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

Oxygen Self-Supplied Nanoplatform for Enhanced Photodynamic Therapy against Enterococcus Faecalis within Root Canals

The successful treatment of persistent and recurrent endodontic infections hinges upon the eradication of residual microorganisms within the root canal system, which urgently needs novel drugs to deliver potent yet gentle antimicrobial effects. Antibacterial photodynamic therapy (aPDT) is a promising tool for root canal infection management. Nevertheless, the hypoxic microenvironment within the root canal system significantly limits the efficacy of this treatment. Herein, a nanohybrid drug, Ce6/CaO2/ZIF-8@polyethylenimine (PEI), is developed using a bottom-up strategy to self-supply oxygen for enhanced aPDT. PEI provides a positively charged surface, which enables precise targeting of bacteria. CaO2 reacts with H2O to generate O2, which alleviates the hypoxia in the root canal and serves as a substrate for Ce6 under 660 nm laser irradiation, leading to the successful eradication of planktonic Enterococcus faecalis (E. faecalis) and biofilm in vitro and, moreover, the effective elimination of mature E. faecalis biofilm in situ within the root canal system. This smart design offers a viable alternative for mitigating hypoxia within the root canal system to overcome the restricted efficacy of photosensitizers, providing an exciting prospect for the clinical management of persistent endodontic infection.

What is the microbial profile in persistent endodontic infections? A scoping review

INTRODUCTION

This scoping review aimed to map the evidence about the microbiota found in persistent endodontic infections.

METHODS

The study protocol was prospectively registered and is available at https://osf.io/3g2cp. The electronic search was performed in MEDLINE via PubMed, Lilacs, BBO, Scopus, Web of Science, Cochrane Library and EMBASE. The eligibility criteria were based on the PCC acronym, where P (Population): patients with teeth presenting persistent endodontic infection; C (Concept): microbial profile; and C (Context): undergoing endodontic retreatment. Clinical studies that evaluated the microbial profile of samples collected from root canals of teeth undergoing retreatment, using classical or molecular methods, were included. Studies that did not show a minimum period of one year between primary endodontic treatment and retreatment or did not radiographically evaluate the quality of primary root canal filling were excluded. Two reviewers independently selected the articles and collected data.

RESULTS

From a total of 957 articles, 161 were read in full and 32 studies were included. The most prevalent species were Enterococcus faecalis, Parvimonas micra, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Dialister invisus, Propionibacterium acnes, Tannerella forsythia and Treponema denticola. Cases with symptomatology or inadequate root canal filling presented an increase in specific bacterial species compared to no symptomatology or adequate filling. A greater number of microorganisms was observed in teeth with inadequate coronal restoration compared to adequate restoration.

CONCLUSION

Persistent endodontic infections have a polymicrobial profile identified by the commonly used methods for bacterial detection/identification and are subject to the limitations present in each of those methods.

Evaluation of the rotary kinematics between actual and set speeds of X-Smart Plus, VDW.Silver and iRoot motors

The present study evaluated the actual rotational speed of three different endodontic motors compared to the values provided by the manufacturers. A total of three endodontic motors (X-Smart Plus, VDW.Silver, and iRoot) were tested at 400 rpm and 800 rpm and 2 N/cm2 torque. The kinematics of the devices was recorded by using a custom angle-measuring disc with a 50-mm diameter attached to the handpiece provided by the manufacturer, whereas their movement was captured by a high-speed camera at 2,400 frames per second, 800 x 800 pixel-resolution and distance of 0.3 m from the target object. Statistical analysis was performed at a significance level of 5%. At 400 rpm, the iRoot motor had a value of 17.94 rpm above that indicated by the manufacturer, which was significantly different from those of X-Smart Plus (5.20 rpm below that indicated by the manufacturer) and VDW.Silver (0.62 rpm above that indicated by the manufacturer) motors (P < 0.05). At 800 rpm, the iRoot motor had a value of 51.34 rpm below that indicated by the manufacturer, whereas the X-Smart Plus motor had a value of 13.00 rpm below that indicated by the manufacturer (P > 0.05). The VDW.Silver motor statistically differed from the iRoot and X-Smart Plus ones, showing a value of 1.68 rpm above that indicated by the manufacturer. In conclusion, the X-Smart Plus, VDW.Silver, and iRoot motors showed lower variations in the rotational speed values compared to those reported by their manufacturers. The endodontic motors presented different behaviors between them, with the VDW.Silver motor presents the most accurate values and the iRoot presents the most divergent values.

Ophthalmic viscoelastics commonly used in cataract surgery: A microbiota investigation

PURPOSE

To survey commonly used, sterile ophthalmic viscoelastic materials used during routine cataract surgery for the presence of bacterial DNA and/or viable bacteria and endotoxin quantification.

METHODS

Samples from three different ophthalmic viscoelastic manufacturers and three different production lots per manufacturer were collected for 16 S ribosomal ribonucleic acid (rRNA) sequencing and conventional aerobic and capnophilic bacterial culture. Other samples of viscoelastic material from the same three manufacturers were collected for endotoxin quantification using a commercially available Limulus amebocyte lysate (LAL) assay. Statistical analysis was performed using Sigma Plot 14.0, and R v4.0.2.0. Differences (p ≤ .05) between sample collection sites in total DNA concentration, microbial richness, mean intra-group distances, and endotoxin quantification alongside reagent controls were evaluated.

RESULTS

Culture yielded two isolates, identified as Staphylococcus epidermidis and Bacillus megaterium. 16 S rRNA sequencing revealed no differences between brands in richness or overall composition. The most common bacterial DNA detected across all brands was Staphylococcus sp., Cutibacterium sp., Flavobacterium sp., and Lactobacillus sp. A significant difference was found between the median endotoxin concentration between Anvision and Hyvisc® viscoelastic (Anvision: 0.171 EU/mL, Hyvisc®: 0.03 EU/mL; p < .001).

CONCLUSIONS

No brand-specific differences in bacterial DNA were detected in the viscoelastic materials. Staphylococcus, Cutibacterium, Flavobacterium, and Lactobacillus were the dominant contributors to the bacterial DNA detected. Although Anvision viscoelastic samples contained significantly more endotoxin than Hyvisc® viscoelastic samples, endotoxin concentrations were below the FDA limit of 0.2 EU/mL for both manufacturers. These data further the understanding of inflammatory outcomes following cataract surgery.

Detoxification of LTA by intracanal medication: analysis by macrophages proinflammatory cytokines production

The aim of this study was to evaluate in vitro the effect of calcium hydroxide [Ca(OH)2], 2% chlorhexidine gel (CHX) on macrophages (RAW 264.7) to produce pro-inflammatory cytokines and nitric oxide after pretreatment with lipoteichoic acid (LTA) of Enterococcus faecalis. Forty-eight human single-rooted teeth were instrumented with R25.08 (RECIPROC) and sterilized by gamma irradiation. LTA was inoculated in the root canal of each specimen for 96 hours. Specimens were instrumented with 40.06 and 50.05 (RECIPROC) and medicated with: I) Pyrogen-free saline solution (SS); II) 2% CHX gel; III) Ca(OH)2 + SS; or IV) Ca(OH)2 + CHX for 14 days. Three samples (S) were performed of the root canal of each specimen at: S1) immediately after instrumentation; S2) after Ethylenediaminetetraacetic acid (EDTA); S3) after intracanal medication removal. Subsequent quantification of cytokines (IL-1β, TNF-α, MIP-1α, IP-10, G-CSF and IL-6) by immunosorbent assay (ELISA) and nitric oxide by the Griess method was carried-out. Data were submitted to a normality test and then analyzed with one-way ANOVA and Tukey test with a significance level of 5% using GraphPad Prism 6. Ca(OH)2 + SS and Ca(OH)2 + CHX presented lower levels of TNF-α, TNF-α, IL-6, G-CSF and nitric oxide. Ca(OH)2 + SS was the most effective in reducing MIP-1α. CHX was effective in reducing IL-6 and G-CSF. Therefore, the combined intracanal medication of calcium hydroxide and chlorhexidine is effective in reducing the cytokines TNF-α, IL-1β, IL-6, G-CSF and nitric oxide.

Efficacy of 6% Sodium Hypochlorite on Infectious Content of Teeth with Symptomatic Irreversible Pulpitis

INTRODUCTION

The objective of this study was to monitor the effects of chemomechanical preparation (CMP) performed with 6% sodium hypochlorite and calcium hydroxide-based intracanal medication (ICM) on the levels and diversity of bacteria, endotoxins (LPS) and lipoteichoic acid (LTA) in root canals of teeth with symptomatic irreversible pulpitis.

METHODS

Samples were collected from ten teeth with symptomatic irreversible pulpitis before CMP (S1), after CMP (S2) and after ICM (S3). The levels of bacteria, LPS and LTA were assessed by using checkerboard DNA-DNA hybridisation, LAL Pyrogent 5000 and enzyme linked immunosorbent assay (ELISA), respectively. Wilcoxon's test, repeated measures ANOVA and Tukey's post-hoc test were used for statistical analysis at a significance level of 5%.

RESULTS

Forty species were detected at S1. Two species were eliminated after CMP and five after ICM. Resistant and pain-related species were detected in the root canals. Higher levels of culturable bacteria were detected at S1. However, CMP and ICM effectively reduced the microbial load in the root canals. Higher levels of LPS and LTA were detected at S1. CMP was effective in reducing both LPS and LTA (P < 0.05). ICM produced additional reduction in the levels of LPS (P > 0.05) and LTA (P < 0.05).

CONCLUSION

Chemomechanical preparation using 6% sodium hypochlorite and calcium hydroxide-based intracanal medication were effective in reducing the levels of bacteria, endotoxins and lipoteichoic acid in teeth with vital pulp and irreversibly inflamed pulp.

Bacteria and virulence factors in periapical lesions associated with teeth following primary and secondary root canal treatment

AIM

This cross-sectional study aimed to investigate the microbial profile and to quantify the levels of endotoxins (LPS) and lipoteichoic acid (LTA) present in periapical lesions associated with root filled teeth and those that had received root canal retreatment. It also aimed to investigate the association between microorganisms and their virulence factors with clinical and radiographic features.

METHODOLOGY

Patients with periapical lesions in teeth with post-treatment endodontic disease following primary root canal treatment (n = 19) and unsuccessful root canal retreatment (n = 13) were treatment planned for endodontic microsurgery, where the periapical lesions were collected. Clinical and radiographic data were also collected. For microbiological analysis, nested polymerase chain reaction was used to detect 17 bacterial species. Levels of LPS and LTA were determined using limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively. The Student t-test or Wilcoxon-Mann-Whitney tests were applied to compare the data on LPS and LTA with clinical and radiographic features. The associations between the clinical and radiographic features and the bacterial species were analysed using the Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Bacterial DNA, LPS and LTA were detected in all samples. Parvimonas micra was the most commonly detected species in all groups, followed by Enterococcus faecalis, Fusobacterium nucleatum and Porphyromonas endodontalis. The type of endodontic treatment, whether a primary root canal treatment or retreatment, was not associated with the presence of any bacterial species in periapical lesions. The levels of LPS and LTA in periapical lesions of root filled teeth were not significantly different from those that had been retreated. Associations between the levels of LPS and LTA with clinical signs and symptoms were found. No association was found between specific bacteria and clinical features.

CONCLUSION

Periapical lesions associated with teeth after primary root canal treatment and retreatment had similar polymicrobial composition. The levels of LPS and LTA in periapical lesions associated with teeth after primary root canal treatment and retreatment were similar, and both were associated with the same symptomatology.

Microbiological Investigation in Teeth with Persistent/Secondary Endodontic Infection in Different Stages of Root Canal Retreatment

Objective:

The present clinical study investigated the microbiota of teeth with persistent secondary endodontic infection in the different phases of root canal retreatment.

Methods:

Twenty filled single-rooted teeth with apical periodontitis were included. Samples were collected with sterile paper points before chemo-mechanical preparation (CMP) (S1), after CMP (S2) and after 30 days of calcium hydroxide-based intracanal medication (ICM) (S3). Cultivable bacteria were assessed by colony forming units count (CFU/mL). DNA was extracted and assessed by using nested PCR. Paired t-test and repeated measures ANOVA were applied for intragroup analysis in the stages of endodontic therapy at a significance level of 5%.

Results:

Cultivable bacteria were detected in all initial samples. CMP reduced bacteria by 99.4% and ICM by 99.5%. The most prevalent species found in the initial samples were E. faecalis (20/20), P. gingivalis (20/20), F. nucleatum (17/20) and A. actinomycetemcomitans (10/20), whereas D. pneumosintes, F. alocis, P. nigrescens and T. socranskii were not detected. After CMP, A. israelii, A. naeslundii, G. morbillorum, T. forsythia and T. denticola were not detected (P<0.05) either. E. faecalis and P. gingivalis had a low reduction (P>0.05) and F. nucleatum had its DNA significantly reduced after CMP (P<0.05). ICM had no additional effect on microbial reduction.

Conclusion:

The microbiota of teeth with persistent/secondary endodontic infection consists of a polymicrobial community with Gram-positive and Gram-negative species, bacillus and cocci, facultative and strict anaerobes. E. faecalis and P. gingivalis were frequently detected in all stages of root canal retreatment, evidencing their great resistance to endodontic procedures. The endodontic procedures were effective in reducing the levels of bacteria from teeth presenting with persistent/secondary endodontic infection.

Investigation of microbial profile, levels of endotoxin and lipoteichoic acid in teeth with symptomatic irreversible pulpitis: a clinical study

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.

Microbiological analysis of endodontically treated teeth with apical periodontitis before and after endodontic retreatment

OBJECTIVE

To characterize the microbiota of teeth with endodontic treatment failure by 16S ribosomal RNA genetic sequencing (GS) and PCR at the different phases of the endodontic retreatment and to associate the presence of specific bacteria with clinical and radiographic features in teeth with apical periodontitis.

MATERIALS AND METHODS

Twenty infected root canals of single-rooted teeth were selected. Samples were collected with sterile paper points before chemo-mechanical preparation (CMP) (S1), after CMP (S2) and after 30 days of intracanal medication (ICM) (S3). Microbial identification was performed using GS and PCR. Tukey-Kramer post hoc test and post hoc ANOVA were used for intergroup analysis. Paired t test and repeated-measures ANOVA were applied for intragroup analysis, at a significance level of 5%.

RESULTS

A total of 89 strains were identified using GS. Sixty-five strains were recovered in S1 and 15 strains in S2, and 9 strains remained in S3. Enterococcus faecalis was the most predominant bacteria. Gram-positive cocci bacteria predominated. Gram-negative species were also detected. Using species-specific PCR primers to detect seven species, the most prevalent ones at all the phases of the endodontic retreatment were E. faecalis and Porphyromonas gingivalis. However, Parvimonas micra and P. gingivalis were associated with previous pain, P. gingivalis was associated with tenderness to percussion and E. faecalis, Fusobacterium nucleatum and P. gingivalis were associated with periapical lesion > 3 mm.

CONCLUSIONS

In conclusion, the microbiota of persistent infection is polymicrobial with predominance of E. faecalis and P. gingivalis in all phases of the endodontic retreatment, regardless of the method used for microbial identification. Associations were found between specific bacteria and clinical/radiographic features.

CLINICAL RELEVANCE

The characterization of the bacteria present at all phases of the endodontic retreatment is important for the monitoring of the effectiveness of the techniques used and to better understand the susceptibility of these species to the disinfection agent used during the procedures.

Effect of sodium hypochlorite solution and gel with/without passive ultrasonic irrigation on Enterococcus faecalis, Escherichia coli and their endotoxins

Background: Sodium hypochlorite (NaOCl) is the most commonly used irrigant in endodontics . The purpose of this study was to evaluate the effect of NaOCl solution (2.5%) and gel (3%) with/without passive ultrasonic irrigation (PUI) on Enterococcus faecalis, Escherichia coli, and their endotoxins, lipopolysaccharide (LPS) and lipoteichoic acid (LTA).

Methods: 40 human lower premolars were contaminated with E. coli (ATCC 25922) for 28 days and E. faecalis (ATCC 29212) for 21 days. Specimens were randomly divided into four groups: (1) 2.5% NaOCl irrigating the canals without PUI activation; (2) 2.5% NaOCl with PUI; (3) 3% NaOCl gel irrigating the canals without PUI; and (4) 3% NaOCl gel with PUI. 40 mL of irrigant was used for each group. PUI activation was carried out using E1-Irrisonic stainless-steel tip at 10% frequency. After treatment, all specimens were filled with 3mL of 17% ethylenediaminetetraacetic acid (EDTA) for 3min and then washed with nonpyrogenic saline solution. Three samples were collected from the canals: S1, at baseline to confirm biofilm formation; S2 after treatment; and S3 after EDTA. Samples were assessed for E. coli and E. faecalis colony forming units, and LPS and LTA were assessed using chromogenic kinetic LAL assay and ELISA, respectively. Data were analyzed by Kruskal-Wallis, Friedmann and Dunn tests with α≤0.05.

Results: All groups were effective in reducing the microbial load of E. coli and E. faecalis after treatment without a significant difference among the groups. NaOCl and NaOCl gel groups had no significant difference in reducing LPS and LTA. Statistically increased reduction was seen for NaOCL + PUI and NaOCl gel + PUI compared for groups without PUI.

Conclusions: NaOCl gel has the same antimicrobial action of NaOCl solution and can partially detoxify endotoxins. PUI improves NaOCl (gel or solution) action over E. faecalis and E. coli and their endotoxins.

Participation of endotoxin in root canal infections: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the relationship between endotoxin levels and presence of clinical signs/symptoms and radiographic features in patients with endodontic infection. Electronic searches were performed on Medline/PubMed, Embase, Cochrane Library, Scielo, Science Direct, Web of Knowledge and Scopus databases for identification of relevant studies published up to December 2016. Grey literature was searched in Google Scholar. The selected literature was reviewed independently by two authors. Clinical studies evaluating the levels of endotoxin and the presence of clinical and radiographic features were included in this review. In order to determine the relationship between endotoxin levels and presence of clinical signs/symptoms and radiographic features meta-analyses were performed. Among the 385 articles identified in the initial search, 30 were included for full-text appraisal and only eight studies met the inclusion criteria for this systematic review. Meta-analysis revealed that individuals having teeth with tenderness to percussion (TTP) (P = 0.04; I² 57%) and previous episode of pain (PEP) (P = 0.001; I² 81%) had higher levels of endotoxin than their counterparts. Size of radiographic lesion >2 mm (P = 0.02; I² 68%) and presence of root canal exudation (EX) (P = 0.0007; I² 0%) were associated with higher levels of endotoxin. This systematic review and meta-analyses provided a strong evidence that endotoxin are related with the presence of clinical signs/symptoms and radiographic features in patients with endodontic infection.

Etiologic role of root canal infection in apical periodontitis and its relationship with clinical symptomatology

Evidence shows the polymicrobial etiology of endodontic infections, in which bacteria and their products are the main agents for the development, progression, and dissemination of apical periodontitis. Microbial factors in necrotic root canals (e.g., endotoxin) may spread into apical tissue, evoking and supporting a chronic inflammatory load. Thus, apical periodontitis is the result of the complex interplay between microbial factors and host defense against invasion of periradicular tissues. This review of the literature aims to discuss the complex network between endodontic infectious content and host immune response in apical periodontitis. A better understanding of the relationship of microbial factors with clinical symptomatology is important to establish appropriate therapeutic procedures for a more predictable outcome of endodontic treatment.

Bacterial species associated with persistent apical periodontitis exert differential effects on osteogenic differentiation

AIM

To determine if bacteria associated with persistent apical periodontitis induce species-specific pro-inflammatory cytokine responses in macrophages, and the effects of this species-specific microenvironment on osteogenic differentiation.

METHODOLOGY

Macrophages were exposed to Enterococcus faecalis, Streptococcus oralis, Streptococcus mitis, Fusobacterium nucleatum, Treponema denticola or Tannerella forsythia, and levels of TNF-α and IL-1β elicited were determined by immunoassay. Following treatment of MG-63 pre-osteoblasts with conditioned media from bacteria-exposed macrophages, osteogenic differentiation and viability of osteoblasts were analyzed by Alizarin Red Staining and MTS assay, respectively. Statistical analysis was carried out by one-way anova with the Tukey post-hoc test. Differences were considered to be significant if P < 0.05.

RESULTS

Macrophages exposed to Gram-positive bacteria did not produce significant amounts of cytokines. F. nucleatum-challenged macrophages produced up to four-fold more TNF-α and IL-1β compared to T. denticola or T. forsythia. Only conditioned media from macrophages treated with Gram-negative bacteria decreased mineralization and viability of osteoblasts.

CONCLUSIONS

Gram-positive bacteria did not impact osteogenic differentiation and appeared innocuous. Gram-negative bacteria, in particular F. nucleatum elicited an enhanced pro-inflammatory response in macrophages, inhibited osteogenic differentiation and reduced cell viability. The findings suggest that the presence of this organism could potentially increase the severity of persistent apical periodontitis.

Investigation of Bacterial Contents From Persistent Endodontic Infection and Evaluation of Their Inflammatory Potential

This clinical study investigated and quantified cultivable bacteria and their levels of endotoxins in persistent endodontic infection, determining their antigenicity against macrophages and fibroblast cells by IL-1β and TNF-α secretion and evaluating their relationship with clinical and radiographic features. Samples from the root canals were obtained after root filling removal. Culture techniques were used to determine the bacterial count and the endotoxins were determined by LAL-assay. PCR analysis (16S rDNA) was used for bacterial detection. Raw 264.5 macrophages and V79 fibroblast were stimulated with endodontic contents. ELISA assay measured the amounts of IL-1ß/TNF-?#61537; secretion. Bacteria and endotoxin medians were 1.24x105 CFU/mL and 9.62 EU/mL, respectively. Porphyromonas endodontalis was the most frequently detected species. Higher levels of endotoxins were found in teeth with pain on palpation (23.56 EU/mL) rather than in its absence (8.21 EU/mL). Larger areas of bone destruction were related to higher levels of endotoxins and IL-1β and TNF-α secretion. The study findings revealed the presence of Gram-negative bacteria species in persistent endodontic infection, with their endotoxins related to both severity of bone destruction and development of symptomatology. Moreover, larger areas of bone destruction were related to higher levels of IL-1β and TNF-α secreted by macrophages and fibroblast cells.

Root Canal Irrigation: Chemical Agents and Plant Extracts Against Enterococcus faecalis

BACKGROUND

There are various microorganisms related to intra and extra-radicular infections and many of these are involved in persistent infections. Bacterial elimination from the root canal is achieved by means of the mechanical action of instruments and irrigation as well as the antibacterial effects of the irrigating solutions. Enterococcus faecalis can frequently be isolated from root canals in cases of failed root canal treatments. Antimicrobial agents have often been developed and optimized for their activity against endodontic bacteria. An ideal root canal irrigant should be biocompatible, because of its close contact with the periodontal tissues during endodontic treatment. Sodium hypoclorite (NaOCl) is one of the most widely recommended and used endodontic irrigants but it is highly toxic to periapical tissues.

OBJECTIVES

To analyze the literature on the chemotherapeutic agent and plant extracts studied as root canal irrigants. In particularly, the study is focused on their effect on Enterococcus faecalis.

METHOD

Literature search was performed electronically in PubMed (PubMed Central, MEDLINE) for articles published in English from 1982 to April 2015. The searched keywords were "endodontic irrigants" and "Enterococcus faecalis" and "essential oil" and "plant extracts".

RESULTS

Many of the studied chemotherapeutic agents and plant extracts have shown promising results in vitro.

CONCLUSION

Some of the considered phytotherapic substances, could be a potential alternative to NaOCl for the biomechanical treatment of the endodontic space.

Avaliação da suscetibilidade antimicrobiana de bactérias anaeróbias facultativas isoladas de canais radiculares de dentes com insucesso endodôntico frente aos antibióticos de uso sistêmico

<title>Resumo</title><sec><title>Introdução</title><p>Bactérias associadas ao insucesso do tratamento endodôntico são capazes de adquirir e expressar resistência aos agentes antimicrobianos comumente empregados para tratar infecções, o que torna necessário, em determinadas situações, a realização de testes laboratoriais para detectar a resistência ou a suscetibilidade antimicrobiana desses micro-organismos.</p></sec><sec><title>Objetivo</title><p>avaliar a suscetibilidade antimicrobiana das cepas de <italic>Enterococcus faecalis</italic>, <italic>Enterococcus faecium</italic>, <italic>Actinomyces viscosus</italic> e <italic>Staphylococcus aureus</italic> isoladas de canais radiculares de dentes com insucesso endodôntico.</p></sec><sec><title>Material e método</title><p>Cepas clínicas de <italic>Enterococcus faecalis</italic> (n=3), <italic>Enterococcus faecium</italic> (n=3), <italic>Actinomyces viscosus</italic> (n=3) e <italic>Staphylococcus aureus</italic> (n=3), coletadas in vivo de canais radiculares com insucesso endodôntico, foram testadas quanto à suscetibilidade antimicrobiana por meio do método E-test em duplicata, utilizando os antibióticos: Amoxicilina (AC), Rifampicina (RI), Moxifloxacina (MX), Vancomicina (VA), Tetraciclina (TC), Ciprofloxacina (CI), Cloranfenicol (CL), Benzilpenicilina (PG), Amoxicilina + ácido clavulânico (XL), Doxiciclina (DC), Eritromicina (EM) e Azitromicina (AZ).</p></sec><sec><title>Resultado</title><p>Todas as cepas clínicas testadas foram suscetíveis aos antibióticos AC, XL, PG, DC, MX, TC e VA. Todos os isolados das espécies de <italic>S. aureus</italic> foram suscetíveis aos 12 antibióticos testados. As cepas de <italic>E. faecalis</italic>, <italic>E. faecium</italic> e <italic>A. viscosus</italic> mostraram padrão de suscetibilidade intermediário contra EM. Algumas cepas de <italic>E. faecalis</italic> e <italic>E. faecium</italic> foram resistentes a AZ e RI.</p></sec><sec><title>Conclusão</title><p>As cepas clínicas isoladas dos canais radiculares de dentes com insucesso endodôntico mostraram perfis diferentes de suscetibilidade antimicrobiana e nenhum isolado de <italic>E. faecalis</italic> e <italic>E. faecium</italic>apresentou-se suscetível a AZ e EM.</p></sec>

Chlorhexidine in Endodontics

Chemical auxiliary substances (CAS) are essential for a successful disinfection and cleanness of the root canals, being used during the instrumentation and if necessary, as antimicrobial intracanal medicaments. Different CAS have been proposed and used, among which sodium hypochlorite (NaOCl), chlorhexidine (CHX), 17% EDTA, citric acid, MTAD and 37% phosphoric acid solution. CHX has been used in Endodontics as an irrigating substance or intracanal medicament, as it possesses a wide range of antimicrobial activity, substantivity (residual antimicrobial activity), lower cytotoxicity than NaOCl whilst demonstrating efficient clinical performance, lubricating properties, rheological action (present in the gel presentation, keeping the debris in suspension); it inhibits metalloproteinase, is chemically stable, does not stain cloths, it is odorless, water soluble, among other properties. CHX has been recommended as an alternative to NaOCl, especially in cases of open apex, root resorption, foramen enlargement and root perforation, due to its biocompatibility, or in cases of allergy related to bleaching solutions. The aim of this paper is to review CHX's general use in the medical field and in dentistry; its chemical structure, presentation form and storage; mechanism of action; antimicrobial activity including substantivity, effects on biofilms and endotoxins, effects on coronal and apical microbial microleakage; tissue dissolution ability; interaction with endodontic irrigants; effects on dentin bonding, metalloproteinases and collagen fibrils; its use as intracanal medicament and diffusion into the dentinal tubules; its use as disinfectant agent of obturation cones; other uses in the endodontic therapy; and possible adverse effects, cytotoxicity and genotoxicity.