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

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)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 (R) 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 (p<0.05), however, the root canal preparation was not able to eliminate the endotoxin. Conclusions: Under the conditions of this study, it was concluded that the reduction of endotoxin levels of the dental root canals could be predicted by increasing the apical enlargement size.206661666Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [10/51113-1, 10/17877-4, 10/19136-1, 11/50510-0]CNPq [302575/2009-0, 150557/2011-6

Quantification of cultivable bacteria and endotoxin in post-treatment apical periodontitis before and after chemo-mechanical preparation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This clinical study was conducted to quantify cultivable bacteria and endotoxin in root canals with post-treatment apical periodontitis by correlating their levels with clinical features and to evaluate the effect of chemo-mechanical preparation (CMP) with 2 % chlorhexidine gel + 17 % EDTA on bacterial and endotoxin removal/elimination. Moreover, target strict Gram-negative anaerobic bacteria were investigated by polymerase chain reaction (PCR). Fifteen teeth with post-treatment apical periodontitis were sampled before (s1) and after (s2) CMP. Culture techniques determined the number of colony-forming units (CFU). PCR (16S rDNA) and limulus amebocyte lysate (LAL) assay were used for bacterial and endotoxin detection, respectively. Prevotella nigrescens (4/15), Prevotella intermedia (2/15), and Tannerella forsythia (2/15) were the most frequently detected species. Endotoxin was recovered in 100 % of the samples. At s1, bacteria and endotoxin were detected at a median value of 5.14 x 10(3) CFU/mL and 3.96 EU/mL, respectively. Higher levels of endotoxin were related to a larger size of radiolucent area (> 5 mm) (p < 0.05). CMP was more effective in reducing bacteria (99.61 %) than endotoxin (60.6 %) (both p < 0.05). Our findings indicated that the levels of endotoxin found in infected root canals were related to a larger size of radiolucent area in the periapical region. Moreover, CMP was effective in reducing both bacterial and endotoxin contents in post-treatment apical periodontitis.311025752583Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [08/58299-3, 08/57551-0, 08/56425, 10/51113-1, 10/17877-4, 10/19136-1, 11/50510-0, 11/50051-5]CNPq [302575/2009-0, 150557/2011-6

Clinical Investigation of the Efficacy of Chemomechanical Preparation with Rotary Nickel-Titanium Files for Removal of Endotoxin from Primarily Infected Root Canals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Introduction: This clinical study was conducted to investigate the ability of chemomechanical preparation with 25% NaOCl + 17% ethylenediaminetetraacetic acid (EDTA) and rotary nickel-titanium (NiTi) system in removing endotoxin from primary root canal infection with apical periodontitis. Methods: Twenty-one root canals with necrotic pulps were selected. Samples were collected before (s1) and after chemomechanical preparation (s2). The limulus amebocyte lysate (LAL) assay was used to quantify endotoxins. Results: The LAL assay indicated that endotoxins were present in 100% of the root canals investigated (19/19) before (s1) and after chemomechanical preparation (s2). Analyses of the quantitative data revealed that the endotoxin content was significantly reduced at s2 (98.06%) compared with that at Si (P < .05). Conclusions: Our findings indicate that chemomechanical preparation with 2.5% NaOCl + 17% EDTA and rotary NiTi files was effective in reducing endotoxin load in the root canal infection from primarily infected teeth with apical periodontitis. (1 Endod 2010;36:1766-1769)361117661769Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [07/58518-4, 08/58299-3, 08/5755-10, 08/57954-8]CNPq [3470820/2006-3, 471631/2008-6, 302575/2009-0