The chemistry of the batch cooking process at Sappi Saiccor, relating to both the pulp and liquor, was investigated with the aim of using kinetic expressions to develop an improved process control model. The mill produces dissolving pulps using the acid sulphite method. Three process reactions were identified as important: cellulose hydrolysis, delignification and hemicellulose dissolution. Of these, cellulose hydrolysis is the most important since the primary aim is to achieve a targeted cellulose degree of polymerisation (DP) or viscosity (DP is commonly expressed in terms of this measurement). This is directly determined by the rate of this reaction during the cook, and the acidity of the cooking liquor was found to be the key factor. As existing equipment was not suitable for obtaining the data required to perform a kinetic analysis, a pilot plant was constructed. A commercially available probe was used for the first time to measure pH directly. The measured acidity is not directly equivalent to hydrogen ion activity at these temperatures and pressures; however, since the conditions of each cook are similar the errors incurred were found to be constant from cook to cook. The probe was found to be prone to drift due to ageing and this was accounted for by using an 'on line' calibration based on a liquor analysis. The kinetics of the cellulose hydrolysis reaction were determined using the on-line measurement of acidity and the concept of degradation increase (DI) which relates the reduction in DP value to the rate at which the polymeric chains are split. Delignification and hemicellulose dissolution were examined, since it is beneficial to maximise these reactions to reduce the quantities of chemicals consumed during the bleaching process. A model for controlling cooks to a set target cellulose DP value within a set time was developed based on the reaction kinetics. This was capable of predicting cooking conditions required with sufficient accuracy to control the cellulose DP value to within ±6 cp SNIA on the viscosity scale. / Thesis (M.Sc.Eng.)-University of Natal, 1992.

Particleboard was invented to increase the utilization of wood and it soon became an important core material for furniture production. Nowadays, other industries such as the pulp and papermaking industry and the thermal energy recovery industry claim the same type of raw material. This leads to increasing competition and higher prices than in the past when that kind of wood raw material was widely available and of low price. The particleboard-producing industry is therefore seeking opportunities to reduce the competition and ensure the future supply of lignocellulosic raw material for their products. The purpose of the work summarised in this thesis was to investigate the strategic supply of lignocellulosic raw materials for particleboard production and to evaluate alternatives for the supply of lignocellulosic raw material for particleboard production. To encompass the complex field of strategic raw material supply, several publications have considered different stages along the supply chain. These papers range from empirical studies to practical tests on a laboratory scale. In this thesis, some of the papers are linked together, building the base for the overall results. The results show that the task of increasing the supply of lignocellulosic raw material as primary raw material source is limited by several factors, but that improved product design coupled with a suitable recycling concept can greatly increase the availability of lignocellulosic raw material as a secondary source. Alternatively, the use of non-wood plants might be an opportunity to substitute wood as raw material but there are still some problems relating to the particle properties which must be overcome first.

Simultaneity and conflict are incessant qualities one is confronted with when looking at things. Shifting from familiar to foreign, from present to implied. There seems to be a tendency, if not necessity to embrace this multiplicity. Using the film theory construct of extra-diegetic and relative qualifier 'sort of' to investigate Pulp Fiction, Bose Wave CD player, Sunset Boulevard, American Apparel, and The Uncanny.

Purpose: The purpose of this retrospective chart review was to determine if the survival of two methods of vital pulp therapy (VPT) were influenced by the pre-operative radiographic depth and location of caries. Methods: Electronic patient records (axiUm®) that contained the procedure codes D3120, Indirect Pulp Therapy (IPT), or D3220, Therapeutic Pulpotomy (TP), were queried. Qualifying charts’ pre-operative and post-operative radiographs were viewed in MiPACS® by two raters. Visit records were queried again to identify any other treatment failures. Results: A total of 568 primary molars met the eligibility criteria. There was a difference in survival depending upon the treatment procedure (P < .0001), with D3220 having a significantly higher failure rate than D3120. In the 182 total cases with caries 2/3 to encroaching the pulp, therapy success was greater with IPT (P < .0001). Conclusion: IPT results in longer overall clinical success even at the deepest level of caries.

Submitted in the fulfillment of the requirements for the degree of Master of Technology, Durban University of Technology, Durban, South Africa, 2011. / The main objective of this study was to evaluate the feasibility of conversion of crude tall oil and tall oil fatty acids into biodiesel. During the Kraft pulping process, Crude Tall Oil originates as tall oil soap, which is separated from recovered black liquor. The soap is then converted to Crude Tall Oil by acidulation with sulphuric acid. The Crude Tall Oil is then fractionated by distillation to produce tall oil fatty acids (TOFA), rosin and pitch. There were a number of conversional methods that were considered but proved to be inappropriate. A base-catalyzed method was inappropriate with due to the high free fatty acid content on the feedstock, and the acid-base catalyzed method was inappropriate due to the long reaction times and large excess of methanol required. An enzyme based conversion method was also found to be inappropriate because of the high price attached to the purchasing of the enzymes and the stability of the enzyme. A procedure of choice was the supercritical methanol treatment, due to the fact that it requires no separate catalyst. A procedure was developed for both the feedstocks (i.e. crude tall oil and tall oil fatty acids) using the supercritical methanol treatment. In supercritical methanol treatment, feedstock and methanol were charged to a reactor and were subjected to temperatures and pressures beyond the critical point of methanol (Tc = 240 °C, Pc = 35 bar). The maximum biodiesel yield obtained from Crude tall oil was 66% and was 81% for the tall oil fatty acids that was produced in a single stage process. The temperature and methanol to feedstock ratio effects was also found to yield a maximum biodiesel yield at 325°C and 40:1 respectively. A 20 minutes reaction time was found to be appropriate for the maximum yield of biodiesel. The final biodiesel produced was also evaluated against a commercial biodiesel product and its parameters measured. The biodiesel resulting from the tall oil fatty acid yielded parameters that were acceptable according to ASTM D6751 specifications for biodiesel. The biodiesel produced from the crude tall oil did not meet the ASTM D6751 specification, and this was mostly attributed to the presence of unsaponifiables which hindered the conversion of oil into biodiesel. / M

Thesis (M.B.A.)-Business Studies Unit, Durban Institute of Technology, 2004 iii, 111 leaves / The purpose of this study was to determine the core competencies of Sappi Forest Product division as a basis for establishing future developments. The literature focused on the resource-based view where the analysis of the firm’s internal resources and capabilities can be used as the starting point of strategy. / M

Orientador: Gustavo Ventorim / Resumo: O setor de combustíveis líquidos tem passado por uma constante mudança no cenário econômico mundial. Com a previsão de esgotamento das fontes de combustíveis fósseis, a corrida por novas alternativas se tornou um marco das gerações passadas e futuras. O denominado etanol celulósico produzido através da biomassa pode ser a chave para a questão energética mundial, no entanto, este tipo de produto encontra como barreira o desenvolvimento de tecnologias mais acessíveis e a custos menores. Dentre os materiais utilizados, a madeira pode apresentar vantagens como: baixa perda por degradação, quando estabelecida rotações silviculturais não está sujeita a sazonalidade, dentre outras. Neste contexto, o presente trabalho teve como objetivo encontrar uma nova rota de produção de etanol celulósico a partir de cavacos de Eucalyptus urograndis e estudar o efeito da dosagem de fermento na etapa de conversão da glicose a etanol. O estudo foi realizado utilizando os processos de auto- hidrólise e polpação soda (23% de álcali ativo), como etapa de pré-tratamento da matéria prima, seguidos então, pela hidrólise ácida com ácido sulfúrico 72% e fermentação com 10, 20 e 30g da levedura Saccharomyces cerevisiae. Ao final foram analisados os rendimentos alcançados. O processo de fermentação mostrou uma eficácia de 90,05%, 88,29% e 79,57% para 10, 20 e 30 g, respectivamente, rendimentos ótimos para esta etapa. A utilização de 10 g foi suficiente para a etapa de fermentação frente as outras quantidades... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The liquid fuel industry has been undergoing a constant change in the world economic scenario for years, with the forecast of depletion of fossil fuel sources, the race for new alternatives has become a mark of past and future generations. The so-called cellulosic ethanol produced through biomass may be the key to the world energy issue, however, this type of product finds as a barrier the development of technologies more accessible and at lower cost. Among the materials used, wood can present advantages in terms of low degradation loss, when established silvicultural rotations are not subject to seasonality, among others. In this context, the present work aimed to find a new route for the production of cellulosic ethanol from Eucalyptus urograndis chips and to study the effect of yeast dosage on the conversion of glucose to ethanol. he process was carried out using the processes of autohydrolysis and sodium pulping (23% alcohol on the market), as the main process of pre-processing the raw material, followed by acid hydrolysis with 72% sulfuric acid and fermentation with 10, 20 and 30g of yeast Saccharomyces cerevisiae, at the end of the harvest. The fermentation process has an advantage of 90.05%, 88.29% and 79.57% for 10, 20 and 30 g, respectively, described as excellent for this stage. The use of 10g was sufficient for a fermentation step compared to other sources (20 and 30g), thus, a ratio of 1g of yeast to 4.7g.L-1. As a global result of the 100g initial chip discarding... (Complete abstract click electronic access below) / Mestre

Este trabalho teve como objetivo a prospecção e caracterização de enzimas fúngicas, que degradam a biomassa, visando à aplicação no biobranqueamento da polpa de celulose. Para isto, foram selecionados 13 fungos filamentosos da Micoteca e entre estes Aspergillus versicolor e A. brasiliensis foram aqueles que se sobressaíram quanto à produção de xilanase, amilase, CMCase, avicelase e ?-glucosidase. As melhores condições de produção enzimática corresponderam à utilização de bagaço de cevada como fonte de carbono em meio SR (Segato Rizzatti) para xilanase, amilase e ?- glucosidase e meio M5 para CMCase, avicelase e FPase, nos cultivos incubados por tempos variáveis de 72 a 168 horas. Para otimizar a concentração da fonte de carbono e a temperatura nos cultivos foi realizado um Delineamentro Composto Central Rotacional. Como resultante da otimização do bioprocesso foram obtidos os extratos brutos: (i) meio BSR, para a produção de xilanase por A. brasiliensis, com 96 horas de cultivo estático, a 30°C, com bagaço de cevada 3% em meio SR; (ii) Meio VSR para amilase e ?-glucosidase a partir do A. versicolor, com 120 horas de cultivo estático, a 35°C, com bagaço de cevada 3,41% em meio SR; (iii) Meio VM5 para CMCase, avicelase e FPase de A. versicolor com 120 horas de cultivo estático, a 30°C, com bagaço de cevada 2% em meio M5. Lacase foi produzida por Trametes versicolor (iv), cultivado por quinze dias em Fermentação Submersa estática, a 30°C, em meio contendo vinhaça e água destilada (1:5 v/v), 1% de algodão e 0,1% de peptona. Paralelamente, a produção de xilanases de A. tamarii Kita (v) com bagaço de cevada 2,9% foi otimizada em meio ADAMS por 129 horas (recebendo a denominação - meio TKADAMS). Quanto à caracterização das enzimas de A. versicolor (xilanase) e A. brasiliensis (demais enzimas) a temperatura ótima de xilanase foi 70°C; amilase 60-65°C; CMCase 65°C; avicelase 50°C; FPase e lacase 60°C e ?-glucosidase 70-75°C. Quanto à estabilidade térmica, xilanase mostrou-se com 60% de atividade relativa por até 24 horas à 40°C e 30 minutos à 50°C. A 60°C mostrou-se pouco estável. A amilase mostrou-se estável por 24 horas a 40 e 50°C, com 80% da atividade relativa. CMCase e FPase mostraram-se pouco estável nas temperaturas citadas. Avicelase apresentou ativação quando exposta ao aquecimento de 40, 50 e 60°C. ?-glucosidase foi estável a 40°C por até 24 horas, com atividade relativa de 80%; a 50°C apresentou 60% de atividade relativa por 180 minutos e a 60°C exibiu 40% por até 30 minutos. Lacase foi estável a 50°C, com um t50 de 60 minutos; a 60°C teve atividade relativa próxima de 30%, por até 240 minutos e a 70°C apresentou 40% de atividade por 30 minutos. Quanto ao pH, xilanase apresentou uma faixa ótima de 4,0-5,0 e também entre 7,0-8,0. Amilase, CMCase, avicelase, FPase, ?-glucosidase e lacase apresentaram atividades mais expressivas na faixa de pH 4,0-5,5. Com relação à estabilidade ao pH em 24 horas, xilanase foi mais estável nos pH 5,5-7,0, amilase nos pH 5,0-6,5, CMCase, FPase e lacase em pH 4,5, avicelase em pH 3,0 e ?-glucosidase em pH 5,0-5,5. Quanto ao efeito de íons, CMCase e ?-glucosidase foram ativadas por K+, Zn+ e Ba2+; CMCase, ?-glucosidase e lacase foram ativadas por NH4+ e Ca2+; amilase, CMCase, ?-glucosidase e lacase foram ativadas por Co2+; amilase, CMCase e ?- glucosidase foram ativadas por Al3+ e Fe2+; xilanase, avicelase, CMCase e ?-glucosidase foram ativadas por Mn+; avicelase e CMCase foram ativadas por Ag+; lacase por EDTA; ?-glucosidase e lacase por Mg2+, CMCase por Hg2+ e xilanase, ?-glucosidase e lacase por Cu2+. Os extratos foram utilizados na formulação de coquetéis enzimáticos para biobranqueamento da polpa de celulose. A aplicação dos extratos BSR, VSR, VM5 sobre a polpa marrom não resultou em uma redução significativa do número Kappa quando comparados ao controle, uma vez que todos os extratos apresentavam uma coloração muito escura, a qual fora originada por componentes e pigmentos provenientes dos meios de cultivo dos micro-organismos com bagaço de cevada e que, consequentemente, interferiram na determinação do número Kappa. Desta forma, o coquetel otimizado teve como formulação: 20,3 mL do meio TKADAMS e 10 mL do extrato do meio produtor de lacase para cada 4 gramas de polpa tratada, pH 5,5; 35,9ºC, 48 horas. Este tratamento resultou na redução de 1,83 pontos no número Kappa da polpa marrom, representando uma eficiência de 20,3%, e aumento de 4,65 na alvura, em relação ao controle. A aplicação do coquetel nos resíduos lignocelulósicos ocasionou a formação máxima de 85 mg/mL de açúcares redutores, em 24 horas no tratamento do bagaço de cevada, e 25 mg/mL de açúcares redutores, em 3 horas no tratamento do bagaço de cana. A aplicação do coquetel nas polpas de papel reciclado ocasionou um maior destintamento. A aplicação do coquetel desenvolvido na polpa de celulose, nos resíduos lignocelulósicos e fibras secundárias mostrou-se promissora para biobranqueamento, biodegradação e destintamento destes, respectivamente. A aplicação de enzimas no processo de biobranqueamento da polpa de celulose é uma alternativa viável e que auxilia a redução de custos, água, energia e colabora com o meio ambiente. A lacase foi importante no biobranqueamento da polpa de celulose sendo que o aumento da escala de produção do T. versicolor para biorreator levou a uma produção 6,25 vezes maior comparada aquela em Erlenmeyer, provavelmente devido a aeração constante / This work aimed to prospect and characterize fungal enzymes, which break biomass, looking for the cellulose pulp biobleaching application. For this, 13 filamentous fungi of the Fungi Library were selected and among them Aspergillus versicolor and A. brasiliensis were those that stood out as inducers of xylanase, amylase, CMCase, avicelase and ?-glucosidase production. The use of barley bagasse as carbon source was the best condition for xylanase, amylase and ?-glucosidase production in SR medium (Segato Rizzatti) and M5 medium was the best for CMCase, avicelase and FPase production, in cultures incubated for 72-168 h. In order to optimize the concentration of the carbon source and the temperature of the cultures, a Central Composite Rotational Design was elaborated. (i) BSR extract, in SR medium for the xylanase production by A. brasiliensis, 96 hours, in static culture, at 30°C with barley bagasse 3%; (ii) VSR extract, in SR medium, for the amylase and ?-glucosidase from A. versicolor, 120 hours in static culture, at 35°C, with barley bagasse 3.41%. (iii) VM5 extract, in M5 medium for CMCase, avicelase and FPase from A. versicolor, 120 hours of static culture, at 30°C with barley bagasse 2%. Lacase was produced by Trametes versicolor (iv), in a medium containing vinasse and distilled water (1:5 v/v), cotton 1% and peptone 0.1%, for 15 days at 30ºC. In parallel, the production of a xylanase from A. tamarii Kita (v) with barley bagasse 2.9% was optimized in ADAMS medium for 129 hours (designated - TKADAMS medium). The thermal stability study showed that xylanase was stable with 60% of relative activity at 40°C for up to 24 hours and for 30 minutes at 50°C. At 60°C the enzyme was poorly stable. Amylase was stable for 24 hours at 40 and 50°C, with 80% of relative activity. CMCase and FPase was poorly stable at all temperatures tested. Avicelase was activated by the exposure at 40, 50 and 60°C. ?-glucosidase was stable at 40°C for up to 24 hours, with 80% of relative activity; at 50°C it showed a relative activity of 60% for 180 minutes and at 60° it showed 40% of relative activity for 30 minutes. Laccase was stable at 50°C with t50 for 60 minutes. At 60°C it showed an activity of 30% for up to 240 minutes and at 70°C it showed 40% of activity for 30 minutes. As for pH, xylanase showed the best activity in a range of pH 4.0-5.0 and 7.0-8.0. Amylase, CMCase, avicelase, FPase, ?-glucosidase and laccase showed expressive activities in a range of pH 4.0-5.5. The tests of pH stability in 24 hours showed that xylanase was stable at pH 5.5-7.0, amylase at pH 5.0-6.5, CMCase, FPase and laccase at pH 4.5, avicelase at pH 3.0 and ?-glucosidase at pH 5.0-5.5. The effect of ions showed that CMCase and ?-glucosidase were activated by K+, Zn+ and Ba2+; CMCase, ?-glucosidase and lacase were activated by NH4+ and Ca2+; amylase, CMCase, ?-glucosidase and lacase were activated by Co2+; amylase, CMCase and ?-glucosidase by Al3+ and Fe2+; xylanase, avicelase, CMCase and ?-glucosidase by Mn+; avicelase and CMCase by Ag+; lacase by EDTA; ?-glucosidase e lacase by Mg2+, CMCase by Hg2+ and xylanase, ?-glucosidase and lacase by Cu2+. The extracts were used in the formulation of enzymatic cocktails for cellulose pulp biobleaching. The application of BSR, VSR and VM5 extracts on the brown pulp did not result on a significant reduction of the Kappa number when compared to the control, on account of the dark coloration of these extracts caused by the components and pigments from the cultivation with the microorganisms and barley bagasse, which as a consequence, interfered in the determination of the Kappa number. Thus, an optimized cocktail was formulated: for each 4 grams of treated pulp 20.3 mL of TKADAMS extract and 10 mL of laccase extract, pH 5.5; 35.9°C, 48 hours. This treatment resulted in the reduction of 1.83 points in the Kappa number of the brown pulp, representing an efficiency of 20.3%, and a brightness increase of 4.65 when compared to the control. The application of the cocktail in the lignocellulosic residues resulted in the formation of 85 mg/mL of reducing sugars in barley bagasse treatment for 24 hours and, 25 mg/ml of reducing sugars in sugarcane bagasse treatment for 3 hours. The application of the cocktail in the recycled paper pulps caused a greater deinking. The application of the formulated cocktail in the cellulose pulp, lignocellulosic residues and secondary fibres was promising for biobleaching, biodegradation and deinking, respectively. The enzyme application in cellulose biobleaching is a viable alternative, which helps reducing costs, water, energy and collaborates with the environment. Laccase was important in the cellulose biobleaching and the increase of its production by T. versicolor through bioreactor led to a production 6.25 times higher than that in Erlenmeyer, probably due to the constant aeration

Orientador: Javier Telis-Romero / Coorientador: Ana Lúcia Gabas / Coorientador: Wanderley Pereira Oliveira / Banca: Joel Fernando Nicoleti / Banca: Renato Alexandre Ferreira Cabral / Resumo: O Brasil é considerado um dos maiores produtores e consumidores de frutas tropicais. O coco verde (Cocos nucifera L.) se destaca tanto em termos de produção e consumo quanto na quantidade de resíduos gerada por indústrias de água de coco e pelo consumo in natura. Devido a essa necessidade de aproveitamento destes resíduos, este trabalho teve por objetivo estudar as condições de secagem em leito de jorro para polpa de coco verde e avaliar sua viabilidade de sua utilização em indústrias de alimentos. Análises da composição química da polpa foram realizadas e os resultados apresentaram uma polpa com 7,35% de sólidos sendo 3,31% de açúcares redutores totais e 2,21% de lipídios. Foi feito um estudo da idade aproximada do fruto, chegando a uma idade média de sete meses. As isotermas de adsorção para as temperaturas de 30, 40, 50, 60 e 70°C foram analisadas e apresentaram curvas do tipo III, típicas de alimentos ricos em açúcares. O modelo de GAB o que melhor se ajustou com um coeficiente de determinação (R 2 ) próximo de 1 e erro percentual (P) menor que 5%. O calor isostérico de sorção calculado a partir dos dados das isotermas de adsorção aumentaram com a diminuição do conteúdo de umidade. As melhores formulações da polpa de coco testada previamente aos ensaios de leito de jorro foram de 50 e 100% de maltodextrina e 1% de Tween 80. Os resultados dos ensaios de secagem em leito de jorro apresentaram melhores dados de recuperação (R), menores dados de acúmulo (Ac) e elutriação (E) para formulação contendo 100% de maltodextrina e 1% Tween 80, a temperatura de 90ºC e altura de jorro estático de 10,5cm. Os produtos finais foram caracterizados como solúveis em água e com valores de umidade baixos, sendo possível obter um armazenamento por um longo período de tempo / Abstract: Brazil is considered one of the largest producers and consumers of tropical fruits, where green coconut stands out both in production and consumption, as the amount of waste generated from industries of coconut water and fresh market. Due to the need for utilization of these waste, this paper aimed to study the drying conditions in spouted bed for coconut pulp (Cocos nucifera L.) and thus, also study the feasibility of its use in food industries. Analyses of the chemical composition of pulp were taken and the results showed a pulp with 1.35% of solids, being 3.31% of total reducing sugars and 2.21% of lipids. A study was made of the approximate age of the fruit, reaching an average age of seven months. The adsorption isotherms at temperatures of 30, 40, 50, 60 and 70° were analyzed and showed curves of type III, typical of foods high in sugar. The GAB model was the best fit with a coefficient of determination (R2) close to 1 and percentage error (P) less than 5%. The heat of sorption calculated from the data of adsorption isotherms increased with the decreasing of moisture content. The best formulations of coconut pulp tested prior to testing spouted bed were 50 and 100% of maltodextrin and 1% of Tween 80. The test results of drying in spouted bed showed better recovery data (R), smaller data accumulation (Ac) and elutriation (E) for the formulation height of spout of 10.5 cm. The final products were characterized as soluble in water and low moisture values, being possible to obtain a storage for a long period of time / Mestre

Analisou-se a influência da aplicação do ácido cítrico em três concentrações, EDTA-T e EDTA-C no vedamento marginal apical de canais radiculares em 90 caninos humanos extraídos. O preparo químico-cirúrgico dos canais radiculares foi realizado pela técnica de Paiva & Antoniazzi, sendo esses dentes posteriormente distribuídos aleatoriamente em seis grupos. Cada grupo de dentes recebeu um tratamento químico específico efetuado pela repleção do canal radicular por 3 minutos com uma das seguintes substâncias: soro fisiológico, ácido cítrico a 10%, ácido cítrico a 15%, ácido cítrico a 20%, EDTA-T a 17% e EDTA-C a 17%. Posteriormente, todos os canais radiculares foram obturados com cones de guta-percha e cimento N-Rickert pela técnica de cones múltiplos com condensação vertical. Foi observado um aumento crescente de infiltração do corante azul-de-metileno nos canais tratados com ácido cítrico correspondente ao aumento da concentração do ácido. A maior média de infiltração verificada ocorreu nos canais radiculares tratados com EDTA-C e as menores registradas naqueles tratados com soro fisiológico ou EDTA-T. As diferenças entre as médias de infiltração apical nos seis grupos experimentais, analisadas conjuntamente, não foram estatisticamente significantes. Em comparações individualizadas, houve diferença significante (p < 0,05) entre o grupo G6 (EDTA-C) tanto em relação ao grupo G5 (EDTA-T) quanto ao grupo G1 (soro fisiológico). / Ninety extracted human teeth were analysed in this work to verify the influence of citric acid application under three concentrations, EDTA-T and EDTA-C in the apical marginal sealing of root canals. Chemical and surgical root canal preparations were performed by Paiva & Antoniazzi technique, being these teeth randomly distributed in six groups. Each group had specific chemical treatment of filling the root canal for 3 minutes with one of the following substances: saline solution, 10% citric acid, 15% citric acid, 20% citric acid, 17% EDTA-T and 17% EDTA-C. All root canals were filled with gutta-percha cones and N-Rickert cement by the multiple cone technique with vertical condensation. A crescent increase of methylene blue dye penetration could be observed in the root canals treated with citric acid equivalent to the increase in acid concentration. The highest penetration mean was shown in the root canals treated with EDTA-C and the lowest in those treated wint saline solution or EDTA-T. The differences between the apical penetration means in the six experimental groups that had been together analysed showed no statistical significance. When individually compared, there was a significant difference (p<0,05) between group G6 (EDTA-C), group G5 (EDTA-T) and group G1 (saline solution).