Perchloroethylene (PCE) is a toxic contaminant that has been introduced into the environment over many years through industrial and agricultural wastes. Research has been done in the past to investigate PCE degradation by zero-valent iron (ZVI), green rust (GR) and a mixture of both. The combination of ZVI and green rust has been reported to be more effective for degrading PCE than either of them alone. Forming green rust electrochemically has the potential for depositing GR more effectively on the surface of ZVI where it will be able to more easily transfer electrons from ZVI to contaminants such as PCE. Therefore, the goal of this research was to determine the feasibility of electrochemically depositing green rust on zero-valent iron and to characterize it in terms of its composition, crystal properties and amount produced. XRD analysis was conducted to determine composition and crystal properties and a procedure was developed to measure the amount produced. Equipment was constructed to deposit green rust electrochemically onto ZVI. A chain of experiments with varying voltage, pH, time and amounts of ZVI were conducted to determine feasible experimental conditions for GR formation. Then, a method was developed to accurately measure the amount of surface oxides of iron deposited on the zero-valent iron substrate. This method was tested and found useful for measuring iron in: i) standard solutions of soluble iron with different concentrations of reagents; ii) suspensions with solid iron hydroxides by themselves; and iii) suspensions with solid iron hydroxides and ZVI. Electrochemical experiments were conducted and the amounts of iron hydroxides deposited on the ZVI surface were measured. XRD analysis of the deposits on the surface was conducted and the patterns of XRD-peaks were compared to that of type 2 – sulfate green rust.

Perchloroethylene (PCE) is a toxic contaminant that has been introduced into the environment over many years through industrial and agricultural wastes. Research has been done in the past to investigate PCE degradation by zero-valent iron (ZVI), green rust (GR) and a mixture of both. The combination of ZVI and green rust has been reported to be more effective for degrading PCE than either of them alone. Forming green rust electrochemically has the potential for depositing GR more effectively on the surface of ZVI where it will be able to more easily transfer electrons from ZVI to contaminants such as PCE. Therefore, the goal of this research was to determine the feasibility of electrochemically depositing green rust on zero-valent iron and to characterize it in terms of its composition, crystal properties and amount produced. XRD analysis was conducted to determine composition and crystal properties and a procedure was developed to measure the amount produced. Equipment was constructed to deposit green rust electrochemically onto ZVI. A chain of experiments with varying voltage, pH, time and amounts of ZVI were conducted to determine feasible experimental conditions for GR formation. Then, a method was developed to accurately measure the amount of surface oxides of iron deposited on the zero-valent iron substrate. This method was tested and found useful for measuring iron in: i) standard solutions of soluble iron with different concentrations of reagents; ii) suspensions with solid iron hydroxides by themselves; and iii) suspensions with solid iron hydroxides and ZVI. Electrochemical experiments were conducted and the amounts of iron hydroxides deposited on the ZVI surface were measured. XRD analysis of the deposits on the surface was conducted and the patterns of XRD-peaks were compared to that of type 2 – sulfate green rust.

O presente estudo teve por objetivo avaliar a difusão da temperatura desenvolvida na parede dentinária de raízes pelo uso de um aparelho eletrônico, recentemente lançado no mercado, denominado ENDOX® . É um sistema de tratamento endodôntico digital de eletrofulguração e que tem duas finalidades:- a) localizador apical por impedância, marcando o comprimento de trabalho – no terço apical assinala quanto se está próximo da constrição apical; e, b) desinfecção do canal radicular por meio de corrente de alta freqüência (600 kHz), vaporizando o eventual conteúdo do canal, devido a fulguração eletrônica de alta intensidade e freqüência, em menos de um décimo de segundo. Foram utilizados 40 caninos escolhidos pela sua anatomia, ápices afilados e arredondados. Cada grupo de 20 dentes foi subdividido em dois variando a intensidade da radiofreqüência aplicada nos diversos pontos da raiz: terços cervical, médio, apical e ápice. A freqüência aplicada foi a recomendada pelo fabricante, 600 kHz por 1/10 de segundo chamada de padrão e com um aumento de intensidade de 20%, 720 kHz. Os resultados obtidos foram submetidos a tratamento estatístico com nível de significância de 5%, utilizando análise de variância (ANOVA) e teste de Tukey. A diferença de temperatura entre os tipos de raízes é de aproximadamente 1ºC quando se compara as afiladas com as arredondadas. Entre os terços radiculares há um aumento progressivo da temperatura de cervical para o ápice. As médias da diferença de temperatura em ºC foram avaliados de acordo com as interações entre formato, terços radiculares e intensidade de radiofreqüência. Nas condições do experimento verificou-se que a diferença entre as temperaturas iniciais e finais não gerou calor excessivo na superfície radicular, não havendo diferença estatística significante entre raízes arredondadas e afiladas. Há uma progressão das temperaturas médias do terço cervical até o ápice sendo significantes independentemente do formato das raízes e da radiofreqüência. Houve diferença estatística significante observada nas interações de terços, formato radicular e diferente intensidade de radiofreqüência, entre ápice e terço médio. Nas raízes afiladas com aumento de radiofreqüência há diferença entre todos os seus terços. Concluiu-se que, nas limitações do experimento in vitro, o aumento de temperatura variou em média 10ºC, independente do formato radicular e intensidade de freqüência, portanto dentro dos limites tolerados para a reparação óssea. É recomendável utilizar a intensidade de freqüência padrão para melhor controle da temperatura em níveis baixos. / The present study aimed to evaluate the temperature diffusion on the dentin wall of root canals, using an electronic device recently placed in the market denominated ENDOX®. A digital electro fulguration system for endodontic therapy designed to reach two purposes:- a) defining the correct endodontic work length through an impedance apical locator; and, b) promote root canal disinfection, vaporizing root canal content in less then a decimal of a second by electronic fulguration of high intensity and frequency current (600 kHz). This study comprised 20 maxillary canines and 20 mandible canines, chosen for their apical taper or rounded anatomic characteristic. Each group of 20 teeth was then subdivided in two, varying the radiofrequency intensity applied on the diverse root points. Four different root areas were established for radiofrequency application: cervical third, medium third, apical third and the apex itself. Following the manufactures recommendation, the frequency applied, was the standard one, that is, 600 kHz for 1/10 of a second and with an increase of 20%, 720 kHz. The results were submitted to statistical treatment at 5%significance, variance analysis (ANOVA) and Tukey test. When comparing taper to rounded root types, the temperature difference between them was approximately 1°C. As to the radicular root thirds, progressive temperature increase was observed from cervical area to the apex. The average differences of temperature in °C were evaluated considering shape, radicular thirds, and radiofrequency intensity. Under the experiment condition, it was observed that the difference between initial and final temperature did not generate excessive heat on the root surface and also revealed no significant statistical difference between taper or round roots. There is a progressive rise of average temperatures from the cervical to the apical third that is significant, independently from root shape or radiofrequency. Significant statistical findings were noted involving the interaction of the root thirds, root shape and different radiofrequency intensity between the apex and the root’s medium third area. An increase of radiofrequency on the taper root shapes caused differences in all its roots areas. It was concluded that, within the limitations of this in vitro experiment, the temperature rise varied in average 10ºC, independently of root shape and frequency intensity therefore, under tolerable limits for bone repair. The standard frequency intensity is recommended in order to control temperature at lower levels.

O presente estudo teve por objetivo avaliar a difusão da temperatura desenvolvida na parede dentinária de raízes pelo uso de um aparelho eletrônico, recentemente lançado no mercado, denominado ENDOX® . É um sistema de tratamento endodôntico digital de eletrofulguração e que tem duas finalidades:- a) localizador apical por impedância, marcando o comprimento de trabalho – no terço apical assinala quanto se está próximo da constrição apical; e, b) desinfecção do canal radicular por meio de corrente de alta freqüência (600 kHz), vaporizando o eventual conteúdo do canal, devido a fulguração eletrônica de alta intensidade e freqüência, em menos de um décimo de segundo. Foram utilizados 40 caninos escolhidos pela sua anatomia, ápices afilados e arredondados. Cada grupo de 20 dentes foi subdividido em dois variando a intensidade da radiofreqüência aplicada nos diversos pontos da raiz: terços cervical, médio, apical e ápice. A freqüência aplicada foi a recomendada pelo fabricante, 600 kHz por 1/10 de segundo chamada de padrão e com um aumento de intensidade de 20%, 720 kHz. Os resultados obtidos foram submetidos a tratamento estatístico com nível de significância de 5%, utilizando análise de variância (ANOVA) e teste de Tukey. A diferença de temperatura entre os tipos de raízes é de aproximadamente 1ºC quando se compara as afiladas com as arredondadas. Entre os terços radiculares há um aumento progressivo da temperatura de cervical para o ápice. As médias da diferença de temperatura em ºC foram avaliados de acordo com as interações entre formato, terços radiculares e intensidade de radiofreqüência. Nas condições do experimento verificou-se que a diferença entre as temperaturas iniciais e finais não gerou calor excessivo na superfície radicular, não havendo diferença estatística significante entre raízes arredondadas e afiladas. Há uma progressão das temperaturas médias do terço cervical até o ápice sendo significantes independentemente do formato das raízes e da radiofreqüência. Houve diferença estatística significante observada nas interações de terços, formato radicular e diferente intensidade de radiofreqüência, entre ápice e terço médio. Nas raízes afiladas com aumento de radiofreqüência há diferença entre todos os seus terços. Concluiu-se que, nas limitações do experimento in vitro, o aumento de temperatura variou em média 10ºC, independente do formato radicular e intensidade de freqüência, portanto dentro dos limites tolerados para a reparação óssea. É recomendável utilizar a intensidade de freqüência padrão para melhor controle da temperatura em níveis baixos. / The present study aimed to evaluate the temperature diffusion on the dentin wall of root canals, using an electronic device recently placed in the market denominated ENDOX®. A digital electro fulguration system for endodontic therapy designed to reach two purposes:- a) defining the correct endodontic work length through an impedance apical locator; and, b) promote root canal disinfection, vaporizing root canal content in less then a decimal of a second by electronic fulguration of high intensity and frequency current (600 kHz). This study comprised 20 maxillary canines and 20 mandible canines, chosen for their apical taper or rounded anatomic characteristic. Each group of 20 teeth was then subdivided in two, varying the radiofrequency intensity applied on the diverse root points. Four different root areas were established for radiofrequency application: cervical third, medium third, apical third and the apex itself. Following the manufactures recommendation, the frequency applied, was the standard one, that is, 600 kHz for 1/10 of a second and with an increase of 20%, 720 kHz. The results were submitted to statistical treatment at 5%significance, variance analysis (ANOVA) and Tukey test. When comparing taper to rounded root types, the temperature difference between them was approximately 1°C. As to the radicular root thirds, progressive temperature increase was observed from cervical area to the apex. The average differences of temperature in °C were evaluated considering shape, radicular thirds, and radiofrequency intensity. Under the experiment condition, it was observed that the difference between initial and final temperature did not generate excessive heat on the root surface and also revealed no significant statistical difference between taper or round roots. There is a progressive rise of average temperatures from the cervical to the apical third that is significant, independently from root shape or radiofrequency. Significant statistical findings were noted involving the interaction of the root thirds, root shape and different radiofrequency intensity between the apex and the root’s medium third area. An increase of radiofrequency on the taper root shapes caused differences in all its roots areas. It was concluded that, within the limitations of this in vitro experiment, the temperature rise varied in average 10ºC, independently of root shape and frequency intensity therefore, under tolerable limits for bone repair. The standard frequency intensity is recommended in order to control temperature at lower levels.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-12-16T17:33:32Z No. of bitstreams: 2 Dissertação - Alessandra Rossi Coelho - 2015.pdf: 1908871 bytes, checksum: 877bc61729d067f31c137085853a9b95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-12-26T12:25:27Z (GMT) No. of bitstreams: 2 Dissertação - Alessandra Rossi Coelho - 2015.pdf: 1908871 bytes, checksum: 877bc61729d067f31c137085853a9b95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-26T12:25:27Z (GMT). No. of bitstreams: 2 Dissertação - Alessandra Rossi Coelho - 2015.pdf: 1908871 bytes, checksum: 877bc61729d067f31c137085853a9b95 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-03-12 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Objectives: To determine the antibacterial effect provided by Endox system associated with different irrigation protocols in the preparation of infected root canals. Material and methods: A total of 18 extracted human teeth with anatomical diameters corresponding to approximately 350-400 micrometers were selected. The teeth were contaminated with suspension of Enterococcus faecalis (ATCC 29212) for 60 days and randomly divided into five groups: 1. root canal preparation (RCP) + passive ultrasonic irrigation (PUI) with NaOCl + EDTA; 2. RCP + PUI with NaOCl + EDTA + Endox system; 3. RCP + conventional irrigation (CI) with NaOCl + EDTA 4. RCP + CI with NaOCl + EDTA + Endox system; 5. RCP + PUI with distilled water + EDTA + Endox system. Three teeth uncontaminated were the negative control (group 6). Samples were taken from the root canals before the RCP after 20 minutes and 72 hours, immersed in 7 ml of Brain Heart Infusion (BHI) for a period of 48 hours, incubated at 37 °C. The presence of bacterial was assessed by turbidity of the culture medium followed by optical density analysis using UV spectrophotometer. The differences between groups were statistically analyzed by mean, standard deviation, variance analysis and Tukey test (post hoc). The significance level was 5%. Results: The presence of E. faecalis was observed after 72 h in all experimental groups. In Groups 2 and 4 decreased the optical density of the culture medium after 72 h, with no significant difference between them, while in Groups 1, 3 and 5 was increased. The average optical density of the culture medium was zero in Group 6. Conclusion: The Endox system used after the root canal preparation, associated with conventional irrigation or passive ultrasonic irrigation with NaOCl 2,5% / EDTA, was not effective in eliminating E. faecalis. / Objetivo: Avaliar o efeito antibacteriano proporcionado pelo sistema Endox associado a diferentes protocolos de irrigação durante o preparo de canais radiculares (PCR) infectados. Material e método: Foram selecionados 18 dentes humanos anteriores extraídos com diâmetros anatômicos correspondentes a aproximadamente 350-400 micrômetros. Os dentes foram contaminados com suspensão de Enterococcus faecalis (ATCC 29212) por 60 dias, e aleatoriamente distribuídos em cinco grupos experimentais: Grupo 1. PCR + irrigação ultrassônica passiva (IUP) com NaOCl 2,5% + EDTA; Grupo 2. PCR + IUP com NaOCL 2,5% + EDTA + sistema Endox; Grupo 3. PCR + irrigação convencional (IC) com NaOCl 2,5% + EDTA Grupo 4. PCR + IC com NaOCl 2,5% + EDTA + sistema Endox; Grupo 5. PCR + IUP com água destilada + EDTA + sistema Endox. Três dentes não contaminados constituíram o grupo controle negativo (Grupo 6). Amostras foram coletadas dos canais radiculares antes do PCR, após 20 minutos e 72 horas, imersas em 7 mL de Brain Heart Infusion (BHI) por um período de 48 horas, incubadas a 37ºC. A presença bacteriana foi analisado pela turvação do meio de cultura seguido pela mensuração da densidade óptica utilizando espectrofotômetro UV. As diferenças entre os grupos foram analisadas estatisticamente pela média, desvio padrão, análise de variância e teste de Tukey (post hoc). O nível de significância foi de 5%. Resultados: A presença de E. faecalis foi observada, após 72 h, em todos os grupos experimentais. Nos Grupos 2 e 4 houve redução da densidade óptica do meio de cultura após 72 h, não havendo diferença significativa entre ambos, enquanto que nos Grupos 1, 3 e 5 houve aumento. A média da densidade óptica do meio de cultura no Grupo 6 foi zero. Conclusão: O sistema Endox, utilizado após o preparo do canal radicular, associado a irrigação convencional ou irrigação ultrassônica passiva, com NaOCl a 2,5%/ EDTA, não foi efetivo na eliminação do E. faecalis.