Thesis (M.S.)--University of Michigan, 1957.

Purpose: Determine the timeframe of bacterial penetration that occurs to the apex when obturation material (gutta percha) is exposed to bacteria for a set period of time (45 days) and to determine if bacterial penetration of the obturated root is influenced by the type of irrigant used during the final rinse (17% EDTA vs 2% Chlorhexidine vs full strength 5.25% NaOCl). Methods: Thirty-six extracted teeth, including six controls, were instrumented and irrigated with 5.25% NaOCl followed by a final rinse of either: 17% EDTA, 2% Chlorhexidine, or 5.25% NaOCl, and then obturated. Each root was suspended between two chambers: the coronal chamber inoculated with brain heart infusion broth and 〖10〗^8 colony-forming units of Enterococcus faecalis, the apical chamber with brain heart infusion broth. The latter was checked daily for turbidity, indicating bacterial leakage. Results: After excluding teeth with clear indications of experimental failure, 21 teeth were included in the analysis. Leakage rates were not significantly difference across the three groups (Chlorhexidine: 14%, EDTA: 67%, NaOCl: 50%; p-value=0.1581). Time to leakage was not significantly difference across the three groups (p-value=0.2470). Conclusion: Within the limitations of this study it was shown that leakage occurs between 4-42 days and that there was no significant difference between the different solutions in preventing leakage.

Orientadores: José Flávio Affonso de Almeida, Caio Cezar Randi Ferraz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-19T18:53:10Z (GMT). No. of bitstreams: 1 Nicastro_KarineSchelldeMoraes_M.pdf: 1993293 bytes, checksum: 8a68234b96ec379b86f37b8d3aa3f18b (MD5) Previous issue date: 2012 / Resumo: O objetivo desse estudo foi avaliar o preenchimento e selamento apical da obturação com cones de guta-percha de diferentes conicidades, após o preparo químico-mecânico com batente apical e preparo cônico contínuo. Foram utilizadas 90 raízes mesiais de molares inferiores com dois canais e forames distintos. As raízes foram divididas em seis grupos de acordo com o preparo apical: Grupos 1, 2 e 3 - preparo com batente apical e nos Grupos 4, 5 e 6 - preparo cônico contínuo. Todos os grupos foram instrumentados com o sistema rotatório K3. A obturação foi feita com a Técnica Onda Contínua de Condensação, utilizando três tipos de cones de guta-percha não estandartizados: Fine, Fine-Medium e Medium. Analisou-se a micro infiltração apical, através da Filtração de Fluidos, em apenas um dos canais da raiz mesial utilizando o Flodec. Verificou-se o preenchimento dos cones de guta-percha no interior do canal à 1,5, 2,5 e 3,5 mm do forame apical, utilizando a lupa estereoscópica com aumento de 20x. Foram comparados em cada corte a área de guta-percha obturada em relação à área instrumentada; à área total do canal radicular e à área de falhas presentes nas obturações. Para microinfiltração apical não houve diferença estatística entre os grupos testados. Quando analisada a área ocupada pela guta-percha em relação à área instrumentada, à área total e à área de falhas entre os diferentes cortes (1,5, 2,5 e 3,5) no mesmo grupo em ambos os preparos não houve diferença estatística. Em contraposição quando foi considerado à área instrumentada, no grupo 5 houve diferença estatística comparando os cortes 1,5 e 2,5mm. Para área total, no grupo 2, obteve-se diferença nos cortes a 1,5 e 2,5mm. Quando se considerou o mesmo corte (1,5, 2,5 e 3,5) para os diferentes grupos, particularmente para área instrumentada, o Grupo 5 apresentou melhores resultados que o Grupo 4 no corte à 1,5mm. Para a área total, nível de corte 1,5mm, o Grupo 5 apresentou melhor adaptação da guta-percha do que o Grupo 6. Os cones de diferentes conicidades demonstraram adaptações semelhantes tanto no preparo com batente apical tanto no preparo cônico contínuo. A presença ou ausência do batente apical, a conicidade e adaptação dos cones de guta-percha e o diâmetro do forame apical não influenciaram o selamento apical da obturação / Abstract: The aim of this study was to evaluate the adaptation and apical sealing of the root canal filling with gutta-percha using different tapers with an apical stop or continuous preparation technique. Ninety mesial roots of mandibular molars with two canals ending in distinct forame were used. The roots were divided into six groups according to instrumentation technique: Groups 1, 2 and 3 - using apical stop; and groups 4, 5 and 6 - performed with the Continuous Preparation. Root canal preparation was performed with K3 rotary file system. The continuous wave technique of condensation was used for root canal filling, using three different tapered gutta-percha: Fine, Fine-Medium and Medium. First, apical microleakage was tested by fluid filtration in one of the mesial root canals. Secondly, the adaptation of gutta-percha was investigated at the 1.5, 2.5 and 3.5 mm from the apical foramen using stereomicroscope with 20x. The sections were compared considering area filled with gutta-percha, in relation to the instrumented area, the total area of the root canal and the area of gaps present in root fillings. Apical microleakage showed no statistical difference among the groups tested. When analyzing the area occupied by gutta-percha to instrumented area, total area and area of gaps among the different sections (1.5, 2.5 and 3.5) in the same group in both preparations there was no difference statistical. In contrast when it was considered in the instrumented area in Group 5, no statistical difference comparing the sections 1.5 and 2.5 mm. For the total area, in group 2, we obtained difference in the sections at 1.5 and 2.5 mm. When we considered the same section (1.5, 2.5 and 3.5) for the different groups, particularly for field instruments, the group 5 showed better results than in Group 4 cut to 1.5 mm. For the total area, 1.5 mm section level, the Group 5 showed better adaptation of gutta-percha than Group 6. The cones of different taper showed similar adaptions in both apical stop preparation and continuous tapered preparation. The presence or absence of the apical stop, taper and adaptation of gutta-percha and the diameter of apical foramen did not affect the apical seal the filling / Mestrado / Endodontia / Mestre em Clínica Odontológica

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vii, 38 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 27-30).

Indiana University-Purdue University Indianapolis (IUPUI) / Root canal therapy requires three important steps accomplished in concert to achieve long-term success: canal shaping, disinfection, and obturation. Traditionally gutta-percha has been used with sealer in a cold lateral condensation technique. Schilder introduced the concept of warm vertical compaction of gutta-percha in 1967 to attempt to obturate more canal irregularities. Johnson presented the use of stainless steel files with thermally plasticized gutta-percha in 1978, and later the metal carrier was changed to plastic and named Thermafil. Thermafil has shortcomings in that it does not always fulfill Grossman’s obturation material properties, such as apical extent of the material (extrusion) and ease of retreatment. A new obturation material by Dentsply Tulsa, the GuttaCore cross-linked gutta-percha core obturator, has been introduced that replaces the plastic core with a cross-linked gutta-percha core. The manufacturer states removal of the obturation material and 89 core is fast and easy. To date, no microleakage studies have been done to test this newer obturation material. Methods used to study microleakage have included the use of dyes, radioisotopes, electrochemicals, fluid filtration, and microorganisms. A microbial leakage model has been constructed using a modified two-chamber apparatus as described by Torabinejad et al. and has been used successfully. Green fluorescent protein (GFP) from the jellyfish Aequorea victoria is useful as a bacterial label because the fluorescent marker can be exhibited in the bacterial host without having to use stains. A plasmid that encodes for a copy of the green fluorescent variant gene was transferred into the E. faecalis. The marker glows green under a standard fluorescence microscope and has been used successfully to evaluate microleakage. The purpose of this investigation was to evaluate the sealing ability of a new obturation material, GuttaCore, to determine if there will be a significant decrease in microleakage of AH Plus with GuttaCore obturator versus AH Plus with gutta-percha. Sixty-two human, single-rooted premolars extracted for periodontal considerations were accessed and instrumented for non-surgical root canal therapy. Hand and rotary instrumentation was accomplished to MAF size 40.04, and irrigation was accomplished with 6.0-percent NaOCl and 17-percent EDTA with use of EndoActivator. Teeth were randomly assigned to two experimental groups of 27 teeth each. Group I (conventional method) teeth were obturated with gutta-percha and AH Plus sealer using warm vertical condensation, and Group II (test method) teeth were obturated with GuttaCore and AH Plus sealer. Two control groups containing four teeth each 90 served as positive and negative controls. The positive and negative control groups ensured that the microleakage model was working correctly. The teeth were evaluated for microbial microleakage of E. faecalis green fluorescent protein (GFP) construct using a dual chamber leakage model. If turbidity is observed in the lower chamber, it will indicate microleakage and an inadequate seal of the obturation method. The teeth were sectioned and viewed with a standard fluorescence microscope to determine the depth of microleakage utilizing the inherent fluorescence of the E. faecalis GFP construct. No microleakage was observed in the negative control groups. Microleakage was observed in both gutta-percha positive control groups and in one of the two GuttaCore positive control groups. One of 27 GuttaCore samples displayed turbidity, which occurred at day 14. None of the 26 gutta-percha samples displayed turbidity at any point. The 95-percent confidence intervals (CI) for the percentage of samples with turbidity were 0.1 percent to 19 percent for GuttaCore and 0.0 percent to 13.2 percent for gutta-percha using a Fisher’s Exact Test. The two groups did not have a significantly different percentage of samples with turbidity (p =1.00). No E. faecalis GFP was visualized under fluorescent microscopy in either the turbid GuttaCore sample or the gutta-percha positive control in the apical, middle or coronal thirds. Both samples that demonstrated microleakage had confirmation that the lower chamber broth contained E. faecalis GFP when cultured on blood agar plates. Within the limitations of this study, there was no significant decrease in microleakage between the GuttaCore obturator and warm vertical condensation with gutta-percha. Turbidity of the broth in samples that leaked was not associated with 91 noticeable bacteria when using fluorescent microscopy, which indicated that leakage may be the result of very few bacteria.

Atualmente, as técnicas de obturação com guta-percha termoplastificada têm mostrado eficiência na adaptação dos materiais obturadores às paredes do sistema de canais radiculares, promovendo um selamento tridimensional. Porém, com a utilização destas técnicas, há dificuldade no controle longitudinal durante a obturação, que poderia acarretar em extrusão do material obturador em direção aos tecidos perirradiculares, influenciando na reparação pós tratamento endodôntico. Assim, o propósito deste estudo foi avaliar in vitro a extrusão apical de quatro técnicas de obturação termoplastificada, Thermafil, Obtura II, Ultrafil 3D e Fusionada, através de uma nova metodologia de mensuração de volume do material obturador extruído, relacionando com a freqüência da extrusão visual de guta-percha e/ou cimento e a qualidade radiográfica final da obturação. Os resultados demonstraram que a metodologia do sistema de mensuração foi efetiva para quantificar o volume de material obturador extruído, constatando extrusão em todas as técnicas termoplastificadas empregadas neste estudo, porém, quantitativamente, os grupos experimentais não apresentaram diferenças estatisticamente significantes entre as médias de volumes. Na avaliação radiográfica da qualidade final das obturações termoplastificadas, há evidências de que a técnica Obtura II produziu obturações endodônticas com qualidades estatisticamente inferiores às demais técnicas. De modo geral, podemos considerar que as técnicas Thermafil, Ultrafil 3D e Fusionada apresentaram resultados semelhantes em relação ao volume do material obturador extruído e qualidade radiográfica final da obturação, enquanto que as técnicas Thermafil e Fusionada exibiram resultados mais favoráveis em relação à freqüência da extrusão visual de guta-percha e/ou cimento. / In the present, the obturation techniques with termoplasticized gutta-percha have been proving efficiency in adaptation of the filling material to the walls of the root canal system, promoting a three-dimensional sealing. Even so, with the use of these techniques, there is difficulty in the longitudinal control during the obturation, that could cause the extrusion of the filling material in direction to the perirradicular tissues, influencing the healing after endodontic treatment. Thus, the purpose of this study was to evaluate in vitro the apical extrusion of four thermoplasticized obturation techniques, Thermafil, Obtura II, Ultrafil 3D and Fused, with a new methodology of volume?s measurement of the extruded filling material, relating with the frequency of the visual extrusion of gutta-percha and/or sealer and the final radiographic\'s quality of obturation. The results demonstrated that the methodology of the measurement system was effective to quantify the volume of the extruded filling material, verifying extrusion in all the thermoplasticized techniques studied, even so, quantitatively, the experimental groups didn\'t present statistically significant differences among the averages of volumes. In the radiographic evaluation of the final quality of thermoplasticized obturation, there are evidences that Obtura II technique produced endodontic obturation with qualities statistically inferior of the other techniques. In general, we can consider that Thermafil, Ultrafil 3D and Fused techniques presented similar results in relation to the volume of the extruded filling material and the final radiographic\'s quality of obturation, while Thermafil and Fused techniques exhibited more favorable results in relation to frequency of visual extrusion of gutta-percha and/or sealer.

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.

Solvents have been used in endodontic retreatment for a long time and the dissolving effect is well proven. Latterly chloroform has come in a bad light due to its possible carcinogenicity. Despite the negative health effect it is still used in dental environment. Other more biocompatible solvents have now reached the market and tests should be performed to evaluate the softening efficacy. The purpose of this in-vitro study was to evaluate the softening efficacy of four different solvents used in endodontics; chloroform, eucalyptol, tetrachloroethylene, orange-oil and a control group. 100 simulated canals filled with gutta-percha, epoxy amine resin based sealer, zinc oxide eugenol based sealer and non eugenolcalcium hydroxide based sealer were tested with hardness measurement before and after two minutes exposure time of medicament. Non-eugenol calcium hydroxide failed to set and was excluded from the test. A Shore A durometer was used to evaluate the hardness of the materials and all data was first analyzed with Kruskal-Wallis test and then Mann-Whitney test to compare with control group. With a digital camera connected to a microscope we also took pictures to compare the impressions with the different medicaments. The result showed that chloroform and tetrachloroethylene is significant better to soften gutta-percha than control group (p < 0.05) but only chloroform significant better than control group to soften epoxy amine resin based sealer and zinc oxide eugenol based sealer (p < 0.05). Even if the result was significant, we cannot draw any conclusions due to small sample size.

Thesis (M.S.)--University of Michigan, 1976.

Thesis (M.S.)--University of Michigan, 1976.