Clinical endodontic procedures modulate periapical cytokine and chemokine gene expressions.

OBJECTIVES: To identify the gene expression of the cytokines IL-9, TNF-α, IL-1, INF-γ, IL-17A, and IL-10 and the chemokines CCL-2/MCP-1 and CCR-6 in the periapical fluid of human root canal infections. MATERIALS AND METHODS: Twenty samples were collected immediately and 7 days after the cleaning and shaping procedures (after reducing the intracanal microbial load) in an attempt to characterize the expression of these genes. The endogenous expression levels of cytokines and chemokines were analyzed by real-time polymerase chain reaction. The Shapiro-Wilk and the Wilcoxon tests analyzed data. RESULTS: Significantly higher levels of the IL-9, INF-γ, TNF-α, IL-1, and IL-10 markers on day 7 were observed compared with day 0 (p < 0.05). However, IL-17A and the chemokines CCL-2/MCP-1 and CCR-6 did not show a significant difference in mRNA expression when comparing both timepoints (p > 0.05). CONCLUSIONS: The clinical variation of the periapical immune status after endodontic therapy suggests that the cytokine and chemokine-mediated pro-inflammatory response appears to be modulated in an IL-10/IL-9-dependent manner. CLINICAL RELEVANCE: Few studies have investigated the role of Th9 cells in periapical lesions. IL-9 presents exciting plasticity, performing immunosuppressive actions, and it is also capable of changing their phenotype in the presence of IL-17. Hence, it is relevant to investigate its role in the context of the known mediators involved the periapical immune process.

Microbial Ecosystem Analysis in Root Canal Infections Refractory to Endodontic Treatment.

INTRODUCTION: The purpose of this study was to combine multiple displacement amplification and checkerboard DNA-DNA hybridization to qualitatively and quantitatively evaluate the microbiota present in infections refractory to endodontic treatment. METHODS: The subjects of this study were 40 patients presenting with periapical lesions refractory to endodontic treatment. Samples were taken by scraping or filing root canal walls with a #10 K-type hand file. Sample DNA was amplified by multiple displacement amplification, and the levels of 107 bacterial taxa were analyzed by checkerboard DNA-DNA hybridization. The taxa were divided into 3 distinct microbial populations depending on their mean proportion in samples (% DNA probe counts ± standard error of the mean) as follows: dominant (≥3.0%), subdominant (>1.6%-3.0%), and residual (≤1.6%) populations. The significance of differences was determined using the Mann-Whitney test. RESULTS: The taxa present with the highest mean proportions (constituting the dominant population) were Corynebacterium diphtheriae (8.03 ± 0.98), Porphyromonas gingivalis (5.42 ± 2.09), Streptococcus sobrinus (5.33 ± 0.69), and Stenotrophomonas maltophilia (4.72 ± 1.73). Among the subdominant population were Eubacterium saphenum (3.85 ± 1.06), Helicobacter pylori (3.16 ± 0.62), Dialister pneumosintes (3.12 ± 1.1), Clostridium difficile (2.74 ± 0.41), Enterobacter agglomerans (2.64 ± 0.54), Salmonella enterica (2.51 ± 0.52), Mobiluncus mulieris (2.44 ± 0.6), and Klebsiella oxytoca (2.32 ± 0.66). In the population of bacteria present at the lowest mean proportions (the residual population), Bacteroides ureolyticus (0.04 ± 0.01), Haemophilus influenzae (0.04 ± 0.02), and Prevotella oris (0.01 ± 0.01) were found at the lowest mean proportions. Enterococcus faecalis was detected in the residual population (0.52 ± 0.26). CONCLUSIONS: The microbial climax community in teeth refractory to endodontic treatment not only harbors medically important species but also contains distinct microbial consortia present with different population levels.