Introduction: There are currently no established guidelines to determine which cases general practitioners should refer to an endodontist for root canal treatment. The American Association of Endodontists (AAE) has developed the EndoCase mobile application (ECA), which utilizes either a full or abridged rubric to assign case difficulty level and provide referral guidelines to general practitioners and dental students. Objective: The objective of this study was to determine whether the abridged criteria of the EndoCase application can help predict the incidence of procedural errors in nonsurgical root canal treatment of mandibular molars in an undergraduate dental clinic based on the difficulty level. Methods: A list of patients who received primary root canal treatment on mandibular first molars in the undergraduate dental clinic from 2015-2020 was obtained. Ninety patients qualified for inclusion. Case difficulty level was assessed using the ECA by three providers with differing levels of experience. Incidence of procedural errors was determined from post-operative radiographs by two calibrated independent observers. Results: The most common endodontic mishaps were errors during access cavity preparation followed by the presence of voids in the root filling, with an incidence of 54.4% and 45.6%, respectively. There were no significant differences regarding case difficulty level and the incidence of total procedural errors nor number of treatment visits. Of the individual error types, the presence of obturation >2mm short of the radiographic apex was weakly correlated with case difficulty level (r = 0.226, pConclusion: There is minimal correlation between the difficulty level of mandibular molars determined by the ECA and the number of treatment visits or overall incidence of procedural errors.

Indiana University-Purdue University Indianapolis (IUPUI) / The primary goal of root canal treatment is to eliminate microbes from the root canal system, which is the cause of pulpal and periapical infections. Research shows that after a single visit of chemomechanical debridement microbes continue to remain within the canal system. An interappointment medication step has been advocated to maximize potential elimination of microbes within the root canal system. Previous studies have shown propolis to be antibacterial against common endodontic microbes. Studies have shown trends in different microbes being present in primary verus secondary endodontic infections. The majority of literature has focused on the efficacy of propolis against Enterococcus faecalis, a microbe commonly implicated in secondary endodontic 95 infections. The aim of this study was to demonstrate the efficacy of propolis against Fusobacterium nucleatum, a microbe commonly found in primary endodontic infections. This study aims to demonstrate the efficacy of propolis against a bacterium of primary endodontic infections (F. nucleatum) as well as against microbial biofilm to further support its potential use as a novel intracanal medicament. Dilutions of propolis were added to cultures of F. nucleatum in microtiter plates in a range from 390 μg/ml to 50,000 μg/ml. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the minimum biofilm inhibitory concentration (MBIC) were determined. The MIC was determined of the total solution (biofilm+planktonic), planktonic, and biofilm (MBIC) after a 48-hour incubation period. The MBIC was determined by fixing biofilm to the wells and using crystal violet staining with spectrophotometry. The MBC was examined by plating solution from each concentration test well and reading the plates after 48 hours of incubation. The results show that the MIC of the total (biofilm+planktonic) appears to occur at a concentration of 6250 μg/ml. The MBIC appears to occur at the concentration of 1562.5 μg/ml. The planktonic results exhibit no significant difference in test and control wells. There was no MBC at any of the test concentrations. The propolis appears to inhibit bacterial growth and biofilm formation but does not appear to be bactericidal at any of the tested concentrations. The results of this study indicate that propolis has an MIC and MBIC when tested in vitro against F. nucleatum, although it does not show an MBC. There appears to be potentially significant interaction of propolis with biofilm as displayed by the lower concentration needed to exibit inhibitory effects on biofilm formation. This information 96 may contribute to the ability to develop a proper concentration of propolis to use in vivo when treating endodontic infections.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Some intracanal medicaments used in regenerative endodontics may compromise the bond strength of root cements and lead to tooth discoloration. Objectives: To evaluate the effects of 1) low concentrations of TAP and DAP (1 mg/mL) on push-out bond strength of various root cements, and 2) low concentrations of TAP and DAP (1 mg/mL and 10 mg/mL) on crown discoloration. Materials and Methods: Single rooted human teeth (n = 144) were horizontally decoronated and instrumented according to standardized protocol. The samples were randomized into six experimental groups (Ca(OH)2, 1000 mg/mL TAP and DAP, 1 mg/mL TAP and DAP, and no medicament control group. After four weeks, the medicaments were removed and each group was divided into three subgroups to receive MTA cement, Biodentine cement, or Endosequence Bioceramic putty cement for two weeks. Then, two root cylinders were obtained from each root and push-out bond strength testing was performed. For the crown discoloration experiment, 160 crowns were obtained from intact human molars and randomized into experimental groups as described earlier with the addition of two groups (10 mg/mL TAP and DAP). The pulp chambers in half of the samples from each group were coated with an adhesive bonding agent before receiving the assigned intracanal medicament. Color changes (ΔE) were detected by spectrophotometer at 1 day, 1 week, and 4 weeks after application, as well as after thermocycling. Results: In the push-out bond strength experiment, 1 mg/mL DAP generally demonstrated significantly higher bond strength of root cements compared with the other treatment groups. For the crown discoloration experiment, when an adhesive bonding agent was used prior to (10 mg/mL or 1000 mg/mL) TAP, the crowns had significantly less discoloration than those without adhesive. DAP 10 mg/mL had the least significant color change at all time points regardless of whether adhesive was used. Conclusion: 1) 1 mg/mL DAP and Ca(OH)2 did not have significant negative effect on the bond strength of calcium-silicate-based cement to radicular dentin. 2) 1 mg/mL and 10 mg/mL of DAP and Ca(OH)2 had significantly less effect on the color change of the human tooth crown than all intracanal medicaments used in this study. / 2020-08-13

Aims Use of 3D printed models in Endodontics has been gaining popularity since the technology to create them became more affordable. Currently, there are no studies that evaluate the influence of 3D models on endodontic surgical treatment planning and on operator confidence. Therefore, aims of this study were to: (i) Determine whether the availability of a 3D printed analogue can influence treatment-planning and operator confidence; and, (ii) Assess which factors of operator confidence are influenced, if any. Materials and Methods Endodontists were asked to analyze a pre-selected CBCT scan of an endodontic surgical case and to answer a questionnaire that determined their surgical approach for that case. After 30 days, the same participants were asked to analyze again the same CBCT scan. This time however, a 3D printed model of the scan was made available to the participants and to perform a mock osteotomy on the model. The participants were then asked to respond to the same questionnaire that they responded to 30 days prior to determine if there would be any changes to their treatment plan. A new set of questions were added to the survey to evaluate the influence of the 3D printed model on participants’ confidence in performing endodontic surgery. The responses were statistically analyzed using Chi square test followed by either logistic or ordered regression analysis while adjusting for experience of participant. Adjustment for multiple comparison analysis was done using Bonferroni correction. Statistical significance was set at £0.005. Results Availability of the 3D printed model and the CBCT scan together resulted in statistically significant differences in the participants’ responses to their ability to clearly detect bone landmarks, accurately predict the location of osteotomy, and in determining the following: size of osteotomy, angle of instrumentation, involvement of critical structures in flap reflection and involvement of vital structures during curettage. In addition, the participants’ confidence in performing surgery was significantly higher versus having CBCT scans alone. There were no statistically significant changes with decisions on flap design and extent, visualizing critical structures, lesion size, injury to vital structures during osteotomy, the length of root that could be resected and the number of roots involved. Conclusions The availability of 3D printed models did not alter the participants’ surgical approach, but it significantly improved their confidence for endodontic microsurgery, which can be attributed to better visualization of anatomical structures.

Introducción: El tratamiento de endodoncia es un procedimiento odontológico importante para preservar la pieza dentaria; sin embargo, en muchos casos los pacientes tienen una información limitada, que podría estar relacionada con la percepción hacia el tratamiento. Objetivo: Determinar la asociación entre el nivel de conocimiento y percepción sobre el tratamiento de endodoncia en pacientes que acuden a un centro odontológico en Chiclayo en el año 2023. Materiales y Métodos: Investigación de tipo transversal, con diseño observacional, participaron 196 pacientes que acudieron al Centro Especializado en Formación Odontológica en la ciudad de Chiclayo, periodo septiembre a octubre del 2023. Se incluyeron participantes de 18 a 60 años de edad que acudieron para atención odontológica y que desearon participar en la investigación. Se utilizo un cuestionario previamente validado para medir el conocimiento y la percepción acerca del tratamiento de endondoncia. Resultados: Se encontró que 77% de los pacientes obtuvo un nivel alto de conocimiento; mientras que, el 68.9% presentó un nivel bueno respecto a percepción. Además, se observó que existe asociación estadísticamente significativa entre el nivel de conocimiento, sexo, grupo etario y grado de instrucción; a diferencia de percepción, en donde solo se encontró asociación estadísticamente significativa entre grado de instrucción. Conclusión: Se encontró asociación entre conocimiento y percepción sobre el tratamiento de endodoncia en pacientes que acudieron a un centro odontológico en Chiclayo en el año 2023. / Introduction: Endodontic treatment is an important dental procedure to preserve the tooth; however, in many cases patients have limited information, which could be related to the perception towards the treatment. Objective: To determine the association between the level of knowledge and perception of endodontic treatment in patients attending a dental center in Chiclayo in the year 2023. Materials and Methods: Cross-sectional research with observational design, 196 patients who attended the Specialized Center for Dental Training in the city of Chiclayo from September to October 2023 participated. Participants between 18 and 60 years of age who came for dental care and who wished to participate in the research were included. A previously validated questionnaire was used to measure knowledge and perception of endondontia treatment. Results: It was found that 77% of the patients had a high level of knowledge, while 68.9% had a good level of perception. In addition, it was observed that there was a statistically significant association between the level of knowledge, sex, age group and level of education; in contrast to perception, where a statistically significant association was only found between level of education. Conclusion: An association was found between knowledge and perception of endodontic treatment in patients who attended a dental center in Chiclayo in the year 2023.

El objetivo del presente estudio fue determinar in vitro que grupo de dientes analizados con reabsorción radicular interna tratados endodónticamente y reparados con tres distintos selladores presentó la mayor resistencia a la fractura. Metodología, el estudio fue de nivel básica; de tipo prospectivo, longitudinal y exploratorio; de diseño experimental in vitro; y de enfoque cuantitativo. La población, estuvo conformada por piezas dentarias del grupo premolar mandibulares y de un sólo conducto radicular; la muestra, fue conformada de manera no aleatoria por conveniencia, constituida por 60 piezas dentarias, divididas en seis grupos de 10 dientes cada uno (A: Biodentine + Biodentine, B: Biodentine + gutapercha + Neo Sealer, C: Neo Putty + Neo Putty, D: Neo Putty + gutapercha + cemento Neo sealer, grupo control positivo y grupo control negativo); asimismo, se consideró los criterios de inclusión y exclusión. Para la medición de la resistencia a la fractura se utilizó la máquina universal Instron, en el Laboratorio High Technology Laboratory Certificate S.A.C, San Juan de Lurigancho – Lima, 2023. Resultados, se halló que la resistencia a la fractura promedio de los grupos control positivo y negativo fueron 558.147N y 648.212N, respectivamente; y, la resistencia a la fractura promedio en los grupos experimentales fueron los siguientes: 485.938N para el grupo D, 419.382N para el grupo A, 410.417N para el grupo C y 407.824N para el grupo B. Además, se mostró que existe diferencia significativa entre las medias resistencia a la fractura de los dientes de los grupos experimentales con respecto a los grupos controles, pues los grupos controles tuvieron un mayor rango promedio de la resistencia a la fractura que los dientes tratados con los sellantes endodónticos (p-valor = 0.002, p<0.05). Conclusión, se concluyó que entre los grupos experimentales, el grupo sellador Neo Putty + gutapercha + sellador Neo Sealer fue aquel que mostró la mayor resistencia a la fractura en los dientes con reabsorción radicular interna tratados endodónticamente; sin embargo, esta resistencia fue menor a la hallada en los grupos controles. / The purpose of the present study was to determine in vitro which group of teeth analyzed with internal root resorption treated endodontically and repaired with three different sealants presented the greatest resistance to fracture. Methodology, the study was basic level; prospective, longitudinal and exploratory; in vitro experimental design; and quantitative approach. The population was made up of teeth from the mandibular premolar group and a single root canal; The sample was formed in a non-random manner for convenience, consisting of 60 teeth, divided into six groups of 10 teeth each (A: Biodentine + Biodentine, B: Biodentine + gutta-percha + Neo Sealer, C: Neo Putty + Neo Putty, D: Neo Putty + gutta percha + Neo sealer cement, positive control group and negative control group); Likewise, the inclusion and exclusion criteria were considered. To measure the fracture resistance, the Instron universal machine was used, at the High Technology Laboratory Certificate S.A.C, San Juan de Lurigancho – Lima, 2023. Results, it was found that the average fracture resistance of the positive control groups and negative were 558.147N and 648.212N, respectively; and, the average fracture resistance in the experimental groups were as follows: 485.938N for group D, 419.382N for group A, 410.417N for group C and 407.824N for group B. In addition, it was shown that there is significant difference between the average fracture resistance of the teeth of the experimental groups with respect to the control groups, since the control groups had a greater average range of fracture resistance than the teeth treated with endodontic sealants (pvalue = 0.002, p<0.05). Conclusion, it was concluded that among the experimental groups, the Neo Putty sealer + gutta-percha + Neo Sealer sealer group was the one that showed the greatest resistance to fracture in teeth with endodontically treated internal root resorption; However, this resistance was lower than that found in the control groups.

A proposta deste estudo foi avaliar o impacto da cavidade endodôntica conservativa no preparo de canais radiculares com diferentes sistemas de instrumentação e no comportamento biomecânico de pré-molares superiores restaurados com diferentes materiais restauradores. Noventa pré-molares superiores com bifurcação radicular no terço cervical ou médio foram selecionados e escaneados em microtomógrafo para determinação de parâmetros bidimensionais (2D) e tridimensionais (3D) dos canais radiculares e dados de comprimento e volume de coroa e raiz. A partir desses dados, os espécimes foram distribuídos de acordo com a cavidade endodôntica de acesso: controle (hígido) (n=10), cavidade endodôntica convencional (CC) (n=40) e cavidade endodôntica conservativa (CEC) (n=40), e quanto ao sistema de instrumentação (n=10): Protaper Universal (PTU), Reciproc (RP), Reciproc Blue (RB) e Hiflex EDM (HEDM). As CC e CEC foram realizadas usando de brocas 1014 HL e Endo Z e inserto ultrassônico E7D e os espécimes foram escaneados para quantificar o tecido dental removido. Os dentes foram instrumentados com os sistemas PTU, RP, RB e HEDM seguindo as orientações dos fabricantes. Após o preparo biomecânico foi realizado novo escaneamento para avaliação das alterações dos parâmetros 2D e 3D dos canais radiculares e nova aleatorização quanto ao material restaurador (n=10): controle (material restaurador provisório), resina composta convencional, resina composta bulk fill regular e resina composta bulk fill fluida associada a resina composta convencional. Os espécimes foram obturados com cimento à base de resina epóxica e cone único e selados com cimento provisório. Após sete dias os dentes foram restaurados de acordo com seus respectivos grupos utilizando resina composta convencional por meio da técnica incremental, resina composta bulk fill regular em incremento único e incremento único de resina composta bulk fill fluida com camada de resina composta convencional. Novo escaneamento foi realizado para analisar o material restaurador e presença de espaços vazios, seguido de inclusão para simulação do ligamento periodontal e ensaio de resistência à fratura e determinação do padrão de fratura. Foram gerados modelos tridimensionais das condições de acesso endodôntico e material restaurador para análise pelo método de elementos finitos. Os dados de preparo e comportamento biomecânico foram submetidos ao teste de T pareado, ANOVA e teste Tukey e qui-quadrado (=0,05). As cavidades endodônticas de acesso e sistemas de instrumentação apresentaram valores estatisticamente semelhantes para dados 2D e 3D, no entanto, observou-se que a CC propiciou maior centralização do canal radicular quando comparada a CEC. Os sistemas RB e HEDM apresentaram maior centralização quando comparados ao sistema PTU. O sistema Protaper apresentou maior percentual de paredes não tocadas em CEC. Menor percentual de material restaurador foi observado em CEC (78,7%) comparado a CC (96,3%), sendo observado em CEC maior percentual de material obturador e espaços vazios. Os valores de resistência à fratura e padrão de falha foram estatisticamente semelhantes para o grupo controle e grupos experimentais. Os grupos avaliados apresentaram comportamento similar na análise de elementos finitos, com maior concentração de tensões na cúspide palatina comparada à cúspide vestibular e maiores tensões na região de sulco principal e cristas marginais. Pode-se concluir que a CEC impactou negativamente na centralização do preparo biomecânico, sendo que PTU promoveu maior desvio e percentual de paredes não tocadas. A cavidade endodôntica de acesso não alterou o comportamento biomecânico de pré-molares superiores, no entanto, CEC apresentaram material obturador remanescente após tratamento endodôntico e maior percentual de espaços vazios no material obturador / The purpose of this study was to evaluate the impact of the conservative endodontic cavity in the biomechanical preparation with different systems and in the biomechanical behavior of maxillary premolars restored with different restorative materials. Ninety maxillary premolars with root bifurcation in the cervical or middle third were selected and scanned in microcomputed tomography for the determination of two-dimensional (2D) and three-dimensional (3D) parameters of root canals and length and volume data of the root and crown. From these data, the specimens were distributed according to the endodontic access cavity: control (higid) (n=10), conventional endodontic cavity (CC) (n=40) and conservative endodontic cavity (CEC) (n=40); and according the biomechanical preparation system (n=10): Protaper Universal (PTU), Reciproc (RP), Reciproc Blue (RB) and Hiflex EDM (HEDM). CC and CEC were performed using 1014 HL and Endo Z drills and E7D ultrasonic insert, followed by a new micro tomographic examination to quantify the removed dental tissue. The teeth were prepared with the PTU, RP, RB and HEDM systems following the manufacturers\' guidelines. After the biomechanical preparation, a new scanning was performed to evaluate the 2D and 3D root canal parameters changes and a new randomization was performed for the restorative material (n=10): control (temporary restorative material), conventional composite resin, bulk fill regular composite resin and resin composite bulk fill flow associated with conventional composite resin. The specimens were filled with epoxy resin-based sealer and single cone, and sealed with temporary restorative cement. After seven days the teeth were restored according to their respective groups with conventional composite resin using the incremental technique, composite resin bulk fill regular using a single increment and single increment of composite resin bulk fill flow with conventional composite resin layer. New scanning was performed to analyze the restorative material and presence of voids, followed by the inclusion for periodontal ligament simulation and fracture strength test and determination of fracture pattern. Three-dimensional models of endodontic access conditions and restorative material were generated for finite element analysis. The biomechanical preparation and biomechanical behavior data were submitted to paired T test, ANOVA and Tukey test and chi-square test (=0.05). The endodontic access cavities and biomechanical preparation systems presented statistically similar values for 2D and 3D data, however, it was observed that CC showed a greater centralization of the root canal compared to CEC. The RB and HEDM systems presented greater centralization compared to the PTU system. The Protaper system presented a higher percentage of untouched walls in CEC. A lower percentage of restorative material was observed in CEC (78.7%) compared to CC (96.3%), showing the presence of filling material and greater percentage of empty spaces in CEC. The values of fracture strength and failure pattern were statistically similar for the control group and experimental groups. The evaluated groups presented similar behavior in finite element analysis, with a higher stress concentration in the palatal cusp compared to the vestibular cusp and higher stress in the main sulcus region and marginal ridges. It can be concluded that the CEC had a negative impact on the centralization of the biomechanical preparation, and that PTU promoted greater deviation and percentage of untouched walls. The endodontic access cavity did not alter the biomechanical behavior of maxillary premolars, however, CEC had remaining filling material after endodontic treatment and greater percentage of voids

O presente estudo teve por objetivo avaliar in vivo a eficácia do preparo de canais radiculares na redução bacteriana em dentes portadores de periodontite apical primária, com auxílio do sistema EndoVac de irrigação e aspiração. Foram coletadas amostras dos canais radiculares de 20 pacientes, antes (S1) e após (S2) o preparo com instrumentos rotatórios Protaper, variando somente a técnica utilizada para irrigação e aspiração: Grupo A (irrigação convencional n=10) e Grupo B (irrigação com auxílio do sistema EndoVac n=10). Após a extração do DNA presente nas amostras, este foi quantificado através da reação de PCR em tempo real, pelo método SYBR Green, identificando o número de cópias do gene 16SrRNA. Em todas as amostras, com exceção de uma pós-preparo com EndoVac, foram identificadas cópias do gene alvo. A média para todos os casos foi de 1,6 X 108 e 8,8 X 105 cópias do 16SrRNA, antes e após o preparo, respectivamente. Para os grupos isoladamente, os mesmos valores foram: 2,0 X 108 e 5,5 X 105 (convencional), e 1,1 X 108 e 1,2 X 106 (EndoVac). O percentual médio de redução foi de 97,52% (97,02% para convencional e 98,04% para o EndoVac). O teste de Mann-Whitney permitiu concluir que ambas as técnicas reduziram significativamente os microrganismos presentes antes do preparo (p<0,0001), sem haver diferença entre as mesmas (p=0,9705). Nenhuma das técnicas foi efetiva na eliminação completa de bactérias sob a metodologia utilizada. A eficácia antibacteriana do sistema EndoVac, sob esta metodologia, foi semelhante a obtida com a irrigação e aspiração convencional. / The present study aimed to analyze in vivo the effectiveness of root canal preparation on bacterial reduction in patientss teeth with primary apical periodontitis. Samples were collected from 20 patients before (S1) and after (S2) preparation with ProTaper rotary files, varying only the technique used for irrigation and aspiration: Group A (conventional irrigation - n = 10) and Group B (with the aid of EndoVac system - n = 10). After extraction, the DNA present in the samples was quantified by real-time PCR with the SYBR Green method, identifying the number of 16SrRNA gene copies. In all samples, except for a post-preparation case with EndoVac, copies of the target gene were identified. Average for all cases was 1,6 X 108 and 8,8 X 105 copies of the 16SrRNA, before and after preparation, respectively. For the groups separately, the same values were 2,0 X 108 and 5,5 X 105 (conventional) and 1,1 X 108 and 1,2 X 106 (EndoVac). The mean percentage of reduction was 97.52% (97.02% for the conventional and 98.04% for the EndoVac). The Mann-Whitney test concluded that both techniques significantly reduced the microrganisms after preparation (p<0,0001), with no differences between them (p=0,9705). None of the techniques were effective in the complete elimination of bacteria under this methodology. The antibacterial efficacy of the EndoVac system under this methodology was similar to that obtained with conventional irrigation and aspiration.

Durante o preparo químico-cirúrgico são utilizados instrumentos e substâncias químicas, que constituem um binômio indivisível e necessário para alcançar a modelagem e a sanificação dos canais radiculares. Assim, propõe-se com este trabalho avaliar in vivo, por meio de método molecular de PCR quantitativo, baseado em DNA (qPCR), a eficiência do preparo químico-cirúrgico empregando como agente de irrigação o Hipoclorito de Sódio (NaOCL) a 2,5% ou o Gel de Endo PTC associado ao Hipoclorito de Sódio a 1,0% na redução bacteriana de canais radiculares de dentes portadores de periodontite apical primária. Foram selecionados 30 pacientes portadores de infecção endodôntica primária, totalizando 30 dentes, com rarefação óssea periapical visível na radiografia, sem tratamento endodôntico prévio. Os pacientes foram divididos de forma randomizada em dois grupos distintos, de acordo com a substância química auxiliar utilizada durante a instrumentação, NaOCL 1% + Endo-PTC leve ou NaOCL 2,5%. Em todos os casos empregou-se instrumentos Reciproc R40 ou R50 e as coletas foram realizadas antes (S1) e após o prepare químico-cirúrgico (S2). A análise de aderência foi realizada por meio do teste de Kolmogorov-Smirnov, as análises intragrupo foram realizadas com teste de Wilcoxon para amostras relacionadas e as comparações entre os dois grupos foram realizadas com o teste de Mann-Whitney, para a análise quantitativa de bactérias. Em ambos os grupos, houve diminuição significativa no número de bactérias entre S1 e S2 (p<0,05). No grupo NaOCL 1% + Endo-PTC leve, houve redução de 3,7x105(S1) para 5,7x104 (S2). No grupo NaOCl 2,5%, redução de 1,3x105 (S1) para 1,1x104(S2). Na comparação entre grupos, o NaOCL a 2,5% (91,62%) promoveu maior redução bacteriana do que o grupo NaOCL 1% + Endo-PTC (84,60%) (p<0,05). / During the chemomechanical preparation, instruments and chemical substances are used, which constitute an indivisible and necessary binomial to achieve modeling and sanification. Knowing the auxiliary chemical substances, understanding their mechanisms of action, being able to use them efficiently, is fundamental, so that the chemical-surgical preparation is well performed by the clinician. Thus, the purpose of this study is to evaluate in vivo, the efficiency of the chemomechanical preparation using as the irrigant agent 2,5% sodium hypochlorite and Endo-PTC gel, associated to 1% sodium hypochlorite, to assess the bacterial reduction of root canals of teeth with primary apical periodontitis, using a molecular quantitative method DNA-based - polymerase chain reaction (qPCR). Were selected 30 patients with primary infection totaling 30 teeth, with visible periapical bone rarefaction on the radiography, without previous endodontic treatment. Patients were randomly divided into two distinct groups according to the auxiliary chemical substances used during the instrumentation, 1% sodium hypochlorite associated with Endo-PTC gel or 2,5% sodium hypochlorite. In all cases, reciproc instruments R40 or R50 were used and the samples were taken before (S1) and after chemical surgical preparation (S2). The adherence analysis was performed using the Kolmogorov-Smirnov test, intragroup analysis were performed with Wilcoxon test for related samples and comparisions between the two groups were performed with the Mann-Whitney test for the quantitative analysis of bacteria. In the both groups, there was a significant decrease in the number of bacteria between S1 and S2 (p<0,05), the inicial sample (S1) of the group Endo-PTC, the median 3,7x105, reduced to 5,7x104. In the other group of NaOCl, the median in S1 was 1,3x105 that reduced to 1,1x104 . In the comparision between groups, the 2,5% NaOCl promoted a greater microbial reduction of 91,62%, than the Endo-PTC associated with 1% NaOCl (p<0,05) 84,60%.

O digluconato de clorexidina reage com o hipoclorito de sódio formando um precipitado, que segundo a literatura, é composto por para-cloroanilina (PCA), ou por para-clorofenil uréia (PCU) e para-clorofenilguanidil-1,6-diguanidil-hexano (PCGH). Este estudo visou analisar quimicamente os produtos formados e a presença de PCA no precipitado. Para isso, foi realizada a reação de 50 mL de solução de hipoclorito de sódio a 5% (NaOCl) e de 50 mL de solução de digluconato de clorexidina a 2% (CLX) em proporções iguais (1:1). O precipitado foi separado do sobrenadante e desidratado. A CLX pura, uma amostra do precipitado puro e outra amostra de precipitado com adição de PCA foram diluídas em dimetilsulfóxido deuterado e analisados em ressonância magnética nuclear 1D 1H (RMN) para verificar, por comparação, a presença da PCA no precipitado e para obtenção dos deslocamentos químicos dos produtos presentes no precipitado. Outra amostra do precipitado, de solução de CLX e de PCA foram separadas em cromatografia líquida de alta eficiência e analisadas em espectrômetro de massa (HPLC-ESI-MS) para identificação dos pesos moleculares dos compostos. A comparação do espectro do precipitado puro e do espectro do precipitado com adição de PCA permitiu analisar que o dubleto presente na região dos compostos aromáticos, referente à PCA, não está presente no espectro do precipitado puro demonstrando que não há PCA no precipitado. A análise do espectro de RMN do precipitado puro sugere que há formação de compostos com um e dois anéis aromáticos. Os espectros de massa permitem sugerir que há quebra da molécula de CLX, pelo hipoclorito de sódio, em sítios específicos (grupo biguanidil) que resultam na formação de fragmentos da molécula de clorexidina que se reorganizam formando oligômeros, ou seja, moléculas em que algumas unidades se repetem e, uma vez formadas, são estáveis e insolúveis em água. É possível concluir que no precipitado não há presença de PCA, sugerindo-se que haja PCGH e outros compostos com pesos moleculares maiores que o da clorexidina, denominados, neste estudo, C3, C4, C5, C6 e C7. / The reaction between chlorhexidine digluconate and sodium hypochlorite result in a precipitate, which according to the literature, is composed of para-chloroaniline (PCA), or para-chlorophenylurea (PCU) and para-chlorophenylguanidyl-1,6- diguanidyl-hexane (PCGH). The purpose of this study was to determine the chemical composition, the relative molecular weight of the compounds and whether PCA is formed in the precipitate. A 2% chlorhexidine digluconate solution was mixed in a 1:1 ratio with 5% NaOCl solution producing the precipitate. It was centrifuged, separed from the supernatant and dried. Pure CHX, the precipitate, as well as a mixture of precipitate and pure PCA were dissolved in deuterated dimetilsulfoxide and then analyzed using one-dimensional 1H nuclear magnetic resonance (MNR) to determine whether PCA was formed and to obtain precipitates chemical shifts. Other precipitate, CHX digluconate solution and PCA samples were analized using high performance liquid chromatography - electrospray ionization - mass spectrometry (HPLC-ESI-MS). Comparing the spectrum of the precipitate alone and precipitate with PCA allow to identify that PCA doublet peaks are not present in the spectrum of the precipitate alone, demonstrating that there are no PCA in the precipitate. NMR spectrum of the precipitate alone suggests that there is compounds with one and two aromatic rings. Mass spectra suggests that breaks in chlorhexidine molecule on specific sites (biguanidil groups), by sodium hypochlorite, results in fragments that forms oligomers molecules in wich some units are repeated and, once formed, are stable and insoluble in water. On the basis of this study, there is no PCA in the precipitate and suggesting that there may be other compounds like PCGH and others compounds, all of which are bigger in size than CHX, called, in this study, C3, C4, C5, C6 and C7.