Introdução: Os objetivos deste estudo foram comparar a extrusão apical de debris durante a desobturação com WaveOne Gold, ProTaper retratamento, D-RaCe ou limas manuais; descrever as falhas e/ou fraturas ocorridas nos instrumentos de NiTi; e comparar o WaveOne Gold com os sistemas ProTaper e RaCe em relação à quantidade de material obturador remanescente, transporte apical (TA) e tempo de trabalho após a desobturação e após o repreparo de canais radiculares curvos. Materiais e Métodos: Quarenta canais mésiovestibulares de molares superiores foram preparados, obturados e divididos em 4 grupos (n=10): WOG) WaveOne Gold Primary e Medium; PTG) ProTaper Retreatmento e ProTaper Next; RCG) D-RaCe e RaCe; e LM) Limas manuais. A extrusão de debris foi determinada subtraindo-se o peso final do peso inicial dos Eppendorfs. Os instrumentos de NiTi (n=18) foram analisados em MEV antes e após a desobturação. A quantidade de material obturador remanescente e o TA foram avaliados em micro-TC. O tempo de trabalho foi anotado e comparado. Os dados foram estatisticamente analisados (α=.05). Resultados: WOG extruiu menos debris do que LM e RCG (P<.05), e foi similar ao PTG (P>.05). Não houve diferença entre LM, PTG e RCG (P>.05). A análise em MEV mostrou, dos 18 instrumentos avaliados, 3 fraturas e 10 deformações. Nas duas etapas avaliadas, WOG apresentou similar (P>.05) e menor (P<.05) quantidade de material obturador remanescente do que PTG e RCG, respectivamente. A quantidade de material no WOG e RCG foi menor após o repreparo (P<.05). Na desobturação, WOG teve maior TA em 4mm do que em 2mm (P<.05). Em 2mm, o TA do WOG foi menor do que RCG (P<.05), e em 4mm foi igual ao PTG e RCG (P>.05). Na desobturação, o tempo de trabalho no grupo LM foi maior que nos demais (P<.05). No repreparo, WOG foi mais rápido do que PTG e RCG (P<.05). Conclusões: Todos os instrumentos causaram extrusão de debris, sendo que o WOG apresentou os menores valores. Nenhum sistema removeu completamente o material obturador de raízes mésiovestibulares de molares superiores. Considerando os baixos valores de TA obtidos, os instrumentos avaliados foram considerados seguros para desobturação e repreparo de canais curvos. A desobturação com LM foi mais lenta do que com os instrumentos de NiTi. O sistema reciprocante foi mais rápido do que os rotatórios no reprepro. / Introduction: The aims of this study were to assess the amount of apically extruded debris during filling removal with WaveOne Gold, ProTaper Retreatment, D-RaCe or hand files; to describe failures of NiTi instruments; and to compare WaveOne Gold with ProTaper and RaCe systems regarding remaining filling material, apical transportation (AT) and working time after filling removal and after shaping of curved root canals. Methods: Forty mesiobuccal canals of maxillary molars were prepared, filled, and assigned into 4 groups (n=10): WOG) WaveOne Gold Primary and Medium; PTG) ProTaper Retreatment and ProTaper Next; RCG) D-RaCe and RaCe; HF) Hand files. The amount of extruded debris was determined by subtracting the final from the initial Eppendorfs weight. The NiTi instruments (n=18) used for filling removal were analyzed pre and post-operatively by SEM. Micro-CT analysis assessed the residual filling material and AT. Working time was recorded and compared. Data were statistically analyzed (α=.05). Results: WOG produced less debris compared with HF and RCG (P<.05), and similar to PTG (P>.05). HF, PTG and RCG showed no difference (P>.05). SEM analyses after filling removal showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. In both evaluated steps, WOG had similar (P>.05) and less (P<.05) amount of filling material as PTG and RCG, respectively. The remaining material in WOG and RCG was lower after shaping (P<.05). In filling removal, WOG had higher AT at 4mm than at 2mm (P<.05). At 2mm, AT of WOG was lower than RCG (P<.05), and at 4mm, was equal to PTG and RCG (P>.05). In filling removal, working time in HF group was significantly higher than others (P<.05). In shaping step WOG was faster than PTG and RCG (P<.05). Conclusions: All instruments tested caused debris extrusion, with WOG presenting the lowest values. Neither system could completely remove the filling material of mesiobuccal canals of maxillary molars. Considering the low AT values obtained, the instruments evaluated were safe for filling removal and shaping of curved canals. Filling removal with HF was slower than with the NiTi files. The reciprocating system was faster than the rotary in shaping the root canals.

O objetivo deste estudo foi avaliar os métodos de espectroscopia Raman e espectroscopia de absorção de infravermelho (FTIR) na identificação da degradação do trans-1,4-poliisopreno de cones de guta-percha sem uso, e o comportamento do material após diferentes períodos decorridos de sua fabricação por testes de indentação de nanodureza (IHT). Para a análise, foram selecionadas 27 amostras de cones de guta-percha sem uso, de 5 marcas comerciais vendidas no mercado brasileiro, cedidas por Cirurgiões-dentistas. As amostras foram avaliadas através de espectroscopia Raman, com base no sinal da ligação C=C, indicando a presença de trans-1,4-poliisopreno; FTIR, levando-se em consideração a ligação C=O, indicativa de oxidação do material; IHT, avaliando-se rigidez e módulo de elasticidade. Os dados foram analisados de maneira descritiva. Observam-se, nos espectros de Raman, amostras nas quais os picos relativos à ligação C=C foram identificados, bem como outras em que não foi percebido o referido pico, sem uma relação direta com os tempos decorridos da fabricação dos cones de guta-percha sem uso. Em relação ao FTIR, em todas as amostras analisadas foram observados picos relativos à ligação C=O, indicando haver algum grau de oxidação no material. Os testes de nanodureza, realizados em cones sem uso, mostraram não haver homogeneidade dos valores de dureza e módulo de elasticidade. A análise pelos métodos de espectroscopia Raman e FTIR em cones de guta-percha é dificultada pelos vários componentes presentes no material e a separação do polímero trans-1,4-poliisopreno pode evitar número excessivo de picos e facilitar a interpretação dos espectros. Espectroscopia Raman e FTIR são capazes de identificar a degradação do poliisopreno. A presença, ou não, da ligação C=C, nos espectros de Raman, não teve relação direta com a idade dos cones. Os cones de guta-percha sem uso apresentaram algum grau de degradação, devido à presença da oxigênio no polímero. As análises de nanodureza não foram conclusivas quanto ao comportamento do material relacionado ao envelhecimento. / The aim of the present study was to evaluate the methods Raman spectroscopy and infrared absorption spectroscopy (FTIR) to analyze the degradation of trans-1,4-polyisoprene polymer in gutta-percha points, before use. Mechanical properties were assessed through the instrumented hardness tests (IHT). Twenty-seven samples of gutta-percha cones collected before use, belonging to five different commercial brands sold in Brazil, were obtained from Dental Surgeons. The samples were evaluated by Raman spectroscopy, based on the sign of the C=C bond (representing the trans-1,4-polyisoprene polymer); FTIR, considering the C=O bond (indicating polymer oxidation), and instrumented hardness tests (IHT), to assess both rigidity and elasticity modulus. Descriptive analysis was performed. Raman spectra showed that there were samples of gutta-percha before use where the C=C was identified, an others no. There was no relation between its detection and the time from manufacturing. FTIR showed C=O bond in all samples, indicating that there was some degree of oxidation on the material. Nanoindentation tests showed no homogeneity between hardness and modulus of elasticity. The analysis by Raman and FTIR in gutta-percha points is difficult because there are several components that form the material, and polymer isolation can facilitate the interpretation of the spectra. Both methods were able to evaluate polymers’ degradation. The presence of C=C bond, in Raman spectra, have no relation to their age. The gutta-percha points showed some degree of degradation, due to the presence of oxygen in the polymer. Nanoindentation tests did not provid conclusive results regarding the material’s aging behavior.

O presente estudo teve por objetivo avaliar comparativamente o emprego de tomografias e cortes transversais na quantificação de material obturador endodôntico remanescente à desobturação e repreparo dos canais radiculares. Para tal, 32 dentes preparados, obturados e após periodo necessário para o ennvelhecimento do cimento obturador foram desobturados e repreparados. Os espécimes tiveram o conteúdo de material obturador remanescente avaliado por diferentes métodos: aferição em tomógrafo computadorizado de múltiplos detectores e aferição em software Leica Qwin. Inicialmente foram medidos os volumes de material obturador remanescente no tomógrafo computadorizado com os espécimes ainda íntegros. Em seqüência, realizou-se nos mesmos cortes transversais com espessura de 1mm permitindo assim aferição: do volume em tomógrafo computadorizado após o corte; das áreas de material remanescente em cada corte com auxílio do software Leica Qwin. Para que fosse possível a comparação dos métodos, os valores de área foram utilizados para cálculo do volume de material remanescente em cada espécime através da fórmula do volume do cone truncado. Os resultados obtidos foram submetidos a análise pelo teste t de Student para dados vinculados, o qual identificou diferença estatisticamente significante em nível de 5% na quantificação de material obturador remanescente quando da comparação dos volumes obtidos com a análise do software Leica Qwin e aplicação da fórmula do volume do cone 11 truncado aos volumes obtidos pelas aferições tomográficas, sendo que a análise dos cortes pelo software Leica Qwin permitiu maior quantificação de material, mostrandose método adequado para análise. Em relação ao método tomográfico não houve diferença estatística significante entre a avaliação do remanescente de material obturador nos cortes ou nos espécimes íntegros. / The aim of the present study was to evaluate the effectiveness of computed tomography and cross section in quantifying the remaining filling material during retreatment. For that, 32 teeth were prepared, filled and after the period necessary to the sealer set, the specimens had their filling material removed and were reprepared. The amount of filling material were evaluate for different methods: computed tomography and Leica Qwin software. First, the volumes of filling material remaining were measured through the computed tomography with the specimens still entire. After, they were cross sectioned with a thickness of 1mm allowing measure of: the volume through computed tomography and the areas of remaining material in which section through the Leica Qwin software. To allow a comparative analysis among methods, the area values were used to calculate the filling material remaining volume using the truncated cone formula. The results were submitted to the t Student test for linked data which identify a significant difference to the level of 5% in the quantification of remaining material when the comparison of the volumes obtained after Leica Qwin analysis and application of truncated cone formula in relation to the results obtained from computed tomography, being the first method that allow the bigger quantification, therefore, most efficient. In relation the tomographic method there was no significant difference between the measured made in the intact specimen or after they were cross-sectioned.

O presente estudo teve por objetivo avaliar ex vivo a eficiência de sistemas reciprocantes e rotatórios (Wave One e ProTaper Universal Retratamento), na desobturação de molares inferiores, por meio de microtomografia computadorizada. Foram utilizados canais mesiais com curvatura entre 20 e 40 graus, de 50 molares inferiores, preparados com ProTaper Universal, obturados com cone do próprio sistema e cimento AH Plus, pela técnica de condensação lateral. Para a desobturação, os dentes foram divididos em 5 grupos (I: Instrumentos manuais associados ao uso de brocas Gates Glidden e solvente; II: Sistema ProTaper Universal Retratamento; III: Sistema ProTaper Universal Retratamento e solvente; IV: Sistema Wave One; V: Sistema Wave One e solvente. Durante a desobturação, a quantidade de detritos extruídos, bem como o tempo de desobturação foram mensurados. A captura de imagem foi realizada por meio de microtomografia computadorizada onde foi avaliado o volume de material obturador remanescente nos canais. Os dados obtidos foram tabulados e submetidos a análise estatística por meio do teste de Kruskal-Wallis para determinar a ocorrência de diferença estatística entre os grupos experimentais (p<0,05). Nenhum dos métodos avaliados removeu por completo o material obturador. O método que utilizou o sistema ProTaper Retratamento com solvente apresentou menor volume percentual médio de material obturador remanescente no terço apical, entretanto, não houve diferença estatística significante entre os grupos testados em nenhum dos terços analisados. O sistema WaveOne com solvente teve o maior volume de extrusão de material após a desobturação. Os grupos que utilizaram o sistema ProTaper Retratamento, com e sem o auxílio da solução solvente, foram os que apresentaram menor tempo para remoção de material obturador. Concluiu-se que o uso de Sistema ProTaper Retratamento favorece uma desobturação mais rápida e com menor extrusão de material obturador. / This study aimed to evaluate ex vivo the efficiency of reciprocating and rotary systems (Wave One and ProTaper Universal Retreatment), in the disobturation of mandibular molars, using micro-computed tomography. Mesial canals were used with curvature between 20o and 40o, from 50 mandibular molars prepared with ProTaper Universal, obturated with ProTaper single cones and AH Plus sealer using the lateral condensation technique. For the disobturation, the teeth were divided into 5 groups (I: manual instruments associated with the use of Gates Glidden drills and solvent; II: Protaper Universal Retreatment system; III: Protaper Universal Retreatment system and solvent; IV: Wave One system; V: Wave One system and solvent. During the disobturation the amount of extruded debris, as well as the time of the retreatment procedure, were measured. The capture of images was performed using microcomputed tomography which assessed the volume of the filling material remaining in the canals. Data were tabulated and submitted to statistical analysis using theKruskal-Wallis test to determine the occurrence of statistical differences among the experimental groups (p<0.05). None of the methods evaluated completely removed the filling material. The method that used the ProTaper Retreatment system with solvent showed lower average percent volume of remaining filling material in the apical third. However, there was no statistically significant difference between the groups tested in any of the analyzed thirds. The Wave One system with solvent had the largest volume of extrusion material after the disobturation. Groups using the ProTaper Retreatment system, with and without the use of solvent solution, were those that demanded less time for the removal of the filling material. The study concluded that the use of ProTaper Retreatment system favors a faster disobturation and with less extrusion of filling material.

Following chemo-mechanical cleaning of the root canal system, the provision of a fluid-tight seal is one of the main requirements for successful endodontic treatment. Gutta percha with a sealer has been considered as the gold standard root canal filling for many years. However, it does not have all the properties of an ideal root canal filling. A resin-based root filling, Resilon, has been introduced which has the advantage of bonding to the root canal dentine forming a “monoblock”. Different properties of Resilon have been investigated, but some properties using different obturation techniques and in retreatment need further investigation. The aim of this project was to investigate selected properties of Resilon in primary endodontic treatment (quality of obturation using either cold lateral condensation or thermal compaction, and push-out bond strength following the use of different intracanal medicaments) and secondary endodontic treatment (removability using a combination of hand and rotary instrumentation, fracture resistance and leakage resistance following different removal techniques).Using micro-CT, the volume of voids in root canals obturated with Resilon in comparison with gutta percha using either cold lateral condensation or thermal compaction was investigated. The results showed that there was no significant difference between the two materials regardless of the obturation technique. The use of Vitapex and iodoform was found to significantly reduce the bond strength of Resilon to dentine in comparison with calcium hydroxide and its aqueous combination with iodoform (Calcipast1). The effectiveness of the combined use of hand K-files and ProTaper retreatment files in removal of Resilon using either cold lateral condensation or thermal compaction was compared to that of gutta percha. Micro-CT assessment showed that Resilon resulted in significantly more remaining material than gutta percha when thermal compaction was used. Fracture resistance of retreated roots filled with Resilon was found to be not significantly different from those filled with gutta percha irrespective to the removal technique (either hand K-files or ProTaper retreatment files). Using the same retreatment techniques, dye leakage resistance of root canals re-filled with Resilon was compared with that of primarily treated root canals. The results showed that there was no significant difference in leakage resistance between re-treated and primarily treated root canals. Obturation with Resilon was shown to have no significant advantage over gutta percha in terms of quality of obturation and fracture resistance in retreated roots. More investigation of the clinical performance of Resilon is required before it can be considered as a replacement for gutta percha.

Introdução: Os objetivos deste estudo foram comparar a extrusão apical de debris durante a desobturação com WaveOne Gold, ProTaper retratamento, D-RaCe ou limas manuais; descrever as falhas e/ou fraturas ocorridas nos instrumentos de NiTi; e comparar o WaveOne Gold com os sistemas ProTaper e RaCe em relação à quantidade de material obturador remanescente, transporte apical (TA) e tempo de trabalho após a desobturação e após o repreparo de canais radiculares curvos. Materiais e Métodos: Quarenta canais mésiovestibulares de molares superiores foram preparados, obturados e divididos em 4 grupos (n=10): WOG) WaveOne Gold Primary e Medium; PTG) ProTaper Retreatmento e ProTaper Next; RCG) D-RaCe e RaCe; e LM) Limas manuais. A extrusão de debris foi determinada subtraindo-se o peso final do peso inicial dos Eppendorfs. Os instrumentos de NiTi (n=18) foram analisados em MEV antes e após a desobturação. A quantidade de material obturador remanescente e o TA foram avaliados em micro-TC. O tempo de trabalho foi anotado e comparado. Os dados foram estatisticamente analisados (α=.05). Resultados: WOG extruiu menos debris do que LM e RCG (P<.05), e foi similar ao PTG (P>.05). Não houve diferença entre LM, PTG e RCG (P>.05). A análise em MEV mostrou, dos 18 instrumentos avaliados, 3 fraturas e 10 deformações. Nas duas etapas avaliadas, WOG apresentou similar (P>.05) e menor (P<.05) quantidade de material obturador remanescente do que PTG e RCG, respectivamente. A quantidade de material no WOG e RCG foi menor após o repreparo (P<.05). Na desobturação, WOG teve maior TA em 4mm do que em 2mm (P<.05). Em 2mm, o TA do WOG foi menor do que RCG (P<.05), e em 4mm foi igual ao PTG e RCG (P>.05). Na desobturação, o tempo de trabalho no grupo LM foi maior que nos demais (P<.05). No repreparo, WOG foi mais rápido do que PTG e RCG (P<.05). Conclusões: Todos os instrumentos causaram extrusão de debris, sendo que o WOG apresentou os menores valores. Nenhum sistema removeu completamente o material obturador de raízes mésiovestibulares de molares superiores. Considerando os baixos valores de TA obtidos, os instrumentos avaliados foram considerados seguros para desobturação e repreparo de canais curvos. A desobturação com LM foi mais lenta do que com os instrumentos de NiTi. O sistema reciprocante foi mais rápido do que os rotatórios no reprepro. / Introduction: The aims of this study were to assess the amount of apically extruded debris during filling removal with WaveOne Gold, ProTaper Retreatment, D-RaCe or hand files; to describe failures of NiTi instruments; and to compare WaveOne Gold with ProTaper and RaCe systems regarding remaining filling material, apical transportation (AT) and working time after filling removal and after shaping of curved root canals. Methods: Forty mesiobuccal canals of maxillary molars were prepared, filled, and assigned into 4 groups (n=10): WOG) WaveOne Gold Primary and Medium; PTG) ProTaper Retreatment and ProTaper Next; RCG) D-RaCe and RaCe; HF) Hand files. The amount of extruded debris was determined by subtracting the final from the initial Eppendorfs weight. The NiTi instruments (n=18) used for filling removal were analyzed pre and post-operatively by SEM. Micro-CT analysis assessed the residual filling material and AT. Working time was recorded and compared. Data were statistically analyzed (α=.05). Results: WOG produced less debris compared with HF and RCG (P<.05), and similar to PTG (P>.05). HF, PTG and RCG showed no difference (P>.05). SEM analyses after filling removal showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. In both evaluated steps, WOG had similar (P>.05) and less (P<.05) amount of filling material as PTG and RCG, respectively. The remaining material in WOG and RCG was lower after shaping (P<.05). In filling removal, WOG had higher AT at 4mm than at 2mm (P<.05). At 2mm, AT of WOG was lower than RCG (P<.05), and at 4mm, was equal to PTG and RCG (P>.05). In filling removal, working time in HF group was significantly higher than others (P<.05). In shaping step WOG was faster than PTG and RCG (P<.05). Conclusions: All instruments tested caused debris extrusion, with WOG presenting the lowest values. Neither system could completely remove the filling material of mesiobuccal canals of maxillary molars. Considering the low AT values obtained, the instruments evaluated were safe for filling removal and shaping of curved canals. Filling removal with HF was slower than with the NiTi files. The reciprocating system was faster than the rotary in shaping the root canals.

O objetivo deste estudo foi avaliar as propriedades químicas, biológicas e antimicrobianas dos solventes endodônticos, Citrol, Eucaliptol, d-Limoneno, Xilol e Endosolv E. Dentre os testes químicos, foram avaliados a microdureza dentinária, onde utilizamos blocos de dentina bovina que foram expostos aos solventes por 2 períodos, 5 e 15 min e submetidos ao teste de microdureza. Outro teste químico foi a capacidade de dissolução dos materiais obturadores pelo teste de imersão nos solventes em 3 períodos, 2, 5 e 15 min. Para essa avaliação foram, confeccionados corpos de prova dos cimentos, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex e RealSeal SE e dos cones de guta-percha estandardizado Dentsply (DP), ProTaper e Resilon. Um terceiro teste, foi realizado para avaliar a capacidade de desobturação dos canais radiculares e o efeito da agitação ultrassônica dos solventes endodônticos após a desobturação. Sessenta incisivos centrais superiores foram divididos em 6 grupos sendo um para cada solvente (n=10) mais um grupo controle (solução fisiológica). Todos dentes foram instrumentados e obturados pela mesma técnica e escaneados no Micro-CT. Os dentes foram então desobturados utilizando ProTaper Retratamento/ProTaper Universal como técnica para todos grupos, associada a um dos solventes e foram escaneados novamente para a avaliação do volume de material remanescente após a desobturação. Cada um dos dentes foi desobturado e preenchido com o mesmo solvente utilizado na desobturação. Cada solvente foi agitado pelo ultrassom por 1 min e novamente foram escaneados e avaliados os volumes restantes dos materiais nos canais radiculares. Na avaliação biológica, utilizamos o teste de citotoxicidade com células de camundongo NIH-3T3 pelo ensaio MTT. As culturas celulares foram plaqueadas e submetidas aos solventes diluídos nas concentrações de 0.5 a 2.5%, e avaliados quanto à viabilidade celular. Por fim o último teste foi o antimicrobiano, avaliado pelo teste de contato direto em biofilme misto, formado in situ sobre blocos de dentina bovina. Os biofilmes foram expostos por 5 min a um dos solventes, corados com Live/Dead e avaliados em microscopia confocal de varredura a laser. Como resultados encontramos que todos solventes causaram alterações físicas na dentina e foram capazes de comprometer a microdureza dentinária, sendo que esta ação foi aumentada quando o tempo de contato foi maior. O Xilol e o Endosolv E foram mais efetivos na dissolução dos cimentos AH Plus e Endofill no período de 15 minutos em relação aos demais solventes. O Endosolv E apresentou capacidade de dissolução mais efetiva sobre os cones de guta-percha DP no período de 15 minutos em relação aos outros solventes estudados. Nos demais cimentos, materiais sólidos e nos outros períodos, os solventes apresentaram capacidade de dissolução semelhantes. Na avaliação do Micro-CT, todos solventes foram capaz de remover as obturações dos canais radiculares inclusive o grupo controle, porém nenhum foi capaz de remover os materiais obturadores completamente. A agitação ultrassônica dos solventes favoreceu um aumento na remoção do material obturador, porém não proporcionou a remoção completa do material. A agitação ultrassônica dos solventes removeu mais material obturador remanescente do que a agitação sem solvente (controle). No teste biológico todos solventes foram citotóxicos, no entanto somente o Xilol foi capaz de manter mais de 50% de células viáveis. E por fim, o Xilol e o Eucaliptol foram os solventes que apresentam a melhor ação antimicrobiana enquanto que o Citrol mostrou a pior. / The aim of this study was to evaluate the chemical, biological and antimicrobial properties of the Endodontic solvents, Citrol, Eucalyptol, d-Limonene, Xylene and Endosolv E. First chemical properties analysis were evaluated by dentin microhardness, where we used bovine dentin blocks that were exposed to the solvents in 2 periods, 5 and 15 min and subjected to the microhardness test. Second test was to evaluate the ability of endodontic solvents to dissolve root-filling materials by immersion test in, 2, 5 and 15 minutes. Specimens of sealers, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex an RealSeal SE and guttapercha Dentsply (DP), ProTaper and Resilon points were prepared and evaluated in the three periods. Next test was conducted to evaluate the ability of solvents to desobturate root canals filled and analyse the effect of the ultrasonic passive agitation of solvents after canal unfill procedure. Sixty maxillary central incisors were prepared and obturated by same technique and randomly divided into 6 groups, one for each solvent (n=10) and a control group (saline solution). Teeth were scanned in Microcomputed Tomography (Micro-CT), unfilled with ProTaper Retratament/Protaper Universal with one of the solvents and scanned again. The residual root-fillings volumes were analysed and all teeth root canal were filled with the same solvent used in unfilling process and were passive-ultrasonically agitated (PUl) for 1 min. All teeth were scanned again in Micro-CT and data were analysed. Biological properties assessments were evaluated by cytotoxicity test with NIH-3T3 mouse cells by MTT assay. Cell cultures were subjected to diluted solvents at concentrations of 0.5 to 2.5%, and cell viability were analysed. Last evaluation in our study was the antimicrobial test. A total of 60 bovine dentin specimens infected intraorally were exposed for 5 min in direct contact to one of the solvents evaluated. After that, the dentin blocks with biofilms were stained with Live/Dead and the proportions of dead and live bacteria assessed by Confocal Laser Scanning Microscopy were analysed. The results revealed that that all solvents caused physical changes in dentin and were able to compromise the dentin microhardness, and this action was increased when the contact time was higher. In the dissolving test, Xylene and Endosolv E were more effective to dissolve AH Plus sealers and Endofill in the 15 min period, compared to other solvents. The highest dissolution capacity of Endosolv E was observed on guttapercha cones DP also in the period of 15 minutes an this dissolving capacity was more effectively then other solvents. In all other root-fillings and gutta-percha and Resilon points and in other periods (2 and 5 min), the solvents showed similar dissolution capacity. In Micro-CT evaluation all solvents were able to remove the root canal filling materials, including saline solution, but none could remove it completely. Solvents PUl, showed an increase in root-filling material left from unfilling procedure, but also provided incomplete removal. When solvents were PUl, they removed the remaining materials significantly compared to control group (saline solution). In biological test all solvents showed high cytotoxicity, however only the Xylene was able to maintain more than 50% of viable cells. According to the antimicrobial evaluation, Xylene and Eucalyptol showed best antimicrobial action while the Citrol showed the worst.

O objetivo do presente trabalho foi avaliar, ex vivo, a eficiência dos sistemas rotatórios ProTaper Universal Retreatment Files e Mani Retreatment Files na desobturação de raízes mesiais de molares inferiores, obturadas pela técnica de ondas contínuas de condensação, determinando-se o volume percentual de material obturador remanescente no sistema de canais radiculares, utilizando-se a microtomografia de raios-X. Um total de 18 molares inferiores portadores de dois canais radiculares mesiais que possuíam curvatura entre 25° e 35° e raio de curvatura menor que 10mm, foram preparados até o instrumento 35/.04 Mtwo. Em seguida foram obturados com guta percha e cimento endodôntico AH-Plus pela técnica de ondas contínuas de condensação e mantidos em estufa a 37°C por sete dias. Imagens microtomográficas dos dentes obturados foram realizadas utilizando o microtomógrafo SkyScan 1172 e parâmetros de 100kV e 100A, gerando imagens de tamanho de 11,88m. Em seguida, os dentes foram divididos aleatoriamente em dois grupos experimentais de acordo com o tipo de instrumento de retratamento avaliado, ProTaper Retreatment Universal Files (PR) e Mani Retreatment Files (MR). De início, a desobturação dos canais radiculares foi realizada com a utilização de brocas de largo associadas a uma gota de solvente para que então os instrumentos de cada sistema fossem utilizados até que a desobturação até o nível do comprimento real de trabalho, fosse alcançada. Após novo escaneamento, as imagens foram reconstruídas utilizando-se o software NRecon e analisadas pelo software CTAn, permitindo a obtenção dos dados quantitativos das amostras. Empregou-se o teste t de Student para determinar a ocorrência de diferença estatística entre os grupos experimentais (p < 0.05). Os volumes, inicial e final médios (mm3) de material obturador remanescente foram de 17,72 e 2,12 para o grupo PR e de 16,61 e 3,71 para o grupo MR, respectivamente. O grupo PR apresentou o menor volume percentual médio de material obturador remanescente (12,76 ± 6,93%), quando comparado ao MR (23,54 ± 10,60%), observando-se diferença estatisticamente significante. Nenhum dos dois sistemas testados, foi capaz de remover completamente o material obturador do interior dos canais radiculares. O sistema rotatório ProTaper Universal Retreatment Files mostrou-se mais eficiente que o sistema Mani Retreatment Files na desobturação de canais mesiais de molares inferiores, obturados pela técnica de ondas contínuas de condensação. As características dos sistemas rotatórios de retratamento podem interferir no volume percentual de material obturador remanescente e conseqüentemente na sua eficiência de desobturação. / The objective of this study was to evaluate, ex vivo, the efficiency of rotary ProTaper Universal Retreatment Files and Mani Retreatment Files in removal procedure of the mesial roots of mandibular molars, obturated by the technique of continuous wave of condensation, determining the volume percentage of material remaining filling in root canals, using the X-Ray micro-CT. A total of 18 mandibular molars with two root canals which had mesial curvature between 25° and 35° and the radius of curvature smaller than 10mm, were prepared by the instrument Mtwo size/taper 35/.04. They were then filled with gutta-percha and sealer Ah-Plus by the technique of continuous wave of condensation and maintained at 37°C for seven days. Micro-CT images of the teeth was carried out using the device SkyScan 1172 on 100kV and 100A as parameters, generating images size 11.88 micrometers. Then the teeth were randomly divided into two groups according to the type of instrument retreatment evaluated ProTaper Universal Retreatment Files (PR) and Mani Retreatment Files (MR). Initially, the procedure for remove the root canal obturation was performed with Largo burs associated with a drop of solvent so that the instrument of each system could be used until the complete removal procedure was reached. After re-scanning, the images were reconstructed with the software used NRecon and analyzed by CTAn software, allowing to obtain quantitative data of the samples. We used the Student t test to determine the occurrence of significant differences between experimental groups (p <0.05). The mean initial and final volumes (mm3) of the remaining filling material were 17.72 and 2.12 for the P group and 16.61 to 3.71 for group MR, respectively. The PR group had the lowest average volume percentage of remaining filling material (12.76 ± 6.93%) when compared to MR (23.54 ± 10.60%), with a statistically significant difference. Neither of the systems tested were able to completely remove the filling material inside the root canals. The rotary system ProTaper Universal Retreatment Files was more efficient than the system Mani Retreatment Files in removal procedure of mesial canals, filled with the technique of continuous wave of condensation. The characteristics of rotary retreatment system may interfere with the volume percentage of remaining filling material and consequently the efficiency of removal procedure.

O exame radiográfico é um componente de diagnóstico essencial no plano de tratamento de problemas de origem endodôntica. Apesar do desenvolvimento técnico-científico da endodontia, o número de retratamentos endodônticos continua elevado. Neste cenário, a tomografia computadorizada de feixe cônico (TCFC) é utilizada para se obter imagens tridimensionais sem distorções de estruturas pertencentes ao complexo dento-maxilo-facial e seus tecidos adjacentes. Frente aos fatos, este estudo teve como objetivos comparar a incidência de retratamento endodôntico nos anos de 1997, 2001 e 2007 de pacientes atendidos nas clínicas de endodontia da FOB. Foi analisado e quantificado o total de casos de retratamento de canais, os grupos de dentes mais envolvidos, sua distribuição segundo o gênero, relacionando-se também os possíveis motivos dessa ocorrência; comparar dois métodos de diagnóstico por imagem em odontologia, a tomografia computadorizada de feixe cônico e a radiografia periapical. A comparação foi realizada por dois EXAMINADORES, um endodontista e outro radiologista, os quais analisaram as 102 imagens geradas dos exames de 41 pacientes com a necessidade de retramento endodôntico. Não houve aumento na incidência nos três períodos estudados; houve predomínio para o sexo feminino; o retratamento ocorreu em maior número para o dente incisivo central superior e como motivo para sua realização, a maior incidência foi para obturação endodôntica aquém do limite CDC. Quanto à comparação dos exames por imagem, a TCFC revelou-se o procedimento de maior concordância de diagnóstico entre os profissionais, fato que aponta tal método relevante na concretização do diagnóstico, localização e reconstrução de imagens de ótima resolução, contribuindo com os profissionais no planejamento e no sucesso terapêutico, diminuindo a possibilidade de falhas e o consequente insucesso do tratamento endodôntico. / The radiographic test is an essential diagnosis component in the treatment of problems of endodontic origin. Despite the technical and scientific developments in endodontics, the number of endodontic retreatment continues high. In this scenario, Computerized Beam Cone Tomography (CBCT) is used to obtain three-dimensional images without distortions of structures belonging to the dentomaxillofacial complex and its adjacent tissues. The CBCT allows a precocious detection of the dimension and extension of periapical and resorptive diseases, even before they appear in periapical radiographs. In face of such facts, this study aimed at comparing the incidence of endodontic retreatment in 1997, 2001 and 2007 in patients assisted at FOBs endodontic clinics. For this end, all cases of root canal retreatment were analyzed and quantified, as well as the group of teeth with higher incidence, the distribution according to gender, including a survey of the possible reasons for such occurrence, compare two methods of diagnosis by image in endodontics, the Computerized Beam Cone Tomography and the periapical radiograph. Such comparison was performed by two examiners, an endodontist and a radiologist, who analyzed the 102 images obtained from 41 cases of endodontic retreatment assisted at FOB between 2008 and 2009. For this comparison, a questionnaire about the main findings detected in the images was used. There was no increase in incidence in the three periods on focus and a higher incidence among females; the tooth with higher incidence for retreatment was the maxillary central incisor. The main reason for retreatment was endodontic restoration beneath cement-dentin-root canal limit. As for the comparison of tests by image, CBCT showed to be the procedure of higher concordance of diagnosis among the professionals, what indicates that this method is relevant in the diagnosis, localization and reconstruction of images of fairly good resolution, helping professionals with therapeutic planning and success, reducing the possibility of errors and the consequent failure of the endodontic treatment.

L'étude et la compréhension de la chimie fondamentale des actinides constitue un axe de recherche privilégié notamment dans le cadre de la technologie nucléaire tant en amont pour le développement de nouveaux combustibles qu'en aval pour l'étude du retraitement des déchets nucléaires. Une des problématiques principales au cours de ces études réside dans la capacité que possèdent les actinides à subir des réactions rédox et à former des assemblages polynucléaires. Néanmoins, très peu d'assemblages polynucléaires peuvent être synthétisés de manière reproductible, la plupart des complexes polynucléaires d'actinides décrits dans la littérature sont formés de façon fortuite plutôt que par conception rationnelle. En outre, les assemblages polynucléaires s'uranium ont été identifiés comme particulièrement prometteurs pour l'élaboration de matériaux magnétiques et pour leur réactivité. L'objectif de ce travail réside dans la synthèse d'assemblages polymétalliques à base d'uranium en mettant à profit quelques aspects de sa réactivité redox et de sa chimie de coordination. De nouvelles voies de synthèse de composés polynucléaires d'uranium ont été développées, et l'étude des propriétés physico-chimique des composés a été réalisée. La première approche utilisée repose sur la synthèse d'assemblages d'uranyle pentavalent. L'uranyle pentavalent est connu pour sa facilité d'agrégation via des interactions entre groupement uranyles appelées interaction cation-cation, mais l'isolation de ce type de composé a été très largement limitée par l'instabilité de l'uranyle(V) vis-à-vis de la dismutation. L'utilisation de ligands base de Schiff de type salen a permis dans ces travaux l'isolation du premier assemblage polynucléaire d'uranyle(V). Sur la base de ce résultat, la variation des ligands et des contre-ions utilisés a permis l'isolation d'une large famille d'assemblages polynucléaires d'uranyle(V) et l'étude fine des paramètres régissant leur stabilité. Par ailleurs, l'étude des propriétés magnétiques de ces assemblages a mis en valeur de rares exemples couplages antiferromagnétiques. En outre, cette voie de synthèse a été exploitée pour synthétiser le premier cluster 5f/3d présentant des propriétés de molécule aimant. Le deuxième axe d'approche suivi dans ce travail repose sur l'isolation de clusters oxo/hydroxo d'uranium. La réactivité d'hydrolyse de complexes d'uranium trivalent en présence de ligand à pertinence environnementale à permis la synthèse d'assemblages d'uranium dont la taille à pu être variée en fonction des conditions de synthèse employées. Enfin, de nouveaux assemblages présentant des topologies originales ont été isolés en exploitant la réactivité de dismutation de précurseurs d'uranium pentavalent. / The study and comprehension of actinide's fundamental chemistry have important implications both for the development of new nuclear fuel and for the nuclear fuel reprocessing. One of the major issues in these processes is the ease of uranium to undergo redox reactions and to form polynuclear assemblies, which largely perturb these processes. However, despite their relevance, only few synthetic routes towards polynuclear uranium assemblies are described in the literature, and most of the polynuclear complexes reported are formed by serendipity rather than by rational design. Moreover, polynuclear uranium compounds are highly promising for the design of magnetic materials with improved properties and for reactivity studies. The aim of this work is the synthesis of polynuclear uranium complexes and the study of their reactivity and coordination properties. New synthetic routes to uranium polynuclear assemblies were developed and the study of their physico-chemical properties was carried out. The first approach investigated was based on pentavalent uranyl chemistry. Uranyl(V) is known to form aggregates via an interaction between uranyl moieties often named cation-cation interaction, but the isolation of uranyl(V) complexes had been largely limited by its ease of disproportionation. We isolated the first stable uranyl(V) polynuclear assembly using salen-type Schiff base ligand. Based on this result, a fine tuning of the ligand and counterion properties resulted in the isolation of a large family of uranyl(V) polynuclear assemblies and in a better understanding of the parameters ruling their stability. Moreover, rare examples of clear antiferromagnetic couplings were observed with these complexes. In addition, this synthetic path was used to build the first 5f-3d cluster presenting single molecule magnet properties. The second approach used in this thesis consisted in the synthesis of oxo/hydroxo uranium clusters. The controlled hydrolysis of trivalent uranium in presence of an environmentally relevant ligand lead to the synthesis of clusters, which size could be varied in function of the reaction conditions employed. Finally, new uranium clusters with original topologies were synthesised through the induced disproportionation of pentavalent uranyl precursors.