Influence of the apical enlargement size on the endotoxin level reduction of dental root canals

Gram-negative bacteria play an essential role in endodontic infections because they have virulence factors such as endotoxin. Due to its potential cytotoxic activity, special attention has been given to the removal/neutralization of this endotoxin in the root canal system. OBJECTIVE: The aim of this study was to evaluate the influence of the apical enlargement size (AES) by using rotary instruments on the endotoxin level reduction of dental root canals. MATERIAL AND METHODS: Forty root canals of the mandibular premolar teeth were used. Escherichia coli endotoxin (055: B55) was inoculated into thirty root canals. Ten teeth served as the negative control group. After the incubation period, the first endotoxin samples were collected from the root canals with a sterile/apyrogenic paper point for the analysis of the endotoxin units (EU/mL) present before instrumentation (S1). Specimen instrumentation was performed with the Mtwo® rotary system in the sequence 10/.04, 15/.05, 20/.06, 25/.06, 30/.05, 35/.04 and 40/.04. To monitor the effectiveness of increasing apical enlargement on endotoxin removal, the second endotoxin samples were collected from all the root canals after instrumentation with the following instruments: #25/.06- (S2); #30/.05- (S3); # 35/.04- (S4); and #40/.04- (S5). Limulus amebocyte lysate (LAL) was used to quantify the levels of endotoxin. The results were statistically compared by using repeated measures of ANOVA with post hoc Tukey testing. RESULTS: Increasing levels of endotoxin removal was achieved by large sized apical enlargement: S2 (AES #25/.06)- 89.2%, S3 (AES #30/.05)- 95.9%, S4 (AES #35/.04)- 97.8% and S5 (AES #40/.04)- 98.2%. Substantial reduction of endotoxin content was obtained in S4 and S5 compared to S2 (

Monitoring the effectiveness of root canal procedures on endotoxin levels found in teeth with chronic apical periodontitis

Objective: The aim of this study was to monitor the effectiveness of root canal procedures by using different irrigants and intracanal medication on endotoxin levels found in root canals of teeth with chronic apical periodontitis. Material and methods: Thirty root canals of teeth with pulpal necrosis associated with periapical lesions were selected and randomly divided into groups according to the irrigants used: GI - 2.5% NaOCl, GII - 2% chlorhexidine (CHX) gel, and GIII - saline solution (SS) (all, n=10). Samples were collected with sterile/apyrogenic paper points before (S1) and after root canal instrumentation (S2), after use of 17% ethylenediaminetetraacetic acid (EDTA) (S3), and after 30 days of intracanal medication (Ca(OH)2+SS) (S4). A turbidimetric kinetic Limulus Amebocyte Lysate assay was used for endotoxin measurement. Results: Endotoxins were detected in 100% of the root canals investigated (30/30), with a median value of 18.70 EU/mL. After S2, significant median percentage reduction was observed in all groups, irrespective of the irrigant tested: 2.5% NaOCl (99.65%) (GI), 2% CHX (94.27%) (GII), and SS (96.79%) (GIII) (all p0.05). Intracanal medication for 30 days was able to significantly reduce residual endotoxins: 2.5% NaOCl (90%) (GI), 2% CHX (88.8%) (GII), and SS (85.7%) (GIII, p<0.05). No differences were found in the endotoxin reduction when comparing S2 and S4 treatment groups. Conclusion: Our findings demonstrated the effectiveness of the mechanical action of the instruments along with the flow and backflow of irrigant enduring root canal instrumentation for the endotoxin removal from root canals of teeth with chronic apical periodontitis. Moreover, the use of intracanal medication for 30 days contributed for an improvement of endotoxin reduction226490495CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP302575/2009-0sem informação13/02402- 9; 10/13743-3; 10/19136-1; 10/17877-4; 11/09047-

Monitoring the effectiveness of root canal procedures on endotoxin levels found in teeth with chronic apical periodontitis

Objective: The aim of this study was to monitor the effectiveness of root canal procedures by using different irrigants and intracanal medication on endotoxin levels found in root canals of teeth with chronic apical periodontitis. Material and Methods: Thirty root canals of teeth with pulpal necrosis associated with periapical lesions were selected and randomly divided into groups according to the irrigants used: GI - 2.5% NaOCl, GII - 2% chlorhexidine (CHX) gel, and GIII - saline solution (SS) (all, n=10). Samples were collected with sterile/apyrogenic paper points before (S1) and after root canal instrumentation (S2), after use of 17% ethylenediaminetetraacetic acid (EDTA) (S3), and after 30 days of intracanal medication (Ca(OH)2+SS) (S4). A turbidimetric kinetic Limulus Amebocyte Lysate assay was used for endotoxin measurement. Results: Endotoxins were detected in 100% of the root canals investigated (30/30), with a median value of 18.70 EU/mL. After S2, significant median percentage reduction was observed in all groups, irrespective of the irrigant tested: 2.5% NaOCl (99.65%) (GI), 2% CHX (94.27%) (GII), and SS (96.79%) (GIII) (all p;0.05). Intracanal medication for 30 days was able to significantly reduce residual endotoxins: 2.5% NaOCl (90%) (GI), 2% CHX (88.8%) (GII), and SS (85.7%) (GIII,

Identificação de patógenos endodônticos por PCR e quantificação de DNA em amostras extraídas de dentes com periodontite apical pós-tratamento

Objetivo: O objetivo deste estudo clínico foi quantificar a concentração de DNA e detectar algumas espécies bacterianas de amostras de dentes tratados endodonticamente com periodontite apical após a remoção da guta-percha (S1), após o preparo químico-mecânico na primeira sessão (S2), 5 dias após o preenchimento do canal com solução fisiológica estéril (S3), após reinstrumentação na segunda sessão (S4), e 14 dias após a inserção da medicação intracanal na terceira sessão (S5). Métodos: Quinze dentes tratados endodonticamente foram selecionados. A remoção da guta-percha foi realizada por meio da técnica coroa-ápice. Utilizaram-se limas manuais associadas à clorexidina gel a 2% durante o preparo químico-mecânico. A medicação intracanal selecionada foi à base de hidróxido de cálcio. DNA foi isolado das amostras e foram investigadas 14 espécies bacterianas (primer espécie-específi co16S rDNA). A concentração de DNA foi quantifi cada utilizando o espectrofotômetro NanoDropTM 2000. Resultados: Em todos os casos foram detectadas bactérias, como revelado por meio do primer universal. DNA foi isolado de todas as amostras, com uma concentração média de 4,24 ± 2,9 ng/µL (S1), 3,39 ± 1,54 ng/ µL (S2), 4,0 ± 1,94 ng/µL (S3), 2,66 ± 0,98 ng/µL (S4) e 3,97 ± 2,32 ng/µL (S5). Parvimonas micra e Enterococcus faecalis (S1), P. micra (S2), Porphyromonas endodontalis e E. faecalis (S3), E. faecalis e Prevotella nigrescens (S4/S5) foram as espécies mais frequentemente detectadas. A concentração de DNA diminuiu entre S3 e S4 (p = 0,0256), ao passo que um aumento foi observado entre S4 e S5. Conclusão: Uma ampla variedade de espécies bacterianas foi detectada em canais radiculares de dentes tratados endodonticamente com periodontite apical. Além disso, o uso da medicação intracanal não potencializou a redução da concentração de DNA bacteriano.Aim: The aim of this clinical study was to quantify the concentration of DNA and to detect selected bacterial species from samples of infected root-fi lled teeth with post-treatment apical periodontitis after removal of gutta-percha (S1), after chemo-mechanical preparation at the fi rst appointment (S2), 5 days after the canal was fi lled with sterile physiological solution (S3), after reinstrumentation at the second appointment (S4), and 14 days after an intracanal dressing was placed at the third appointment (S5). Methods: Fifteen root-fi lled teeth were selected. Removal of gutta-percha was performed using the crown-down technique. Chemo-mechanical preparation was performed with hand fi les associated with 2% chlorhexidine gel. An intracanal dressing based on Ca(OH)2 was used. DNA was extracted from the samples and 14 endodontic 16S rDNA species-specifi c primers were tested. The concentration of DNA was quantifi ed using a NanoDropTM 2000 spectrophotometer. Results: Bacteria were present in all cases at all sampling times, as revealed by a universal primer. DNA was isolated from all samples, with an average concentration of 4.24 ± 2.9 ng/µL (S1), 3.39 ± 1.54 ng/µL (S2), 4.0 ± 1.94 ng/µL (S3), 2.66 ± 0.98 ng/µL (S4) and 3.97 ± 2.32 ng/µL (S5). Parvimonas micra and Enterococcus faecalis (S1), P. micra (S2), Porphyromonas endodontalis and E. faecalis (S3), E. faecalis and Prevotella nigrescens (S4/S5) were the species most frequently deteced. DNA concentration reductions were detected between S3 and S4 (p = 0.0256), whereas an increase was found between S4 and S5. Conclusion: A wide variety of bacterial species was detected in root-fi lled teeth with post-treatment apical periodontitis. Moreover, the use of an intracanal dressing was unable to further reduce the concentration of bacterial DNA

Investigation of microorganisms and endotoxins in primary endodontic infection and evaluation of antigenicity infectious content against macrophages by the levels of pro-inflammatory cytokines

Orientador: Brenda Paula Figueiredo de Almeida GomesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Bactérias Gram-negativas (BG-) e seu sub-produto [Lipopolisacarídeo (LPS) - endotoxina) são capazes de estimular células a produzirem citocinas pró-inflamatórias envolvidas na destruíção tecidual periapical. Os objetivos propostos foram: 1) analisar os diferentes métodos de LAL para quantificação de endotoxinas, revelando o (s) que melhor (es) se adapta (m) para investigação de endotoxina nas infecções de origem endodôntica (capítulo 1); 2) estudar o perfil da microbiota e níveis de endotoxinas nas infecções endodônticas primárias com lesão periapical, determinando a antigenicidade do conteúdo endodôntico contra macrófagos através da produção de IL1- ß e TNF-? (capítulo 2); 3) investigar a presença de espécies bacterianas Gram-negativas "alvos" e níveis de endotoxinas nas infecções endodônticas primárias com lesão periapical, determinando seu potencial antigênico contra macrófagos através da produção de PGE2 (capítulo 3); 4) detectar espécies de Treponema spp e os níveis de endotoxinas em infecções endodônticas primárias e determinar sua antigenicidade contra macrófagos através dos níveis de IL-6 e IL-10, avaliando sua correlação com os achados clínicos e radiográficos (capítulo 4); 5) avaliar a atividade antigênica de LPS isolado de P. gingivalis e F. nucleatum encontrados em canais radiculares infectados sobre macrófagos (RAW 264.7) através dos níveis de IL-1? e TNF-? (capítulo 5); 6) comparar "in vivo" a efetividade do preparo químico-mecânico com NaOCl 2.5% e CLX-gel 2% na eliminação de LPS de bactérias orais presentes em dentes com necrose pulpar e presença de lesão periapical (capítulo 6); 7) avaliar o efeito do preparo químico-mecânico com NaOCl 2.5% + EDTA 17% e limas rotatórias NiTi (Mtwo®) na remoção de endotoxinas de dentes com necrose pulpar e presença de lesão periapical (capítulo 7); 8) comparar a capacidade de diferentes sequências clínicas do sistema rotatório Mtwo® na remoção de endotoxinas em canais radiculares contaminados. (capítulo 8). Método: amostras foram coletadas de canais radiculares com IEPL utilizando cones de papel estéreis/despirogenizados. PCR (16s rDNA) e método LAL foram utilizados. Níveis de citocinas inflamatórias foram quantificados através de ELISA (Duoset-Kit, R&D systems). Resultados: Os testes cinéticos (KQCL - Kinetic Quantitative Chromegenic Limulus e turbidimétrico) mostraram níveis de endotoxinas inferiores (7,49 EU/mL e 9,19 EU/mL, respectivamente), quando comparados ao teste QCL (Quantitative Chromegenic Limulus) (34,20 EU/mL) (p<0,05). Prevotella nigrescens (13/21) foi mais frequentemente encontrada. Dente com exsudato foi relacionado com a presença de F. alocis (p<0,05). Correlações positivas (p<0,05) foram encontradas entre: número de BG- e níveis de IL-1 ß, TNF-? e PGE2; níveis de endotoxinas e de TNF-? (p<0,05); IL-1 ß e tamanho de lesão periapical. Endotoxina foi detectada em 100% dos canais radiculares estudados. Maior redução de entodotoxina foi encontrada nos dentes instrumentados com NaOCl 2,5% (57,98%) versus CLX-gel 2% (47,12%) (p<0,05) utilizando limas manuais K-file. Após PQM com NaOCl 2,5% e limas rotatórias NiTi endotoxina foi reduzida em 98,06% (p<0,05). Conclusão: 1) Os testes cinéticos turbidimétrico e cromogênico de LAL apresentaram resultados mais precisos e de melhor reprodutibilidade quando comparados ao QCL (capítulo 1);. 2) A antigenicidade do conteúdo endodôntico não está relacionada apenas com a quantidade de endotoxinas encontrada nos canais radiculares, mas também com o número de diferentes espécies Gram-negativas presentes na infecção. Maior destruíção óssea periapical foi relacionado com níveis elevados de IL-1ß (capítulo 2); 3) O número de espécies BG- presentes nas IEPL foi relacionado com diferentes níveis de secreção de PGE2 via macrófagos. Maior produção de PGE2 foi relacionada com a presença de sintomatologia clínica (capítulo 3); 4) espécies de Treponema spp. exercem seu papel na patogênese das infecções endodônticas primárias. Além disso, o conteúdo bacteriano e particularmente os níveis de endotoxinas presents nos canais radiculares estimularam a produção de IL-6 e IL-10 por macrófagos (capítulo 4); 5) LPS isolados de P. gingivalis e F. nucleatum de canais radiculares infectados estimulam a produção de IL-1? e TNF-?, que são mediadores inflamatórios pleiotrópicos, podendo iniciar a resposta inflamatória e estimular a produção de mediadores secundários envolvidos na destruição tecidual (capítulo 5); 6) PQM com NaOCl 2,5% ou CLX-gel 2% não foram eficazes na eliminação de endotoxinas presentes na IEPL (capítulo 6); 7) PQM com NaOCl 2,5% + EDTA 17% e limas rotatórias NiTi (Mtwo®) foi eficaz na remoção de endotoxinas em 98,06% (capítulo 7); 8) redução significativa de endotoxinas foi obtida utilizando as sequências Mtwo® finalizadas com o preparo apical final #40.04 or #25.07 (capítulo 8)Abstract: Gram-negative bacteria (G-ve) and its by-product [Lipopolysaccharide (LPS) - endotoxin] are capable to stimulate cells to release proinflammatory cytokines that lead to tissue destruction. The aims of this study were: 1) to determine which of the quantitative methods, namely, chromogenic endpoint, chromogenic kinetic and turbidimetric kinetic ones, best fit for the analysis of primary endodontic infections (chapter 1); 2) to investigate the microbial profile and the levels of endotoxin found in primary root canal infection with apical periodontitis (PEIAP), and to determine their antigenicity against macrophages through the levels of IL-1ß and TNF-alpha, evaluating their relationship with clinical and radiographic findings (chapter 2); 3) to investigate target G-ve bacteria species and endotoxin in PEIAP, determining their antigenicity against macrophages through the levels of PGE2 and evaluated their relationship with clinical findings (chapter 3); 4) investigation of Treponema spp. and endotoxin in primary endodontic infection and evaluation of the antigenicity of the infectious content against RAW 264.7 macrophages by the levels of IL-6 and IL-10 production (chapter 4); 5) to evaluate the antigenic activity of LPS purified from P. gingivalis and F. nulceatum isolated from infected root canals on macrophages cells (RAW 264.7) by the levels of IL-1? and TNF-?. (chapter 5); 6) to compare the efficacy of chemomechanical preparation with 2.5% NaOCl and 2% CHX-gel on eliminating oral bacterial LPS in teeth with PEIAP (chapter 6); 7) to investigate the ability of chemo-mechanical preparation (CMP) with 2.5% NaOCl + 17% EDTA and rotary NiTi system Mtwo® in removing endotoxin from PEIAP (chapter 7); 8) Comparison of different clinical sequences of NiTi rotary files Mtwo® in the removal of endotoxin from infected root canals (chapter 8). Methods: Samples were taken from root canals with PEIAP with paper points. PCR technique (16S rDNA) was used for the detection of the target bacteria. Limulus Amebocyte Lysate (LAL) was used to measure endotoxin. The amounts of IL-1ß, TNF-alpha and PGE2 in macrophages supernatants were measured by enzyme-linked immunosorbent assay - Duoset-kit (ELISA). Results: The KQCL and Turbidimetric -assay yielded a median value of endotoxin of 7.49 EU/mL and 9.19 EU/mL respectively, significantly different from the endpoint-QCL (34.20 EU/mL) (p<0.05). Prevotella nigrescens (13/21) was the most frequently Gram-negative bacteria species detected. Tooth with radiolucent area ? 2mm was related to Treponema denticola. Correlation was found between the number of Gram-negative bacteria and the levels of IL-1ß, TNF-alpha and PGE2 (p<0.05). Increased levels of endotoxin were followed by TNF-alpha release (p<0.05). Higher levels of IL-1ß (p<0.05) and endotoxin contents were related to the larger size of radiolucent area. Elevated levels of PGE2 were found in teeth with tenderness to percussion and pain on palpation. Endotoxin was detected in 100% of the root canals investigated. Higher percentage value of endotoxin reduction was found in 2.5% NaOCl (57.98%) when compared to 2% CHX-gel (47.12%) (p<0.05) using manual K-files. After chemo-mechanical preparation with 2.5% NaOCl and rotary NI-TI files endotoxin was significantly reduced to 98.06% (p<0.05). Conclusion: 1) Quantitative kinetic-turbidimetric and kinetic-chromogenic LAL methods are best fitted for analysis of endotoxin in root canal infection, both being more precise and allowing better reproducibility compared to the endpoint-QCL assay; 2) The antigenicity of the endodontic contents is not related to only the amount of endotoxin found in root canal, but also with the number of different species of Gram-negative bacteria involved in the infection. Moreover larger size (? 2mm) of radiolucent area was related to IL-1ß and endotoxin; 3) Additive effect between the number of G-ve bacterial species involved in endodontic infection regarding the induction of pro-inflammatory cytokine by macrophage cell. Moreover, teeth with clinical symptomatology were related to higher levels of endotoxin and PGE2 secretion; 4) a wide variety of Treponema species do play a role in primary endodontic. Moreover, the bacterial endodontic contents, particularly the levels of endotoxin present in root canals, were a potent stimuli for the production IL-6 and IL-10 in macrophages; 5) LPS of the P. gingivalis and F. nucleatum isolated from root canal infection is involved in the induction of IL-1 ? and TNF-?, which are pleiotropic inflammatory mediators, that can play a role in the initiation of the upregulation of the inflammatory response and can also stimulate the production of secondary mediators involved in tissue destruction; 6) 2.5% NaOCl and 2% CHX-gel were not effective on eliminating endotoxin from the primarily infected root canals using manual K-files; 7) CMP with 2.5% NaOCl + 17% EDTA and rotary NiTi files was effective in reducing 98.06% of endotoxin from PEIAP; 8) substantial reduction of endotoxin contents was achieved by using the Mtwo® sequences finished in APS #40.04 or #25.07DoutoradoEndodontiaDoutor em Clínica Odontológic

Microbiologic investigation, quantification of endotoxin and antimicrobial susceptibility in primary endodontic infection and the salivary carriage of selected endodontic pathogens

Orientador: Brenda Paula Figueiredo de Almeida GomesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O conhecimento das espécies microbianas assim como da suscetibilidade das mesmas à terapia endodôntica é importante para o sucesso do tratamento. Sendo assim, a proposta do presente estudo foi: 1) Analisar a microbiota endodôntica de dentes com necrose pulpar e presença de lesão periapical (C1) e correlacionar com os sinais e sintomas clínicos; 2) investigar mudanças microbiológicas após o preparo químico-mecânico (PQM) (C2); 3) investigar a presença de Entreococcus spp., Candida spp. e enterobactérias na saliva dos pacientes submetidos a terapia endodôntica; 4) quantificar endotoxinas antes (C1) e após PQM (C2); 5) determinar in vitro a suscetibilidade antimicrobiana de algunsmicrorganismos isolados das infecções endodônticas primárias. Amostras microbiológicas foram coletadas da saliva e do canal radicular de 30 pacientes. Foram identificados 182 microrganismos nos canais radiculares, sendo 65,38% anaeróbios estritos. As espécies mais freqüentemente encontradas foram P. micros (63,3%), P. intermedia (50%), S. mitis (30%). Associações positivas foram encontradas entre dor à percussão e E. lentum; dor à palpação e G.haemolysans e E. lentum; fístula e P. micros; exsudato purulento e Bifidobacterium spp. As espécies Peptostreptococcus spp., Fusobacterium spp., Porphyromonas spp., Prevotella spp. foram analisadas e mostraram-se suscetíveis a ação da amoxicilina e da mesma associada ao ácido clavulânico. Maiores concentrações de endotoxinas foram quantificadas nos dentes com sintomatologia clínica. Associação positiva entre LPS e a presença de dor à percussão foi encontrada (p<0,01) Conclusão: A infecção endodôntica primária caracterizou-se ser do tipo mista e polimicrobiana, com predomínio de microrganismos anaeróbios estritos, principalmente bacilos Gramnegativos; a presença de sinais e/ou sintomas clínicos mostrou estar relacionada com determinadas espécies tais como Eubacterium lentum, Gemella haemolysans, Peptostreptococcus micros e Bifidobacterium spp. comumente isoladas em infecções endodônticas primárias; Candida spp. e Enterococcus spp. foram mais freqüentemente isolados da saliva do que as Enterobacteria spp. O isolamento das espécies C. albicans e E. faecalis no canal radicular foram associados com a identificação das espécies na saliva; o PQM dos canais radiculares foi eficaz na redução do número de microrganismos. Mudança na microbiota foi encontrada após PQM. Amoxicilina associada ao ácido clavulânico mostrou ser uma potente combinação contra microrganismos envolvidos na infecção de origem endodôntica. Altas concentrações de endotoxinas nos canais radiculares parecem estar relacionadas com a presença de sintomatologia clínica, particularmente com a dor à percussão. O PQM foi capaz de reduzir a concentração inicial de endotoxinas em todos os canais radiculares, entretanto não foi capaz de eliminá-lasAbstract: Bacteria and their by-products play an important role in the etiology and development of pulp and periapical diseases. The knowledge of endodontic microbiota and its susceptibility to endodontic therapy is important to a successful treatment. Therefore the aims of this study were: 1) to analyse the root canal microbiota in infected teeth with pulp necrosis and periapical lesions (C1) and its correlation with the clinical signs and symptoms; 2) to investigate the variations in the susceptibilities of endodontic microflora to biomechanical procedures (C2); 3) to investigate Candida spp., Enterococcus spp. and enterobacteria in saliva from the patients under endodontic therapy; 4) to quantify endotoxins before (C1) and after chemo-mechanical preparation (CMP) (C2); 5) to determine in vitro the antimicrobial susceptibility rates of the microrganisms recovered from the root canals with primary endodontic infections. Thirty root canals were microbiologically sampled before (C1) and after CMP (C2). At the baseline samples (C1), a total of 182 microrganisms were identified. Strict anaerobic or microphilic species predominated in 65.38%. P. micros (63.3%), P. intermedia (50%), S. mitis (30%) were the most frequent species recovered from the root canals at the baseline samples (C1). Associations between terderness to percussion and the presence of E. lentum; pain on palpation and G. haemolysans and E. lentum; sinus tract and P. micros; Purulent exudate and Bifidobacterium spp. (p<0.05) were found. Peptostreptococcus spp., Fusobacterium spp., Porphyromonas spp., Prevotella spp. were susceptible to amoxicilin and amoxicillin + clavulanate. Higher levels of endodotoxin were detected in teeth with clinical symtphomatology. A positive association was found between the presence of LPS and tenderness to percussion (p<0.01).It was concluded that microbiota from infected root canals with pulp necrosis and periapical lesions was comprised by a mixed and polimicrobial flora, dominated by strict anaerobes, particulary Gram-negative rods. Signs and symptoms seemed to be related to the presence of specific bacteria species Eubacterium lentum, Gemella haemolysans, Peptostreptococcus micros e Bifidobacterium spp.. Candida spp. and Enterococcus were more requently recovered from saliva than Enterobacteria spp. Isolation of C. albicans and E. faecalis from root canals were associated with their identification in the saliva samples. CMP was efficient in reducing the number of microorganisms. Changing in root canal flora was detected after endodontic procedures. Amoxicilin associated with clavulanate was an effective and a strong antimicrobial agent against microorganisms involved in endodontic infections. High contents of LPS seem to be related to the presence of clinical symptomatology, particulary tenderness to percussion. CMP was effective in reducing the initial amount of endotoxin in all root canal samplings but was not able to eliminate itMestradoEndodontiaMestre em Clínica Odontológic