Confocal laser scanning, scanning electron, and transmission electron microscopy investigation of Enterococcus faecalis biofilm degradation using passive and active sodium hypochlorite irrigation within a simulated root canal model

Poly(methylmethacrylate-co-dimethyl acrylamide)-silver nanocomposite prevents biofilm formation in medical devices

Aim: To investigate whether medical devices coated with a synthesized nanocomposite of poly(methylmethacrylate-co-dimethyl acrylamide) (PMMDMA) and silver nanoparticles (AgNPs) could improve their antibiofilm and antimicrobial activities. We also investigated the nanocomposite's safety. Materials & methods: The nanocomposite was synthesized and characterized using analytical techniques. Medical devices coated with the nanocomposite were evaluated for bacterial adhesion and hemolytic activity in vitro. Results: The nanocomposite formation was demonstrated with the incorporation of AgNPs into the polymer matrix. The nanocomposite proved to be nonhemolytic and significantly inhibited bacterial biofilm formation. Conclusion: The PMMDMA-AgNPs nanocomposite was more effective in preventing biofilm formation than PMMDMA alone and is a promising strategy for coating medical devices and reducing mortality due to hospital-acquired infections.

Cleaning efficacy of EDDY versus ultrasonically-activated irrigation in root canals: a systematic review and meta-analysis

BACKGROUND

Ultrasonically-activated irrigation (UAI) is effective in root canal irrigation but may damage canal walls. EDDY is a sonic activation system with flexible working tips that cause no harm to dentinal walls. This review explores the intracanal cleaning efficacy of EDDY compared with UAI in vitro.

METHODS

The systematic review was registered in the PROSPERO database (CRD42021235826). A literature search was conducted in six electronic databases. In vitro studies that compared the removal of smear layer, debris, soft tissue or microbes in root canals between EDDY and UAI were included. Data extraction and quality assessment were performed. Meta-analyses were conducted on smear layer removal and debris elimination with the standardized mean difference (SMD). Heterogeneity was measured using the I² test and the Chi² test. The random-effect model was used when I² > 50%, or p < 0.1, otherwise the fixed-effect model was applied. The level of significance was set at p < 0.05.

RESULTS

19 articles were included in this systematic review and 7 articles were included in meta-analyses. Meta-analyses on smear layer removal showed unimportant differences between EDDY and UAI at any canal third (coronal [SMD = 0.08, 95% confidence interval (95%CI): -0.29 to 0.45; p = 0.44, I² = 0%]; middle [SMD = 0.02, 95% CI: -0.44 to 0.47; p = 0.94, I² = 0%]; apical [SMD = 0.01, 95%CI: -0.35 to 0.38; p = 0.70, I² = 0%]). Meta-analyses on debris removal evaluated by scanning electron microscope (coronal [SMD = 0.03, 95% CI: -0.41 to 0.46; p = 0.27, I² = 23%]; middle [SMD = -0.24, 95% CI: -0.83 to 0.35; p = 0.80, I² = 0%]; apical [SMD = 0.24, 95%CI: -0.20 to 0.67; p = 0.36, I² = 2%]) and micro-CT (SMD = 0.36, 95% CI: -0.67 to 1.40; p = 0.03, I² = 70%) both found insignificant differences. No meta-analysis was undertaken on soft-tissue removal and disinfection due to the various study designs, but the qualitative analyses implied that EDDY achieved similar performance to UAI in both aspects.

CONCLUSIONS

Limited evidence indicated that EDDY was comparable to UAI in removing smear layer, debris, soft tissue and microbes ex vivo. Considering UAI may damage canal walls, EDDY might be a substitute for UAI in irrigation activation. But more randomized clinical trials are required to explore the clinical extrapolation of the results in this review.

Biofilms and Benign Colonic Diseases

The colon has a very large surface area that is covered by a dense mucus layer. The biomass in the colon includes 500-1000 bacterial species at concentrations of ~10¹² colony-forming units per gram of feces. The intestinal epithelial cells and the commensal bacteria in the colon have a symbiotic relationship that results in nutritional support for the epithelial cells by the bacteria and maintenance of the optimal commensal bacterial population by colonic host defenses. Bacteria can form biofilms in the colon, but the exact frequency is uncertain because routine methods to undertake colonoscopy (i.e., bowel preparation) may dislodge these biofilms. Bacteria in biofilms represent a complex community that includes living and dead bacteria and an extracellular matrix composed of polysaccharides, proteins, DNA, and exogenous debris in the colon. The formation of biofilms occurs in benign colonic diseases, such as inflammatory bowel disease and irritable bowel syndrome. The development of a biofilm might serve as a marker for ongoing colonic inflammation. Alternatively, the development of biofilms could contribute to the pathogenesis of these disorders by providing sanctuaries for pathogenic bacteria and reducing the commensal bacterial population. Therapeutic approaches to patients with benign colonic diseases could include the elimination of biofilms and restoration of normal commensal bacteria populations. However, these studies will be extremely difficult unless investigators can develop noninvasive methods for measuring and identifying biofilms. These methods that might include the measurement of quorum sensing molecules, measurement of bile acids, and identification of bacteria uniquely associated with biofilms in the colon.

Identification of quinoline derivatives as growth inhibitors of MDR pathogen Klebsiella pneumoniae

Aims: This study was aimed to identify compounds with significant inhibitory potential against multidrug-resistant (MDR), multidrug-sensitive, and clinical isolates of Klebsiella pneumoniae. Materials & methods: Antibacterial activity of the nitroquinoline derivatives was assessed by micro-plate Alamar Blue assay. Results: Nitroquinoline derivatives 9, 11 and 14 showed inhibitory activity against MDR K. pneumoniae. Docking studies of these compounds with topoisomerase IV of K. pneumonia indicated the interactions of these compounds at the active site residues of enzyme near to cofactor (Mg⁺²). Furthermore, compound 11 was identified as a reactive oxygen species (ROS) inducer. None of the compounds showed hemolytic effect. Conclusion: This study was designed to identify compounds active against MDR K. pneumoniae which causes infections, such as pneumonia and urinary tract infections.

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.

Quantification of Bacterial DNA from Infected Human Root Canals Using qPCR and DAPI after Disinfection with Established and Novel Irrigation Protocols

The removal of bacterial infections within the root canal system is still a challenge. Therefore, the cleansing effect of established and new irrigation-protocols (IP) containing silver diamine fluoride (SDF) 3.8% on the whole root canal system was analyzed using quantitative PCR (qPCR) and 4′,6-diamidino-phenylindole-(DAPI)-staining. Extracted human premolars were instrumented up to F2 (ProTaper Gold) under NaCl 0.9% irrigation and incubated with Enterococcus faecalis for 42 days. Subsequently, different ultrasonically agitated IP were applied to the roots: control (no irrigation), 1. NaOCl 3%, EDTA 20%, CHX 2%, 2. NaOCl 3%, EDTA 20%, 3. NaOCl 3%, EDTA 20%, SDF 3.8%, 4. SDF 3.8%, and 5. NaCl 0.9%. One half of the root was investigated fluorescent-microscopically with DAPI. The other half was grinded in a cryogenic mill and the bacterial DNA was quantified with qPCR. The qPCR results showed a statistically significant reduction of bacteria after the application of IP 1, 2, and 3 compared to the control group. While IP 4 lead to a bacterial reduction which was not significant, IP 5 showed no reduction. These data corresponded with DAPI staining. With qPCR a new molecular-biological method for the investigation of the complete root canal system was implemented. The novel IP 3 had an equally good cleansing effect as the already established IP.

3D printed tetrakis(triphenylphosphine)palladium (0) impregnated stirrer devices for Suzuki–Miyaura cross-coupling reactions

In a novel approach, SLA 3D-printed Pd(PPh3)4 containing stirrer beads have been used to catalyse the Suzuki–Miyaura reaction between a range of substrates.

Antimicrobial and cytotoxic activity of electrosprayed chitosan nanoparticles against endodontic pathogens and Balb/c 3T3 fibroblast cells

The aims of this study were to synthesize highly positively charged chitosan nanoparticles (Ch-Np) using the electrospraying technique, and to test their antimicrobial activity against endodontic pathogens, and cytotoxicity against fibroblast cells. Ch-Np were synthesized from low molecular weight chitosan (LMW-Ch) using the electrospraying technique, and characterized. The antimicrobial activity was evaluated against Streptococcus mutans, Enterococcus faecalis, and Candida albicans in their planktonic state using a Time-Kill Test performed by using broth micro-dilution technique, and against biofilm biomass using a microtiter plate biofilm assay. The cytotoxicity was evaluated using Balb/c 3T3 fibroblast cells with the standard MTT assay. Electrospraying of LMW-Ch produced Ch-Np with an average size of 200 nm, and a surface charge of 51.7 mV. Ch-Np completely eradicated S. mutans and E. faecalis in the planktonic state and showed fungistatic activity against C. albicans. Furthermore, it significantly reduced the biofilm biomass for all the tested microbial species [S. mutans (p = 0.006), E. faecalis (p < 0.0001), and C. albicans (p = 0.004)]. When tested for cytotoxicity using 3T3 cells, Ch-Np showed no cytotoxicity. In conclusion, the highly positively charged, colloidal dispersion of Ch-Np are effective as a biocompatible endodontic antimicrobial agent.

Diagnosis of biofilm infections: current methods used, challenges and perspectives for the future

The diagnosis of biofilms continues to be a challenge, and there is no standardized protocol for such a diagnosis in clinical practice. In addition, some proposed methodologies are expensive to require significant amounts of time and a high number of trained staff, making them impracticable for clinical practice. In recent years, mass spectrophotometry/matrix-assisted laser desorption ionization time of flight (MALDI-TOF) has been applied it in biofilm studies. However, due to several problems and limitations of the technique, MALDI-TOF is far from being the gold standard for identifying biofilm formation. The omics analysis may prove to be a promising strategy for the diagnosis of biofilms in clinical laboratories since it allows the identification of pathogens in less time than needed for conventional techniques and in a more specific manner. However, omic tools are expensive and require qualified technical expertise, and an analysis of the data obtained needs to be careful not to neglect subpopulations in the biofilm. More studies must therefore be developed for creating a protocol that guarantees rapid biofilm identification, ensuring greater chances of success in infection control. This review discusses the current methods of microbial biofilm detection and future perspectives for its diagnosis in clinical practice.

Microbial Biofilms in the Food Industry-A Comprehensive Review

Biofilms, present as microorganisms and surviving on surfaces, can increase food cross-contamination, leading to changes in the food industry’s cleaning and disinfection dynamics. Biofilm is an association of microorganisms that is irreversibly linked with a surface, contained in an extracellular polymeric substance matrix, which poses a formidable challenge for food industries. To avoid biofilms from forming, and to eliminate them from reversible attachment and irreversible stages, where attached microorganisms improve surface adhesion, a strong disinfectant is required to eliminate bacterial attachments. This review paper tackles biofilm problems from all perspectives, including biofilm-forming pathogens in the food industry, disinfectant resistance of biofilm, and identification methods. As biofilms are largely responsible for food spoilage and outbreaks, they are also considered responsible for damage to food processing equipment. Hence the need to gain good knowledge about all of the factors favouring their development or growth, such as the attachment surface, food matrix components, environmental conditions, the bacterial cells involved, and electrostatic charging of surfaces. Overall, this review study shows the real threat of biofilms in the food industry due to the resistance of disinfectants and the mechanisms developed for their survival, including the intercellular signalling system, the cyclic nucleotide second messenger, and biofilm-associated proteins.

Quantification of Bacterial Colonization in Dental Hard Tissues Using Optimized Molecular Biological Methods

Bacterial infections of root canals and the surrounding dental hard tissue are still a challenge due to biofilm formation as well as the complex root canal anatomy. However, current methods for analyzing biofilm formation, bacterial colonization of root canals and dental hard tissue [e.g., scanning electron microscopy, confocal laser scanning microscopy (CLSM) or determination of colony forming units (CFU)] are time-consuming and only offer a selective qualitative or semi-quantitative analysis. The aim of the present study is the establishment of optimized molecular biological methods for DNA-isolation and quantification of bacterial colonization via quantitative PCR (qPCR) from dental hard tissue. Root canals of human premolars were colonized with Enterococcus faecalis. For isolation of DNA, teeth were then grinded with a cryo mill. Since the hard tissues dentin and especially enamel belong to the hardest materials in the human organism, the isolation of bacterial DNA from root dentin is very challenging. Therefore, treatment steps for the isolation of DNA from grinded teeth were systematically analyzed to allow improved recovery of bacterial DNA from dental hard tissues. Starting with the disintegration of the peptidoglycan-layer of bacterial cells, different lysozyme solutions were tested for efficacy. Furthermore, incubation times and concentrations of chelating agents such as EDTA were optimized. These solutions are crucial for the disintegration of teeth and hence improve the accessibility of bacterial DNA. The final step was the determination of prior bacterial colonization of each root canal as determined by qPCR and comparing the results to alternative methods such as CFU. As a result of this study, optimized procedures for bacterial DNA-isolation from teeth were established, which result in an increased recovery rate of bacterial DNA. This method allows a non-selective and straightforward procedure to quantify bacterial colonization from dental hard tissue. It can be easily adapted for other study types such as microbiome studies and for comparable tissues like bones.

Detection, treatment and prevention of endodontic biofilm infections: what's new in 2020?

Endodontic disease, a biofilm infection of the root canal space, is a significant cause of dental morbidity worldwide. Endodontic treatment, or root canal treatment, as it is commonly known is founded on the ability to eradicate microbial biofilm infection and prevent re-infection of the highly complex root canal space. Despite many "advances" in clinical endodontics we have seen little improvement in outcomes. The aim of this critical review paper is to provide a contemporary view of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease.

Comparison of Five Different Irrigation Techniques on Smear Layer Removal in Apical Thirds of Root Canals of Mandibular First Premolar: A Scanning Electron Microscopic Study

Aim:

This study was conducted to compare smear layer removal by five different irrigation techniques—conventional needle irrigation (CI), manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and negative apical pressure (NAP).

Materials and Methods:

Fifty freshly extracted mandibular first premolars were cleaned and shaped by One Curve rotary files and 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. The samples were divided into five equal groups (n = 10), according to the final irrigation activation technique: Group I, CI; Group II, MDA; Group III, PUI; Group IV, SI; and Group V, NAP. The samples were prepared and observed under a scanning electron microscope. The photomicrographs were recorded and evaluated with a scoring system.

Results:

Group I and Group II had the highest scores, which showed a statistically significant difference between the other groups (P < 0.05). This was followed by PUI, NAP, and SI.

Conclusion:

Final irrigation activation with SI and NAP resulted in the better removal of smear layer when compared to that with other groups.

Design and development of 3D printed catalytically-active stirrers for chemical synthesis

In a novel approach, 3D-printed pTsOH containing stirrer beads have been used to catalyse the Mannich reaction.

Er,Cr:YSGG Laser-Activation Enhances Antimicrobial and Antibiofilm Action of Low Concentrations of Sodium Hypochlorite in Root Canals

The onset and persistence of endodontic infections due to residual biofilm after chemical disinfection promotes secondary bacterial infection. Alternative methods to disinfect operated root canals are a matter of great interest. The aim was to evaluate the antibacterial effectiveness of sodium hypochlorite (NaOCl) at low concentrations activated by the Er,Cr:YSGG laser-activated irrigation (LAI) against 10-day-old intracanal Enterococcusfaecalis biofilm. Biofilms were formed inside the root canals and divided into 7 groups (n13): 0.5% NaOCl + Er,Cr:YSGG; Saline + Er,Cr:YSGG; 0.5% NaOCl + syringe irrigation(SI); 2.5% NaOCl + SI; 5% NaOCl + SI; positive and negative controls. Bacterial survivors were counted and specimens visualized under scanning electron and confocal laser scanning microscopy. Treatments with 0.5% NaOCl + Er,Cr:YSGG and 2.5% NaOCl + SI gave a significant reduction in the number of CFU/mm². Moreover, scanning electron microscopy and confocal laser scanning microscopy imaging confirmed and reinforced bacteriological data. Thus, Er,Cr:YSGG LAI proved to be able to improve the intracanal distribution of 0.5% NaOCl after 60 s of activation, reaching the same level of effectiveness than 2.5% NaOCl. This is regarded as of clinical interest, since working with lower concentrations may contribute to reduce undesired effects.

Antibiofilm Activity of Three Different Irrigation Techniques: An in Vitro Study

The microbial infection of the endodontic space occurs in a necrotic tooth as a result of dental caries, trauma, periodontal disease, or previous root canal therapy. The disruption of the biofilms and the reduction of the bacterial load inside root canals are crucial for the success of root canal therapy. The aim of this study was to compare, in vitro, the antibiofilm efficacy of a novel passive sonic irrigation (PSI) device with passive ultrasonic irrigation (PUI) and conventional needle irrigation (CNI). Forty-four single-rooted human teeth were inoculated with a culture of E. faecalis for 28 days. The specimens were randomly divided into three groups: PUI, CNI, and PSI (n = 12). The activation protocols were performed using both 17% EDTA and 5.25% NaOCl. Residual bacterial biofilm was taken by means of a canal brush and colony-forming unit (CFU) were counted. The data were analyzed using one-way ANOVA and Games-Howell's post hoc tests. A major reduction in CFU was observed in the PSI and PUI groups, in comparison with the CNI group. No difference was found (p > 0.05) in terms of CFU reduction between PSI and PUI. PSI could be as effective as PUI in the removal of bacterial biofilms from straight root canals.

Testing Anti-Biofilm Polymeric Surfaces: Where to Start?

Present day awareness of biofilm colonization on polymeric surfaces has prompted the scientific community to develop an ever-increasing number of new materials with anti-biofilm features. However, compared to the large amount of work put into discovering potent biofilm inhibitors, only a small number of papers deal with their validation, a critical step in the translation of research into practical applications. This is due to the lack of standardized testing methods and/or of well-controlled in vivo studies that show biofilm prevention on polymeric surfaces; furthermore, there has been little correlation with the reduced incidence of material deterioration. Here an overview of the most common methods for studying biofilms and for testing the anti-biofilm properties of new surfaces is provided.

Comparison of bacterial removal from dentinal tubules with different irrigant agitation techniques: An in vitro study

Aim

This investigation was conducted to assess the ability of various irrigant agitation devices to eradicate Enterococcus faecalis from the dentinal tubules of extracted teeth.

Methodology

Fifty roots of extracted human teeth were instrumented to size 30 k with a 0.04 taper. The roots were autoclaved and then injected with E. faecalis. The canals were assigned to one of four intervention groups and disinfected using (A) standard needle irrigation, (B) EndoUltra® Ultrasonic Activator, (C) the EndoActivator system, or (D) EDDY sonic activation and to two control groups that were (E) treated with saline and (F) not inoculated with any bacteria. The roots were split in half, dyed with a LIVE/DEAD Back Light Bacterial Viability Kit, and then scanned with a confocal laser scanning microscope (CLSM) to identify live/dead bacteria in the dentinal tubules.

Results

CLSM images revealed differences among the groups. Both the EndoUltra® Ultrasonic Activator group and the EDDY group had a combination of dead and live bacteria, while the EndoActivator group had mostly dead bacteria, in contrast to single needle irrigation which had mostly live bacteria. Activation of the irrigating solution resulted in more dead bacteria than standard needle irrigation at the coronal, middle, and apical parts of the roots. Overall, the EndoActivator system was superior to all other techniques in reducing live bacteria within the root canal.

Conclusion

Activation of sodium hypochlorite with sonic and ultrasonic systems dramatically reduced live bacteria contamination in the dentinal tubules of infected root canals.

Targeting the Bacterial Protective Armour; Challenges and Novel Strategies in the Treatment of Microbial Biofilm

Infectious disease caused by pathogenic bacteria continues to be the primary challenge to humanity. Antimicrobial resistance and microbial biofilm formation in part, lead to treatment failures. The formation of biofilms by nosocomial pathogens such as Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Klebsiella pneumoniae (K. pneumoniae) on medical devices and on the surfaces of infected sites bring additional hurdles to existing therapies. In this review, we discuss the challenges encountered by conventional treatment strategies in the clinic. We also provide updates on current on-going research related to the development of novel anti-biofilm technologies. We intend for this review to provide understanding to readers on the current problem in health-care settings and propose new ideas for new intervention strategies to reduce the burden related to microbial infections.

Middle ear irrigation using a hydrodebrider decreases biofilm surface area in an animal model of otitis media

Objective

To compare the safety and efficacy of manual and powered irrigation of the middle ear using saline or 1% baby shampoo to treat biofilm‐forming bacterial middle ear infections.

Background

Biofilms play a major role in recalcitrant otitis media and are challenging to treat. Many therapeutic strategies have been attempted and the role of topical therapies is still being investigated. Topical irrigation using saline or 1% baby shampoo and the use of a hydrodebrider have been investigated in biofilms involved in chronic rhinosinusitis and their role within the middle ear is yet to be determined.

Methods

Twenty‐two adult chinchillas underwent bilateral trans‐bullar inoculation of non‐typable biofilm forming Haemophilus influenza followed by unilateral middle ear irrigation 5 days later using saline administered via a powered hydrodebrider or manual irrigation of saline or 1% baby shampoo. Contralateral inoculated ears served as control and were not irrigated. Two days following irrigation, the bullae were harvested and processed for scanning electron microscopy to assess biofilm surface area. Auditory brainstem responses were performed before bacterial inoculation and prior to euthanasia.

Results

Manual and powered irrigation were effective in reducing the surface area of biofilm when compared to the control group. The hydrodebrider demonstrated to be more effective at eradicating biofilm than manual irrigation, especially in areas of difficult access, such as the ventral portion of the chinchillas' bullae. There was no difference in manual irrigation of saline when compared to 1% baby shampoo. Irrigations either manually or using the hydrodebrider did not affect hearing, the vestibular system or facial function.

Conclusion

Middle ear biofilms can be treated safely and effectively with rinses using either normal saline or 1% baby shampoo administered manually or with a powered hydrodebrider.

Level of Evidence

NA.

The evaluation of E. faecalis colonies dissolution ability of sodium hypochlorite in microenvironment by a novel device

Enterococcus faecalis(E. faecalis) is a common microorganism could be isolated from the infected canals, especially in the case of refractory apical periodontitis. Due to its ability to invade the dentinal tubules and highly resistant to antimicrobial strategies, the thorough debridement of E.faecalis is hard to achieve. And that may be one of the reasons to cause reinfection and therapeutic failure. According to the anatomy of dentinal tubules published before and the results of our team previous work, we designed six types of microtubes with different sizes. By using the method of centrifugation and incubation, a standard infected model mimicking dentinal tubules was established. Sodium hypochlorite (NaClO) is the most popular irrigant applied in root canal treatment. We used three different concentrations with four distinct irrigation duration to observe the antibacterial process of E. faecalis colonies within microtubes dynamically. We concluded that the role of NaClO in the microtubes is concentration dependent and duration dependent. And the interpretation of the results has a certain reference value for clinicians.

Effectiveness of supplementary irrigant agitation with the Finisher GF Brush on the debridement of oval root canals instrumented with the Gentlefile or nickel titanium rotary instruments

AIM

To examine the efficacy of a novel supplementary irrigant agitating brush (Finisher GF Brush, MedicNRG, Kibbutz Afikim, Israel) on the debridement of root canals prepared with a novel stainless steel rotary instrumentation system (Gentlefile; MedicNRG), or nickel titanium rotary instruments in oval root canals.

METHODOLOGY

Mandibular premolars (n = 72) were selected and divided randomly into three experimental groups (n = 24) after microCT scanning: group 1, canal preparation to rotary NiTi size 20, .04 taper (R20); group 2, rotary NiTi to size 25, .04 taper (R25) and group 3, Gentlefile size 23, .04 taper (GF). Specimens were subdivided into two subgroups: subgroup A, syringe-and-needle irrigation (SNI); subgroup B, Finisher GF Brush (GB). Ten untreated canals served as controls. Specimens were processed for histological evaluation, and the remaining pulp tissue (RPT) was measured. Data were analysed using Mann-Whitney and Kruskal-Wallis tests (P = 0.05).

RESULTS

All experimental groups had significantly less RPT than the control (P < 0.05). Group 3B (GF-GB) had significantly less RPT than groups 1B (R20-GB) and 2B (R25-GF; P < 0.05). When irrigated with SNI, there was no significant difference in the RPT between the three groups (P > 0.05). When instrumented with R20, there was no significant difference between SNI and GF (P < 0.05) whilst GB had significantly less RPT than SNI for R25 (P < 0.05).

CONCLUSIONS

Supplementary irrigant agitation with the Finisher GF Brush improved the debridement of canals prepared with Gentlefile and size 25, .04 taper rotary NiTi. Root canal debridement did not significantly differ between the instruments when syringe irrigation was used.

Confocal laser scanning, scanning electron, and transmission electron microscopy investigation of Enterococcus faecalis biofilm degradation using passive and active sodium hypochlorite irrigation within a simulated root canal model

Root canal irrigation is an important adjunct to control microbial infection. The aim of this study was to investigate the effect of 2.5% (wt/vol) sodium hypochlorite (NaOCl) agitation on the removal, killing, and degradation of Enterococcus faecalis biofilm. A total of 45 root canal models were manufactured using 3D printing with each model comprising an 18 mm length simulated root canal of apical size 30 and taper 0.06. E. faecalis biofilms were grown on the apical 3 mm of the models for 10 days. A total of 60 s of 9 ml of 2.5% NaOCl irrigation using syringe and needle was performed, the irrigant was either left stagnant in the canal or agitated using manual (Gutta-percha), sonic, and ultrasonic methods for 30 s. Following irrigation, the residual biofilms were observed using confocal laser scanning, scanning electron, and transmission electron microscopy. The data were analyzed using one-way ANOVA with Dunnett post hoc tests at a level of significance p ≤ .05. Consequence of root canal irrigation indicate that the reduction in the amount of biofilm achieved with the active irrigation groups (manual, sonic, and ultrasonic) was significantly greater when compared with the passive and untreated groups (p < .05). Collectively, finding indicate that passive irrigation exhibited more residual biofilm on the model surface than irrigant agitated by manual or automated (sonic, ultrasonic) methods. Total biofilm degradation and nonviable cells were associated with the ultrasonic group.