Alkaline Sodium Hypochlorite Irrigant and Its Chemical Interactions

Exploring Periostracum as an Alternative Root Canal Irrigant: Insights From Zebrafish Embryo Experiments

Objectives Root canal treatments aim to eliminate biofilms effectively. Considering the limitations of chemical irrigants, there is growing interest in natural alternatives like periostracum due to their antibacterial and fouling-resistant properties. This study aimed to assess periostracum's toxicity as a root canal irrigant by investigating its effects on zebrafish embryos' heart rate, survival rate, and hatching rate, as well as inflammation studies using neutral red assays comparing it to standard irrigants like ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX), and sodium hypochlorite (NaOCl). Materials and methods Zebrafish embryos were exposed to varying concentrations of periostracum irrigant and standard irrigants. Heart rate, survival rate, and hatching rate were evaluated as indicators of developmental toxicity using microscopy. Statistical analysis, utilizing GraphPad Prism software (version 5.03, GraphPad Software, LLC, San Diego, California, United States), involved one-way ANOVA and Tukey's post-hoc test to determine significance levels (p < 0.05) across control and other groups based on triplicate means and standard deviation. Results The periostracum irrigant demonstrated superior survival rates, heart rates, and hatching rates at specific concentrations compared to standard irrigants (p < 0.01), maintaining favorable heart rates and hatching rates at those concentrations. However, higher concentrations resulted in diminished hatching rates (p < 0.05). Additionally, this study revealed increased inflammation when larvae were treated with NaOCl, EDTA, and CHX. Conversely, no inflammation was observed when subjected to periostracum irrigants. These findings suggest potential advantages of periostracum as a root canal irrigant due to its increased biocompatibility. Conclusion Periostracum displayed promising attributes in zebrafish embryo experiments, such as stable heart rate, hatching rate, and survival rate, along with reduced developmental toxicity and inflammation, indicating potential advantages as a root canal irrigant, including reduced toxicity compared to conventional agents. Further research involving diverse demographics and long-term effects is crucial to validate periostracum's clinical applicability and safety in endodontic therapies.

Is a mix - A fix? "A microscopic analysis of depth of penetration of three combinations of irrigants"

Aims

The aim of the study is to evaluate the penetration depth of irrigants mixed with NaOCl into dentinal tubules at the apical third of the root canal using a confocal laser scanning microscope (CLSM).

Materials and Methods

Thirty-six single-rooted teeth were selected, decoronated, and straight-line access established. Then, the canal was enlarged with hand Protaper till size F3. The samples were divided randomly into three groups: Group 1 was irrigated with 3% NaOCl mixed with 1% phytic acid; Group 2 was irrigated with 3% NaOCl mixed with 18% etidronic acid; and Group 3 was irrigated with 3% NaOCl mixed with chitosan. The samples were subjected to CLSM evaluation. One-way analysis of variance with Tukey's post hoc was used for statistical analysis.

Results

Group 3 (NaOCl with chitosan) showed a greater depth of penetration in comparison to Groups 1 and 2.

Conclusion

Within limitations, it can be concluded that chitosan, in combination with NaOCl can be used as an alternative to the current irrigation protocol.

Effect of the use of bromelain associated with bioactive glass-ceramic on dentin/adhesive interface

OBJECTIVES

To evaluate the effect of bromelain associated with Biosilicate on the bond strength (BS) of a universal adhesive system to sound (SD) and caries-affected dentin (CAD), and on the proteolytic activity.

MATERIALS AND METHODS

Cavities were prepared in 360 molars, half submitted to cariogenic challenge. Teeth were separated into groups (n=20): Control-No treatment; CHX-0.12% chlorhexidine; NaOCl-5% sodium hypochlorite; Br5%-5% bromelain; Br10%-10% bromelain; Bio-10% Biosilicate; NaOClBio-NaOCl+Bio; Br5%Bio-Br5%+Bio; Br10%Bio-Br10%+Bio. Following treatments, the adhesive system was applied, and cavities were restored. Samples were sectioned into sticks and stored at 37 °C for 24 h, 6 months, and 1 year. Microtensile BS (2-way ANOVA, Bonferroni's test, α=0.05), fracture patterns (SEM), and adhesive interfaces (TEM) were evaluated. Bacterial collagenase assay and in situ zymography were performed.

RESULTS

In CAD, Br10% presented higher BS (p=0.0208) than Br5%Bio. Br5% presented higher BS (p=0.0033) after 6 months than after 24 h; and association of treatments, higher BS (p<0.05) after aging than after 24 h. Mixed fractures were the most prevalent. Association of treatments promoted a more uniform hybrid layer with embedded Bio particles. Experimental groups presented lower (p<0.0001) relative fluorescence units than Control. Bromelain, associated or not with Bio, showed collagenolytic degradation.

CONCLUSIONS

Bromelain associated with Biosilicate did not affect the BS to SD. In CAD, Br5%Bio decreased immediate BS but had no long-term influence. This association decreased the proteolytic activity.

CLINICAL RELEVANCE

Bromelain and Biosilicate may enhance the longevity of adhesive restorations by inhibiting endogenous proteases.

Can Heated Distilled Water Effectively Prevent Precipitate Formation between NaOCl and CHX?

Introduction

The present study aimed to investigate the capacity of different irrigation protocols using heated distilled water at 65°C (HDW), in preventing the formation of the brown-orange precipitate observed after the interaction between sodium hypochlorite (NaOCl) and chlorhexidine (CHX).

Methods

Forty human canines were selected, prepared, and cleaved in two halves. Images of delimited areas in each root canal thirds were obtained through a stereomicroscope (16x and 40x). After reassembly, the teeth were distributed into four groups (n = 10) according to the final irrigation protocol: G1 (no HDW): EDTA + NaOCl + CHX with conventional irrigation (CI); G2 (HDW + CI): EDTA with passive ultrasonic irrigation (PUI) + NaOCl (PUI) + HDW (CI) + CHX (PUI); G3 (HDW + PUI): EDTA + NaOCl + HDW + CHX with PUI; G4 (HDW + CUI): EDTA (PUI) + NaOCl (PUI) + HDW with continuous ultrasonic irrigation (CUI) + CHX (PUI). After irrigation, the teeth were re-separated and images of the same delimited areas were obtained again. Scores were assigned according to the amount of precipitate observed, comparing the initial and final images. The data were submitted to Kruskal-Wallis, Dunn and Friedman statistical tests (α = 5%).

Results

G1(no HDW) showed the highest scores in the analysis between groups (p < 0.001), with a greater amount of precipitate in the cervical and medium thirds (p < 0.001). The thirds of the other experimental groups did not differ from each other (p > 0.05).

Conclusion

The intermediate irrigation with heated distilled water at 65°C prevented the formation of brown-orange precipitate, regardless of the use of ultrasonic activation (PUI or CUI).

Effectiveness of continuous chelation irrigation protocol in endodontics: a scoping review of laboratory studies

This scoping review aimed to synthesize and explore the current boundaries and limitations of laboratory research on the effectiveness of continuous chelation irrigation protocol in endodontics. This scoping review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. Literature search was conducted on Pubmed and Scopus to identify all laboratory studies evaluating smear layer and hard-tissue debris removal or, antimicrobial efficacy, or dentine erosion induced by continuous chelation. Two independent reviewers performed the all review steps and the relevant items were recorded. Seventy-seven potentially relevant studies were identified. Finally, 23 laboratory studies met the eligibility criteria for qualitative synthesis. Seven studies focused on the smear layer/debris removal outcome, 10 on antimicrobial activity, and 10 on dentine erosion. In general, the continuous chelation protocol was equally or more effective in the cleanliness of root canals and antimicrobial activity compared with traditional sequential protocol. In addition, etidronate solutions seemed to be milder chelating agents compared to those with EDTA, thus resulting in reduced or no dentine erosion and roughness modification. Yet, the methodological differences among the included studies limit the results' generalizability. The continuous chelation seems to be equally or more effective in all investigated outcomes when compared with the traditional sequential protocol. The methodological variability among the studies and shortcomings in the methods employed limit the generalizability and clinical relevance of the results. Standardized laboratory conditions combined with reliable three-dimensional investigation approaches are necessary to obtain clinically informative findings.

Comparative evaluation of effect of nisin-incorporated ethylenediamine tetraacetic acid and MTAD on endodontic biofilm eradication, smear layer removal, and depth of sealer penetration

OBJECTIVES

To comparatively evaluate the nisin-incorporated ethylenediamine tetraacetic acid (N-EDTA) and MTAD on cytotoxicity, endodontic biofilm eradication potential, smear layer removal ability, and sealer penetration depth.

MATERIALS AND METHODS

N-EDTA was prepared and characterized using high-performance liquid chromatography (HPLC). Minimum inhibitory, minimum bactericidal, and minimum biofilm inhibitory concentration (MBC, MIC, and MBIC) were determined on Enterococcus faecalis (E. faecalis) strain. The cytocompatibility of N-EDTA and MTAD was evaluated using 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based colorimetric assay. Dentin specimens (n = 88 for antibacterial analysis, n = 170 for sealer penetration depth) were prepared and subjected to the classical irrigating strategy and obturation, respectively. The scanning electron microscopic evaluation (SEM) was done for the evaluation of biofilm disruption and smear layer removal. Confocal laser scanning microscopy (CLSM) evaluation was done for determining percentage of bacterial viability and sealer penetration depth. Statistical analysis of one-way ANOVA and Tukey's HSD post hoc tests for bacterial viability and Kruskal-Wallis test and Mann-Whitney test for smear layer removal and depth of penetration were done with the significance level set at p < 0.05.

RESULTS

MTAD and N-EDTA showed cytocompatibility without any statistical differences from each other. For N-EDTA, the MIC and MBC values were 12.5 μg/ml (1:8), and MBIC values were 36 μg/ml. Biofilm disruption and killed bacterial percentage of N-EDTA was statistically higher than MTAD, whereas both the materials showed similar efficacy in the removal of the smear layer and sealer penetration depth.

CONCLUSION

N-EDTA had negligible cytotoxicity with similar smear layer removal ability, sealer penetration, and better antibiofilm potential than MTAD.

CLINICAL RELEVANCE

N-EDTA can serve as a viable alternative endodontic irrigant.

Traditional and Recent Root Canal Irrigation Methods and Their Effectiveness: A Review

According to contemporary dental standards, the primary goal of endodontic therapy is the chemo-mechanical cleaning of the complex root canal system. Watering root canals with approved solutions and activating them are essential parts of this operation. This review outlines various irrigant activation methods for root canal therapy. Specifically, a comparison among the methods of manual dynamic activation, sonics (subsonic, sonic, and ultrasonic), internal heating, and lasers, was conducted. The results in this work were gathered using Scopus, Web of Science, Google Scholar, and PubMed databases by searching the following keywords: sodium hypochlorite, cleaning, activation, and irrigation methods. The present work concluded that the use of irrigant activation has a greater benefit than its absence. Regardless, it is impossible to point to a single effective activation method.

Antimicrobial FiteBac® K21 promotes antimicrobial Potency and wound healing

Objectives

Successful root canal therapy is dependent on the efficacy of complete instrumentation and adequate use of chemical irrigant to eliminate the biofilm from dentin surface. The aim of the study was to examine antibiofilm and antimicrobial effectiveness of newly formulated Quaternary ammonium silane (QAS/also codenamed K21; against Fusobacterium nucleatum (F. nucleatum) and Enterococcus faecalis (E. faecalis) biofilm on radicular dentin with evaluation of the anti-inflammatory consequence in vivo.

Methods

Fourier Transform Infrared Spectroscopy (FTIR) was performed after complete hydrolysis of K21 solution. Human teeth were inoculated with biofilms for 7-days followed by treatment with various irrigants. The irrigant groups were Sodium hypochlorite [NaOCl (6%)], Chlorhexidine [CHX (2%)], K21 (0.5%), K21 (1%) and Saline. Scanning electron microscopy (SEM) was performed for biofilm and resin-dentin penetration. Transmission Electron Microscopy (TEM) of biofilms was done to evaluate application of K21. For in vivo evaluation, Albino wistar rats were injected subcutaneously and sections were stained with haematoxylin/eosin. Macrophage, M1/M2 expression were evaluated along with molecular simulation. Raman measurements were done on dried biofilms.

Results

FTIR K21 specimens demonstrated presence of ethanol/silanol groups. Raman band at 1359 cm-1 resemble to -CH2- wagging displaying 29Si atoms in Nuclear Magnetic Resonance (NMR). 0.5%K21 showed cells exhibiting folded membranes. SEM showed staggering amount of resin tags with 0.5% K21 group. TEM showed membrane disruption in K21-groups. K21 groups were initially irritant, which subsided completely afterwards showing increased CD68. K21 and MMP/collagen complex was thermodynamically favourable.

Conclusion

K21 root canal irrigant was able to penetrate bacterial wall and can serve as a potential irrigant for therapeutic benefits. Expression of M2 polarized subsets showed K21 can serve in resolving inflammation and potentiate tissue repair.

Interactions between calcium hypochlorite and irrigants commonly used in endodontic practice: a chemical analysis

INTRODUCTION

This study aimed to identify possible products resulting from chemical interactions between calcium hypochlorite [Ca(OCl)₂] and other irrigants for endodontic use using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS).

METHODS

The 5.25% Ca(OCl)₂ was associated with either 70% ethanol solution, distilled water, saline solution (0.9% sodium chloride), 5% sodium thiosulfate, 10% citric acid, 17% EDTA, or 2% chlorhexidine (CHX). The reaction ratio was 1:1 and the products obtained were analyzed by ESI-QTOF-MS.

RESULTS

The interactions between Ca(OCl)₂ and CHX generated an orange-brown precipitate, without identification of para-chloroaniline (PCA), and between Ca(OCl)₂ and sodium thiosulfate a milky-white precipitate. Furthermore, when the oxidizing agent was associated with EDTA and citric acid, chlorine gas was released. As for the other associations, 70% ethanol, distilled water, and saline solution, no precipitation or gas release occurred.

CONCLUSION

The orange-brown precipitate occurs due to the chlorination of guanidine nitrogens, and the milky-white precipitate is due to the partial neutralization of the oxidizing agent. The release of chlorine gas occurs due to the low pH of the mixture, which results in the rapid formation and decomposition of chlorine. In this context, an intermediate rinsed with distilled water, saline solution and ethanol between Ca(OCl)₂ and CHX, citric acid and EDTA seems to be appropriate to prevent the formation of by-products when these irrigants need to be used in the canal. Furthermore, if it is necessary to use sodium thiosulfate, a larger volume of the solution must be used than that used for the oxidizing solution.

The Interaction of Two Widely Used Endodontic Irrigants, Chlorhexidine and Sodium Hypochlorite, and Its Impact on the Disinfection Protocol during Root Canal Treatment

In recent years, sodium hypochlorite and chlorhexidine digluconate have been the gold standard of irrigation solutions utilized within the disinfection protocol during root canal treatments. Nowadays, it is known that, during chemical disinfection of the root canal, consecutive application of sodium hypochlorite and chlorhexidine digluconate leads to the formation of an orange-brown precipitate. This precipitate is described as being chemically similar to para-chloroaniline, which is suspected to have cytotoxic and carcinogenic effects. Concerns also exist regarding its influence on the leakage of root canal fillings, coronal restorations, and tooth discoloration. The purpose of this article is to review the literature on the interaction of sodium hypochlorite and chlorhexidine digluconate on the tooth and its surrounding tissues, and to discuss the effect of the precipitate formed during root canal treatment. We further address options to avoid the formation of the precipitate and describe alternative irrigation solutions that should not interact with sodium hypochlorite or chlorhexidine digluconate.

Irrigation in Endodontics: Polyhexanide Is a Promising Antibacterial Polymer in Root Canal Treatment

Background:chronic apical periodontitis is a common pathology in dentistry, especially in endodontics. It is necessary to systematize data concerning commonly used irrigation solutions. The development of new protocols for endodontic treatment is a very promising direction. The use of a polyhexanide-based antiseptic can positively affect the results of endodontic treatment. Methods: the review was carried out involving the search for English language research and meta-analyses in the Google Scholar and PubMed databases. Results: the number of literary sources that were identified during the literature review is 180. After excluding publications that did not match the search criteria, the total number of articles included in the systematic review was determined to be 68. Conclusions: polyhexanide is a promising solution for infected root canal irrigation. The antibacterial activity of this substance is suitable for the elimination of pathogens responsible for the appearance of apical periodontitis.

Effect of Endodontic Irrigating Solutions on Radicular Dentine Structure and Matrix Metalloproteinases-A Comprehensive Review

Irrigating solutions play an important role in the eradication of intracanal microbes and debris dissolution during endodontic treatment. Different combinations of solutions and protocols have been advocated, with sodium hypochlorite (NaOCl), ethylenediamine tetra acetic acid (EDTA), and chlorhexidine (CHX) remaining the most widely used ones by many clinicians. Although these solutions provide efficient inorganic dissolution and antimicrobial capacity, their use has also been reported to cause undesired effects on root dentin composition and mechanical and biomechanical properties, such as microhardness, surface roughness, bond strength, and matrix metalloproteinase (MMP) activity. Several corroborating studies attribute these changes in mechanical properties of dentine to the use of irrigating solutions, and there are limited reports on how the solutions affect the expression of MMPs, which may be a correlating link to understanding the role of these enzymes in dentin collagen and changes in the mechanical properties of dentin. Hence, using the basis of several studies from the literature, the objective is to comprehensively review the influence of individual and combined irrigating solutions on root dentine structure and the activity of the MMPs.

Efficacy of Common Antiseptic Solutions Against Clinically Relevant Planktonic Microorganisms

Prosthetic joint infections (PJIs) are among the most devastating complications after joint replacement. There is limited evidence regarding the efficacy of different antiseptic solutions in reducing planktonic microorganism burden. The purpose of this study was to test the efficacy of different antiseptic solutions against clinically relevant planktonic microorganisms. We designed an experiment examining the efficacy of several antiseptic solutions against clinically relevant planktonic microorganisms in vitro. Regarding planktonic microorganisms, povidone-iodine had 99.9% or greater reduction for all microorganisms tested except for methicillin-resistant Staphylococcus aureus, which was reduced by 60.44%. Irrisept (Irrimax Corp) had 99.9% or greater reduction for all microorganisms except Staphylococcus epidermidis (98.31%) and Enterococcus faecalis (48.61%). Bactisure (Zimmer Surgical Inc) had 99.9% or greater reduction for all microorganisms tested. Various measures exist for PJI prevention, one of which is intraoperative irrigation. We tested irrigants against clinically relevant planktonic microorganisms in vitro and found significant differences in efficacy among them. Further clinical outcome data are necessary to determine whether these solutions can impact PJI in vivo. [Orthopedics. 2022;45(2):122-127.].

Laser-fluorescence assessment of sodium hypochlorite quenching reversal agents on human dentine

BACKGROUND

Laser-fluorescence diagnostic technology for real-time clinical assessment of residual bacteria could help assist in determining the endpoints for root canal debridement. Sodium hypochlorite (NaOCl) can however quench fluorescence and lead to false low reading. This study aims to evaluate various antioxidant for their ability to recover quenched fluorescence in dentine treated with NaOCl.

METHODS

Human dentine fluorescence was measured using 655 nm laser at baseline and again after a 2 min application of 4% NaOCl. The putative recovery agents were then applied, and the fluorescence measured after 5, 10, 20, 30 and 60 min. Recovery from quenching was also assessed using laser confocal scanning microscopy (CLSM) with a bound tetracycline fluorophore using 488 nm excitation.

RESULTS

A 5 min application of vitamin E oil or buffered 2% lignocaine solution (1:80,000 adrenaline) was effective in regaining quenched fluorescence within the following 5 mins. Distilled water, sodium thiosulfate, unbuffered 2% lignocaine with 1:80000 adrenaline and phosphate buffered saline were less effective, and of equal performance. Ascorbic acid and butylated hydroxyanisole were not effective and had deleterious effects on the levels of dentine fluorescence. CLSM provided confirmation of recovery from quenched fluorescence using vitamin E oil.

CONCLUSION

Based on these findings, reversal agents should be employed when assessing the fluorescence of dentine that has been exposed to NaOCl or other quenching agents.

Long-term treatment of dentine with triple antibiotic paste promotes stem cell viability and attachment

Objective

Successful regenerative endodontic procedures in dental treatment are critically associated with complete disinfection of the root canal and require irrigants and medicaments. One factor for consideration is the biocompatibility of the medicament as this can affect the intracanal dentine and subsequently the dental stem cell viability required for the repair of the dentine–pulp complex. This in vitro study investigated the effect of a 4-week treatment of calcium hydroxide [Ca(OH)₂] and triple antibiotic paste (TAP) on the irrigated radicular dentine by analysing dentine interaction with dental stem cells.

Methods

TAP consists of metronidazole, ciprofloxacin and minocycline. Dentine chips were prepared and treated with either Ca(OH)₂ or TAP for 4-weeks, irrigated by 1.5% sodium hypochlorite (NaOCl), rinsed with saline, followed by 17% ethylenediaminetetraacetic acid (EDTA). Dental pulp stem cells (DPSCs) cultured on the surface of the dentine chips were analysed on days 1, 3 and 7 of cell seeding for PrestoBlue viability assays, 6-diamidino-2 phenylindole (DAPI) staining and scanning electron microscopy (SEM). An independent t-test (SPSS software version 24.0) was used to statistically analyse the PrestoBlue assay data.

Results

DPSCs grown from dentine treated with TAP showed significantly higher cell viability than the Ca(OH)₂ and control groups (p < 0.05). DAPI staining of the seeded DPSCs on the treated dental chips complemented the findings of the viability assay. SEM studies also revealed improvements in the cell spreading and attachment of DPSCs grown on TAP-treated dentine compared with Ca(OH)₂.

Conclusion

The treatment of dentine with TAP for 4 weeks provided a better microenvironment for the viability and attachment of DPSCs when compared to Ca(OH)₂.

Antibacterial and antibiofilm efficacy of k21-E in root canal disinfection

OBJECTIVES

The aim of the current project was to study the antimicrobial efficacy of a newly developed irrigant, k21/E against E. faecalis biofilm.

METHODS

Root canals were instrumented and randomly divided into the following groups: irrigation with saline, 6% NaOCl (sodium hypochlorite), 6% NaOCl+2% CHX (Chlorhexidine), 2% CHX, 0.5% k21/E (k21 - quaternary ammonium silane) and 1% k21/E. E. faecalis were grown (3-days) (1×10⁷CFU mL^-1), treated, and further cultured for 11-days. Specimens were subjected to SEM, confocal and Raman analysis and macrophage vesicles characterized along with effect of lipopolysaccharide treatment. 3T3 mouse-fibroblasts were cultured for alizarin-red with Sortase-A active sites and Schrödinger docking was performed. TEM analysis of root dentin substrate with matrix metalloproteinases profilometry was also included. A cytotoxic test analysis for cell viability was measured by absorbance of human dental pulp cells after exposure to different irrigant solutions for 24h. The test percentages have been highlighted in Table 1.

RESULTS

Among experimental groups, irrigation with 0.5% k21/E showed phase separation revealing significant bacterial reduction and lower phenylalanine 1003cm^-1 and Amide III 1245cm^-1 intensities. Damage was observed on bacterial cell membrane after use of k21/E. No difference in exosomes distribution between control and 0.5%k21/E was observed with less TNFα (*p<0.05) and preferential binding of SrtA. TEM images demonstrated integrated collagen fibers in control and 0.5%k21/E specimens and inner bacterial membrane damage after k21/E treatment. The k21 groups appeared to be biocompatible to the dental pulpal cells grown for 24h.

SIGNIFICANCE

Current investigations highlight potential advantages of 0.5% k21/E as irrigation solution for root canal disinfection.

The impact of irrigation protocols on epoxy sealer penetration depth in dentinal tubules. Study involving laser confocal microscopy

The aim was to assess the impact of irrigation protocols ended with ethanol or chlorhexidine on AH Plus penetration into dentinal tubules. 45 root canals were prepared to ISO 40/04, divided into three groups and irrigated with three protocols: Group 1 (control): 5.25% NaOCl; Group 2: 40% CA (citric acid), 5.25% NaOCl, 40% CA, water, ethanol; Group 3: 40% CA, 5.25% NaOCl, 40% CA, water, 2% chlorhexidine. Canals were filled using vertical condensation technique with gutta-percha and fluorescein-stained AH Plus sealer. After 72 h, 1 mm thick cross-sections were cut at 2, 5, 8 mm from the apex. Confocal laser microscope was used to measure the sealer penetration into dentinal tubules. Mean depth of sealer penetration (in micrometres) was 107, 131, 170 (Group 1); 146, 233, 317 (Group 2); 185, 301, 542 (Group 3); in apical, middle and coronal parts, respectively. Irrigation protocol ended with chlorhexidine resulted in the deeper sealer penetration compared with alcohol.

An MSN-based synergistic nanoplatform for root canal biofilm eradication via Fenton-enhanced sonodynamic therapy

The validity and biocompatibility of irrigating agents are imperative for the success of root canal therapy. The imperfections in the currently available irrigants highlight the fact that more advanced technologies and strategies are required for complete disinfection in endodontic treatments. In the present study, a Fenton reaction-enhanced antimicrobial sonodynamic therapy (SDT) platform was fabricated for root canal disinfection. Firstly, mesoporous silica nanoparticles (MSNs) were synthesized, grafted with an amino group and then conjugated with sonosensitizer protoporphyrin IX (PpIX). Iron ions were then anchored (M@P-Fe) to initiate a Fenton reaction. Nanoparticle characterization by size and zeta potential measurements, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis confirmed that the platform was successfully developed. Reactive oxygen species (ROS) generation assessment, methylene blue degradation and electron spin resonance assays illustrated upon ultrasound (US) irradiation, that augmented ROS, can be produced by US activated PpIX and iron mediated Fenton reactions from low concentration H2O2 (0.01%). In vitro anti-Enterococcus faecalis efficacy was demonstrated by growth curve and colony forming unit measurements. Confocal laser scanning microscopy and scanning electron microscopy observations illustrated the effectiveness of the platform on in situ biofilm eradication in root canal. Owing to the stronger oxidizing capability and short lifetime of ROS, the Fenton reaction-enhanced SDT can induce detrimental oxidative damage to bacteria upon activation of US while avoiding nonspecific toxicity to cells, which was verified by cytotoxicity evaluations using CCK-8 assay and morphology observation of MC3T3-E1 cells. Compared to commonly used NaClO, this nanoplatform displayed desirable anti-bacterial, anti-biofilm abilities and better biocompatibility. These results highlight that the integrated M@P-Fe + US + H2O2 platform is a promising candidate for US enhanced root canal irrigation and disinfection.

Efficacy of common antiseptic solutions against clinically relevant microorganisms in biofilm

AIMS

Periprosthetic joint infections (PJIs) are among the most devastating complications after joint arthroplasty. There is limited evidence on the efficacy of different antiseptic solutions on reducing biofilm burden. The purpose of the present study was to test the efficacy of different antiseptic solutions against clinically relevant microorganisms in biofilm.

METHODS

We conducted an in vitro study examining the efficacy of several antiseptic solutions against clinically relevant microorganisms. We tested antiseptic irrigants against nascent (four-hour) and mature (three-day) single-species biofilm created in vitro using a drip-flow reactor model.

RESULTS

With regard to irrigant efficacy against biofilms, Povidone-iodine treatment resulted in greater reductions in nascent MRSA biofilms (logarithmic reduction (LR) = 3.12; p < 0.001) compared to other solutions. Bactisure treatment had the greatest reduction of mature Pseudomonas aeruginosa biofilms (LR = 1.94; p = 0.032) and a larger reduction than Vashe or Irrisept for mature Staphylococcus epidermidis biofilms (LR = 2.12; p = 0.025). Pooled data for all biofilms tested resulted in Bactisure and Povidone-iodine with significantly greater reductions compared to Vashe, Prontosan, and Irrisept solutions (p < 0.001).

CONCLUSION

Treatment failure in PJI is often due to failure to clear the biofilm; antiseptics are often used as an adjunct to biofilm clearance. We tested irrigants against clinically relevant microorganisms in biofilm in vitro and showed significant differences in efficacy among the different solutions. Further clinical outcome data is necessary to determine whether these solutions can impact PJI outcome in vivo. Cite this article: Bone Joint J 2021;103-B(5):908-915.

Insight into the Reaction of Alexidine with Sodium Hypochlorite: A Potential Error in Endodontic Treatment

Therapeutic success in endodontic treatment depends on successful infection control. Alexidine dihydrochloride (ALX) was recently proposed as a potential alternative to 2% chlorhexidine (CHX) as it possesses similar antimicrobial properties, expresses substantivity and does not produce p-chloroaniline (PCA) when mixed with sodium hypochlorite (NaOCl). However, the products released in this reaction have not been described to date. The aim of this study was to identify detected chemical compounds formed in the reaction of ALX and NaOCl with the ultra-high-performance liquid chromatography–mass spectrophotometry (UHPLC-MS) method and assess whether precipitates and PCA are formed in this reaction. Solutions of ALX were mixed with the equivalent volume of 2% and 5.25% (w/v) NaOCl solutions. As control, 2% (w/v) CHX was mixed with 2% and 5.25% (w/v) NaOCl. Samples were subjected to the UHPLC-MS analysis. The mixture of ALX and NaOCl resulted in a yellowish precipitate formation, the amount of which depended on NaOCl concentration. Interaction of ALX and NaOCl resulted in the production of aliphatic amines. No PCA was formed when NaOCl was mixed with ALX. However, for the first time, we identified the possible products of the interaction. The interaction between NaOCl and ALX results in the formation of aliphatic amines; therefore, these compounds should not be mixed during endodontic treatment.

Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment

Objectives

The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution.

Materials and Methods

Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (E_corr). The pitting potential (E_pit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for E_corr) and the Student t-test for independent samples (for E_pit).

Results

The mean E_corr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with E_pit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected.

Conclusions

Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.

The effect of smear layer on bacterial penetration through roots obturated using zinc oxide eugenol-based sealer

BACKGROUND

Smear layer removal has been shown to reduce bacterial penetration through root canal obturations when resin-based endodontic sealer is used. The purpose of this in vitro study was to test this effect when a non-resin-based sealer is used.

MATERIAL AND METHODS

Thirty root segments were assigned to the following groups: Smear layer removed (n = 8); smear layer retained (n = 8); negative controls (n = 10; 5 with smear layer, 5 without); and positive controls (n = 4; 2 with smear layer, 2 without). After rotary instrumentation, smear layers were removed in the treatment group and half of controls using 17% ethylenediamenetetraacetic acid (EDTA) prior to obturation. Each obturated root was affixed into a dual-chamber leakage model employing Streptococcus mutans. Roots were incubated at 37 °C for 120 d. Days until lower chamber turbidity occurred was recorded for each sample, and data were analyzed using Kaplan-Meier survival curve analysis (p = 0.05).

RESULTS

No negative controls leaked, while all positive controls were turbid within 1 day. Mean days to leakage for roots with smear layer intact was 82.75 (+/- 33.29, 95% CI), although three never leaked. Mean days to leakage through roots with smear layer removed was 46.25 (+/- 26.67, 95% CI), and all leaked. Treatment survival curves were significantly different (p = 0.048).

CONCLUSIONS

Under the conditions and limitations of this study, retaining the smear layer reduced the rate of bacterial penetration through canals which had been obturated using zinc oxide eugenol (ZOE) -based sealer.

Chlorhexidine Gel Use in the Oral District: A Systematic Review

Chlorhexidine compounds and their different formulations have been investigated several times, especially in the dentistry field. Chlorhexidine application for mouth rinsing immediately underwent oral contraindications, linked to the possibility of causing pigmentation to the teeth or relating to possible cytotoxic events after oral surgery. The positive effects, however, are considerable and its topical antiseptic action has been widely demonstrated by in vitro and clinical research. That’s the reason for its large application in different fields of dentistry. The aim of this study is to collect all the literature regarding the use of chlorhexidine gel in dentistry and all the numerous applications. The initial search on search engines obtained 232 results; then, following the application of the inclusion criteria there were 24 selected articles. The chlorhexidine gel appliance in the dental daily practice is direct to oral surgery, conservative endodontics, prevention and prophylaxis. The use of chlorhexidine has shown some positive effects, also in the case of systemic diseases prevention. Surely, this topical medicine used both professionally and prescribed for home use, can be considered a great help for the prevention of several oral pathologies with systemic implications too.

Experimental Human Root Canal Irrigant NaOCl Against Enterococcus Faecalis and 3T3, and Determination of Cytotoxicity Effect

The main aim of endodontic treatment is disinfection of root canal and to prevent chances of reinfection. The most commonly isolated species due to oral infections is Enterococcus faecalis. For nonsurgical endodontic procedures Sodium hypochlorite (NaOCl) has been the irrigant of choice. The mechanism by which endodontic irrigants induce cytotoxicity is still unclear. However, many studies clearly indicated that rapid expression of the reactive oxygen species (ROS) leads to free radicals formation which results in cytotoxicity and cell death. Hence this study was done to determine the viability of cells and oxidative stress mediated by NaOCl, an endodontic irrigant. The irrigants were tested for their effect against fibroblast isolated from human primary buccal mucosa and against 3T3 Cell line. Antibacterial activity was performed against Enterococcus faecalis. Cytotoxicity was determined by MTT. To determine the oxidative stress, total intracellular glutathione, superoxide radical scavenging activity, and catalase assays were performed. The MIC (Minimal Inhibitory Concentration) for the irrigants against Enterococcus faecalis was found to be 10 µl. 10 µl of NaOCl plain 5.2% produced the same effect as that of 10 μl of NaOCl plain 3%. The higher concentration of the irrigants decreased viability of the cells during dye exclusion assay. Enzyme based study showed there is a decrease in enzyme dehydrogenase when treat with irrigants. Glutathione, SOD level was increased gradually on 3T3 cells. But CAT level was increased when the irrigants concentration less. The results of this study indicated that endodontic irrigants were potentially controlling the Enterococcus faecalis and non-toxic/reduced viability of 3T3 cells by MTT which could be due to the oxidative stress and loss of cellular integrity probably due to the liberation of ROS evidenced by the alteration of antioxidant enzymes Glutathione, SOD and CAT.