Faecalis Biofilm Research Articles

Effect of eucalyptus oil on Streptococcus mutans and Enterococcus faecalis growth

ObjectivesThere is a significant apprehension in medicine and dentistry concerning the emergence of antibiotic-resistant pathogens, as it composes a significant threat to global health, particularly oral health. The growing concern that oral pathogens may develop resistance against standard preventive measures raises the need for alternative measures to prevent these pathogens’ growth without inducing microbial resistance. Therefore, this study aims to assess the antibacterial properties of eucalyptus oil (EO) against two main oral disease pathogens, Streptococcus mutans, and Enterococci faecalis.MethodsS. mutans and E. faecalis biofilms were initiated using brain-heart infusion (BHI) broth supplemented with 2% sucrose with and without diluted EO. After 24 h of biofilm formation, total absorbance was measured via spectrophotometer; then, the biofilm was fixed, stained with crystal violet dye, and measured at 490 nm. An Independent t-test was used to compare the outcomes.ResultsDiluted EO revealed significant total absorbance reduction against S. mutans and E. faecalis compared to the control (p ≤ 0.001). For the biofilm measurement, S. mutans and E. faecalis biofilms were reduced by around 60- and 30-fold, respectively, compared to the group with no EO (p ≤ 0.001).ConclusionBased on this study’s results, using EO as an organic compound could be considered an adjunctive tool in preventing the growth of oral pathogens causing dental caries and endodontic infection.

Pengaruh ekstrak daun jambu biji (psidium guajava linn.) Terhadap biofilm enterococcus faecalis

Background: Enterococcus faecalis biofilm is one of the causes of root canal treatment failure. The success of root canal treatment is achieved by mechanical and chemical functions. Irrigation is the only way to reach areas of the root canal wall that instrumentation cannot reach. Guava (Psidium guajava Linn.) leaves contain compounds such as flavonoids, saponins, tannins, triterpenoids and essential oils which have antibacterial properties. Objective: To determine the anti-biofilm effect of guava leaf extract (Psidium guajava Linn.) on Enterococcus faecalis Methods: Microdilution method laboratory experimental study using Enterococcus faecalis ATCC 29212 culture with P. guajava leaf extract assay concentrations of 100%, 80%, 60%, 40% and 20%. Results: In testing P. guajava leaf extract against E. faecalis biofilm, it was found that 60% concentration had the highest inhibition. Conclusion: Guava leaf extract (Psidium guajava Linn.) effectively inhibits Enterococcus faecalis biofilm growth.

Comparative assessment of antibacterial effect of two types of laser and their effect on morphology and mineral content of dentin

Background/aim Scientists have proven that the main cause of endodontic diseases and failures is the existence of micro-organisms in the root canals and inside the dentinal tubules. So the aim of the study was to compare the antibacterial effect of Erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser and diode laser 980 nm alone and in combination with 5.25% sodium hypochlorite (NaOCl) irrigant against Enterococcus faecalis biofilm and also compare their effect on the morphology and mineral content of root canal dentin by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. Materials and methods The specimens used in our study were fifty four extracted human single-rooted teeth. They were collected from the Dental Department of the Research Institute of Ophthalmology, Egypt. Mechanical preparation was done to all teeth after their crowns were removed. They were autoclaved, and after that, they were inoculated with Enterococcus faecalis for 30 days. Roots were divided into six groups (each=9) according to type of treatment. Group A: 5.25% NaOCl, group B: Er,Cr:YSGG laser, group C: 5.25% NaOCl and Er,Cr:YSGG laser, group D: diode laser 980 nm, group E: 5.25% NaOCl and diode laser 980 nm, in addition to control group: saline. Their antibacterial effect was assessed before and after treatment. Changes in the morphology and mineral content of root canal dentin were assessed by SEM and EDX. Statistical analysis was done. Results Group C had significantly the highest percentage of Enterococcus faecalis reduction (98.95%), followed by group E (98.04%), then group D (95.27%), then group A (94.65%), then group B (92.99%), while the control group had significantly the lowest percentage of Enterococcus faecalis reduction (0.22%). Regarding SEM results, group B and group D exhibited score 1 (88.9%), control group and group C score 3 (77.8%), group A score 4 (88.9%), and group E score 5 (88.9%). Regarding EDX results, group B was significantly the lowest in Ca/P ratio, while there was an insignificant difference between other groups. Conclusions Er,Cr:YSGG laser, and diode laser, when used without 5.25% NaOCl irrigant, produced less morphological changes to dentinal tubules, but when combined with 52.5% NaOCl irrigant, produced more antibacterial effect against Enterococcus faecalis. Lasers alone or combined with 5.25% NaOCl irrigant produced changes in the mineral content of root canal dentin.

Antimicrobial Efficacy of Sodium Hypochlorite and Er, Cr: YSGG Laser against E Faecalis Biofilm - A Systematic Review

Background: The complexity of the root canal system makes it difficult to completely disinfect is the leading cause for endodontic retreatment. Sodium hypochlorite (NaOCl) is the traditionally used irrigation solution and has improved its efficacy with various adjuncts. The use of lasers in disinfecting the canal system has come into prominence in recent years. Aim: To assess the efficacy of sodium hypochlorite and Er, Cr: YSGG laser against E faecalis biofilm. Methodology: A systematic search was conducted using a search strategy in PubMed and Google scholar for studies published between 1st January 2011 and 21st March 2022. Hand searching of relevant articles in Institutional library was also performed. Comparative in vitro studies in English language or articles in other languages which had a possibility of translation into English comparing sodium hypochlorite and Er, Cr: YSGG laser for irrigation against E faecalis biofilm were included in the review whereas, studies comparing efficacy against biofilm other than E faecalis, comparison with other laser activated intracanal irrigation, data reported through letter to editors, short communications and conference proceedings were excluded from the review. Results: A preliminary search yielded a total of 67 studies of which seven articles giving 11 estimates were included for qualitative synthesis. Data on colony forming units for both the groups (sodium hypochlorite and Er, Cr: YSGG laser) was extracted. Overall, four studies presented significant difference in the effectiveness of sodium hypochlorite and Er, Cr: YSGG laser whereas three studies presented with no difference among the two groups. Conclusion: Irrigation of root canal by sodium hypochlorite and Er, Cr: YSGG laser activation both prove to be effective in reducing the E faecalis colony forming units. However, it is difficult to provide a conclusive statement on the superiority of Er, Cr: YSGG laser activated irrigation over sodium hypochlorite solution as half of the studies gave contrasting results. Future studies with larger sample size on complex anatomical root structure are recommended.

The Evaluation of SWEEPS Plus Antimicrobial Photodynamic Therapy with Indocyanine Green in Eliminating Enterococcus faecalis Biofilm from Infected Root Canals: An In Vitro Study.

This study aimed to assess the efficacy of shockwave-enhanced emission photoacoustic streaming (SWEEPS) plus antimicrobial photodynamic therapy (aPDT) using indocyanine green (ICG) for the elimination of Enterococcus faecalis biofilm from infected root canals. thirty sound human single-canal teeth were chosen and standardized to have 12 mm of root length. The root canals were shaped and prepared by means of ProTaper rotary files. After sterilization of the teeth, the canals were inoculated with E. faecalis for 2 weeks. The teeth were then randomly divided into six groups (n = five) of control, ICG, ICG + 808 nm diode laser, ICG + SWEEPS, ICG + 808 nm diode laser + SWEEPS, and 5.25% sodium hypochlorite (NaOCl). Following treatment, the number of colony-forming units (CFUs)/mL were calculated for each group. Statistical analysis was carried out using one-way ANOVA. For multiple comparisons, Tukey's test was used as the post hoc test. NaOCl alone showed the highest efficacy (p < 0.001). The ICG + 808 nm diode laser + SWEEPS group displayed significantly lower amounts of bacteria than either the ICG + 808 nm diode laser or SWEEPS (p < 0.001). There was a statistically significant difference detected between the ICG + 808 nm diode laser and ICG + SWEEPS (p = 0.035). SWEEPS can effectively increase the photosensitizer distribution in the root canal space, and its application along with irrigants can bring about promising results.

Effect of Enterococcus faecalis Biofilm on Corrosion Kinetics in Titanium Grade 4 Alloys with Different Surface Treatments.

E. faecalis has been associated with bacteremia, sepsis, and bacterial endocarditis and peri-implantitis. This microorganism can remain in the alveolus even after extraction of the root remnant. This study aimed to evaluate the corrosion on different surfaces of commercially pure titanium (Ti) grade 4 (Ticp-G4) as a function of the bacterial biofilm effect of Enterococcus faecalis. A total of 57 discs were randomly divided according to their surface finish (n = 19). For microbiological analysis (n = 9), the discs were placed in 12-well plates containing E. faecalis culture and incubated at 37 °C for 7 days. The results show that for the intergroup analysis, considering the "electrolyte" factor, there was a difference between the groups. There was greater biofilm formation for the D.A.Zir group, with greater electrochemical exchange for Biofilm, and the presence of biofilm favored greater electrochemical exchange with the medium.

Cinnamaldehyde inhibits Enterococcus faecalis biofilm formation and promotes clearance of its colonization by modulation of phagocytes in vitro

The nosocomial pathogen, Enterococcus faecalis plays a crucial role in the pathogenesis of variety of infections including endocarditis, urinary tract, and recurrent root canal infections. Primary virulence factors of E. faecalis such as biofilm formation, gelatinase production and suppression of host innate immune response can severely harm host tissue. Thus, novel treatments are needed to prevent E. faecalis biofilm development and pathogenicity due to the worrisome rise in enterococcal resistance to antibiotics. The primary phytochemical in cinnamon essential oils, cinnamaldehyde, has shown promising efficacy against a variety of infections. Here, we looked into how cinnamaldehyde affected the growth of biofilms, the activity of the enzyme gelatinase, and gene expression in E. faecalis. In addition, we looked at the influence of cinnamaldehyde on RAW264.7 macrophages' interaction with biofilm and planktonic E. faecalis in terms of intracellular bacterial clearance, NO generation, and macrophage migration in vitro. According to our research, cinnamaldehyde attenuated the biofilm formation potential of planktonic E. faecalis and gelatinase activity of the biofilm at non-lethal concentrations. The expression of the quorum sensing fsr locus and its downstream gene gelE in biofilms were also found to be significantly downregulated by cinnamaldehyde. Results also demonstrated that cinnamaldehyde treatment increased NO production, intracellular bacterial clearance, and migration of RAW264.7 macrophages in presence of both biofilm and planktonic E. faecalis. Overall these results suggest that cinnamaldehyde has the ability to inhibit E. faecalis biofilm formation and modulate host innate immune response for better clearance of bacterial colonization.

Effect of the association of different substances at the physical and antimicrobial properties of the EDTA

We aimed to assess the physical, chelating, antibacterial properties and cytotoxicity of EDTA used with and without antibacterial additives. Material and methods: Solutions of 17% EDTA with or without additives together with 2.5% sodium hypochlorite and saline control were tested. The antibacterial properties of the solutions were assessed using a biofilm which was inoculated in human dentine either before exposure to irrigating solution or after. The smear layer removal capacity was tested by using scanning electron microscopy (SEM). The irrigants were also evaluated for dentine wettability by the sessile drop method, and the surface tension of solutions was verified by the pendent drop test. The effect of irrigating solutions on fibroblast cell viability was assessed by reducing MTT assay. Results: The addition of antibacterial substances to EDTA resulted in improving its antibacterial action against Enterococcus faecalis biofilm, without compromising the EDTA chelating action or elevating its cytotoxicity. Lower surface tension and better wettability of the irrigants was obtained by sodium hypochlorite or by adding benzalkonium chloride or N-acetylcysteine to EDTA. Conclusion: EDTA-benzalkonium chloride showed effectiveness not only preventing the formation of biofilm and root canal re-infection, but also against Enterococcus faecalis biofilm itself. It also lowered EDTA surface tension and allowed better dentine wettability, being outstanding compared with the other chelator solutions. Therefore, the use of this association as a final rinse in endodontic treatment should be further studied.

Gram-negative quorum sensing signalling enhances biofilm formation and virulence traits in gram-positive pathogen Enterococcus faecalis

ABSTRACT Acyl-homoserine lactones (AHLs) are typical quorum-sensing molecules of gram-negative bacteria. Recent evidence suggests that AHLs may also affect gram-positives, although knowledge of these interactions remains scarce. Here, we assessed the effect of AHLs on biofilm formation and transcriptional regulations in the gram-positive Enterococcus faecalis. Five E. faecalis strains were investigated herein. Crystal violet was employed to quantify the biomass formed, and confocal microscopy in combination with SYTO9/PI allowed the visualisation of biofilms’ structure. The differential expression of 10 genes involved in quorum-sensing, biofilm formation and stress responses was evaluated using reverse-transcription-qPCR. The AHL exposure significantly increased biofilm production in strain ATCC 29212 and two isolates from infected dental roots, UmID4 and UmID5. In strains ATCC 29212 and UmID7, AHLs up-regulated the quorum-sensing genes (fsrC, cylA), the adhesins ace, efaA and asa1, together with the glycosyltransferase epaQ. In strain UmID7, AHL exposure additionally up-regulated two membrane-stress response genes (σV, groEL) associated with increased stress-tolerance and virulence. Altogether, our results demonstrate that AHLs promote biofilm formation and up-regulate a transcriptional network involved in virulence and stress tolerance in several E. faecalis strains. These data provide yet-unreported insights into E. faecalis biofilm responses to AHLs, a family of molecules long-considered the monopole of gram-negative signalling.

Effectiveness of katuk leaf chlorophyll (Sauropus androgynus (L) Merr) with blue and red laser a ctivation to reduce Aggregatibacter actinomycetemcomitans and Enterococcus faecalis biofilm

In this study, the efficacy of using Sauropus androgynus (L) Merr, a katuk leaf chlorophyll photosensitizer, to reduce Aggregatibacter actinomycetemcomitans and Enterococcus faecalis biofilm was investigated. A red and blue diode laser is used as the light source. The sample was split into four groups: a negative control group, a positive control group, a blue laser treatment group (B), and a red laser treatment group (R), both with and without the addition of katuk leaf chlorophyll 1.6 mg/ml, and with varying densities of laser energy exposure of 2.5 J/cm2, 5 J/cm2, 7.5 J/cm2, and 10 J/cm2. Laser exposure and chlorophyll photosensitizer were tested using ELISA and ANOVA. At an energy density of 10 J/cm2, the optimal bacterial mortality rate was obtained in each treatment group. Namely, in the Aggregatibacter actinomycetemcomitans biofilm, the negative group, the number of deaths was 73.30% using a blue diode laser and 63.25% using a red diode laser. In the positive group, the number of deaths was 86.12% using a blue diode laser and 83.29% using a red diode laser. In the Enterococcus faecalis biofilm, in the negative group, the number of deaths was 67.78% using the blue diode laser and 75.33% using the red diode laser, and in the positive group, the number of deaths was 71.71% using the blue diode laser and 86.41 using a red diode laser. Exposure to blue and red diode lasers activates chlorophyll in katuk leaves, killing bacteria and reducing biofilms.

Effect of Essential Oils of Apiaceae, Lamiaceae, Lauraceae, Myrtaceae, and Rutaceae Family Plants on Growth, Biofilm Formation, and Quorum Sensing in Chromobacterium violaceum, Pseudomonas aeruginosa, and Enterococcus faecalis

The biological role played by essential oils extracted from aromatic plants is progressively being recognized. This study evaluated the potential antibacterial activity of ten essential oils against Chromobacterium violaceum, Pseudomonas aeruginosa, and Enterococcus faecalis by measuring their minimum inhibitory concentration. We found that essential oils exert different antimicrobial effects, with Origanum vulgare and Foeniculum vulgare demonstrating the most significant inhibitory effect on bacterial growth for C. violaceum and E. faecalis. The growth of P. aeruginosa was not affected by any essential oil concentration we used. Sub-inhibitory concentrations of essential oils reduced in C. violaceum and E. faecalis biofilm formation, violacein amount, and gelatinase activity, all of which are biomarkers of the Quorum Sensing process. These concentrations significantly affect the global methylation profiles of cytosines and adenines, thus leading to the hypothesis that the oils also exert their effects through epigenetic changes. Considering the results obtained, it is possible that essential oils can find a broad spectrum of applications in counteracting microbial contamination and preserving sterility of surfaces and foods, as well as inhibiting microbial growth of pathogens, alone or in combination with traditional antibiotics.

Biological and chemical properties of 2-in-1 calcium-chelating and antibacterial root canal irrigants

ObjectivesTo evaluate the capacity of canal wall smear layer removal, precipitation caused by irrigant interaction, antibacterial activity and cytotoxicity of three 2-in-1 root canal irrigating solutions. MethodsForty single-rooted teeth were mechanically instrumented and irrigated with QMix, SmearOFF, Irritrol or 0.9% saline. Each tooth was evaluated for smear layer removal using scanning electron microscopy. Precipitation after interaction of the irrigating solutions with sodium hypochlorite (NaOCl) was evaluated with 1H nuclear magnetic resonance and mass spectroscopy. Confocal laser scanning microscopy was used to evaluate the antimicrobial activity of the irrigants against Enterococcus faecalis biofilms. Neutral red and clonogenic assays were performed on Chinese hamster V79 cells to evaluate the short-term and long-term cytotoxicity of the irrigants. ResultsThere was no significant difference between QMix and SmearOFF in eliminating smear layers from the coronal-third and middle-third of the canal spaces. In the apical-third, SmearOFF removed smear layers effectively. Irritrol incompletely removed smear layers from all the canal-thirds. When mixed with NaOCl, precipitation was evident only with Irritrol. QMix demonstrated a higher E. faecalis cell death percentage and a smaller biovolume. SmearOFF exhibited a larger decrease in biovolume compared with Irritrol, although Irritrol had a higher death percentage. Irritrol was more cytotoxic than the other irrigants on a short-term interval. In terms of long-term cytotoxicity, both Irritrol and QMix were cytotoxic. ConclusionQMix and SmearOFF performed better in smear layer removal and antimicrobial activity. QMix and Irritrol were cytotoxic when compared to SmearOFF. Irritrol was associated with precipitation after interacting with NaOCl. Clinical significanceEvaluation of the smear layer removal capability, antibacterial activity and cytotoxicity of 2-in-1 root canal irrigants is necessary to ensure that they are safe to use during root canal treatment.

Antibacterial effectiveness of multi-strain probiotics supernatants intracanal medication on Enterococcus faecalis biofilm in a tooth model

BackgroundTo assess the antibacterial activity of multi-strain probiotics supernatants (MSP); Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus acidophilus as an intracanal medication on Enterococcus faecalis (E. faecalis) biofilm in a tooth model.MethodsSixty extracted human single-rooted teeth with single canals were instrumented, sterilized, and inoculated with E. faecalis. After 21 days of incubation, four specimens were randomly selected to validate the biofilm formation by scanning electron microscope (SEM). The remaining specimens were randomly divided (n = 14), according to the intracanal medication (ICM) received into: Ca(OH)2: calcium hydroxide paste (35% Ultra Cal XS Ca(OH)2), Probiotics supernatants: MSP in poloxamer gel vehicle Poloxamer: poloxamer gel vehicle and, Control: E. faecalis biofilm only. The tested groups were further subdivided into two equal subgroups (n = 7) according to the incubation period (24 h and 7 days). Shaved dentin chips were obtained and collected by H-files and paper points, respectively for bacterial culture. The antibacterial activity was assessed after each incubation period quantitatively and qualitatively using bacterial colony-forming units per milliliter (CFUs/ml) and SEM, respectively.ResultsThe lowest CFUs/ml was found in Ca (OH)2 with a significant difference compared to other groups after 24 h. After 7 days, a similar outcome was found with a further significant reduction of CFUs/ml in all groups with no statistical difference between Ca(OH)2 and probiotics supernatants groups. Ca (OH)2 and Probiotics supernatants groups showed a significant (p < 0.05) percentage of overall bacterial reduction (100.00 ± 0.00% and 70.30 ± 12.95%, respectively) compared to poloxamer and control groups (27.80 ± 14.45 and 28.29 ± 19.79). SEM images showed a bacteria-free state in the Ca(OH)2 group after 7 days while few bacteria were found in the probiotics supernatants group. An extensive invasion of bacteria was found in poloxamer and controls groups.ConclusionMSP has a potential antibacterial effect on E. faecalis growth closely similar to the routinely used Ca (OH)2.

Effect of Passive Ultrasonic Irrigation, Er,Cr:YSGG Laser, and Photon-Induced Photoacoustic Streaming against Enterococcus faecalis Biofilms in the Apical Third of Root Canals.

This study aimed to compare the antibacterial effectiveness of passive ultrasonic irrigation (PUI), Er,Cr:YSGG laser (WTL), and photon-induced photoacoustic streaming (PIPS) using an Er:YAG laser against Enterococcus faecalis biofilms in the apical third of root canals. Root canals of 70 single-rooted human teeth were instrumented and infected with E. faecalis for 3 weeks to form biofilms. The samples were randomly divided into five groups as follows: (i) PUI + 3% NaOCl (n = 16); (ii) Er,Cr:YSGG laser (n = 16); (iii) PIPS + 3% NaOCl (n = 16); (iv) positive control group (n = 10); and (v) negative control group (n = 10). The bacterial content in the root canal was sampled using (a) the paper-point sampling method before (S1) and after (S2) treatment and (b) pulverising the apical 5 mm of the root. The number of bacteria recovered from each group was counted as colony-forming units (CFUs). The amount of reduction between the groups was compared with the Kruskal-Wallis test and post-test Dunn's multiple comparisons tests. The significance level was set at 5% (p < 0.05). The samples from the paper-point sampling method showed that the amount of bacteria before (S1) and after treatment (S2) was significantly different between PIPS and WTL, as well as between the PUI and WTL groups. In contrast, no significant difference was found between the PIPS and PUI groups. From the pulverised samples, the results indicated no significant difference among all experimental groups in the amount of bacterial reduction in the apical 5 mm of the root. PUI and PIPS showed a significantly greater reduction in bacterial content within the main root canal compared with the WTL. There was no difference among all experimental groups in the apical third of the root.

Bactericidal synergism between phage endolysin Ply2660 and cathelicidin LL-37 against vancomycin-resistant Enterococcus faecalis biofilms

Antibiotic resistance and the ability to form biofilms of Enterococcus faecalis have compromised the choice of therapeutic options, which triggered the search for new therapeutic strategies, such as the use of phage endolysins and antimicrobial peptides. However, few studies have addressed the synergistic relationship between these two promising options. Here, we investigated the combination of the phage endolysin Ply2660 and the antimicrobial peptide LL-37 to target drug-resistant biofilm-producing E. faecalis. In vitro bactericidal assays were used to demonstrate the efficacy of the Ply2660–LL-37 combination against E. faecalis. Larger reductions in viable cell counts were observed when Ply2660 and LL-37 were applied together than after individual treatment with either substance. Transmission electron microscopy revealed that the Ply2660–LL-37 combination could lead to severe cell lysis of E. faecalis. The mode of action of the Ply2660–LL-37 combination against E. faecalis was that Ply2660 degrades cell wall peptidoglycan, and subsequently, LL-37 destroys the cytoplasmic membrane. Furthermore, Ply2660 and LL-37 act synergistically to inhibit the biofilm formation of E. faecalis. The Ply2660–LL-37 combination also showed a synergistic effect for the treatment of established biofilm, as biofilm killing with this combination was superior to each substance alone. In a murine peritoneal septicemia model, the Ply2660–LL-37 combination distinctly suppressed the dissemination of E. faecalis isolates and attenuated organ injury, being more effective than each treatment alone. Altogether, our findings indicate that the combination of a phage endolysin and an antimicrobial peptide may be a potential antimicrobial strategy for combating E. faecalis.

Efficacy of Endodontic Disinfection Protocols in an E. faecalis Biofilm Model—Using DAPI Staining and SEM

The aim of this study was to investigate the antimicrobial efficacy of different disinfection protocols in a novel Enterococcus faecalis biofilm model based on a visualization method and to evaluate the potential alteration of dentinal surface. A total of 120 extracted human premolars were allocated to 6 groups with different irrigation protocols. The assessment of the effectiveness of each protocol and the alteration of dentinal surface were visualized by using SEM and fluorescence microscopy (DAPI). A dense E. faecalis biofilm with a penetration depth of 289 μm (medial part of the root canal) and 93 μm (apical part) validated that the biofilm model had been successfully implemented. A significant difference between the 3% NaOCl groups and all the other groups in both observed parts of the root canal (p < 0.05) was detected. However, the SEM analysis revealed that the dentinal surface in the 3% NaOCl groups was severely altered. The established biofilm model and the visualization method based on DAPI are appropriate for bacterial quantification and evaluation of the depth effect of different disinfection protocols in the root canal system. The combination of 3% NaOCl with 20% EDTA or MTAD with PUI allows the decontamination of deeper dentine zones within the root canal but simultaneously alters the dentinal surface.

Use of a Cellulase from Trichoderma reesei as an Adjuvant for Enterococcus faecalis Biofilm Disruption in Combination with Antibiotics as an Alternative Treatment in Secondary Endodontic Infection.

Apical periodontitis is an inflammation leading to the injury and destruction of periradicular tissues. It is a sequence of events that starts from root canal infection, endodontic treatment, caries, or other dental interventions. Enterococcus faecalis is a ubiquitous oral pathogen that is challenging to eradicate because of biofilm formation during tooth infection. This study evaluated a hydrolase (CEL) from the fungus Trichoderma reesei combined with amoxicillin/clavulanic acid as a treatment against a clinical E. faecalis strain. Electron microscopy was used to visualize the structure modification of the extracellular polymeric substances. Biofilms were developed on human dental apices using standardized bioreactors to evaluate the antibiofilm activity of the treatment. Calcein and ethidium homodimer assays were used to evaluate the cytotoxic activity in human fibroblasts. In contrast, the human-derived monocytic cell line (THP-1) was used to evaluate the immunological response of CEL. In addition, the secretion of the pro-inflammatory cytokines IL-6 and TNF-α and the anti-inflammatory cytokine IL-10 were measured by ELISA. The results demonstrated that CEL did not induce the secretion of IL-6 and TNF-α when compared with lipopolysaccharide used as a positive control. Furthermore, the treatment combining CEL with amoxicillin/clavulanic acid showed excellent antibiofilm activity, with a 91.4% reduction in CFU on apical biofilms and a 97.6% reduction in the microcolonies. The results of this study could be used to develop a treatment to help eradicate persistent E. faecalis in apical periodontitis.

Antibiofilm activity of neem leaf (Azadirachta indica A. Juss) ethanolic extracts against Enterococcus faecalis in vitro

Background: Enterococcus faecalis commonly infects root canals by forming a biofilm. Extracts from neem leaves (Azadirachta indica A. Juss) have been shown to have antibacterial properties, indicating their potential in preventing or treating biofilm formation caused by bacteria. Purpose: This study aims to investigate the phytochemical compounds present in neem leaves (Azadirachta indica A. Juss) and establish the concentration of ethanol-based neem leaf extract that can effectively inhibit the in vitro growth of Enterococcus faecalis biofilm. Methods: This study employed the maceration technique for extraction, gas chromatography mass spectroscopy for the analysis of plant chemicals, and a microtiter plate assay for measuring biofilm formation with treatment concentrations of 6.25%, 12.5%, 25%, 50%, and 75%, with a positive control of 0.2% chlorhexidine. Results: A phytochemical analysis revealed that the ethanol extract of neem leaves contained 22 different metabolites, mainly terpenoids and fatty acids. The extract demonstrated antibiofilm activity only at a concentration of 12.5% with an average biofilm inhibition of 36.85%. However, lower concentrations of 6.25%, 25%, 50%, and 75% had the opposite effect, promoting biofilm formation in Enterococcus faecalis. Conclusion: Phytochemical metabolite contained in the ethanolic extracts of neem leaves might contribute a promising agent in treating a biofilm-mediated root canal infection of Enterococcus faecalis.

Antimicrobial and cleaning effects of ultrasonic-mediated plasma-loaded microbubbles on Enterococcus faecalis biofilm: an in vitro study

BackgroundEnterococcus faecalis (E. faecalis) is the most frequently isolated bacteria from teeth with root canal treatment failure. This study aims to evaluate the disinfection effect of ultrasonic-mediated cold plasma-loaded microbubbles (PMBs) on 7d E. faecalis biofilm, the mechanical safety and the mechanisms.MethodsThe PMBs were fabricated by a modified emulsification process and the key reactive species, nitric oxide (NO) and hydrogen peroxide (H2O2) were evaluated. The 7d E. faecalis biofilm on human tooth disk was constructed and divided into the following groups: PBS, 2.5%NaOCl, 2%CHX, and different concentrations of PMBs (108 mL−1, 107 mL−1). The disinfection effects and elimination effects were verified with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Microhardness and roughness change of dentin after PMBs treatment were verified respectively.ResultsThe concentration of NO and H2O2 in PMBs increased by 39.99% and 50.97% after ultrasound treatment (p < 0.05) respectively. The CLSM and SEM results indicate that PMBs with ultrasound treatment could remove the bacteria and biofilm components effectively, especially those living in dentin tubules. The 2.5% NaOCl presented an excellent effect against biofilm on dishes, but the elimination effect on dentin tubules is limited. The 2% CHX group exhibits significant disinfection effect. The biosafety tests indicated that there is no significant changes on microhardness and roughness after PMBs with ultrasound treatment (p > 0.05).ConclusionPMBs combined with ultrasound treatment exhibited significant disinfection effect and biofilm removal effect, the mechanical safety is acceptable.

Antibacterial Efficacy of Irrigants with Varying Osmolarity on E. faecalis Biofilm: An In Vitro Study.

To evaluate the role of the addition of different concentrations of sodium chloride salt to conventional intracanal irrigants to vary their osmotic values and thereby compare their antibacterial efficacy. In an active attachment biofilm model, Enterococcus faecalis (ATCC 29212) biofilms were grown. Sodium chloride salts were added to 100 mL of distilled water to make 6M (hyperosmotic), 0.5M, and 0.25M (hypoosmotic) sodium chloride solutions, respectively. The experimental groups were divided into three groups: Group I: 5.25% sodium hypochlorite, group II: 2% chlorhexidine, and group III: 2% povidone iodine, and four subgroups within these three groups, such as subgroup A (without salt solution), subgroup B (with 6M of hyperosmotic salt solution), subgroup C (with 0.5M of hypoosmotic salt solution), and subgroup D (with 0.25M of hypoosmotic salt solution), respectively. Biofilms were treated with all the subgroups for a contact time of 15 min. A crystal violet assay was done to estimate the bacterial cell biomass. The results revealed that subgroups IIIB, IB, and IID, ID had a statistical reduction in bacterial biomass at p < 0.05. There were no significant differences between subgroups IC, IIC, and IIIC and subgroups IA, IIA, and IIIA. The antibacterial efficacy of all three irrigants was significantly affected by varying the osmolarities. The results prove that the hyperosmotic and hypoosmotic salt solutions, along with irrigants, have enhanced antibacterial efficacy on E. faecalis biofilm due to its ability to vary the turgor pressure of cell wall, as well as the inherent properties of the irrigants such as hypochlorous acid formation, ionic interaction, and free radical interactions.