Enhancing antibacterial effect of sodium hypochlorite by low electric current-assisted sonic agitation

Sonic irrigation for removal of calcium hydroxide in the apical root canal: A micro-CT and light-coupled tracking analysis

Objective

This study aimed to evaluate the efficacy of three sonic irrigation systems for removal of calcium hydroxide dressing from the apical root canal.

Materials and methods

A total of 96 single-rooted teeth in three categories of root canal curvatures (straight: 0–5°, moderate: 6–20°, and severe: > 20°) were allocated to four groups: conventional needle irrigation, EndoActivator, EQ-S, and Vibringe. The root canals were instrumented using Protaper NEXT and filled with calcium hydroxide. After removal of calcium hydroxide, the remaining volume of calcium hydroxide was measured by micro-CT analysis. Data were compared among root canal curvatures and irrigation systems using the Kruskal-Wallis test and Mann-Whitney test (p < .05). The oscillating range of each irrigation system was measured using light-coupled motion tracking.

Results

The volumes of calcium hydroxide remaining in the canals with severe curvature were significantly higher than in those of straight curvature (p < .05). In the canals of moderate or severe curvature, EQ-S showed the highest removal percentage, followed by EndoActivator, Vibringe, and needle irrigation (p < .05). Light-coupled tracking showed the largest oscillating range in EQ-S (p < .05).

Conclusions

Sonically activated irrigation systems with a flexible tip can be beneficial for calcium hydroxide intracanal dressing removal in the curved apical canals.

Biofilm in Endodontics: In Vitro Cultivation Possibilities, Sonic-, Ultrasonic- and Laser-Assisted Removal Techniques and Evaluation of the Cleaning Efficacy

Incomplete and inadequate removal of endodontic biofilm during root canal treatment often leads to the clinical failure. Over the past decade, biofilm eradication techniques, such as sonication of irrigant solutions, ultrasonic and laser devices have been investigated in laboratory settings. This review aimed to give an overview of endodontic biofilm cultivation methods described in papers which investigated sonic-, ultrasonic- and Er:Yag laser-assisted biofilm removal techniques. Furthermore, the effectiveness of these removal techniques was discussed, as well as methods used for the evaluation of the cleaning efficacy. In general, laser assisted agitation, as well as ultrasonic and sonic activation of the irrigants provide a more efficient biofilm removal compared to conventional irrigation conducted by syringe/needle. The choice of irrigant is an important factor for reducing the bacterial contamination inside the root canal, with water and saline being the least effective. Due to heterogeneity in methods among the reviewed studies, it is difficult to compare sonic-, ultrasonic- and Er:Yag laser-assisted techniques among each other and give recommendations for the most efficient method in biofilm removal. Future studies should standardize the methodology regarding biofilm cultivation and cleaning methods, root canals with complex morphology should be introduced in research, with the aim of simulating the clinical scenario more closely.

Benzimidazole-based turn-on fluorescence probe developed for highly specific and ultrasensitive detection of hypochlorite ions in living cells

Hypochlorite (ClO^- ), as one of the active oxygen species (ROS), plays an essential role in the cellular defence system and organism immunity. In this paper, we successfully synthesized a new 'turn-on' fluorescent probe BMF based on benzimidazole and characterized it by spectroscopic methods. The designed probe can quickly respond to ClO^- with the obvious colour change from pink to colourless. Notably, the probe BMF exhibited almost no fluorescence, but showed strong fluorescence after adding ClO^- , including an excellent fluorescence turn-on effect. The fluorescence turn-on phenomenon of BMF was attributed to the strong oxidation of ClO^- , which severed the connecting double bond and disrupted the intramolecular charge transfer (ICT) system, plus light-induced electron transfer effect between the fluorophore and the recognition group was discontinued. In addition, the cytotoxicity assay showed that the probe had lower cytotoxicity. Based on these advantages, we demonstrated that probe BMF might be a good candidate for detecting ClO^- in biological systems.

Use of electromagnetic stimulation on an Enterococcus faecalis biofilm on root canal treated teeth in vitro

Root canal disinfection is of utmost importance in the success of the treatment, thus, a novel method for achieving root canal disinfection by electromagnetic waves, creating a synergistic reaction via electric and thermal energy, was created. To study electromagnetic stimulation (EMS) for the disinfection of root canal in vitro, single rooted teeth were instrumented with a 45.05 Wave One Gold reciprocating file. Specimens were sterilized and inoculated with Enterococcus faecalis ATCC 29,212, which grew for 15 days to form an established biofilm. Samples were treated with 6% sodium hypochlorite (NaOCl), 1.5% NaOCl 1.5% NaOCl with EMS, 0.9% saline with EMS or 0.9% saline. After treatments, the colony forming units (CFU) was determined. Data was analyzed by Wilcoxon Rank Sums Test (α = 0.05). One sample per group was scored and split for confocal laser scanning microscopy imaging. There was a significant effect with the use of NaOCl with or without EMS versus 0.9% saline with or without EMS (p = 0.012 and 0.003, respectively). CFUs were lower when using 0.9% saline with EMS versus 0.9% saline alone (p = 0.002). Confocal imaging confirmed CFU findings. EMS with saline has an antibiofilm effect against E. faecalis and can potentially be applied for endodontic disinfection.

The effect of physico-chemical treatment in reducing Listeria monocytogenes biofilms on lettuce leaf surfaces

The purpose of this research was to characterize Listeria monocytogenes from several environmental and clinical sources and assess the efficacy of single and combined physico-chemical treatments in reducing biofilm on lettuce leaves. PCR analysis of L. monocytogenes isolates collected from different clinical (10 strains) and environmental sources (12 strains) was used to look for the presence of one Listeria-specific gene and five virulence genes. Biofilms of L. monocytogenes were developed on lettuce leaves over 24 h. A 5-min ultrasound and a 300-ppm sodium hypochlorite (NaOCl) wash resulted in similar reductions in cell numbers of 0.82 log CFU cm-2. For chlorine dioxide (ClO2) at 60 ppm, the cell numbers were reduced by ∼5.45 log CFU cm-2. A combined treatment of 5 min of ultrasound plus 300 ppm NaOCl or 40 ppm ClO2, provided maximal efficacy, reducing the number of L. monocytogenes on the lettuce surface to non-detectable levels. Therefore, ClO2 has the potential to replace NaOCl for the disinfection of food products in the food industry.

Scanning electron microscopic evaluation of the efficacy of 5% ethylenediaminetetraacetic acid for smear layer removal

The purpose of the study was to evaluate the smear layer removal efficacy of novel Saver® irrigating solution including 5% EDTA and to compare the 17% EDTA as the most used counterpart. Forty-four single-rooted teeth were divided into four groups, were instrumented, and irrigated. The smear treatment groups were as follows: sterile distilled water; 5.25% sodium hypochlorite; Saver®; 17% EDTA. The root samples were blinded. The micrographic images of root samples were collected by scanning electron microscope. The percentages of open dentin tubules were quantified using an image analysis software on micrographs. Two-way ANOVA followed by Tukey's multiple comparisons was used (p < .05). The 17% EDTA showed the highest percentages of open dentin tubules than the other treatments (p < .01). The mean percentages of open dentin tubules of 17% EDTA revealed statistically highly significant differences than Saver® treatment in all root regions (p < .01). Dentin tubules were covered by dense smear layer in distilled water irrigation whereas, the tubular pattern of dentin structure was not observed in hypochlorite irrigation. The commercial Saver® product presented to be less cleaning property on the smear layer than 17% EDTA and failed to show any improvement in the removal of smear layer compared with its tested counterpart.

Unravelling the effects of the food components ascorbic acid and capsaicin as a novel anti-biofilm agent against Escherichia coli

This study aimed to evaluate the influence of capsaicin and ascorbic acid on the physiology of biofilm formation and dispersion. The influence of the E. coli ATCC 25922 biofilm and five E. coli isolates were observed in the presence of sodium hypochlorite 2.5 mM and subinhibitory concentrations of capsaicin (7 mM) and ascorbic acid (100 mM). The cells counts were performed through standard plaque count and the architecture visualized by confocal microscopy. The proteins, carbohydrates, and DNA present in the biofilm matrix were also quantified. There was a reduction in adhered cells in the presence of capsaicin (7 mM) and ascorbic acid (100 mM) in the biofilm formation kinetics, however, regarding the dispersion, only capsaicin altered the biofilm, data confirmed by confocal fluorescence microscopy (p < 0.05). It was noted that the matrix composition is dynamic and may be affected by changes in growth conditions such as the presence of antimicrobial substances.

Ultrasonic Irrigant Activation during Root Canal Treatment: A Systematic Review

INTRODUCTION

The aim of this study was to systematically review the evidence on the cleaning and disinfection of root canals and the healing of apical periodontitis when ultrasonic irrigant activation is applied during primary root canal treatment of mature permanent teeth compared with syringe irrigation.

METHODS

An electronic search was conducted of the Cochrane Library, Embase, LILACS, PubMed, SciELO, and Scopus databases using both free-text key words and controlled vocabulary. Additional studies were sought through hand searching of endodontic journals and textbooks. The retrieved studies were screened by 2 reviewers according to predefined criteria. The included studies were critically appraised, and the extracted data were arranged in tables.

RESULTS

The electronic and hand search retrieved 1966 titles. Three clinical studies and 45 in vitro studies were included in this review. Ultrasonic activation did not improve the healing rate of apical periodontitis compared with syringe irrigation after primary root canal treatment of teeth with a single root canal. Conflicting results were reported by the in vitro microbiological studies. Ultrasonic activation was more effective than syringe irrigation in the removal of pulp tissue remnants and hard tissue debris based on both clinical and in vitro studies. Ultrasonic activation groups were possibly favored in 13 studies, whereas syringe irrigation groups may have been favored in 3 studies.

CONCLUSIONS

The level of the available evidence was low, so no strong clinical recommendations could be formulated. Future studies should focus on the antimicrobial effect and healing of apical periodontitis in teeth with multiple root canals.