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Aim: To comparatively analyse the levels of culturable bacteria, endotoxins (LPS), tumour necrosis factor‐alpha (TNF‐α), interleukin‐1 beta (IL‐1β) and substance P in teeth with symptomatic irreversible pulpitis (SIP) and vital normal pulp (VNP) tissues. Methodology: Thirty‐two patients were included (20 teeth with SIP and 12 teeth with VNP tissues) in this cross‐sectional study. Samples were collected from the full length of the root canals (microbial analysis) and periapical tissues (2 mm beyond the apex for immunological analysis), using sterile absorbent paper points. The levels of culturable bacteria (culture method), endotoxins (LAL Pyrogent 5000), TNF‐α, IL‐1β and substance P (ELISA) were assessed. The Mann–Whitney test was used for comparisons between the levels of CFU/mL, LPS, TNF‐α, IL‐1β and substance P in the SIP and VNP groups. The statistical analysis was performed with the significance level set at 5%. Results: Culturable bacteria were recovered from all teeth with SIP. On the other hand, no positive cultures were observed in the VNP tissues group (p >.05). The levels of LPS were approximately four times higher in teeth with SIP than in teeth with VNP tissues (p <.05). Higher levels of TNF‐α and substance P were detected in teeth with SIP (p <.05). On the other hand, no difference in the levels of IL‐1β was detected between the two groups (p >.05). Conclusion: Teeth with symptomatic irreversible pulpitis present higher levels of culturable bacteria, endotoxins, TNF‐α and substance P than those with vital normal pulp tissues. On the other hand, the levels of IL‐1β were similar in teeth from both groups suggesting reduced implications of this inflammatory mediator in the early stages of infection. [ABSTRACT FROM AUTHOR]

Aim: To investigate the microbial profile, and levels of endotoxin (LPS) and lipoteichoic acid (LTA), in infected dentine (ID) and root canals (RC) at different phases of root canal treatment in teeth with symptomatic irreversible pulpitis. Methodology: Ten volunteers were included, and samples were collected from infected dentine (ID) and the root canal lumen (RC) using sterile excavators and paper points, respectively. RC samples were taken before (S1) and after (S2) chemo‐mechanical canal preparation (CMP), and after intracanal medication (ICM; S3). Checkerboard DNA‐DNA hybridization was used for microbial analysis. The levels of LPS and LTA were evaluated using the limulus amebocyte lysate assay and ELISA, respectively. Shapiro–Wilk's test was used to verify data normality. Friedman's test was used to evaluate statistical differences using checkerboard DNA‐DNA hybridization in the ID and RC at the different phases of the RC treatment. Post hoc Dunn's multiple comparison test was used to verify significant differences recorded at the different time‐points. The levels of LPS and LTA were analysed statistically by using repeated measures anova and Tukey's post hoc test to evaluate differences in both sites. The significance level was set at 5% (P < 0.05). Results: A total of 40 DNA probes were used for microbial investigation of ID and RC samples using checkerboard DNA‐DNA hybridization. The levels and complexity of bacteria were similar in the ID and initial RC samples. The levels of LPS and LTA in ID were significantly higher than the initial RC samples (S1; P < 0.05). Canal preparation was effective in significantly decreasing the levels of bacteria, LPS and LTA (P < 0.05). ICM did not provide additional reduction in the levels of bacteria and LPS (P > 0.05). However, a significant reduction in the levels of LTA was observed after ICM (P < 0.05). Conclusion: The microbial profile of infected dentine and root canals of teeth with irreversible pulpitis was complex, harbouring different species including Gram‐positive and Gram‐negative, cocci and bacilli, and facultative and strict anaerobes. Root canal preparation was effective in reducing the levels of bacteria, LPS and LTA from the root canals of teeth with pulpitis. [ABSTRACT FROM AUTHOR]