Detection and function of lipopolysaccharide and its purified lipid A after treatment with auxiliary chemical substances and calcium hydroxide dressings used in root canal treatment

The fermentation of Cordyceps militaris polysaccharide influenced gut bacterial LPS structure formation and changed its antigenicity

Gut bacterial lipopolysaccharide (LPS) could be released into the circulatory system via the gut-liver axis and cause inflammatory immune response, while Cordyceps militaris polysaccharide (CMP40) has been reported to be effective in alleviating this inflammatory response. In this study, the effects of CMP40 gut fermentation on internal LPS structure formation and the subsequent immune response were explored. Results showed that CMP40 could change antigenicity of LPS of Vibrio parahaemolyticus, Salmonella enterica, and enterotoxigenic Escherichia coli, indicated by a reduced level of NO, IL-1β, IL-6, and TNF-α. The LPS structure of these three strains were further elucidated. ESI/MS results revealed that CMP40 fermentation could alter the LPS structure by removing phosphate group from a single Kdo sugar or removing additional sided fatty acid chain. The gene expressions of enzymes that are responsible for group transfer further confirmed this structure modification process. This study focused on the regulation of polysaccharide on gut bacteria LPS and provided a new insight into health effect of CMP40.

Antimicrobial and anti-endotoxin activity of N-acetylcysteine, calcium hydroxide and their combination against Enterococcus faecalis, Escherichia coli and lipopolysaccharides

Background

The management of endodontic infections is a complex challenge, mainly due to the involvement of diverse microorganisms and their by-products. This study aimed to evaluate the efficacy of N-acetylcysteine (NAC), calcium hydroxide (Ca(OH)2), and their combined application as intracanal medications in combating Enterococcus faecalis, Escherichia coli, and lipopolysaccharides (LPS) from E. coli.

Methods

A total of 60 single-rooted human teeth were carefully selected and divided into six groups. These tooth canals were deliberately exposed to E. faecalis (ATCC 29212) and E. coli (ATCC 25922) to induce biofilm formation. Subsequently, the specimens were treated with NAC, Ca(OH)2, or a combination of both substances. Three samples of the root canals were collected at three moments: the first sample (S1) was to confirm the initial contamination, the second sample (S2) was immediately post-instrumentation, and the third sample (S3) was collected after the use of the intracanal medication. The antimicrobial efficacy of these intracanal medications was assessed by enumerating colony-forming units per milliliter (CFU/mL). In addition to this, the kinetic chromogenic Limulus Amebocyte Lysate (LAL) assay by Lonza was used to quantify LPS from E. coli. Data tested for normality; then, Kruskal-Wallis and Friedman tests were used, and Dunn's for multiple comparisons.

Results

The findings of this study showed significant reductions in the microbial load of E. faecalis and E. coli by S3. Notably, there were no statistically significant differences among the treatment groups concerning these microorganisms. However, it was observed that only the combination of NAC and Ca(OH)2 led to a noteworthy decrease in the quantity of E. coli's LPS after 7-days, demonstrating a statistically significant difference from the other treatment groups. NAC + Ca(OH)2 combination, applied for a duration of 7-days, proved to be more suitable in reducing the presence of E. faecalis, E. coli, and LPS from E. coli within the context of endodontic infections.

VMT/ACP/Dextran composite nanosheets against dental caries through promoting mineralization of dentin tubules, pH buffering, and antibacterial

Dental caries is a worldwide public healthcare concern, and is closely related to the acidic environment that caused by bacterial decomposition of food. In this study, a two-step ion exchange liquid-phase stripping method was applied to strip out vermiculite (VMT) nanosheets, then amorphous calcium phosphate (ACP) and dextran were inserted between the VMT nanosheets interlayer to obtain a composite two-dimension nanosheets (VMT/ACP/Dextran). VMT/ACP/Dextran composite nanosheets exhibited excellent biocompatibility and could provide exogenous Ca2+and PO43- from ACP, provide SiO44-, Mg2+, Fe2+ and obtain buffering pH and antibacterial properties from VMT, as well as improve suspension stability and targeting Streptococcus mutans through glucan. The in vitro study showed that the composite materials could promote the mineralization and sealing of dentin tubules by releasing active ions, buffer pH 4.5 (a value close to the pH in the dental plaque environment) to pH 6.6-7.1 (values close to the pH in human saliva) through ion exchange, and exert antibacterial effects by targeting Streptococcus mutans and exerting oxidase like and peroxidase like activities to produce reactive oxygen species (ROS). The in vivo animal study showed that daily cleaning teeth using VMT/ACP/Dextran composite nanosheets could effectively reduce the incidence rate and severity of dental caries in rats. Taking together, the developed VMT/ACP/Dextran composite nanosheets, which integrated the excellent properties of VMT, ACP and dextran, can effectively prevent dental caries through a combination of factors such as buffering acids, antibacterial properties, and promoting calcification, and may be used as an active ingredient for daily oral hygiene or filling materials to prevent and treat dental caries.

Disinfectant effectiveness of chlorhexidine gel compared to sodium hypochlorite: a systematic review with meta-analysis

This study aimed to compare the disinfectant ability of chlorhexidine (CHX) gel and sodium hypochlorite (NaOCl). Systematic searches were conducted from inception until December 8th, 2022 (MEDLINE/PubMed, Cochrane Library, Web of Science, Scopus, Embase, and Grey Literature databases). Only randomized clinical trials were included. The revised Cochrane risk of bias tools for randomized trials were used to assess the quality of studies. Meta-analyses were performed. The overall quality of evidence was assessed through the Grading of Recommendations Assessment, Development, and Evaluation tool. Six studies were included. Five had a low risk of bias and 1 had some concerns. Three studies assessed bacterial reduction. Two were included in the meta-analysis for bacterial reduction (mean difference, 75.03 [confidence interval, CI, -271.15, 421.22], p = 0.67; I2 = 74%); and 3 in the meta-analysis for cultivable bacteria after chemomechanical preparation (odds ratio, 1.03 [CI, 0.20, 5.31], P = 0.98; I2 = 49%). Five studies assessed endotoxin reduction. Three were included in a meta-analysis (mean difference, 20.59 [CI, -36.41, 77.59], p = 0.48; I2 = 74%). There seems to be no difference in the disinfectant ability of CHX gel and NaOCl, but further research is necessary.

Irrigants and irrigation activation systems in Endodontics

Root canal infections are typically polymicrobial and involve strong bacterial interactions. The goal of endodontic treatment is to remove infected content from the root canal system to allow the healing of a pre-existing periapical lesion or to prevent infection of the periradicular tissues. Instrumentation alone is not capable of touching all of the root canal walls. Therefore, the irrigation process is an essential step in the endodontic treatment. However, due to the complex anatomy of the root canal system, this cleaning is very challenging. Although syringe and needle irrigation associated with the use of chemical substances is still the most used method, it does not guarantee optimal cleaning of the root canals. As a result, not only alternative irrigating substances but also numerous activation systems - which are technologies that aim to optimize the action of irrigating substances, both chemically and physically - have been developed. This work aimed to review the characteristics of both classic and current alternatives of irrigating substances and irrigation activation systems.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

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.

Comparison of the effectiveness of single- and multiple-sessions disinfection protocols against endotoxins in root canal infections: systematic review and meta-analysis

This systematic review (SR) addressed the following common clinical question: What is more effective in reducing or eliminating endotoxin in endodontic infections—single or multiple-session treatments using calcium hydroxide medications? Literature searches of Medline/PubMed, Embase, Cochrane Library, Scielo, Science Direct, Web of Knowledge, Scopus, and Google Scholar databases. Two reviewers independently assessed the eligibility for inclusion, extracted data, and evaluated the quality of the studies using the risk of bias tools. Electronic searches resulted in 358 articles, of which 32 studies were included for full-text assessment, and nine were included in this review. Meta-analysis pooling all the nine studies revealed lower levels of endotoxin for multiple-session treatment (P < 0.001). The sub-group analysis indicated no difference between single-session and 7 days of Ca(OH)₂ medication (SMD − 0.32; P = 0.22). However, 14-days (I² = 80.5%, P < 0.001) and 30-days (I² = 78.9%, P < 0.01) of Ca(OH)₂ medication was more effective than single-session treatment (both, p < 0.001). Overall, Overall, this SR provides evidence to support that multiple-session disinfection protocols with the placement of Ca(OH)₂ medications are more effective in reducing the levels of endotoxin from root canal infections compared to single-session when applied for 14 and 30 days.

Photosensitizers attenuate LPS-induced inflammation: implications in dentistry and general health

Antimicrobial photodynamic therapy (aPDT) is a complementary therapeutic modality for periodontal and endodontic diseases, in which Gram-negative bacteria are directly involved. Currently, there are few evidences regarding the effects of aPDT on bacterial components such as lipopolysaccharide (LPS) and it would represent a major step forward in the clinical use of this therapy. In this context, this study aimed to evaluate the efficacy of different photosensitizers (PSs) used in aPDT in LPS inhibition. Four PSs were used in this study: methylene blue (MB), toluidine blue (TBO), new methylene blue (NMB), and curcumin (CUR). Different approaches to evaluate LPS interaction with PSs were used, such as spectrophotometry, Limulus amebocyte lysate (LAL) test, functional assays using mouse macrophages, and an in vivo model of LPS injection. Spectrophotometry showed that LPS decreased the absorbance of all PSs used, indicating interactions between the two species. LAL assay revealed significant differences in LPS concentrations upon pre-incubation with the different PSs. Interestingly, the inflammatory potential of LPS decreased after previous treatment with the four PSs, resulting in decreased secretion of inflammatory cytokines by macrophages. In vivo, pre-incubating curcumin with LPS prevented animals from undergoing septic shock within the established time. Using relevant models to study the inflammatory activity of LPS, we found that all PSs used in this work decreased LPS-induced inflammation, with a more striking effect observed for NMB and curcumin. These data advance the understanding of the mechanisms of LPS inhibition by PSs.