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Proefschrift--Technische Hogeschool, Deltf. 1951. / "Stellingen": [3] p. inserted. Bibliographical footnotes. Also issued in print.

Thesis (M.S.)--West Virginia University, 2005 / Title from document title page. Document formatted into pages; contains xii, 71 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 59-61).

Orientador: Flávio Henrique Baggio Aguiar / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T21:16:27Z (GMT). No. of bitstreams: 1 Mainardi_MariadoCarmoAguiarJordao_M.pdf: 989642 bytes, checksum: dd3fc3a3b18282f2bf45daefa47de5de (MD5) Previous issue date: 2013 / Resumo: O objetivo neste estudo foi avaliar o grau de conversão (GC) e microdureza (KHN) de um cimento resinoso dual utilizado para a fixação de pinos de fibra de vidro. Para isso, foram utilizadas 45 raízes (n=5) de incisivos bovinos, as quais foram submetidas ao tratamento endodôntico e divididas em 8 grupos experimentais e um controle. Após o tratamento endodôntico, as raízes foram desobturadas e pinos de fibra de vidro White Post DC nº 3 foram cimentados, com o cimento resinoso dual RelyX ARC (3M-ESPE). A seguir, a fotoativação foi realizada com o aparelho LED (Valo-Ultradent) em quatro diferentes densidades de energia (7, 14, 20 ou 28 J/cm²) e dois diferentes tempos de espera (0 ou 2 minutos). O grupo controle não foi fotoativado. Após a cimentação as raízes com os pinos cimentados foram armazenadas em água destilada a 37º C durante 15 dias. Após esse período os valores de grau de conversão e microdureza Knoop foram coletados em três diferentes terços do canal radicular (Cervical, Médio e Apical). Os dados foram submetidos à análise de variância três fatores com parcelas subdivididas (ANOVA) e teste de Tukey. Comparações com o grupo controle foram realizadas pelo teste de Dunnett. Através dos resultados obtidos para grau de conversão, pode-se observar que o terço Cervical apresentou os maiores resultados, estatisticamente diferente dos demais terços, para todas as condições experimentais. O grau de conversão para o tempo de espera de 2 minutos foi estatisticamente maior do que aquele apresentado pelo tempo imediato. A densidade de energia 28 J/cm² apresentou os maiores valores de grau de conversão, com diferença estatística significante das demais densidades de energia. Para os valores de microdureza, não houve diferenças estatísticas em relação aos tempos de espera. Dentro dos terços Cervical e Apical, não houve diferenças significantes em relação às densidades de energia. No terço Médio, a fotoativação com 14 J/cm² apresentou os maiores valores de microdureza, enquanto 28 J/cm² resultou nos menores. O terço Apical não diferiu estatisticamente em relação ao mesmo terço do grupo controle. Pelos resultados obtidos pode-se concluir que o grau de conversão foi influenciado pelas densidades de energia e tempos de espera para a fotoativação, assim como pelo terço do canal radicular. Os valores de microdureza não foram influenciados pelo tempo de espera para a fotoativação, e as diferentes densidades de energia apresentaram comportamento semelhante nos terços Cervical e Apical / Abstract: The aim of this study was to evaluate the degree of conversion and microhardness of dual-cured resin cement used for cementation of fiber posts. Forty-five roots of bovine incisors were used for this purpose. These roots were submitted to endodontic treatment and random assigned to 8 experimental groups and a control, all of them with n=5. After seven days, the fiber post White Post DC #3 was cemented with the dual-cured resin cement, RelyX ARC (3M-ESPE) in each root. Following this step, the light curing was performed with the 3ª generation LED device (Valo-Ultradent), with four different energy densities (7, 14, 20 or 28 J/cm²) and two different delay times (o or 2 minutes). The control group was not light-cured. After the cementation, the roots were stored in distilled water at 37º C for 15 days, and the degree of conversion an Knoop microhardness were obtained in three different root segments (Cervical, Medium and Apical). Data were submitted to three-way split-spot ANOVA and Tukey's test. Dunnett's test was used for comparisons with control. Results of degree of conversion showed that the Cervical root segment obtained higher values than the others, at all experimental conditions. The degree of conversion values for 2-minutes delay time were higher than 0-minute delay-time. The energy density of 28 J/cm² obtained the highest values, with significant differences from the others energy densities. For microhardness values there were not significant differences between the delay times. For the Cervical and Apical root segments, there were not statistical differences for the energy densities tested. The energy density of 14 J/cm² showed the higher values of microhardness at the Medium root segment, while the 28 J/cm², showed the lowest. The Apical root segment obtained similar microhardness values from the same third at the control. In conclusion, the degree of conversion was influenced by the energy densities and delay times, as well as the root segment. The microhadness was not affected by the delay time at all conditions, and the energy densities showed similar behavior at Cervical and Apical root segments / Mestrado / Dentística / Mestra em Clínica Odontológica

Magister Scientiae Dentium - MSc(Dent) / Resin composite is one of the most commonly used materials in restorative dentistry. However, it has undergone continuous developments like changes in the fillers and initiators. One such improvement is the new bulk-fill composites which are materials intended for bulk placement up to 4mm. However, an optimum polymerization to the full depth of the restoration i.e. complete depth of cure is of utmost importance in order to obtain proper mechanical and physical properties of resin composites. Aim: The aim of this study was to measure the surface hardness of the top and bottom surfaces of the composites and to determine the depth of cure of bulk-fill composites using two different types of light curing units. Material and methods: A total of 160 specimens were used in this study: four bulk-fill composite were used of which two were conventional viscosity bulk-fill composites namely, Tetric N Ceram (Ivoclar Vivadent) and SureFil bulk-fill composite (Densply Caulk) and two were low viscosity flowable bulk-fill composites namely, SDR flowable (Densply Caulk) and Filtek bulk-fill flowable restorative (3M ESPE). Two different curing light were used namely, LED (Elipar Freelight, 3M ESPE) at 1500mW/cm2 and a Quartz Tungsten Halogen (QTH) curing unit (Megalux CS, Megadenta, Germany) at 600 mW/cm2. To evaluate micro-hardness, Vickers hardness at top and bottom of each sample was measured immediately after light curing and after 24 hours post curing using a Zwick micro-hardness machine load 300g/15 seconds. The mean hardness values obtained from the top and the bottom surface of each material were used to compare the micro-hardness of the various materials. The mean values obtained from the bottom surface were compared to the respective values of the top surface of each material (bottom/top ratio) and used to calculate the depth of cure. Results: The micro-hardness test showed a significant difference between the four materials (ANOVA, p<0.05) immediately after curing and after 24 hours post curing. The material with the greatest micro-hardness was SureFil followed by Tetric N Ceram, Filtek bulk-fill flowable and SDR flowable respectively. The material with the greatest depth of cure was Filtek bulk-fill flowable followed by SDR flowable, Tetric N Ceram and SureFil. When the curing lights were compared the Light Emitting Diode Curing Unit (LED) obtained significantly better depth of cure compared to Quartz Tungsten Halogen Light Curing Units. The LED curing light showed greater micro-hardness values than the QTH curing light except for Tetric N Ceram where the QTH curing showed more hardness values than the LED curing light. For all materials, the surface hardness and depth of cure values increased when tested 24hrs after light curing. Conclusion: There was a difference in the micro-hardness values between the four materials where the conventional viscosity materials showed greater surface hardness values than the low viscosity materials but the depth of cure compared to the bulk-fill flowable LED curing lights showed higher hardness values than QTH curing light except for Tetric N Ceram. Depth of cure ratios were found to be lower than 0.80 for all composite types, however the flowable bulk-fill materials showed higher depth of cure than the conventional viscosity bulk-fills. In general LED curing light produced better hardness and depth of cure values than QTH curing light. The low micro-hardness values for the bulk-fill flowable composites and the inadequate polymerization raises a concern regarding placing these materials in bulk. In such cases, the flowable bulk-fills should be protected with a conventional composite "covering or capping" especially in posterior teeth and in deeper cavities. Furthermore, bulk-fill composites should be used in layering incremental technique to ensure sufficient depth of cure.

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Digitized by Kansas Correctional Industries

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Water pollution due to heavy metals can be hazardous to both the environment and human health. The aim of this research is to provide a low-cost alternative for lead remediation. Biochar was produced from the fast pyrolysis of Douglas fir (DBC). Magnetic biochar (MDBC) was synthesized by mixing aqueous biochar suspensions with an aqueous Fe3+/Fe2+ solution. In chapter I, an overview of lead as an emergent contaminant is given. Different biochar production techniques have been discussed along with different mechanism of adsorption of lead onto biochar. Chapter II is a study of adsorption of lead on DBC and MDBC under different experimental conditions. The main aim of this research is to study the effect of water hardness on adsorption capacity. Three levels of water hardness were employed. Sorption performances were evaluated using Langmuir and Freundlich adsorption isotherms. DBC and MDBC were also successfully applied for lead removal from natural water samples. In chapter III, future projects focused on studying the effects of matrix chemicals found in natural waters on the heavy metal ion adsorption properties of biochar are discussed.

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