meios de envelhecimentos. A RFB e σ0 foram fortemente determinadas pelo tamanho da partícula e pelo momento do jateamento, enquanto o envelhecimento agiu apenas quando a zircônia foi jateada antes da sinterização.
Little is known about the effect of air-abrasion before zirconia sintering on its strength, under aging challenge. This study aimed to verify the influence of the air-abrasion moment (before or after zirconia sintering), particle size (50 or 120 μm) and aging on the mechanical strength of a Y-TZP ceramic. Four hundred pre-sintered zirconia discs were allocated as follows: non-air-abraded; air-abraded with 50 μm or 120 μm Al2O3 particles before (50/BS or 120/BS) or after sintering (50/AS or 120/AS). The discs were non-aged (24h) or aged by: mechanical cycling (MC); hydrothermal aging (HA) or by both methods (MC+HA), totaling 20 groups (n=20). Specimens were subjected to biaxial flexural strength test (BFS). Fractographic analysis was performed to identify the fracture origin. The X-ray diffraction analysis (XRD) was performed under certain conditions to characterize the crystallographic effect of air-abrasion on the zirconia. The BFS data (MPa) were analyzed by ANOVA and Games Howell post hoc test (α=.05). Weibull statistics was also applied. The BFS and the characteristic resistance (σ0) of the 120/AS groups, aged or not, were significantly higher than those of the other air-abraded groups, and statistically similar or higher than the respective groups without air-abrasion. In contrast, the 120/BS/non-aged group and all those 50/BS presented the lowest values. In all groups, the initial defect had its origin on the tensile stress side. Neither air-abrasion nor aging (except for 50/AS/MC+HA) reduced the zirconia reliability compared with the respective controls. Air-abrasion promotes an increase in the monoclinic phase content, while sintering zeroed this phase. Air-abrasion before zirconia sintering yields worse performance for BFS than after sintering, under aging challenges. The BFS and σ0 were strongly determined by the particle size and air-abrasion moment, while aging acted only when the zirconia was air-abraded before sintering.

Introduction: An optimal orthodontic bonding system must minimize damage to the enamel during conditioning, have enough bond strength to prevent bracket de-bonding during treatment, and allow bracket removal at treatment completion, such that minimal damage is inflicted to the tooth.1 Pumice followed by acid etching has been the standard for many years; however, Groman Inc. (Margate, FL, USA) has stated that using their air-abrasion product will result in a tripling of bond strength. This method claims a three-fold increase in bond strength compared to traditional acid etching techniques by substituting air-abrasion using the EtchMaster® (Groman Inc., Margate, FL) 50 μm aluminum oxide in place of pumice prophy prior to acid etching. The purpose of this study is to see if this combination does in fact triple shear bond strength, and if so, what impact it has on the residual enamel surface after bracket removal, or de-bonding. Methods: Ninety recently extracted bovine incisors were randomly divided into three groups. Each of the three groups underwent different conditioning methods prior to bracket bonding. Group A: pumice + acid etch (N=30), Group B: air-abrasion + acid etch (N=30), and Group C: air-abrasion only (N=30). Enamel surface conditions were characterized using a Quanta 200 Scanning Electron Microscope (SEM) (FEI, Hillsboro, OR) and a SZX7 Stereomicroscope System (Olympus, Center Valley, PA). American Orthodontics Master Series System twin MBT mandibular incisor brackets (Sheboygan, WI, USA) were then bonded to each tooth. Following bonding, teeth were stored for twenty-four hours in water at 37°C +/- 2°C. All groups then underwent thermocycling of five hundred cycles in water baths set at five and fifty-five degrees Celsius. Next, the samples were mounted in dental stone and brackets de-bonded using a universal testing machine (Instron, Canton, MA) to obtain shear bond strength (SBS) values. SEM and optical stereomicroscopy were again utilized to evaluate the enamel surface and determine the adhesive remnant index (ARI) was score of each specimen. Results: The mean of Group A (pumice + acid etch) was 21.52 MPa with a standard deviation of 4.97 MPa. The mean of Group B (air-abrasion + acid etch) was 21.83 MPa with a standard deviation of 7.55 Mpa. The mean of Group C (air-abrasion only) was 8.12 MPa with a standard deviation of 3.05 MPa. Analysis of variance showed a main effect of Group on MPa, F(2, 87) = 60.66, p < 0.001, ηp2= 0.58. Post-hoc analyses using Tukey’s HSD indicated that SBS values were higher for teeth in Group A than for those in Group C (p < 0.001), teeth in Group B had higher SBS values than those in Group C (p < 0.001), but no difference was found for SBS between teeth in Group A and Group B (p =0.981). Results from the Fisher’s Exact test, where we controlled the Type I error using a Bonferroni correction, reveals that ARI scores differed by group (p < 0.001). Stereomicroscope images at 38.75x magnification obtained following enamel conditioning show Groups A (P+AE) and B (AA+AE) are almost indistinguishable; however, Group C (AA) has visual differences. Group C had a speckled reflective property that appeared to be residual aluminum oxide particles. Following de-bond, stereomicroscopic and SEM images showed no enamel defects on the tooth. Conclusions: SBS was not significantly different between Group A (pumice + acid etch) and Group B (air-abrasion + acid etch). SBS was significantly different between Groups A and B, and Group C (air-abrasion only). This means there is not a three-fold increase in SBS when using air-abrasion and acid etch, when compared to pumice and acid etch, as claimed by the manufacturer of the air-abrasion unit used in this study. Additionally, the air-abrasion only group displayed a significantly lower SBS than Group A and B. Air-abrasion only is not a suitable enamel preparation method for orthodontic bonding. Images obtained from the stereomicroscope and SEM reveal no observational damage to the enamel surface topography after de-bonding for any group.

Orientador: Lourdes Aparecida Martins dos Santos-Pinto
Banca: Celso Luiz de Angelis Porto
Banca: Maria Cristina Borsatto
Resumo: O sistema de abrasão a ar funciona por meio de energia cinética produzida por um jato pressurizado de partículas de óxido de alumínio, que tem a finalidade de abrasionar a superfície dentária. O objetivo deste estudo foi avaliar a efetividade do sistema de sucção, disponível em consultório odontológico, na captação das partículas de óxido de alumínio emitidas pelo aparelho de abrasão a ar. Um dispositivo metálico, que reproduzia as posições e as distâncias de trabalho do cirurgião-dentista, foi elaborado para a deposição das partículas de óxido de alumínio presentes no campo operatório durante a utilização do sistema de abrasão a ar. Para a aspiração do pó de óxido de alumínio foram empregadas as sucções de alta potência e odontológica convencional com sugadores convencional e modificado por funil. A quantificação das partículas foi obtida pela massa de óxido de alumínio depositada após a aplicação do aparelho de abrasão a ar. Os resultados obtidos pela estatística descritiva gráfica revelaram que a maior deposição das partículas ocorreu a 20 cm do centro da cavidade bucal e na posição de trabalho 9 horas, quando se utilizou o sugador convencional em alta potência de sucção.
Abstract: The air abrasion system works using kinetic energy produced by pressurized air with aluminum oxide particles resulting in abrasion of the dental surface. The aim of this study was to compare the efficacy of high-volume evacuation (HVE) and conventional dental suction (CDS) in aluminum oxide particles evacuation. A metallic device was elaborated to reproduce the dentist operatory positions and to aluminum oxide particles deposition. The dust collection was made by conventional saliva ejector and modified ejector by funnel-shaped. The amount of particles showed that the greatest abrasive particles deposition occurred at the 20cm of distance from the center of the mouth at 9 o'clock operatory position with the conventional saliva ejector attached to high-volume evacuation (HVE).
Mestre

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O sistema de abrasão a ar funciona por meio de energia cinética produzida por um jato pressurizado de partículas de óxido de alumínio, que tem a finalidade de abrasionar a superfície dentária. O objetivo deste estudo foi avaliar a efetividade do sistema de sucção, disponível em consultório odontológico, na captação das partículas de óxido de alumínio emitidas pelo aparelho de abrasão a ar. Um dispositivo metálico, que reproduzia as posições e as distâncias de trabalho do cirurgião-dentista, foi elaborado para a deposição das partículas de óxido de alumínio presentes no campo operatório durante a utilização do sistema de abrasão a ar. Para a aspiração do pó de óxido de alumínio foram empregadas as sucções de alta potência e odontológica convencional com sugadores convencional e modificado por funil. A quantificação das partículas foi obtida pela massa de óxido de alumínio depositada após a aplicação do aparelho de abrasão a ar. Os resultados obtidos pela estatística descritiva gráfica revelaram que a maior deposição das partículas ocorreu a 20 cm do centro da cavidade bucal e na posição de trabalho 9 horas, quando se utilizou o sugador convencional em alta potência de sucção.
The air abrasion system works using kinetic energy produced by pressurized air with aluminum oxide particles resulting in abrasion of the dental surface. The aim of this study was to compare the efficacy of high-volume evacuation (HVE) and conventional dental suction (CDS) in aluminum oxide particles evacuation. A metallic device was elaborated to reproduce the dentist operatory positions and to aluminum oxide particles deposition. The dust collection was made by conventional saliva ejector and modified ejector by funnel-shaped. The amount of particles showed that the greatest abrasive particles deposition occurred at the 20cm of distance from the center of the mouth at 9 o'clock operatory position with the conventional saliva ejector attached to high-volume evacuation (HVE).

Orientadores: Lourenço Correr Sobrinho, Mário Alexandre Coelho Sinhoreti
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo neste estudo foi investigar o efeito de diferentes tratamentos de superfície, fadiga mecânica e termociclagem na resistência da união à microtração da cerâmica IPS e.max (Ivoclar) e do cimento resinoso de ativação dupla. Métodos: 18 blocos de cerâmica (10 mm de comprimento x 7 mm de largura x 3 mm de espessura) foram confeccionados e divididos em 6 grupos (n=3): Grupos 1, 2 e 3 - jateamento por 5 segundos com partículas de óxido de alumínio de 50?m; Grupos 4, 5 e 6 - condicionamento com acido hidrofluorídrico à 10% por 20 segundos. O silano Rely X Ceramic Primer foi aplicado sobre todos os espécimes e seco por 5 minutos. Após, os blocos de cerâmica foram unidos à blocos de compósito restaurador Tetric N-Ceram (Ivoclar-Vivadent) com cimento resinoso RelyX ARC (3M ESPE), sob carga estática de 500 gf por 2 minutos. O excesso de cimento foi removido com micropincel e fotoativado por 160 segundos (40 s cada face) com um aparelho de LED (UltraLume 5, Ultradent). Os espécimes dos grupos 1 e 4 foram armazenados em água destilada a 37°C por 24 h. Nos grupos 2 e 5, os espécimes foram submetidos a 3.000 ciclos térmicos entre 5°C e 55°C. Para os grupos 3 e 6, os espécimes foram submetidos ao ensaio de fadiga mecânica por 100.000 ciclos com 2 Hz. Os espécimes foram seccionados perpendiculares a área de união para obtenção de palitos com área seccional de 1mm2 (25 palitos por grupo) e submetidos ao ensaio de resistência de união à microtração em máquina de teste universal (EZ Test - Shimadzu) com velocidade de 0,5 mm/min. Foi utilizado para verificar o padrão de fratura uma lupa estereoscópica (Olympus) com aumento de 40x. Os dados foram submetidos à Análise de Variância de 2 fatores e ao teste de Tukey (p<0,05). Os valores de resistência de união à microtração (MPa) foram: 26,9 ± 6,9, 22,2 ± 7,8 e 21,2 ± 9,1 para os Grupos 1 a 3 e 35,0 ± 9,6, 24,3 ± 8,9 e 23,9 ± 6,3 para os Grupos 4 a 6. O grupo controle submetido ao teste de fadiga e termociclado mostrou predominância de padrão de fratura adesiva para o tratamento de superfície com acido hidrofluorídrico a 10% e padrões adesiva e mista para tratamento de superfície com 50um de oxido de alumínio. Concluindo a fadiga e a termociclagem diminuíram significantemente a resistência de união à microtração para ambos os tratamentos de superfície das cerâmicas comparada ao grupo controle. Condicionamento com acido hidrofluorídrico a 10% aumentou a resistência de união à microtração para o grupo controle
Abstract: The aim of this study was to investigate the effect of surface treatments, mechanic fatigue and thermocycling tested on the microtensile bond strength of the ceramic IPS e.max Press (Ivoclar Vivadent) luted with dual-cured resin cement. Eighteen ceramic bars (10mm length x 7mm width x 3.0mm thickness) were fabricated, and divided into 6 groups (n=3): Groups 1, 2 and 3 - air particle abraded for 5 s with 50?m aluminum oxide particles; Groups 4, 5 and 6 - acid etched with 10% hydrofluoric acid for 20 s. Coupling agent silane was applied on to all bond surface specimens and allowed to dry for 5 s and the ceramic bars were bonded to a block of composite resin Tetric N-Ceram (Ivoclar-Vivadent) with Rely X ARC (3M ESPE) resin cement and placed under a 500 g static load for 2 min. The cement excess was removed with a disposable microbrush and 40 s light-activation (four activations) were performed using a LED curing unit (UltraLume LED 5, Ultradent). The specimens of the groups 1 and 4 were stored in distilled water at 37°C for 24 hours, groups 2 and 5 were submitted to 3,000 thermocycles between 5°C and 55°C and groups 3 and 6 submitted to a fatigue test for 100,000 cycles with 2 HZ. Specimens were sectioned perpendicular to the bonding area to obtain 1mm2 sectional area beams (25 beams per group) and submitted to a microtensile bond strength test in a universal testing machine (EZ Test - Shimadzu), at a crosshead speed of 0.5mm/min. The fracture specimens were observed under optical microscopy (Olympus) at a 40x magnification. Data were submitted to ANOVA and Tukey's test (p?0.05). Results: The microtensile bond strength values (MPa) were: 26.9 ± 6.9, 22.2 ± 7.8 and 21.2 ± 9.1 for G1-G3 and 35.0 ± 9.6, 24.3 ± 8.9 and 23.9 ± 6.3 for G4-G6. The control group, fatigue tested and thermocycled groups showed a predominance of failure adhesive for surface treatment with 10% hydrofluoric acid and adhesive and mixed for surface treatment with 50 ?m Al2O3. In conclusion the fatigue and thermocycling decreased significantly the microtensile bond strength for both ceramic surface treatments compared to control groups. Etching with 10% hydrofluoric acid increased the microtensile bond strength for the control group
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários

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O objetivo desse trabalho foi avaliar a influência da forma do preparo cavitário na microinfiltração marginal em restaurações em dentes decíduos. Foram preparadas canaletas medindo 2,0 mm nas faces vestibular e lingual de molares decíduos que foram divididas aleatoriamente em 3 grupos de acordo com a técnica de preparo cavitário: Grupo I - alta rotação associado à ponta diamantada; Grupo II - sistema de abrasão a ar; e Grupo III - laser Er:YAG. Após o condicionamento com ácido fosfórico por 15 segundos, foi utilizado o adesivo Single Bond (3M) e a resina Filtek Flow (3M) para restaurar as canaletas. Os espécimes foram então mantidos em estufa a 37ºC por 6 dias, termociclados (500 ciclos com temperatura variando entre 5 e 55ºC), isolados e colocados em solução de fucsina básica à 0,5% durante 24 horas. Após serem seccionados a microinfiltração foi avaliada em microscópio ótico ligado a uma câmera de vídeo com 10 X de aumento. Para se avaliar a forma das cavidades medimos os ângulos oclusal, cervical e de abertura das cavidades, bem como a largura e a profundidade das mesmas por meio de fotomicrografias obtidas em MEV. Os resultados demonstraram semelhança estatística entre as larguras dos preparos cavitários, porém os ângulos oclusal, cervical e de abertura das cavidades apresentaram-se diferentes estatisticamente e que não houve microinfiltração marginal em nenhum dos grupos avaliados e que a diferença na forma de preparo das cavidades não influenciou na microinfiltração marginal dos espécimes estudados.
The aim of this research was the evaluation of the cavity prepare technique on the marginal microleakage in deciduous teeth. Cavities measuring 2.0 mm were prepared on the buccal and lingual faces and were divided into three groups according to the cavity prepare technique: Group I - High speed associated to diamond bur; Group II - air abrasion system; and Group III - Er:YAG laser. After the phosphoric acid etching for 15 seconds, the Single Bond (3M) adhesive and te Filtek Flow (3M) were used for the restoration of the cavities. Then the sample was stored at 37ºC for 6 days, termocycled (500 cycles with temperature varying from 5 to 55º C), isolated and immersed in a 0.5% funcsin solution for 24 hours. After being sectioned the microleakage was examined with a magnification optical microscope connected to a color video camera. In order to evaluate the shape of the cavities the occlusal, cervical and cavity opening angles were measured, as well as the width and depth of then, using SEM photographs. The results showed that there was no marginal microleakage in any of the evaluated groups and that the difference in the cavity shape did not influence the marginal infiltration on the studied samples.

Objetivo: avaliar e comparar os efeitos do jato de óxido de alumínio sobre a superfície do esmalte, quando aplicados por tempos diferentes. Material e métodos: 110 pré-molares foram obtidos por meio de doações do Banco de Dentes da FOUSP. Os dentes foram divididos aleatoriamente em 5 grupos (n=22) para a aplicação de jato de óxido de alumínio por diferentes períodos de tempo. Nos grupos A, B, C, D e E o jato de óxido de alumínio de 50 ?m foi aplicado, respectivamente, por 01, 03, 05, 07 e 10 segundos. Avaliações quantitativas da superfície do esmalte foram realizadas pelas análises das alterações do perfil e da rugosidade (Sa) da superfície vestibular antes e após o seu jateamento, por meio do medidor de perfil Form Talysurf Intra (Taylor Hobson - AMETEK Inc, Pennsylvania) e do interferômetro a laser Talysurf CCl Lite (Taylor Hobson - AMETEK Inc, Pennsylvania), respectivamente. Uma avaliação qualitativa da superfície do esmalte foi realizada por meio da microscopia eletrônica de varredura (MEV). Para esta última análise, um exemplar de cada grupo foi selecionado aleatoriamente para que as superfícies de esmalte jateadas fossem devidamente preparadas para as suas leituras. Os dados quantitativos foram comparados pelo teste ANOVA, seguido do teste post hoc de Tukey, adotando-se um nível de significância de 5% (p= 0,05). Resultados: observou-se maior alteração do perfil e da rugosidade conforme se aumentou o tempo de aplicação do jato de óxido de alumínio. Porém, com relação à alteração do perfil, diferenças estatisticamente significantes foram observadas somente entre o grupo A (1s) quando comparado aos grupos D (7s) e E (10s), e entre o grupo B (3s) quando comparado com o grupo E (10s). Quanto à rugosidade, verificou-se diferença estatisticamente significante apenas entre o grupo E (10s) quando comparado aos demais grupos. As cinco imagens obtidas pelo microscópio eletrônico de varredura (MEV) demonstraram bastante semelhança entre si, com padrão de condicionamento marcado por picos e vales, porém as imagens dos esmaltes jateados por 1 e 3 segundos apresentaram esses picos e vales em menor quantidade. Conclusão: a perda de estrutura dentária e a rugosidade da superfície do esmalte aumentaram conforme se aumentou o tempo de aplicação do jato de óxido de alumínio; a aplicação do jato de óxido de alumínio por 1 e 3 segundos promove menos perda de estrutura de esmalte do que quando se jateia o esmalte por 10 segundos; maior rugosidade pode ser obtida com o jateamento de óxido de alumínio por 10 segundos; entretanto, o aspecto morfológico do esmalte dentário é bastante similar, independentemente do tempo de jateamento.
Objective: To evaluate and compare the effects of aluminium oxide sandblasting on enamel surface when applied at different times. Materials & Methods: 110 premolars were obtained from the local tooth bank. The teeth were randomly divided into 5 groups (n = 22) for application of aluminium oxide sandblasting at different times. In Groups A, B, C, D and E, sandblasting with 50-?m aluminium oxide particles was applied for 01, 03, 05, 07 and 10 seconds, respectively. Quantitative assessments of enamel surface were performed by analysing changes in the profile and roughness (Sa) of the buccal surface before and after sandblasting application by using a profile gauge (Form Talysurf Intra, Taylor Hobson - AMETEK Inc, Pennsylvania, USA) and a laser interferometer (Talysurf CCl Lite, Taylor Hobson - AMETEK Inc, Pennsylvania, USA), respectively. A qualitative assessment of enamel surface was performed by means of scanning electron microscopy (SEM). For this latter analysis, a sample of each group was randomly chosen so that the sandblasted enamel surfaces could be adequately prepared to be evaluated. The quantitative data were compared by using ANOVA test, followed by post-hoc Tukey\'s test, at a significance level of 5% (P = 0.05). Results: Profile and roughness were found to be more altered as the sandblasting application time increased. With regard to the profile, however, statistically significant differences were found only in Group A (1s) compared to Groups D (7s) and E (10s), as well as in Group B (3s) compared to Group E (10s). With regard to the roughness, statistically significant difference was also observed only in Group E (10s) compared to the other groups. Five SEM images were demonstrated to be very similar to each other, with the conditioning pattern being marked by peaks and valleys, although SEM images of enamel blasted for 1 and 3 seconds showed peaks and valleys in lesser amount. Conclusion: Both loss of dental structure and enamel roughness increased as the time for application of aluminum oxide sandblasting also increased; application of aluminum oxide sandblasting for 1 and 3 seconds produced less loss of enamel structure compared to the 10-second application; more roughness can be obtained with application of aluminum oxide sandblasting for 10 seconds; however, the morphological aspect of the tooth enamel is very similar, regardless of the application time.

Thesis (M.S.D.)--Indiana University School of Dentistry, 2010
Title from PDF t. p. (viewed May 12, 2010) Advisor(s): Michael A. Cochran, Chair of the Research Committee, Jeffrey A. Platt, Bruce A. Matis, Carlos Gonzalez-Cabezas, Sopanis D. Cho. Curriculum vitae. Includes abstract. Includes bibliographical references (leaves 64-69).

Enamel damage and demineralisation are common complications associated with fixed orthodontic appliances. In particular, the clean-up of adhesive remnants after debonding is a recognised cause of enamel damage. Furthermore, fixed attachments offer retentive areas for accumulation of cariogenic bacteria leading to enamel demineralisation and formation of white spot lesions (WSLs). Bioactive glasses may be used to remove adhesives, preserving the integrity of the enamel surface, while also having the potential to induce enamel remineralisation, although their efficacy in both respects has received little attention. A systematic review evaluating the remineralisation potential of bioactive glasses was first undertaken. No prospective clinical studies were identified; however, a range of in vitro studies with heterogeneous designs were identified, largely providing encouraging results. A series of glasses was prepared with molar compositions similar to 45S5 (SylcTM; proprietary bioactive glass) but with constant fluoride, reduced silica and increased sodium and phosphate contents. These glasses were characterised in several tests and the most promising selected. This was designed with hardness lower than that of enamel and higher than orthodontic adhesives. Its effectiveness in terms of removal of composite- and glass ionomer- based orthodontic adhesives was evaluated against SylcTM and a tungsten carbide (TC) bur. This novel glass was subsequently used for remineralisation of artificially-induced orthodontic WSLs on extracted human teeth. The novel glass propelled via the air-abrasion system selectively removed adhesives without inducing tangible physical enamel damage compared to SylcTM and the conventional TC bur. It also remineralised WSLs with surface roughness and intensity of light backscattering similar to sound enamel. In addition, mineral deposits were detected on remineralised enamel surfaces; these acted as a protective layer on the enamel surface and improved its hardness. This layer was rich in calcium, phosphate, and fluoride; 19F MAS-NMR, confirmed the formation of fluorapatite. This is particularly beneficial since fluorapatite is more chemically stable than hydroxyapatite and has more resistance to acid attack. Hence, a promising bioactive glass has been developed.

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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Este estudo avaliou a molhabilidade, a morfologia superficial e a influência da ciclagem térmica sobre a resistência de união entre um cimento resinoso e uma cerâmica de zircônia estabilizada por ítrio (Y-TZP) submetida a diferentes protocolos de jateamento. Foram confeccionados 35 discos (diâmetro: 15mm, espessura: 2mm) cerâmicos sinterizados LAVA All-Ceramic System (3M Espe – Seefeld - Alemanha). Os discos foram divididos randomicamente (n=5): A45 - jateamento AL2O3 45μm; A80 - jateamento AL2O3 80μm; C30 - jateamento AL2O3 revestido por SiO2 30μm (Cojet); R30 - Jateamento AL2O3 revestido por SiO2 30μm (Rocatec Soft);R110 - jateamento AL2O3 revestido por SiO2 110μm (Rocatec Plus); R110R30 - R110 + R30; ST - sem tratamento. O jateamento foi realizado de forma padronizada a pressão constante de 2,5bars, distância de 10mm, em movimentos circulares durante 90s. Para o teste de cisalhamento com e sem ciclagem (n=10) sobre o disco cerâmico já fixado no cilindro de resina acrílica foram colocados com cera utilidade quatro matrizes transparentes cilíndricas (Tygon tubing, TYG-030, Saint-Gobain PerformancePlastic, Maime Lakes, FL, EUA – 3 mm de diâmetro interno por 3 mm de altura). As superfícies cerâmicas foram silanizadas por 60s (Monobond S-Ivoclar-Vivadent- Schaan-Liechtenstein) com microbrush (Vigodent, Rio de Janeiro,RJ, Brasil) internamente ao tygon tubing na zircônia de forma ativa por 60s, e realizada a secagem com leve jato de ar por 20 segundos. Foram preenchidas com cimento resinoso Panavia F®(Kuraray, Okayama, Japão) com o auxílio de uma seringa centrix com ponta (Accudose agulha) (Polidental Ind. e Com. Ltda- São Paulo- SP, Brasil). A fotopolimerização foi realizada com o LED Radii-Cal (SDI-Pinheiros-SP,Brasil) com intensidade de 1200mW/cm e tempo de polimerização de 40 segundos. Após, armazenadas em água destilada na estufa (Olidef- Ribeirão Preto - São Paulo-Brasil), à 37ºC durante 24 horas, as matrizes foram removidas com o auxílio de lâminas de bisturi número 12 (Becton Dickinson-New Jersey -EUA). Depois deste período metade das amostras foram submetidas a 3.000 ciclos de termociclagem em uma cicladora Térmica (Ética Equipamento Científicos S/A- São Paulo- Brasil). A outra metade, posteriormente foi levada ao ensaio de cisalhamento (EMIC-DL 2000 - São José dos Pinhais, Paraná). Para análise estatística utilizaram-se os testes ANOVA (dois fatores) e Tukey (α=0,05). Em seguida, a superfície fraturada foi inspecionada em estereomicroscópio (Discovery.V20, Carl Zeiss, LLC, EUA), (n=2) com magnificação de 9X. O modo de fratura foi classificado em três tipos diferentes: Adesiva, Mista e Coesiva. Dois discos a mais de cada grupo (n=2) tiveram suas superfícies jateadas e foram observadas (2000x) em Microscópio Eletrônico de Varredura FEI INSPECT S50 (Brno, República Tcheca). O ângulo de contato foi mensurado por goniometria (Rame-Hart, INC., 100-00, Contact Angle Goniometers - Montain Lakes – EUA)(n=5) em cada amostra, antes e após o protocolo de jateamento. Uma gota de água destilada foi colocada sobre a superfície cerâmica com uma seringa e o ângulo de contato foi medido durante 20 segundos (30 Frames por segundo). Para análise estatística utilizou-se os testes ANOVA (um fator) e Tukey (α=0,05). Observou-se que na ausência da ciclagem térmica, o tratamento de superfície não influenciou na resistência de união (p=0,238). Grupo A80(12,42±4,08); A45(14,38±4,95); C30(16,86±4,53); R30(13,99±5,55); R110(14,02±5,03); R110R30(11,75±4,19); ST(10,57±4,10). A ciclagem térmica influenciou os valores de resistência de união de todos os grupos (p=0,399). Os maiores valores de resistência de união após ciclagem térmica foram obtidos para os grupos A80 (4,927bc±1,53) e R110 (7,175bc±1,34), em comparação com os grupos ST 11 (1,86e±0,30), C30 (2,132e±0,73) e R110R30 (3,251de±1,37). Para todas as amostras analisadas as falhas foram consideradas adesivas. As fotomicrografias ilustram superfícies mais homogêneas para os grupos que apresentaram menores ângulos C30 (62,6;de±0,91), R30 (61,91e±1,05) e R110R30 (61,54e±1,02). O jateamento influenciou estatisticamente no valor do ângulo de contato, onde o grupo ST (110,61a±0,90) apresentou maior ângulo e os grupos R110R30 (61,54e±1,02), R30 (61,91e±1,05), C30 (62,66de±0,91) e A45 (65,50d±0,94) apresentaram os menores ângulos respectivamente. Conclui-se que o jateamento com C30, R30 e R110R30 proporcionaram maior molhabilidade de superfície da cerâmica estudada. Os maiores valores de resistência de união foram para os grupos onde se realizou jateamento com óxido de alumínio 80μm e com Rocatec 110 μm. Apesar dessa união não ser durável. Partículas maiores apesar de causarem maiores danos a superfície cerâmica, produzem valores de resistência de união altos. O protocolo de jateamento de silicatização com partículas maiores foi o tratamento que promoveu ao mesmo tempo maior molhabilidade e maior resistência de união.
This study evaluated the wettability, surface morphology and the influence of thermocycling on the bond strength of a resin cement and a zirconia ceramic stabilized by yttrium (Y-TZP) under different blasting protocols. Were made 35 discs (diameter: 15mm, thickness: 2 mm) sintered ceramic LAVA All-Ceramic System (3M Espe - Seefeld - Germany). The discs were randomly divided (n = 5): A45 - blasting Al2O3 45μm; A80 - blasting Al2O3 80μm; C30 - blasting Al2O3 coated SiO2 30μm (Cojet); R30 - Blasting Al2O3 coated SiO2 30μm (Rocatec Soft); R110 - blasting Al2O3 coated SiO2 110μm (Rocatec Plus); R110R30 - R110 + R30; ST - untreated. The blast was standardized in the constant pressure 2,5bars, distance 10mm, circular motion during 90s. For the shear test with and without cycling (n = 10) on the ceramic disc already fixed in the cylinder of acrylic resin were placed with wax utility four cylindrical transparent matrices (Tygon tubing, TYG-030, Saint-Gobain PerformancePlastic, Maime Lakes, FL, USA - 3 mm internal diameter by 3 mm height). The ceramic surfaces were silanized for 60 seconds (Monobond S-Ivoclar-Vivadent- Schaan-Liechtenstein) with microbrush (Vigodent, Rio de Janeiro, RJ, Brazil) internally to tygon tubing in zirconia actively for 60 seconds, and held drying with light air jet for 20 seconds. Were filled with Panavia F ® (Kuraray, Okayama, Japan) with the aid of a syringe with tip centrix (AccuDose needle) (Polidental Ind. E Com. Ltda- São Paulo-SP, Brazil). The curing was performed with the LED-Cal Radii (SDI-Pine-SP, Brazil) with an intensity of 1200mW / cm and polymerization time of 40 seconds. After stored in distilled water in the oven (Olidef- Ribeirão Preto - São Paulo-Brazil), at 37 ° C for 24 hours, the arrays were removed with the help of number 12 scalpel blades (Becton Dickinson-New Jersey-US). After this period half of the samples were subjected to 3,000 cycles of thermal cycling in a thermal cycler (Ethics Scientific Equipment S / Sao Paulo-A- Brazil). The other half, was later taken to the shear test (EMIC DL-2000 - São José dos Pinhais, Paraná). For statistical analysis we used the ANOVA (two factors) and Tukey (α = 0.05). Then the fractured surface was inspected in stereo (Discovery.V20, Carl Zeiss, LLC, USA) (n = 2) with magnification 9X. The fracture mode was classified into three different types: Adhesive, Mixed and Cohesive. Two discs over each group (n = 2) had their blasted surfaces and observed (2000x) in Scanning Electron Microscope FEI INSPECT S50 (Brno, Czech Republic). The contact angle was measured by goniometer (Rame-Hart, Inc., 100-00, Contact Angle Goniometers -. Montain Lakes - USA) (n = 5) in each sample before and after blasting protocol. A drop of distilled water was placed on the ceramic surface with a syringe and the contact angle was measured 20 seconds (30 frames per second). Statistical analysis was performed using ANOVA (one factor) and Tukey (α = 0.05). It was observed that in the absence of thermal cycling, the surface treatment did not influence the bond strength (p = 0.238). A80 group (12.42 ± 4.08); A45 (14.38 ± 4.95); C30 (16.86 ± 4.53); R30 (13.99 ± 5.55); R110 (14.02 ± 5.03); R110R30 (11.75 ± 4.19); ST (10.57 ± 4.10). Thermocycling influence the bond strength values of all the groups (p = 0.399). The higher bond strength values were obtained after thermocycling for the A80 groups (4,927bc ± 1.53) and R110 (7,175bc ± 1.34) compared with the ST group (1,86e ± 0.30) , C30 (2,132e ± 0.73) and R110R30 (3,251de ± 1.37). For all the samples analyzed were considered failures adhesive. The photomicrographs illustrate more homogeneous surfaces for the groups with smaller angles C30 (62.6; of ± 0.91), R30 (61,91e ± 1.05) and R110R30 (61,54e ± 1.02). The blasting statistically influence the value of the contact angle, where the ST group (110,61a ± 0.90) had a higher 13 angle and R110R30 groups (1.02 ± 61,54e), R30 (61,91e ± 1.05 ), C30 (62,66de ± 0.91) and A45 (65,50d ± 0.94) had the lowest angles respectively. It follows that the blasting C30, R30 and R110R30 provided higher wettability of the surface of the studied ceramics. The highest bond strength values were for the groups where they underwent blasting with aluminum oxide 80μm and Rocatec 110 microns. Despite this union will not be durable. Although larger particles causing greater damage to the ceramic surface, produce higher bond strength values. The silica coating blasting protocol with larger particles was the treatment that promoted while higher wettability and higher bond strength.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A infiltração marginal em restaurações de resina composta classe V foi avaliada nas margens cervical e oclusal de dentes decíduos e permanentes após diferentes tratamentos dentinários. Os preparos cavitários foram confeccionados nas faces vestibular e lingual de 25 molares decíduos e 25 terceiros molares permanentes hígidos utilizando fresas e instrumentos rotatórios e, posteriormente foram divididos em 5 grupos, cada um contendo 10 cavidades: grupo 1 (abrasão a ar e sistema Scotchbond Multi-Uso), grupo 2 (ácido fosfórico e Scotchbond Multi-Uso), grupo 3 (sistema auto-condicionante Clearfil SE Bond), grupo 4 (abrasão a ar, ácido fosfórico e Scotchbond Multi-Uso) e grupo 5 (abrasão a ar e Clearfil SE Bond), todos restaurados com resina Z100. Após polimento, os dentes foram submetidos à termociclagem (500 ciclos) e imersos em solução de nitrato de prata a 50%. Depois de seccionados, foram analisados em lupa estereoscópica (40x) utilizando escores de 0 a 4. Para avaliação dos diferentes tratamentos e tipos de margem, empregou-se o teste de Kruskal-Wallis, seguido de comparações múltiplas dos postos médios pelo teste de Dunn e a comparação entre dentes decíduos e permanentes foi realizada pelo teste de Mann-Whitney, com nível de significância de 5%. A aplicação do sistema de abrasão a ar e Scotchbond Multi-Uso, sem condicionamento ácido produziu os maiores valores de infiltração marginal em dentes decíduos e permanentes. Os resultados demonstraram que a utilização do sistema de abrasão associado a condicionadores ácidos resultou em menor infiltração marginal em dentes decíduos, embora não tenha havido diferença estatisticamente significante. O sistema auto-condicionante promoveu o menor valor de infiltração na margem cervical e o condicionamento com ácido fosfórico acompanhado pelo sistema...
Marginal leakage in gingival and occlusal margins of Class V composite restorations in deciduous and permanent teeth was investigated. Cavities were prepared with burs in high speed in facial and lingual surfaces of 25 deciduous molars and 25 third permanent molars. The specimens were divided into 5 groups of 10 preparations each: group 1 (air abrasion and Scotchbond Multi Purpose), group 2 (phosphoric acid and Scotchbond Multi Purpose), group 3 (Clearfil SE Bond self-etching system), group 4 (air abrasion, phosphoric acid and Scotchbond Multi Purpose) and group 5 (air abrasion and Clearfil SE Bond), all groups were restored with Z100 composite resin. After polish, the teeth were subjected to 500 thermal cycling and immerged in 50% silver nitrate solution. After sectioning, the specimens were analyzed with a stereomicroscope (40x) for assessment of microleakage according to the degree of dye penetration (scores of 0-4). The Kruskal-Wallis test followed by Dunn Multiple Comparison test were performed in order to evaluate the differences among the experimental groups. The Mann-Whitney test was performed to evaluate the differences among deciduous and permanent teeth at a 5% level of significance. Air abrasion and Scotchbond Multi-Purpose without etching, showed the greatest leakage in deciduous and permanent teeth. Air abrasion and acid condicionings produced little leakage in deciduous teeth. The self-etching system demonstrated the least leakage in gingival margins and Scotchbond Multi-Purpose showed the best results in occlusal margins of deciduous teeth. No significant difference was observed among gingival and occlusal margins in deciduous teeth. Air abrasion groups demonstrated the greatest leakage in permanent teeth. Scotchbond Multi- Purpose with phosphoric acid produced the least leakage in permanent teeth, with greater leakage in gingival... (Complete abstract, click electronic address below)

Resumo: O objetivo desse trabalho foi avaliar a influência da forma do preparo cavitário na microinfiltração marginal em restaurações em dentes decíduos. Foram preparadas canaletas medindo 2,0 mm nas faces vestibular e lingual de molares decíduos que foram divididas aleatoriamente em 3 grupos de acordo com a técnica de preparo cavitário: Grupo I - alta rotação associado à ponta diamantada; Grupo II - sistema de abrasão a ar; e Grupo III - laser Er:YAG. Após o condicionamento com ácido fosfórico por 15 segundos, foi utilizado o adesivo Single Bond (3M) e a resina Filtek Flow (3M) para restaurar as canaletas. Os espécimes foram então mantidos em estufa a 37ºC por 6 dias, termociclados (500 ciclos com temperatura variando entre 5 e 55ºC), isolados e colocados em solução de fucsina básica à 0,5% durante 24 horas. Após serem seccionados a microinfiltração foi avaliada em microscópio ótico ligado a uma câmera de vídeo com 10 X de aumento. Para se avaliar a forma das cavidades medimos os ângulos oclusal, cervical e de abertura das cavidades, bem como a largura e a profundidade das mesmas por meio de fotomicrografias obtidas em MEV. Os resultados demonstraram semelhança estatística entre as larguras dos preparos cavitários, porém os ângulos oclusal, cervical e de abertura das cavidades apresentaram-se diferentes estatisticamente e que não houve microinfiltração marginal em nenhum dos grupos avaliados e que a diferença na forma de preparo das cavidades não influenciou na microinfiltração marginal dos espécimes estudados.
Abstract: The aim of this research was the evaluation of the cavity prepare technique on the marginal microleakage in deciduous teeth. Cavities measuring 2.0 mm were prepared on the buccal and lingual faces and were divided into three groups according to the cavity prepare technique: Group I - High speed associated to diamond bur; Group II - air abrasion system; and Group III - Er:YAG laser. After the phosphoric acid etching for 15 seconds, the Single Bond (3M) adhesive and te Filtek Flow (3M) were used for the restoration of the cavities. Then the sample was stored at 37ºC for 6 days, termocycled (500 cycles with temperature varying from 5 to 55º C), isolated and immersed in a 0.5% funcsin solution for 24 hours. After being sectioned the microleakage was examined with a magnification optical microscope connected to a color video camera. In order to evaluate the shape of the cavities the occlusal, cervical and cavity opening angles were measured, as well as the width and depth of then, using SEM photographs. The results showed that there was no marginal microleakage in any of the evaluated groups and that the difference in the cavity shape did not influence the marginal infiltration on the studied samples.
Orientador: Rita de Cássia Loiola Cordeiro
Coorientador: Maria Cristina Borsatto
Banca: Lourdes Aparecida Martins dos Santos Pinto
Banca: Ângela Cristina Cilense Zuanon
Banca: Delsa Deise Machetti Kanaan
Banca: Luís José Floriam
Doutor

Luftföroreningar har en negativ inverkan på både miljön och människors hälsa. Pure Air Zone är en tystgående och energisnål luftrenare som är integrerad i en sänggavel vilket skapar en ren luftzon i huvudhöjd hos användaren. I dagsläget är denna sänggavel klädd i ett meshmaterial vilken inte lämpar sig för sovrumsmiljö på grund av dess utseende. Fokus har därför legat på att ta fram en alternativ textil som kan ersätta den nuvarande, utan att funktionen försämras. De viktigaste egenskaperna som textilien behöver uppfylla är hög luftpermeabilitet, hög formstabilitet och hög nötningshärdighet. Tester utfördes med hjälp av en Martindalemaskin, en dragprovare och en permeabilitetsmätare för att mäta dessa egenskaper. Sju stycken vävda tyger från Ludvig Svensson undersöktes för de nämnda egenskaperna och jämfördes mot det nuvarande materialet. Många av de valda tygerna var glest eller tunt vävda vilka stabiliserades genom att de kviltades samman med en filtervadd. Efter genomförda tester viktades de olika egenskaperna för att ge ett sammanställt resultat för samtliga vävar. I sammanställningen visade det sig att det nuvarande materialet fick sämst resultat. För luftpermeabiliteten, den högst prioriterade egenskapen, fick alla utom en väv bättre resultat än referensmaterialet. Den väv som fick bäst resultat efter sammanställningen var en tunn väv i tuskaftbindning som i denna rapport kallas för Day.
Air pollution has a negative impact on both the environment and the human health. Pure Air Zone is a silent and energy efficient air purifier which has been integrated in a bed frame. This creates a clean airspace where the user will place its head while sleeping. Currently a mesh material is being used to cover the bed frame but this is not well suited for a bedroom environment when looking at the appearance of the textile. The main focus has therefore been to develop an alternative textile that can replace the current mesh without impairing the function. The most important characteristics the textile has to possess are high air permeability, high dimension stability and high abrasion resistance. Tests were carried out by using a Martindale machine, a tensile tester and a permeability tester to measure these characteristics. Seven woven fabrics from Ludvig Svensson were examined for said characteristics and compared to the mesh which acted as a reference material. Majority of the chosen weaves were thinly or sparsely woven and had to be stabilized by quilting them together with filter wadding. After completed tests the characteristics were weighed against each other to present a combined result for all the weaves. In the combined results it was clear that the current mesh material being used for the bed frame got the overall lowest result. For air permeability, the highest weighed characteristic, all but one weave got a better result than the reference material. The weave that got the best combined result was a thin plain weave that will be referred to as Day in this report.

Objective: The goal of the present study was to investigate the effect of chairside surface treatments on biaxial flexural strength and subsurface damage of monolithic zirconia ceramics. Methods: Specimens (15x15x1.2 mm3) were prepared by sectioning from commercially available zirconia blanks (BruxZirTM) and sintering according to manufacturer's recommendations. Fully dense specimens were randomly divided into five groups (n=30) and treated as follows; 1) as-sintered (AS) 2) air abraded with 50 μm alumina fine particles (AAF), 3) air abraded with 250 μm coarse alumina particles (AAC), 4) ground (G), and 5) ground and polished (GP) to mimic chairside and dental laboratory treatments. Microstructural changes were thoroughly characterized by optical and scanning electron microscopy, surface profilometry and atomic force microscopy. Crystalline phases and their depth profile were investigated by x-ray diffraction (XRD) and grazing incidence x-ray diffraction (GIXRD). Results were analyzed by Kruskal-Wallis test and Tukey's adjustment for multiple comparisons. A 0.05 level of significance was used. Reliability was evaluated by Weibull analysis. Results: All treatment groups exhibited a significant difference in mean surface roughness (Rq) compared to the as-sintered group (p<0.05). The AAC group showed the highest surface roughness at 1.08 ± 0.17 μm, followed by the G, AAF and AS groups. The GP group exhibited the lowest surface roughness. The group air abraded with fine particles showed the highest mean biaxial flexural strength (1662.62 ± 202.58 MPa), but was not different from the ground and polished group (1567.19 ± 209.76 MPa). The groups air abraded with coarse particles or ground with diamond bur exhibited comparable mean biaxial flexural strength at 1371.37 ±147.62 MPa and 1356.98 ±196.77 MPa, respectively. The as-sintered group had the lowest mean biaxial flexural strength at 1202.29 ±141.92 MPa. The depth of compressive stress layer, measured by GIXRD was approximately 50 μm in the AAF group, followed by the AAC group with ~35 μm, ~10 μm for the ground group and ~5 μm for the ground and polished group. Deep subsurface cracks were observed in the AAC group (~80 μm in depth) and G group (~25 μm in depth), whereas shallower flaws were present in the AAF and GP groups at 10 and 3 μm, respectively. Weibull analysis represented a greater reliability in zirconia specimens treated with air abrasion groups. Conclusions: Surface treatments induced the t-m transformation in 3Y-TZP and associated development of compressive stresses to a depth that varied with the severity of the treatment performed. GIXRD revealed that AAF led to the thickest compressive stress layer, followed by AAC, G and GP. SEM revealed that subsurface damage was most severe with AAC, followed by G, AAF and GP. We propose that the flexural strength results can be explained by the difference between the depth of the compressive stress layer induced by the transformation and the depth of the subsurface flaws.

Le filage par voie électrostatique est une technique utilisée pour la production de fibres de diamètres extrêmement petits, de l’ordre de quelques centaines de nanomètres, possédant, sous forme de non-tissés, une grande surface spécifique. Les matériaux non-tissés composés de nanofibres sont de plus en plus utilisés pour de multiples applications, notamment dans le domaine de l’ingénierie tissulaire, pour les textiles de protection, la filtration, le biomédical, l’électronique et l’ingénierie environnementale. Le contrôle des paramètres lors du filage par voie électrostatique est primordial pour obtenir des nanofibres dont les propriétés morphologiques seront optimisées (diamètres des nanofilaments obtenus fins et contrôlés ; qualité de filage acceptable). Le but de ces travaux de thèse est d’établir la faisabilité d’électrofilage des deux solutions de polyamide-imide (le KMP et le KMT) fournies par la société Kermel. Puis, une fois la faisabilité de filage établie, de déterminer plus précisément les paramètres influençant le procédé, afin d’optimiser le procédé de filage et obtenir des nanofilaments à partir des deux solutions de polymères, à l’échelle laboratoire et sur un outil de production à l’échelle semi-industrielle. Cette thèse a fait l’objet d’une collaboration entre l'entreprise alsacienne Kermel, fabricant de fibres techniques résistantes à la chaleur et aux flammes, situé à Colmar et le Laboratoire de Physique et Mécanique Textiles (LPMT) à Mulhouse. Les nanofibres ont été définies ainsi que différentes techniques de filage permettant leur obtention. Les fournisseurs d’équipement ont été identifiés dans un souci de production semi-industrielle à terme. La technique de filage par voie électrostatique (avec ou sans aiguilles) est finalement retenue, car il s’agit de l’outil de prototypage et de compétences disponibles au laboratoire LPMT et dont le passage à l’échelle industrielle est envisageable. La technique des plans d’expériences a été utilisée afin d’optimiser le nombre d’essais de filage nécessaires à l‘étude des diamètres de nanofilaments obtenus. Les différents paramètres liés aux propriétés de la solution de polymère (température, viscosité, concentration) ont été étudiés et les aspects rhéologiques affichés. Une interprétation physico-chimique des comportements observés pour les différentes solutions de polymère est faite. Elle nous permet de conclure que le meilleur régime pour obtenir des nanofibres est le régime concentré, puisqu’il s’agit du régime où la densité de macromolécules est la plus forte. La faisabilité de l’électrofilage du polyamide-imide sur l’équipement à échelle laboratoire du LPMT a été établie. La température, l’humidité et la concentration sont étudiées. Les différentes plages d’optimisation d’électrofilage du polymère considéré ont été établies et il est possible d’envisager le passage à l’échelle semi-industrielle. Le paramètre le plus influent sur les diamètres de fibres obtenus est l’humidité relative, ce qui n’avait jusqu’à présent jamais été mis en avant dans la littérature. La même démarche d’optimisation a été réalisée sur l’équipement semi-industriel. Des applications « produit » ont pu être envisagées. Notamment une application liée à la filtration où une étude de perméabilité à l’air a été réalisée. Cette étude a permis de conclure que l’ajout d’une couche de nanofibres sur un support en tissu permet de diminuer d’1/3 à 2/3 les résultats de perméabilité à l’air. Une corrélation est faite entre les diamètres de nanofibres et les résultats de perméabilité à l’air obtenus, qui est cohérente avec le comportement attendu. Enfin des tests « qualité » ont été réalisés sur des échantillons produits : le taux de solvant résiduel obtenu dans les conditions de filage optimisées est inférieur à 8% ; et des tests de résistance à l’abrasion menés sur des non-tissés recouverts de nanofibres ont donné des résultats encourageant [...]
Electrospinning process has been widely used over the past decades for manufacturing nanofibers. The control of the electrospinning parameters is crucial to obtain nanofibers (nonwoven mats) with optimized morphological properties. The aim of this PhD work is to precisely define the electrospinnability of two meta-aramid solutions through wire-based electrospinning setup processing. Although the viscosity of polymer solution as an influent parameter for electrospinning has been widely investigated, only a few studies have yet made a connection between rheological behavior of polymer and electrospinnability. In our PhD work, rheological analyzes on three meta-aramid solutions have been conducted to confirm its electrospinnability and predict the morphological behavior of resultant nanofibers. A couple polymer/solvent of meta-aramid polymer (polyamide-imide) in a polar aprotic solvent (1,3 dimethyl-2-imidazolidinone) at 60 Pa.s in working viscosity is provided by an industrial partner (KERMEL Company). It has been highlighted through rheological study that 60 Pa.s is the best polymer viscosity to obtain good macromolecular conformation of the polyamide-imide chains while electrospinning and sufficient viscoelastic properties. Experiments have been conducted following a design of experiment to study the influence of several process and ambient parameters. Individual effects and/or combined interactions on obtained fiber diameter and general morphology have been investigated. The obtained nanofibers are expected to have thin diameters with high homogeneity of the products, which means low levels of beads, residual solvent or non-fibrous area and a narrow fiber diameter distribution, in order to validate the industrial requirements. A wide range of process parameters are available at industrial-scale with the NS® technology. The five studied process parameters are: applied voltage, relative humidity, temperature, distance between spinning electrode wire and substrate material, and airflow going through the spinning chamber. Each parameter was varied at three levels. Significant effects of parameters have been observed. The obtained results have allowed us to determine the influential factors (humidity and temperature) and reduce the domain study. Moreover, an estimation of the capacity of production for the NS500 has been calculated for the tested meta-aramid solution. Several applications have been investigated. A nanofibrous coating on 50KMP/50VFR woven media has been produced and permeability air tests have been conducted. A decrease of 1/3 to 2/3 of air permeability results has been obtained. A correlation is drawn between mean diameters of nanofibers and air permeability values, which is coherent with the expected behavior. Quality tests have been conducted through thermogravimetric analyses and proton nuclear magnetic resonance. The residual solvent rate obtained in the optimized conditions of spinning is less than 8 %. Abrasion resistance tests have been conducted on KMP non-woven media coated with nanofibrous layer. The use of the bi-layer structure does not lead to the formation of breathable particles

Orientador: Angela Cristina Cilense Zuanon
Banca: Maria Aparecida de Andrade Moreira
Banca: Maria Cristina Borsatto
Banca: Gelson Luis Adabo
Banca: Josimeri Hebling
Resumo: A infiltração marginal em restaurações de resina composta classe V foi avaliada nas margens cervical e oclusal de dentes decíduos e permanentes após diferentes tratamentos dentinários. Os preparos cavitários foram confeccionados nas faces vestibular e lingual de 25 molares decíduos e 25 terceiros molares permanentes hígidos utilizando fresas e instrumentos rotatórios e, posteriormente foram divididos em 5 grupos, cada um contendo 10 cavidades: grupo 1 (abrasão a ar e sistema Scotchbond Multi-Uso), grupo 2 (ácido fosfórico e Scotchbond Multi-Uso), grupo 3 (sistema auto-condicionante Clearfil SE Bond), grupo 4 (abrasão a ar, ácido fosfórico e Scotchbond Multi-Uso) e grupo 5 (abrasão a ar e Clearfil SE Bond), todos restaurados com resina Z100. Após polimento, os dentes foram submetidos à termociclagem (500 ciclos) e imersos em solução de nitrato de prata a 50%. Depois de seccionados, foram analisados em lupa estereoscópica (40x) utilizando escores de 0 a 4. Para avaliação dos diferentes tratamentos e tipos de margem, empregou-se o teste de Kruskal-Wallis, seguido de comparações múltiplas dos postos médios pelo teste de Dunn e a comparação entre dentes decíduos e permanentes foi realizada pelo teste de Mann-Whitney, com nível de significância de 5%. A aplicação do sistema de abrasão a ar e Scotchbond Multi-Uso, sem condicionamento ácido produziu os maiores valores de infiltração marginal em dentes decíduos e permanentes. Os resultados demonstraram que a utilização do sistema de abrasão associado a condicionadores ácidos resultou em menor infiltração marginal em dentes decíduos, embora não tenha havido diferença estatisticamente significante. O sistema auto-condicionante promoveu o menor valor de infiltração na margem cervical e o condicionamento com ácido fosfórico acompanhado pelo sistema... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Marginal leakage in gingival and occlusal margins of Class V composite restorations in deciduous and permanent teeth was investigated. Cavities were prepared with burs in high speed in facial and lingual surfaces of 25 deciduous molars and 25 third permanent molars. The specimens were divided into 5 groups of 10 preparations each: group 1 (air abrasion and Scotchbond Multi Purpose), group 2 (phosphoric acid and Scotchbond Multi Purpose), group 3 (Clearfil SE Bond self-etching system), group 4 (air abrasion, phosphoric acid and Scotchbond Multi Purpose) and group 5 (air abrasion and Clearfil SE Bond), all groups were restored with Z100 composite resin. After polish, the teeth were subjected to 500 thermal cycling and immerged in 50% silver nitrate solution. After sectioning, the specimens were analyzed with a stereomicroscope (40x) for assessment of microleakage according to the degree of dye penetration (scores of 0-4). The Kruskal-Wallis test followed by Dunn Multiple Comparison test were performed in order to evaluate the differences among the experimental groups. The Mann-Whitney test was performed to evaluate the differences among deciduous and permanent teeth at a 5% level of significance. Air abrasion and Scotchbond Multi-Purpose without etching, showed the greatest leakage in deciduous and permanent teeth. Air abrasion and acid condicionings produced little leakage in deciduous teeth. The self-etching system demonstrated the least leakage in gingival margins and Scotchbond Multi-Purpose showed the best results in occlusal margins of deciduous teeth. No significant difference was observed among gingival and occlusal margins in deciduous teeth. Air abrasion groups demonstrated the greatest leakage in permanent teeth. Scotchbond Multi- Purpose with phosphoric acid produced the least leakage in permanent teeth, with greater leakage in gingival... (Complete abstract, click electronic address below)
Doutor

Non-exhaust PM10 is an issue in the urban environment linked to health issues. Emissions of non-exhaust PM10 is relatable to pavement properties. Also of importance is resuspension of road dust stored from surfaces. This depends on the traffic and metrological conditions. Given this, the purpose of the thesis was to give an overview limited to Sweden and the Nordic countries regarding non-exhaust PM10 emissions and road dust. The overview includes how particles are related to human health. Also included is the principle of how particles are emitted from road surface and tyre interaction, both directly and through resuspension of road dust. This thesis also includes an overview of how the use of studded tyres impact on asphalt surfacings and how the properties of the materials used impact on the abrasion wear. This is then linked to the emissions of non-exhaust particles. Further described is how measurements can be done of ambient particles and road dust, followed on two major models for road abrasion wear and non-exhaust PM prediction. Also included is how road operation, e.g. traction sanding and dust binding, influence the particle emissions together with other options to reduce the emissions through, e.g. limiting the use of studded tyres. One special issue discussed in this thesis is the lack of holistic view regarding the environmental problems in the urban environment with focus on particle emissions and road noise emissions, both from the road surface and tyre interaction. Currently the most problematic issue is prioritized and the resulting solution to that specific problem might increase other problems. This thesis shows that much knowledge is available regarding non-exhaust PM10 emissions and road dust, but also that several knowledge gaps exists. Several suggestions on further studies is given together with a brief overview on the continued work forward from this thesis.
Icke-avgasemissioner av PM10 är ett problem i urbana miljöer länkat till flera hälsoaspekter. Dessa emissioner kan relateras till beläggningars egenskaper. Även resuspension av vägdamm från ytor är av betydelse och beror på både trafiken och meterologin. Baserat på detta är syftet med denna avhandling att ge en översikt kring icke-avgas PM10 emissioner och vägdamm, begränsat till Sverige och de övriga nordiska länderna. Denna översikt inkluderar hur partiklar relaterar till människans hälsa. Annat som inkluderas är hur partiklarna emitteras från vägyta-däckinteraktionen, både direkt och genom resuspension av vägdamm. Avhandlingen inkluderar även en översikt kring hur användandet av dubbdäck inverkar på vägbeläggningar och hur dess egenskaper inverkar på nötningsslitage. Detta länkas därefter till partikelemissioner. Vidare beskrivs även hur mätningar kan genomföras av partiklar samt vägdamm vilket följs upp av beskrivningar kring två större modeller kring prediktion av nötningsslitage och prediktion av icke-avgasemissioner. Även hur driftåtgärder inverkar på emissionerna tillsammans med alternativ för att minska emissionerna tas upp. Ett särskilt problem som tas upp i avhandlingen är bristen på helhetssyn beträffande miljöproblem i den urbana miljön med fokus på partikel- och bulleremissioner från vägyta-däckinteraktionen. För närvarande brukar det värsta problemet prioriteras och lösningen till det detta problem kan i sin tur medföra att andra miljöproblem istället förvärras. Denna avhandling visar på att mycket kunskap existerar kring icke-avgasemissioner av PM10 och kring vägdamm, men även att flertalet kunskapsluckor existerar. Flertalet förslag på vidare studier ges tillsammans med en överblick kring det fortsatta arbetet.

QC 20180202

Cerâmicas de alto conteúdo cristalino, como a zircônia policristalina tetragonal estabilizada por ítrio (Y-TZP), apresentam ótimas propriedades mecânicas quando comparadas às cerâmicas convencionais, sendo cada vez mais empregadas como materiais restauradores indiretos. Entretanto, seu sucesso também depende da formação de uma união confiável com os agentes de cimentação. Porém, o aumento do conteúdo cristalino modificou as características de adesão entre cerâmica e cimento resinoso, não existindo um protocolo de cimentação bem estabelecido na literatura. Portanto, este estudo teve como objetivo avaliar o efeito na resistência ao cisalhamento de diferentes tratamentos de superfície sobre a zircônia, utilizando dois cimentos resinosos, assim como avaliar as possíveis diferenças no modo das fraturas. Cento e vinte amostras retangulares de zircônia foram incluídas em resina acrílica e divididas em 12 grupos (n=10), de acordo com os tratamentos de superfície e os cimentos (Panavia F e Rely X U100). Para cada cimento, os grupos experimentais foram formados da seguinte maneira: RU e Pa - controle (sem nenhum tratamento de superfície); ApRU e ApPa (aplicação do Alloy Primer); MzRU e MzPa (aplicação do Metal/Zircônia Primer); JatRU e JatPa (jateamento com partículas de óxido de alumínio de 50µm); JatApRU e JatApPa (jateamento e aplicação de Alloy Primer); JatMzRU e JatMzPa (jateamento e aplicação do Metal/Zircônia Primer). Os corpos de prova foram armazenados em água destilada à temperatura de 37°C por 24 horas, antes do teste de cisalhamento em uma máquina de ensaio universal (EMIC). Os valores foram submetidos primeiro a ANOVA a um critério (resistência ao cisalhamento) e teste de Tukey (p 0,05), independente do tratamento e do sistema de cimentação. Em seguida, ANOVA a dois critérios (tratamento de superfície e sistema de cimentação) e o teste de Tukey foram aplicados para observar com maior precisão a interação entre cimento e tratamento de superfície. Os resultados apresentados foram: RU - 11,71a, ApRU - 21,49b,e, MzRU - 30,38c,d, JatRU - 34,40c, JatApRU - 30,66c,d, JatMzRU - 38,06c, Pa - 11,35a, ApPa - 11,98a, MzPa - 11,46a, JatPa - 33,50c, JatApPa - 23,14b,d,e, JatMzPa - 18,66a,e. Por meio dos resultados obtidos foi possível concluir que a resistência ao cisalhamento pode ser melhorada ao utilizar o jateamento com partículas de óxido de alumínio e, para o RelyX U100, somente a aplicação do Metal/Zircônia Primer resultou em valores de adesão comparavéis ao tratamento mecânico. O cimento RelyX U100 apresentou maior resistência de união quando comparado ao Panavia F.
High crystalline content ceramics, such as yttria stabilized tetragonal zirconia polycrystal (Y-TZP), show great mechanical properties when compared to conventional ceramics, being increasingly used as indirect restorative materials. However, its success also depends on the reliable bond formation with luting agents. Though, the high crystalline content modified the adhesiveness between ceramic and resin cement although there isnt any cementing protocol established in literature. Therefore, the purpose of this study was to evaluate the effect of the shear bond strength after different surface treatments on the zirconia, using two resin cements and to evaluate possible differences in fracture modes. One hundred and twenty rectangular samples of zirconia were embedded in acrylic resin and divided into 12 groups (n=10) according to the surface treatments and the cements (Panavia F and RelyX U100). For each cement, the experimental groups were formed as follow: RU and Pa - control (no surface treatment); ApRU and ApPa (application of Alloy Primer); MzRU e MzPa (application of Metal/Zirconia Primer); JatRU and JatPa (air abrasion with 50µm Al2O3 particles); JatApRU and JatApPa (air abrasion and application of Alloy Primer); JatMzRU and JatMzPa (air abrasion and application of Metal/Zirconia Primer). The specimens were stored in distilled water at 37°C for 24 hours prior to the shear bond strength test in a universal testing machine (EMIC). The data were first analyzed by one-way ANOVA (shear bond strength) and Tukey test (p<0.05), regardless of the treatment and the luting system. Then two-way ANOVA (surface treatment and luting system) and the Tukey test were applied in order to observe more accurately the interaction between cement and surface treatments.The results presented were: RU 11.71a, ApRU 21.49b,e, MzRU 30.38c,d, JatRU 34.40c, JatApRU 30.66c,d, JatMzRU 38.06c, Pa 11.35a, ApPa 11.98a, MzPa 11.46a, JatPa 33.50c, JatApPa 23.14b,d,e, JatMzPa 18.66a,e. Based on the results obtained, it was possible to conclude that the shear bond strength can be improved when air abrasion was used with aluminum-oxide particles and for the RelyX U100, only the application of Metal / Zirconia Primer resulted in adhesion values comparable to mechanical treatment. The RelyX U100 cement showed higher bond strength when compared to Panavia F.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This study aimed to evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and total-etch (TE) mode, adhesive temperature (20ºC or 37ºC) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm² were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a universal testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using to two-way ANOVA and Tukey s test (p<0.01). Interaction between treatment and temperature was statistically significant to SbU applied in SE technique. Both dentin treatments showed higher bond strength to TE mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE mode. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Thus, the dentin pretreatment may be an alternative to improve the adhesive properties of the Scotchbond Universal adhesive system.
O presente estudo avaliou os efeitos do jateamento de partículas abrasivas e da temperatura sobre a resistência adesiva de um sistema adesivo universal à dentina. Utilizou-se 96 terceiros molares humanos hígidos e extraídos, divididos aleatoriamente em 12 grupos (n=8) de acordo com o adesivo Scotchbond Universal (SBU) aplicado no modo autocondicionante (SE) ou condicionamento ácido total (TE), temperatura do adesivo (20ºC ou 37ºC) e jateamento da dentina com partículas de óxido de alumínio ou bicarbonato de sódio. Após a realização das restaurações, foram obtidos espécimes em forma de palito com área seccional de 1 mm² para avaliar a resistência adesiva através do teste de microtração. O teste foi realizado em uma máquina de ensaio universal, a uma velocidade de 0,5 mm/min até a fratura ocorrer. As fraturas foram analisadas sob estereomicroscopia para classificar as falhas em adesiva, coesiva (resina ou dentina) e mista. Os dados foram submetidos ao teste ANOVA a dois fatores e ao teste de Tukey. A interação entre tratamento e temperatura foi estatisticamente significante (p<0,01) para SBU SE. Ambos os tratamentos da dentina resultaram em valores maiores de resistência adesiva para SBU no modo TE, independente da temperatura do adesivo. Já para SBU aplicado na técnica autocondicionante, apenas o jateamento com bicarbonato de sódio foi significativamente diferente quando comparado ao grupo que não recebeu tratamento. O adesivo aquecido não teve influência significativa sobre a resistência adesiva à microtração, para todos os grupos testados. As fraturas adesivas foram predominantes para todos os grupos. Dessa forma, o pré-tratamento dentinário pode ser uma alternativa para melhorar as propriedades adesivas do sistema adesivo Scotchbond Universal.

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The objective of the present work is to develop a study of abrasive wear a specific component of a grain harvester, the bars of unit threshing the combines. For this study it was designed and built a test bench that simulates two types of materials, an ABNT/SAE 1045 steel and an ABNT/SAE 1518 steel underwent a forced to wear an abrasive that simulates the size and condition of a grain at a accelerated rate. This bench is in turn composed of parts used in systems threshing on harvesters in order to bring the test closer to the real. The general condition of the abrasive was compared with the literature in order to obtain better data with respect to wear on the condition. After the wear test was designed to better characterize this wear, where it is noted that medium carbon steel (SAE 1045) had a good initial performance with respect to wear, however the material with manganese (SAE 1518) showed a better resistance at the end of the tests when compared to SAE 1045. Finally, the tests was conducted to validate the bench, and characterization of abrasive wear in relation to which it was possible to sense the increased wear of the samples was performed when adding the SiO2 abrasive to simulate rice hull.
O presente trabalho tem como objetivo desenvolver um estudo de desgaste abrasivo de um componente espec?fico de uma colheitadeira de gr?os, no caso as barras da unidade de trilha da colhedora. Para este estudo foi projetada e constru?da uma bancada de testes para utiliza??o de dois tipos de materiais, um a?o ABNT/SAE 1045 e um a?o ABNT/SAE 1518, submetidos ao desgaste for?ado de abrasivos que simulem o tamanho e condi??o mais pr?xima de um gr?o em ritmo acelerado. Esta bancada por sua vez foi constitu?da de pe?as utilizadas em sistemas de trilha de colheitadeiras, a fim de tornar o teste o mais pr?ximo do real. A condi??o geral do abrasivo foi comparada com a literatura, a fim de se obter melhores dados em rela??o ao desgaste nessa condi??o. A an?lise de dados posterior teve a finalidade de caracterizar melhor este desgaste, onde foi poss?vel perceber que o a?o de m?dio carbono (SAE 1045) teve um desempenho inicial bom em rela??o ao desgaste, no entanto a liga com mangan?s (SAE 1518) apresentou uma resist?ncia ao final dos ensaios melhor quando comparada ao SAE 1045. Por fim nos testes executados, foi realizada a valida??o da bancada, e a caracteriza??o do desgaste em rela??o aos abrasivos onde foi poss?vel perceber o aumento do desgaste das amostras quando se realizava a adi??o de SiO2 no abrasivo para simular a casca do arroz.

Cette thèse vise à comprendre et modéliser l'usure par fretting à sec d'un contact plan/plan en acier soumis à diverses conditions de chargement, notamment le nombre de cycles de fretting, l'amplitude de glissement, la pression de contact, la fréquence de glissement, la taille du contact et l'orientation du contact par rapport à la direction de glissement. La cinétique d'usure a été étudiée en variant ces conditions qui affectent les mécanismes d'usure, y compris la formation et l'éjection de débris en plus de la tribo-oxydation, de l'abrasion et de l'adhésion. Cette investigation montre que, dans la plupart des cas, une trace d'usure composite est détectée combinant une usure oxydo-abrasive et adhésive. Une formulation de cinétique d'usure a été proposée en étendant empiriquement les lois d'usure classiques existantes en tenant compte des paramètres de chargement susmentionnés. Néanmoins, cette formulation supposait une description du taux d'usure global moyen négligeant la nature composite abrasive-adhésive de l'usure et, par conséquent, les variations locales du taux d'usure le long de la trace d’usure.La réalisation d'une description dynamique de la cinétique d'usure intégrant la répartition de l'usure abrasive et adhésive nécessite de comprendre l'évolution de ces mécanismes. Pour atteindre cet objectif, le Concept d’Oxygénation de Contact (COC) est supposé. Cette approche suggère que l'adhésion apparaît dans le centre de contact si la pression partielle de dioxygène est inférieure à une valeur seuil. Dans les côtés latéraux, où les molécules de dioxygène sont présentes en quantité suffisante, l'oxydation et l'abrasion prévalent. Le COC a été quantifié à l'aide du paramètre «distance d'oxygène» défini comme la largeur moyenne de la couronne d'abrasion externe. L'évolution de la distance d’oxygène a été formalisée par rapport aux conditions de chargement en utilisant une formulation de loi puissance qui a permis de prédire les transitions d'usure pour les surfaces lisses et macro-texturées. Cependant, cette formulation est restée paramétrique; par conséquent, une interprétation plus physique du COC est recherchée.Pour atteindre ce dernier objectif, une approche d'Advection-Dispersion-Réaction (ADR) est introduite pour modéliser le transport d'oxygène dans l'interface de fretting en supposant que le lit de débris est un milieu poreux compact. Cette approche ADR a non seulement prédit la répartition de l'abrasion et de l'adhésion, mais a également capturé la transition de l'usure abrasive pure à l'usure adhésive-abrasive mixte pour différentes conditions de chargement
This PhD thesis aims at understanding and modelling dry fretting wear of a flat-on-flat steel contact submitted to various loading conditions including number of fretting cycles, sliding amplitude, contact pressure, sliding frequency, contact size and contact orientation with respect to the sliding direction. Fretting-wear kinetics was studied by varying these loading conditions which affect wear mechanisms including debris formation and ejection in addition to tribo-oxidation, abrasion and adhesion. This investigation shows that, in most cases, a composite wear scar is detected combining oxidative-abrasive and adhesive wear. A wear-kinetics model was proposed by empirically extending the existing classical wear laws taking into account the aforementioned loading parameters. Nevertheless, this model assumed an averaged global wear-rate description neglecting the composite abrasive-adhesive nature of wear and consequently the inherited wear-rate local variations along the fretting scar.Achieving a dynamic wear-kinetics description incorporating the partition of abrasive and adhesive wear necessitates understanding the evolution of these mechanisms. To attain this goal, Contact Oxygenation Concept (COC) is assumed. This approach suggests that adhesion appears in the contact center if the di-oxygen partial pressure is below a threshold value. In the lateral sides, where di-oxygen molecules are sufficient, oxidation and abrasion prevail. COC was quantified using the “oxygen-distance” parameter defined as the averaged width of the external abrasion-corona. Oxygen-distance evolution was formalized versus loading conditions using a power-law formulation which allowed predicting wear transitions for plain and macro-textured surfaces. However, this formulation remained parametric; hence, more physical interpretation of COC is pursued.To achieve the latter objective, an advection-dispersion-reaction approach (ADR) is introduced to model oxygen transport within fretting interface assuming debris bed as a compact porous medium. This ADR approach not only predicted the partition of abrasion and adhesion but also captured the transition from pure abrasive to mixed abrasive-adhesive wear at different loading conditions

An ergonomically designed work environment may decrease work related musculoskeletal disorders, lead to less sick leaves and increase production time for operators and companies all around the world. Volvo Construction Equipment wants to deepen the knowledge and investigate more carefully how operators are actually sitting whilst operating the machines, how this affects placement of controls and furthermore optimize controls placements accordingly. The purpose is to enhance their product development process by suggesting guidelines for control placement with improved ergonomics based on operators’ sitting postures. The goal is to deliver a process which identifies and transfers sitting postures to RAMSIS and uses them for control placement recommendations in the cab and operator environments. Delimitations concerns: physical ergonomics, 80% usability of the resulted process on the machine types, and the level of detail for controls and their placements. Research, analysis, interviews, test driving of machines, video recordings of operators and the ergonomic software RAMSIS has served as base for analysis. The analysis led to (i) the conclusion that sitting postures affect optimal ergonomic placement of controls, though not ISO-standards, (ii) the conclusion that RAMSIS heavy truck postures does not seem to correspond to Volvo CE’s operators’ sitting postures and (iii) and to an advanced engineering project process suitable for all machine types and applicable in the product development process. The result can also be used for other machines than construction equipment. The resulted process consists of three independent sub-processes with step by step explanations and recommendations of; (i) what information that needs to be gathered, (ii) how to identify and transfer sitting postures into RAMSIS, (iii) how to use RAMSIS to create e design aid for recommended control placement. The thesis also contains additional enhancements to Volvo CE’s product development process with focus on ergonomics. A conclusion is that the use of motion capture could not be verified to work for Volvo Construction Equipment, though it was verified that if motion capture works, the process works. Another conclusion is that the suggested body landmarks not could be verified that they are all needed for this purpose except for those needed for control placement. Though they are based on previous sitting posture identification in vehicles and only those that also occur in RAMSIS are recommended, and therefore they can be used. This thesis also questions the most important parameters for interior vehicle design (hip- and eye locations) and suggests that shoulder locations are just as important. The thesis concluded five parameters for control categorization, and added seven categories in addition to those mentioned in the ISO-standards. Other contradictions and loopholes in the ISO-standards were identified, highlighted and discussed. Suggestions for improving the ergonomic analyses in RAMSIS can also be found in this report. More future research mentioned is more details on control placement as well as research regarding sitting postures are suggested. If the resulted process is delimited to concern upper body postures, other methods for posture identification may be used.

Trabalho Final do Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina
Introdução: A obtenção de uma camada híbrida com elevada qualidade é o maior desafio na adesão dentinária, uma vez que é um fator crucial para garantir o sucesso a longo prazo das restaurações adesivas. O jateamento com óxido de alumínio consiste num tratamento mecânico que utiliza partículas de óxido de alumínio para introduzir modificações à superfície e tem sido utilizado como método de limpeza dentinário prévio aos procedimentos adesivos. O objetivo deste estudo é avaliar o efeito do jateamento com óxido de alumínio nas forças de adesão à dentina de diferentes sistemas adesivos.Materiais e Métodos: A porção de esmalte oclusal de 6 molares humanos extraídos foi seccionada e a superfície de dentina lisa resultante foi tratada com uma sequência de lixas de água para criação de uma smear-layer padronizada. Os dentes foram aleatoriamente alocados em 6 grupos experimentais, de acordo com tratamento de superfície e sistema adesivo: G1: Jateamento + Clearfil™ SE Bond; G2: Jateamento + Optibond™ FL; G3: Jateamento + ScotchBond™ Universal; G4: Clearfil™ SE Bond; G5: Optibond™ FL; G6: ScochBond™ Universal. Depois do procedimento adesivo, realizou-se um build-up de 5mm em resina composta, armazenando-se posteriormente em água destilada. As amostras foram seccionadas em dois eixos por forma a obter sticks com área média de 1.41 mm2, testados numa máquina universal de testes. Dois espécimes por grupo foram preparados para microscopia eletrónica de varrimento.Resultados: Two-way ANOVA não detetou diferenças estatisticamente significativas entre os vários sistemas adesivos F(2, 83)=2,548, p=0.084. O jateamento da dentina produziu um decréscimo significativo na força de adesão F(1, 83)=11.04, p=0.001, reduzindo-a, em média, em 7.44 MPa (95%CI:[2.99;11.89]).Conclusões: Tendo em consideração as limitações deste estudo, verificou-se que o jateamento da dentina com óxido de alumínio afetou negativamente a interação entre os sistemas adesivos e o substrato dentinário, diminuindo as forças de adesão.
Introduction: Achieving a reliable hybrid layer is the main challenge of dentinal adhesion, as this is a major factor to ensure the long-term success of adhesive restorations. Aluminum oxide air abrasion consists in a mechanical treatment that uses aluminum oxide particles to introduce surface modifications and has been used as a dentin surface cleansing method prior to adhesive procedures. The aim of this study is to evaluate the effect of aluminum oxide air abrasion on the bond strength of different adhesive systems to dentin.Materials and Methods: Flat dentin surfaces were prepared in 6 extracted human molars. Exposed dentin surfaces were abraded with a sequence of silicon carbide sandpaper to create a standardized smear layer. The teeth were randomly allocated into 6 experimental groups according to the dentin pretreatment and adhesive system tested: G1: Sandblasting + Clearfil™ SE Bond; G2: Sandblasting + Optibond™ FL; G3: Sandblasting + ScotchBond™ Universal; G4: Clearfil™ SE Bond; G5: Optibond™ FL; G6: ScochBond™ Universal. After adhesive procedures, a 5 mm thick composite crown was built over the bonded surface. Following the storage in distilled water, the samples were vertically cross-sectioned until obtaining sticks with 1.41 mm2 of cross-sectional area, which were tested using a universal testing machine. Two specimens of each group were collected for analysis by scanning electron microscopy. Results: Two-way ANOVA did not detect statistically significant differences among adhesive systems F(2, 83)=2,548, p=0.084. Al2O3 sandblasting produced a significant decrease in μTBS F(1, 83)=11.04, p=0.001, reducing the bond strength in 7.44 MPa (95%CI:[2.99;11.89]).Conclusions: Within the limitations of this pilot study, it may be concluded that dentin pre-treatment with Al2O3 adversely affected the interaction pattern between adhesive systems and dentin substrate, decreasing microtensile bond strength.

OBJECTIVES: To evaluate various cements in vitro for adhesion to zirconia, light curing vs. self-curing, the effect of particle abrasion (APA) on the zirconia intaglio for maximizing retention, the effect of thermocycling, and the effect of cement space. METHODS: The tested cements included: Ceramir C&B (Doxa) Panavia F2.0 (Kuraray); Multilink Automix (Ivoclar); Theracem (Bisco); Duolink (Bisco); Bifix (Shofu); CemEZ (Zest Dental). For testing cements retention, custom made zirconia rings 12.5 mm outer diameter, 5.5 mm height and 6.147 mm inner diameter were used to emulate crowns. Round steel rods (McMaster) were manufactured to fit into the zirconia rings allowing a cement space of 50 Microns or 100 Microns. A cementing jig was used to keep the rods at the center of the zirconia rings. Cements were tested using light curing and self-curing (n=10 per each test). Groups of zirconia rings were air braded with 100 Microns aluminum oxide particles for 10 Sec. Half the specimens were stored in water for 24 hours at 37o C in dark environment or thermocycled for 5000 cycles. A ‘push-out’ test using an Instron universal machine at a crosshead speed of 0.5mm/min. Loads to failure were recorded to calculate cements retention. RESULTS: Statistical analysis was performed using JMP Pro 13 software. Data were analyzed using one way ANOVA, multiple t-test, and Tukey-Kramer HSD. For self curing method without APA, retention strength ranking for tested cements were: Ceramir C&B ≥ Theracem > Panavia F2.0 ≥ Duolink ≥ Multilink Automix ≥ Bifix. For light curing method without APA, retention strength ranking for tested cements were: CemEZ ≥ Theracem ≥ Multilink Automix ≥ Duolink ≥ Bifix ≥ Panavia F2.0. There was a significant influence in retention strength for light cured cements compared to self-curing method except for Theracem and Panavia F2.0. For the self-curing method with APA, retention strength ranking for tested cements were: Theracem > Duolink ≥ Panavia F2.0 ≥ Multilink Automix ≥ Bifix > Ceramir C&B. For the light curing method with APA, retention strength ranking for tested cements were: Theracem ≥ Multilink Automix ≥ CemEZ ≥ Duolink ≥ Panavia F.0 ≥ Bifix. A significant increase in retention strength with APA compared to self-curing method with APA. There was no significant effect of thermocycling treatment on retention strength of the cements tested. There was no significant effect of different cement spaces on retention strength except for Ceramir C&B without APA and Multilink Automix with and without APA (P < 0.0001). CONCLUSIONS: 1- There was a significant difference in retention strength to zirconia among tested cements in self and light curing methods. 2- Light curing resin cements influenced retention strength to zirconia for the tested cements. 3- APA influenced the retention strength to zirconia for tested cements except for Ceramir C&B. 4- Increasing the cement space from 50μm to 100μm had no significant difference in retention strength to zirconia except for Ceramir C&B without APA and Multilink Automix with and without APA. 5- Thermocycling had no significant effect of on retention strength to zirconia for the tested cements.
2020-07-30T00:00:00Z

Trabalho final do 5º ano com vista à atribuição do grau de mestre no âmbito do ciclo de estudos de Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina da Universidade de Coimbra.
Objective: The aim of the present pilot study was to assess the effect of sandblasting angulations, new air abrasion powder containing zirconia, and cleaning procedure on Y-TZP ceramic surface. Materials and Methods: A total of 4 cylindrical zirconia ceramic disks were divided in 6 different surface treatment groups and for each group 2 samples (n=2) were prepared: group 1 sandblasted with 50μm alumina powder and a 90° angulation; group 2 sandblasted with 50μm alumina powder and a 30° angulation; group 3 sandblasted with 30μm silica-coated alumina and a 90° angulation; group 4 sandblasted with 30μm silica-coated alumina and a 30° angulation; group 5 sandblasted with 82μm zirconia and alumina and a 90° angulation; group 6 sandblasted with 82μm zirconia and alumina and a 30° angulation. Surface roughness (Alicona InfiniteFocus® optical 3-dimensional micro coordinate system), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis were performed in all samples, before and after cleaning procedures with 9,6% hydrofluoric acid and 37% phosphoric acid. Results: Group 1 had the highest roughness values. Samples sandblasted with 30μm silica-coated alumina and with 82μm alumina and zirconia particles showed higher values of roughness in 30º air abrasion than in 90º procedures, after cleaning protocols. EDS analysis confirmed the presence of silica in zirconia surfaces that were sandblasted with silica-coated alumina particles, even after cleaning protocols. The roughness in all samples presented a decreased after cleaning procedures, indicating the presence of smear-layer, contaminants and dust. Results suggested that the experimental 82μm alumina and zirconia abrasive might produce an appropriate roughness, without leaving a great amount of dust after the air abrasion protocol. Conclusions: In accordance with the goal of this pilot study, results showed that powder composition, air-abrasion angulation and cleaning procedures are crucial in the quality and quantity of zirconia surface roughness. Despite of this, further studies are needed to fully understand zirconia surface behaviour to roughening procedures, and to perform adhesion tests, once they are the reason of this basic procedure.

in english Introduction: Composite restorations in the oral cavity are exposed to an aggressive environment and mechanical challenge that gradually impairs their physical and mechanical properties. This may result in an enhanced wear rate, loss of esthetic properties and an increased risk of a restoration fracture or its marginal failure with a negative impact on the restoration's durability. Worn or failed restorations are usually completely replaced, which increases the irreversible loss of dental hard tissues. Repair of composite restorations by their partial replacement is therefore a minimally invasive, preventive and less time-consuming alternative to their complete replacement and increases their longevity. In the oral cavity, the adhesive bond between the existing composite restoration and the repair composite resin is exposed to various chemical substances and mechanical stress, e.g. surfactants in toothpastes, which can initiate its degradation. By decreasing the surface tension, the penetration of water into the adhesive joint can be enhanced, accelerating the hydrolysis of the adhesive and reducing the composite repair strength. The major and not yet fully resolved issue of composite repairs is how to achieve a strong and durable bond between the existing and repair composite materials....

Indiana University-Purdue University Indianapolis (IUPUI)
Repair is an alternative treatment option in many cases to replacement of resin matrix composite restoration. However, aged resin matrix composites have a limited number of carbon-carbon double bonds to adhere to a new layer of rein. Therefore, surface treatments of the aged resin matrix composite surface prior to repairing could improve the repair bond strength. The objectives of this study were to: 1) To evaluate various surface treatments on shear bond strength of repair between aged and new microhybrid resin matrix composite, and 2) To assess the influence of applying a silane coupling agent after surface treatments. Eighty disk-shaped resin matrix composite specimens were fabricated and thermocycled 5000 times prior to surface treatment. Specimens were randomly assigned to one of the three surface treatments (n = 20): 1) Airborne abrasion with 50 μm aluminum oxide, 2) Tribochemical silica coating (CoJet), or 3) Er,Cr:YSGG laser and control group (n = 20). Specimens were cleaned with 35-percent phosphoric acid, rinsed, and dried. Each group was assigned into two subgroups (n =10): a) no silanization, and b) with silanization. Adhesive agent was applied and new resin matrix composite was bonded to each conditioned surface. Bond strength was evaluated by shear test. Data were analyzed with a two-way ANOVA model. The interaction between conditioning and silanization was significant(p = 0.0163), indicating that comparisons of silanization must be evaluated for each conditioning method, and that comparisons of conditioning methods must be evaluated separately with and without silanization. Airborne particle abrasion showed significantly higher repair bond strength than Er,Cr:YSGG laser without silanization (p < 0.0001) and with silanization(p = 0.0002), and higher repair bond strength than the control without silanization (p < 0.00001) and with silanization (p < 0.00001). Airborne particle abrasion did not have significantly different in repair bond strength than Tribosilica coating without silanization (p = 0.70) or with silanization (p = 0.33). Tribosilica coating had significantly higher repair bond strength than Er,CR:YSGG laser without silanization (p < 0.0001) and with silanization (p < 0.0001), and significantly higher repair bond strength than control without silanization (p < 0.0001), but not with silanization (p =0.16). Er,CR:YSGG laser and control did not have significantly different repair bond strength without silanization (p = 1.00) or with silanization (p = 0.11). There was no effect of silanization on repair bond strength overall (p = 0.34) for any of the surface conditioning methods (p = 0.76 for airborne particle abrasion; p = 0.39 for tribosilica coating; p = 1.00 for Er,Cr:YSGG laser, or p = 0.39 for control). Airborne particle abrasion with 50-μm aluminum oxide particle and tribochemical silica coating followed by the application of bonding agent provided the highest shear bond strength values, suggesting that they might be adequate methods to improve the quality of the repairs of resin-matrix composites.

Introdução: Nos últimos anos, tem surgido na Medicina Dentária novas técnicas e materiais, que têm sido melhorados de modo a permitir o conforto do paciente e a preservação da estrutura dentária sadia através do conceito de medicina dentária minimamente invasiva. Este conceito é de grande importância na clinica de odontopediatria, isto pois o tratamento restaurador com o uso de instrumentos rotativos gera muita ansiedade e medo nas crianças. Objectivo: O objectivo do presente trabalho consiste na elaboração de uma revisão bibliográfica da eficiência e eficácia dos métodos alternativos aos instrumentos rotativos, sendo este o principal propósito da motivação do autor: a de conseguir quebrar o receio, medo e fobia que muitas crianças têm aos instrumentos rotativos, proporcionando-lhes estas abordagens mais conservadoras e menos dolorosas, não só em termos físicos mas também psicológicos. Metodologia: A pesquisa bibliográfica foi efetuada nos motores de pesquisa da MEDLINE/Pubmed, ScienceDirect e SCOPUS, no período compreendido entre novembro de 2016 e fevereiro de 2017, com as seguintes palavras-chave isoladas e combinadas entre elas: chemomechanical caries removal, Carisolv, Papacárie, air abrasion, caries removal, bioactiveglass, laser caries removal e laser Er:YAG. Conclusão: Existem alternativas viáveis aos instrumentos rotativos, não comprometendo o sucesso do tratamento da doença de cárie, visto que alguns métodos são tão eficazes como os instrumentos rotativos. Estes métodos alternativos são de grande importância, pois permitem ao Médico Dentista uma alternativa aquando necessário tratamentos envolvendo pacientes com necessidades especiais. Quanto ás técnicas apresentadas é necessário que o profissional respeites as indicações e contraindicações e a sua aplicabilidade deve ser analisada individualmente em cada caso a fim de escolher o melhor método.
Introduction: In recent years new techniques and materials have arisen in dental medicine that have been improved to allow patient comfort and preservation of healthy tooth structure through the concept of minimally invasive dental medicine. This concept is of great importance in the pediatric dentistry clinic, since the restorative treatment with the use of rotating instruments generates a lot of anxiety and fear in the children. Objective: The objective of the present work is the elaboration of a bibliographical review of the efficiency and effectiveness of alternative methods to rotary instruments, this being the main purpose of the motivation of the author: to be able to break the fear, fear and phobia that many children have to rotary instruments , Giving them these more conservative and less painful approaches, not only in physical but also psychological terms. Methodology: The literature search was carried out in the MEDLINE / Pubmed, ScienceDirect and SCOPUS search engines, from November 2016 to February 2017, with the following keywords isolated and combined: chemomechanical caries removal, Carisolv, Papacari, Air abrasion, caries removal, bioactiveglass, laser caries removal and Er: YAG laser. Conclusion: There are viable alternatives to rotating instruments, not compromising the success of caries disease treatment, since some methods are as effective as rotary instruments. These alternative methods are of great importance as they allow the Dentist an alternative when necessary treatments involving patients with special needs. Regarding the techniques presented, it is necessary that the professional respect the indications and contraindications and their applicability should be analyzed individually in each case in order to choose the best method.

博士
國立臺灣科技大學
機械工程系
101
Surface finish plays an important role in product quality due to its direct effects on product appearance. Hence, improvement of the surface finish is an essential requirement in industrial products. In an attempt to improve the surface finish of bulk metallic glass (BMG) material, some common methods have been used, such as milling, grinding, and lapping. However, the BMG surface finish has not yet been significantly improved by using these methods. Therefore, this thesis proposes sequential abrasive jet polishing (AJP) and annealing processes that can considerably improve the BMG surface finish. In addition, this thesis also takes into account optimal parameters for both the AJP and annealing processes based on the Taguchi’s L18 and L8 orthogonal array experimental results, respectively. The experimental results show that using the optimal AJP parameters, the surface roughness (Ra) of the ground BMG can be significantly improved from 0.675 to 0.016 μm. After the AJP process, the surface roughness (Ra) of the polished BMG can be further improved from 5.7 to 2 nm within an area of 5×5 μm by using the optimal annealing parameters. Furthermore, this thesis also proposes both air-driving fluid jet polishing (FJP) and AJP process that can improve the surface roughness of N-BK7 optical glass. In addition, this thesis also investigates optimal parameters for air-driving FJP and AJP processes based on the Taguchi’s L18 orthogonal array experimental results. The surface roughness (Ra) of ground N-BK7 optical glass can be improved from 0.350 to 0.032 μm by using the optimal air-driving FJP parameters and improved from 0.350 to 0.018 μm by using the optimal AJP parameters. Finally, the determined optimal plane parameters for the air-driving FJP and the AJP are applied to the freeform surface finish of an N-BK7 spherical lens, and the surface roughness (Ra) of the spherical lens can be improved from 0.421 to 0.202 μm within an area of 283.6×200 μm by using the optimal plane air-driving FJP parameters and improved from 0.421 to 0.232 μm within an area of 283.6×200 μm by using the optimal plane AJP parameters.