Root Dentinal Tubules Research Articles

Enterococcus faecalis Extracellular Vesicles Promote Apical Periodontitis

Enterococcus faecalis is an important contributor to the persistence of chronic apical periodontitis. However, the mechanism by which E. faecalis infection in the root canals and dentinal tubules affects periapical tissue remains unclear. Bacterial extracellular vesicles (EVs) act as natural carriers of microbe-associated molecular patterns (MAMPs) and have recently attracted considerable attention. In this study, we investigated the role of EVs derived from E. faecalis in the pathogenesis of apical periodontitis. We observed that E. faecalis EVs can induce inflammatory bone destruction in the periapical areas of mice. Double-labeling immunofluorescence indicated that M1 macrophage infiltration was increased by E. faecalis EVs in apical lesions. Moreover, in vitro experiments demonstrated the internalization of E. faecalis EVs into macrophages. Macrophages tended to polarize toward the M1 profile after treatment with E. faecalis EVs. Pattern recognition receptors (PRRs) can recognize MAMPs of bacterial EVs and, in turn, trigger inflammatory responses. Thus, we performed further mechanistic exploration, which showed that E. faecalis EVs considerably increased the expression of NOD2, a cytoplasmic PRR, and that inhibition of NOD2 markedly reduced macrophage M1 polarization induced by E. faecalis EVs. RIPK2 ubiquitination is a major downstream of NOD2. We also observed increased RIPK2 ubiquitination in macrophages treated with E. faecalis EVs, and E. faecalis EV-induced macrophage M1 polarization was notably alleviated by the RIPK2 ubiquitination inhibitor. Our study revealed the potential for EVs to be considered a virulence factor of E. faecalis and found that E. faecalis EVs can promote macrophage M1 polarization via NOD2/RIPK2 signaling. To our knowledge, this is the first report to investigate apical periodontitis development from the perspective of bacterial vesicles and demonstrate the role and mechanism of E. faecalis EVs in macrophage polarization. This study expands our understanding of the pathogenic mechanism of E. faecalis and provides novel insights into the pathogenesis of apical periodontitis.

Analysis of the depth of penetration of an epoxy resin-based sealer following a final rinse of irrigants and use of activation systems: An in vitro study.

The objective of the study was to compare and evaluate the depth of penetration of an epoxy resin-based sealer following a final rinse of 17% ethylenediaminetetraacetic acid (EDTA) and 18% 1-hydroxyethylidene 1, 1-diphosphonate (HEDP), with diode laser and passive ultrasonic activation (PUI): an in vitro confocal laser scanning microscopy study. Fifty-two extracted human mandibular premolar teeth with single root and single canal were selected. They were disinfected in 0.1% thymol solution, cleaned of calculus and soft tissues, and stored in 0.1% thymol solution till use. All teeth were radiographed and selected as per the inclusion and exclusion criteria. The teeth were decoronated using a diamond disk under copious water spray to acquire a standardized root length of 14 mm. Working length was established by inserting a size 10-K file into each root canal until it is visible at the apical foramen and by subtracting 1 mm from the recorded length. Instrumentation of the root canal was done till master apical file size of F3 using ProTaper universal, rotary instruments. The canals were irrigated with 2 mL of 3% sodium hypochlorite between successive files. Teeth were randomly divided into four subgroups n = 12 according to the intervention. Passive ultrasonic irrigation and diode laser were used to activate the irrigants. Final irrigation was performed with distilled water. These specimens were examined using confocal laser scanning microscope (OLYMPUS FLUOVIEW FV 3000) for dentinal tubule penetration of the sealer. Two-way ANOVA test and Tukey's multiple post hoc test were used for statistical analysis. Highly significant difference was seen between the groups with EDTA and HEDP, with HEDP demonstrating the highest penetration. Among the activation techniques used in this study, PUI showed the highest penetration of the sealer. The least penetration was seen with diode laser activation and EDTA. The irrigation activation techniques significantly influence the penetration of sealer into root dentinal tubules. When penetration of sealer with different irrigation techniques and irrigants was evaluated, significant greater level of sealer penetration was attained with PUI activation of HEDP.

Iontophoresis use for increasing drug penetration into root canals and dentinal tubules: A proof-of-concept study

IntroductionThe success of endodontic treatment depends on the significant disinfection of the root canal system, its irregularities, and dentinal tubules. However, achieving complete disinfection remains challenging, with frequent failures and occurrence of secondary infections. Here, we propose using iontophoresis to increase the penetration and distribution of disinfecting agents into root canals, using methylene blue for proof-of-concept. MethodsThe marker was applied in bovine root canals, and the radial distribution of the dye in the dentinal tubules was evaluated by optical microscopy. Iontophoresis was applied at 0.5 and 1.5 mA for 5 and 15 min. ResultsA significant statistical difference (p < 0.05) was observed in the marker penetration between passive and iontophoretic applications. Both current density and application time had an important effect on methylene blue distribution, with a greater efficacy delivery to the apical region achieved after 1.5 mA for 5 min or 0.5 mA for 15 min, showing longer application time can compensate for lower application current. ConclusionIontophoresis increases the penetration and distribution of methylene blue into bovine root canals and dentinal tubules, including its innermost portions. Clinical significanceIontophoresis has shown to be a promising technique for root canal and dentinal tubule disinfection.

Silver Nanoparticles and Their Therapeutic Applications in Endodontics: A Narrative Review.

The efficient elimination of microorganisms and their byproducts from infected root canals is compromised by the limitations in conventional root canal disinfection strategies and antimicrobials. Silver nanoparticles (AgNPs) are advantageous for root canal disinfection, mainly due to their wide-spectrum anti-microbial activity. Compared to other commonly used nanoparticulate antibacterials, AgNPs have acceptable antibacterial properties and relatively low cytotoxicity. Owing to their nano-scale, AgNPs penetrate deeper into the complexities of the root canal systems and dentinal tubules, as well as enhancing the antibacterial properties of endodontic irrigants and sealers. AgNPs gradually increase the dentin hardness in endodontically treated teeth and promote antibacterial properties when used as a carrier for intracanal medication. The unique properties of AgNPs make them an ideal additive for different endodontic biomaterials. However, the possible side effects of AgNPs, such as cytotoxicity and tooth discoloration potential, merits further research.

Influence of access cavity design on calcium hydroxide removal using different cleaning protocols: a confocal laser scanning microscopy study.

The purpose of this study was to evaluate the influence of endodontic access cavities design on the removal of calcium hydroxide medication of the apical third of mandibular incisor root canal walls and dentinal tubules with different cleaning protocols: EDDY sonic activation, Er,Cr:YSGG laser-activated irrigation, or conventional irrigation with IrriFlex. Seventy-eight extracted human mandibular incisors were assigned to 6 experimental groups (n = 13) according to the endodontic access cavity and cleaning protocol for calcium hydroxide removal: traditional access cavity (TradAC)/EDDY; ultraconservative access cavity performed in the incisal edge (UltraAC.Inc)/EDDY; TradAC/Er,Cr:YSGG; UltraAC.Inc/Er,Cr:YSGG; TradAC/IrriFlex; or UltraAC.Inc/IrriFlex. Confocal laser scanning microscopy images were used to measure the non-penetration percentage, maximum residual calcium hydroxide penetration depth, and penetration area at 2 and 4 mm from the apex. Data were statistically analyzed using Shapiro-Wilk and WRS2 package for 2-way comparison of non-normally distributed parameters (depth of penetration, area of penetration, and percentage of non-penetration) according to cavity and cleaning protocol with the significance level set at 5%. The effect of cavity and cleaning protocol interactions on penetration depth, penetration area and non-penetration percentage was not found statistically significant at 2 and 4 mm levels (p > 0.05). The present study demonstrated that TradAC or UltraAC.Inc preparations with different cleaning protocols in extracted mandibular incisors did not influence the remaining calcium hydroxide at 2 and 4 mm from the apex.

The Differential Effectiveness of Calcium Hydroxide (Ca(OH)2) Combination with Chlorhexidine Digluconate (CHX) 2% and Clindamycin Hydrochloride 5% Against Enterococcus faecalis (in vitro)

Background: The main factor causing failure of root canal treatment is re-infection of the bacterium Enterococcus faecalis, so it is necessary to give the right intracanal medicament. Calcium hydroxide (Ca(OH)2) is an intracanal medicament often used in endodontic treatment. To increase the effectiveness of calcium hydroxide, a mixing agent is needed. Mixing agents such as Chlorhexidine digluconate (CHX) 2% (aqueous) and Clindamycin hydrochloride 5% (viscous). The viscous mixing agent can penetrate well into the dentinal tubules, and the antibiotic can fight various root canal endodontic pathogens and dentinal tubules without causing discoloration. This study aims to determine the differential effectiveness of calcium hydroxide combination of chlorhexidine digluconate 2% and Clindamycin hydrochloride 5% as an intracanal medicament against Enterococcus faecalis (in vitro). Methods: The design was in vitro experimental laboratories that tested the value of turbidity (Optical Density) using a spectrophotometer before and after being treated. Data were analyzed by the Kruskal-Wallis test and then Mann-Whitney U Test. Results: The positive control group had the largest negative Optical Density (OD) difference, followed by a calcium hydroxide combination of Chlorhexidine digluconate 2%, and the third sequence was a calcium hydroxide combination of Clindamycin hydrochloride 5%. A negative OD difference indicates a decrease in the number of bacterial cells. Conclusion: There are differences in the effectiveness of the antibacterial of intracanal medicament calcium hydroxide combination of Chlorhexidine digluconate 2% and calcium hydroxide combination of Clindamycin hydrochloride 5%.

Fucoidan-derived carbon dots against Enterococcus faecalis biofilm and infected dentinal tubules for the treatment of persistent endodontic infections

Enterococcus faecalis (E. faecalis) biofilm-associated persistent endodontic infections (PEIs) are one of the most common tooth lesions, causing chronic periapical periodontitis, root resorption, and even tooth loss. Clinical root canal disinfectants have the risk of damaging soft tissues (e.g., mucosa and tongue) and teeth in the oral cavity, unsatisfactory to the therapy of PEIs. Nanomaterials with remarkable antibacterial properties and good biocompatibility have been developed as a promising strategy for removing pathogenic bacteria and related biofilm. Herein, carbon dots (CDs) derived from fucoidan (FD) are prepared through a one-pot hydrothermal method for the treatment of PEIs. The prepared FDCDs (7.15 nm) with sulfate groups and fluorescence property are well dispersed and stable in water. Further, it is found that in vitro FDCDs display excellent inhibiting effects on E. faecalis and its biofilm by inducing the formation of intracellular and extracellular reactive oxygen species and altering bacterial permeability. Importantly, the FDCDs penetrated the root canals and dentinal tubules, removing located E. faecalis biofilm. Moreover, the cellular assays show that the developed FDCDs have satisfactory cytocompatibility and promote macrophage recruitment. Thus, the developed FDCDs hold great potential for the management of PEIs.Graphical

The morphological and functional relationship between dental pulp and periodontal tissue in the aspect of endo-perio lesions

Relevance. The growing prevalence of combined endo-perio lesions (EPL) attracts the interest of researchers. Insufficiently covered in the scientific literature, issues of the anatomical and functional relationship between periodontal tissues and dental pulp, the lack of an algorithm for diagnosis and treatment of EPL determine the need for their research. The study aimed to arrange the available data on the morpho-functional aspects of the relationship between dental pulp and periodontal tissues and their features that determine the p athogenesis of EPL.Materials and methods. The study found 2875 publications, presented in the international electronic scientific databases PubMed, Google Search, Embase, Web of Science, ScienceDirect, SciELO and eLibrary. Following the inclusion and non-inclusion criteria, we selected 52 publications, which included the results on studying the structure and function of periodontal tissues, roots and pulp of teeth in the aspect of EPL development. The methodology of this study meets the criteria for systematic reviews and meta-analyses (PRISMA).Results. In EPL lesions, inflammation is maintained by an infection, which persists in the additional root canals and dentinal tubules and the periodontal pocket. Prevention of the formation and elimination of infection foci in the root canal system of the tooth, periapical tissues and periodontal pockets is the basis for EPL prevention and treatment. At the same time, there are no diagnostic and therapeutic algorithms, which allow timely detection of EPL and adequate treatment, depending on the primary lesion of pulpal and periodontal tissues and individual characteristics of the patient. The structure specifics of roots, pulp, cementum, periodontium and alveolar bone are described. The characteristic features of blood supply and innervation of the pulpal and periodontal tissues are presented. Promising areas of scientific research in EPL prevention and treatment are identified.Conclusion. Tooth pulp and periodontal tissues are closely related morphologically and functionally. They are principally connected through the apical foramina and additional canals. Bacterial infection can also penetrate the pulp and periodontal tissues from the infected root canal system of the tooth through the dentinal tubules of the tooth root.

Effect of Smear Layer on Penetration Depth of Methylene Blue and Curcumin into Root Dentinal Tubules

Effect of Smear Layer on Penetration Depth of Methylene Blue and Curcumin into Root Dentinal Tubules

Debunking the Concept of Dentinal Tubule Penetration of Endodontic Sealers: Sealer Staining with Rhodamine B Fluorescent Dye Is an Inadequate Method.

The aim of this study was to investigate the suitability of rhodamine B dye staining of an epoxy resin sealer (AH Plus) and calcium-silicate-based sealers (Total Fill BC Sealer, BioRoot RCS) to represent the penetration depth of the sealers into dentinal tubules after root canal obturation. In a three-step process, (1) leaching of rhodamine B from sealers into a buffer solution, (2) passive penetration of leached rhodamine B into dentinal tubules, and (3) conformity of rhodamine B penetration assessed by confocal laser scanning microscopy (CLSM), and sealer penetration assessed by scanning electron microscopy (SEM), in root-canal-filled teeth, were evaluated. Rhodamine B dye massively leached out of Total Fill BC Sealer and BioRoot RCS into the phosphate-buffered saline (PBS). A pinkish coloration of AH Plus was found after contact with PBS. Leached rhodamine B dye passively penetrated dentinal tubules from all three sealers when placed on root dentin. No correlation was observed between sealer penetration in SEM and rhodamine B penetration in CLSM. Staining of sealers using rhodamine B is an inadequate method with which to evaluate sealer penetration depth into dentinal tubules, as it overestimates the penetration of sealers into root dentin tubules.

Development of endodontic sealers containing antimicrobial-loaded polymer particles with long-term antibacterial effects

ObjectiveThe objective of this study is to prepare new dental resins with a long-lasting antimicrobial activity. Specifically, this study evaluates an approach for controlling infection in root canals using sealers containing polyhydroxyethyl methacrylate trimethylolpropane trimethacrylate (polyHEMA/TMPT) particles loaded with cetylpyridinium chloride (CPC). In addition, the physical properties of sealers containing CPC-loaded polyHEMA/TMPT particles (CLP) are determined. MethodsPolyHEMA/TMPT particles with 10 (10%-CLP) and 25wt.% CPC (25%-CLP) with different particle sizes were fabricated and incorporated in HEMA-based sealers. CPC-release profiles were evaluated over 14 days of immersion in water, followed by 14 days of storage and 14 days of water immersion. The antibacterial activity of these sealers against Enterococcus faecalis in dentinal tubules was assessed using a root-canal-infection model. Their sealing abilities were evaluated by fluid filtration and physical properties were tested according to the ISO 6876 standard. The long-term antibacterial activity of the cured sealer containing 25%-CLP (∼21μm particle diameter) was re-assessed after 1 year of storage. ResultsAfter 28 days of immersion, 25%-CLP exhibited a higher and sustained CPC release unlike 10%-CLP. Residual bacteria in root dentinal tubules were eradicated by obturation with 25%-CLP-containing sealers. The incorporation of 25%-CLP (∼21μm) had no adverse effects on the sealing ability and physical properties of the sealer and resulted in long-term antibacterial activity. SignificanceThe incorporation of CPC-loaded particles in HEMA resins yielded endodontic sealers with long-term bactericidal activity against E. faecalis in root canals. These sealers can potentially be used to prevent recurrent apical periodontitis.

Calcium hydroxide/iodoform nanoparticles as an intracanal filling medication: synthesis, characterization, and in vitro study using a bovine primary tooth model.

The aims of this in vitro study were to synthesize, characterize, and evaluate the efficacy of a Calcium Hydroxide/Iodoform nanoparticles (CHIN) paste compared with Ultrapex as intracanal filling medication using an experimental model of bovine primary teeth. CH nanoparticle synthesis was performed via the simple hydrolysis technique of reacting calcium nitrate with sodium hydroxide. SEM-EDS and FT-IR analyses were used to characterize the obtained product. 30% of CH nanoparticles were combined with 40% of iodoform and 30% silicone oil to prepare an intracanal filling paste (CHIN). All endodontic procedures were performed on 34 uniradicular primary bovine teeth. Every root canal was instrumented with K files (up to #35) and obturated with the nanoparticle paste (experimental) or Ultrapex® (control). Three outcome variables were studied: penetration depth through the root dentinal tubules, Ca2+ ion release, and filling paste dissolution rate. The obtained data were analyzed by Student's t test. The X-ray diffraction pattern of CH nanoparticles showed characteristic peaks at CH, as confirmed by FT-IR analyses in which an intense signal was observed at 3643cm-1, characteristic of CH. In the morphological characterization, CH particles could be detected at the nanosize scale. When applied as intracanal filling, the CHIN paste exhibited a higher level of penetration through the root dentin tubules. The global mean penetration measures were 500µm for the experimental paste and 380µm for the control paste (p < 0.05). The release of Ca2+ ions (up to the seventh day) and the dissolution rate were significantly higher in the experimental paste group than in the control group. No significant differences were observed between the groups regarding pH levels. The findings of this study suggest the potential suitability of CHI nanoparticles as an alternative intracanal filling medication for infected or devitalized primary teeth.

The sealer penetration into the dentinal tubules: An appraisal of different irrigation systems: Original research

Introduction:A good endodontic sealer aids in a successful root canal treatment. Sealer in turn depends on the thorough irrigation technique and debris removal. Hence, in the present study, we intend to compare the sealer's dispersion into dentinal tubules of the different irrigation systems by confocal laser scanning microscopy (CLSM).Methodology:Seventy-six single-rooted, freshly removed human mandibular premolars were taken. They were separated into equal groups as conventional endodontic needle irrigation system, Endovacirrigation, Endoactivator irrigation, and manual dynamic agitation groups. Protaper rotary system was used and obturation was done with gutta-percha. The sealer used was AH Plus labeled with fluorescent dye (0.1% Rhodamine B isothcyanate). Transverse sections from the root apex at the levels of 1 mm, 3 mm, and 5 mm were scanned using CLSM. The sealer's penetration for the depth and the percentage were measured.Results:We observed that endovac irrigation system showed maximum percentage and depth of sealer's penetration compared to endoactivator, manual dynamic agitation, and conventional methods at 1, 3, and 5 mm levels from the apex.Conclusion:The irrigation systems significantly influence the penetration of the Sealer into root dentinal tubules. When penetration of sealer at different levels, compared to endoactivator, manual dynamic agitation, and conventional method, significant greater levels were attained with the EndoVac system.

Chemical and mechanical influence of root canal irrigation on biofilm removal from lateral morphological features of simulated root canals, dentine discs and dentinal tubules.

AimTo investigate the anti‐biofilm efficacy of irrigation using a simulated root canal model, the chemical effect of irrigants against biofilms grown on dentine discs and their impact on biofilm viscoelasticity, the efficacy of the irrigants in decontaminating infected dentinal tubules and the capacity of bacteria to regrow.MethodologyBiofilm removal, viscoelastic analysis of remaining biofilms and bacterial viability were evaluated using a simulated root canal model with lateral morphological features, dentine discs and a dentinal tubule model, respectively. Experiments were conducted using a two‐phase irrigation protocol. Phase 1: a modified salt solution (RISA) and sodium hypochlorite (NaOCl) were used at a low flow rate to evaluate the chemical action of the irrigants. Ultrasonic activation (US) of a chemically inert solution (buffer) was used to evaluate the mechanical efficacy of irrigation. Phase 2: a final irrigation with buffer at a high flow rate was performed for all groups. Optical coherence tomography (OCT), low load compression testing (LLCT) and confocal scanning laser microscopy analysis were used in the different models. One‐way analysis of variance (anova) was performed for the OCT and LLCT analysis, whilst Kruskal–Wallis and Wilcoxon ranked tests for the dentinal tubule model.ResultsUS and high flow rate removed significantly more biofilm from the artificial lateral canal. For biofilm removal from the artificial isthmus, no significant differences were found between the groups. Within‐group analysis revealed significant differences between the steps of the experiment, with the exception of NaOCl. For the dentine discs, no significant differences regarding biofilm removal and viscoelasticity were detected. In the dentinal tubule model, NaOCl exhibited the greatest anti‐biofilm efficacy.ConclusionsThe mechanical effect of irrigation is important for biofilm removal. An extra high flow irrigation rate resulted in greater biofilm removal than US in the artificial isthmus. The mechanical effect of US seemed to be more effective when the surface contact biofilm–irrigant was small. After the irrigation procedures, the remaining biofilm could survive after a 5‐day period. RISA and NaOCl seemed to alter post‐treatment remaining biofilms.

Final Endodontic Irrigation with 70% Ethanol Enhanced Calcium Hydroxide Removal from the Apical Third

IntroductionThe purpose of this study was to evaluate the cleanliness of root canal walls and dentinal tubules after attempting to remove the calcium hydroxide dressing with different irrigant solutions and the use of nonactivated irrigation or passive ultrasonic irrigation (PUI). MethodsAfter root canal instrumentation, 80 single-rooted teeth were filled with calcium hydroxide mixed with propylene glycol and 0.1% rhodamine B dye and inserted into canals with a Lentulo spiral. The calcium hydroxide dressing was initially removed with 10 mL saline solution and reinstrumentation with the master apical file. Then, the samples were randomly assigned into 8 experimental groups (n = 10) according to the irrigant solution with or without PUI: 2.5% sodium hypochlorite, 17% ethylenediaminetetraacetic acid + 1.25% sodium lauryl ether sulfate (EDTA-T), 37% phosphoric acid, or 70% ethanol. A final flush with 5 mL saline solution was performed. The percentage of clean root canal walls and the depth of clean dentinal tubules were measured with images of confocal laser scanning microscopy. The groups were compared using the 2-way analysis of variance test with the Bonferroni post hoc test for depth analysis and the Kruskal-Wallis with Dunn post hoc test for the perimeter analysis. ResultsIrrigation with 70% ethanol presented a significantly higher percentage of clean root canal walls and a higher depth of clean dentinal tubules when compared with irrigation with 2.5% sodium hypochlorite and 17% EDTA-T for both irrigation methods (P < .05). No differences were observed between nonactivated irrigation or PUI protocols (P > .05). ConclusionsSeventy percent ethanol enhanced calcium hydroxide removal from the apical root third compared with 2.5% sodium hypochlorite or 17% EDTA-T.

Electrochemical Disinfection of Experimentally Infected Teeth by Boron-Doped Diamond Electrode Treatment.

Disinfection and prevention of re-infection are the decisive treatment steps in endodontic therapy. In this study, boron-doped diamond (BDD) electrodes have been fabricated and used for disinfecting the root canals of extracted human teeth, which had been covered with bacterial biofilms formed by Bacillus subtilis and Staphylococcus epidermidis. The growth of B. subtilis could be successfully impaired, achieving a complete disinfection after 8.5 min treatment time with the success of disinfection depending on the insertion depth of the electrode in the root canal. S. epidermidis could completely be removed after 3.5 min treatment time. A clinically applicable electrode array led to complete disinfection after treatment times of 10 min for S. epidermidis and 25 min for B. subtilis. BDD electrode application allowed for the improved disinfection of root canals and dentin tubules based on a continuous production of reactive oxygen species and their enhanced penetration of dentin tubules most likely due the formation of a continuous stream of small gas bubbles. The treatment times that are required here will be shortened in clinical application, as mechanical shaping of the canal system would precede the disinfection process.

Quantification of Fusobacterium nucleatum at Depths of Root Dentinal Tubules in the Tooth Using Real-time Polymerase Chain Reaction: An In Vitro Study.

Introduction: Microorganisms have been known to cause pain and infection in the tooth. Fusobacterium nucleatum was always found predominantly in failed root canal treatments.Objective: The aim of the present study was to quantify Fusobacterium nucleatum at the inner and peripheral half of coronal, middle and apical region of the root by using real-time polymerase chain reaction (qPCR).Methods: Extracted maxillary incisors were taken. After shaping and cleaning, the root canals were inoculated with Fusobacterium nucleatum. Samples were taken from both the inner and peripheral halves of dentin. The inoculated teeth were maintained in anaerobic jars for two weeks, and the bacterial isolates were changed every third day. The quantification was done using qPCR.Results: The cycle threshold (Ct) value in all groups showed the presence of Fusobacterium nucleatum.Conclusion: Fusobacterium nucleatum penetrates to the entire thickness of dentin in the middle and apical region. The coaggregation with other microorganisms could be responsible for the symptomatic endodontic patients.

Anti-biofilm efficacy of root canal irrigants against in-situ Enterococcus faecalis biofilms in root canals, isthmuses and dentinal tubules

ObjectiveTo investigate the anti-biofilm efficacy of root canal irrigants in canal spaces, isthmi and dentinal tubules of root canals ex vivo. MethodsFifty-one single-rooted premolars, each containing an isthmus, were instrumented, autoclaved and inoculated with Enterococcus faecalis for 4 weeks. One specimen was sectioned for bacteria-specific staining to confirm the presence of biofilms using light microscopiy. The remaining specimens were randomly divided to five groups: (1) 0.9% NaCl, (2) SilverSol/H2O2, (3) HYBENX, (4) QMix 2 in1, (5) 6% NaOCl. Bacterial sampling was performed before (S1) and after (S2) canal irrigation. Diluted bacteria suspension was cultured for 48 h for counting the colony forming units (CFU). Percentages of dead bacteria and biofilm thickness were evaluated by confocal laser scanning microscopy (CLSM). Metabolic activity, lactic acid and polysaccharide synthesis of E. faecalis derived from S2 samples were analysed. ResultsThe percentages of dead bacteria were significantly affected by the factor “irrigant” (p < 0.001) and the factor “location” (p = 0.017). The percentages of dead bacteria in the isthmi and canals were both in the ordor: NaCl < SilverSol/H2O2 < HYBENX < QMix 2 in1 < NaOCl (p < 0.05). Only 6% NaOCl disrupted biofilms and significantly reduced their thickness. The CFU, metabolic activity, polysaccharide and lactic acid production of E. faecalis were all reduced by the disinfecting solutions. ConclusionsSilverSol/H2O2 and HYBENX were less adept than QMix 2 in1 at killing biofilm bacteria in root canals. None of these antibacterial irrigants were effective, compared with 6% NaOCl, in disrupting biofilms. Clinical significanceThere is advantage in using HYBENX or QMix 2 in1 to kill intratubular bacteria biofilms because of their capability in removing the inorganic component of the smear layer. SilverSol/H2O2 requires extra time to eradicate intratubular biofilms upon removal of the organic and inorganic components of the smear layer by other root canal irrigants.

Bactericidal efficacy of three parameters of Nd:YAP laser irradiation against Enterococcus faecalis compared with NaOCl irrigation.

The success of endodontic treatment depends on the thorough removal of microorganisms from the root canal system. The search for new ways to eliminate the microorganisms is therefore justified. Nd:YAP is a laser that uses yttrium aluminum perovskite, doped with neodymium crystal, as active laser medium. We used the Nd:YAP laser in an in vitro experiment to evaluate the bactericidal effect of three parameters of Nd:YAP laser-activated irrigation on biofilms of Enterococcus faecalis in root canals. The canals of 45 extracted human single-root teeth were prepared on a #35 Mtwo instrument and contaminated with E. faecalis for 14days. Forty infected single-root teeth were then randomly divided into four groups according to the irrigation agitation protocols as follows: 5.25% sodium hypochlorite (NaOCl), Nd:YAP laser (180mJ) + NaOCl, Nd:YAP laser (280mJ) + NaOCl, and Nd:YAP laser (360mJ) + NaOCl. The remaining bacteria were counted immediately using the cell count method. Teeth were firstly spilt and one half examined by scanning electron microscopy (SEM). The other half involved examination of bacterial colonization in dentinal tubules using confocal laser scanning microscopy (CLSM). Nd:YAP laser (280mJ) + NaOCl and Nd:YAP laser (360mJ) + NaOCl completely removed the E. faecalis biofilms from the root canal walls and made it the cleanest among the treatment groups. Bacterial reductions in the treatment groups for dentinal tubules are presented in a descending order as follows: Nd:YAP laser (360mJ) (53.7%), Nd:YAP laser (280mJ) (51.5%) > Nd:YAP laser (180mJ) (45.3%) > 5.25% NaOCl (31.9%) > control (19.3%) (p < 0.05). Nd:YAP laser of 280mJ and 360mJ showed effective bactericidal effect in removing E. faecalis biofilm from the root canal walls and dentinal tubules.

Efficacy of different irrigation techniques on calcium hydroxide removal from the root canal

Summary Introduction Calcium hydroxide (CH) is a medicament widely used in endodontic treatment due to its antibacterial, regenerative and biocompatible properties. Studies have shown that remaining CH on root canal walls and dentinal tubules can compromise sealer penetration, leading to its weak adhesion, volume change and, consequently, apical leakage. The aim of this study was to compare the efficacy of four different techniques in removing calcium hydroxide from the root canal. Material and Methods 32 extracted single-rooted teeth with one canal were used in this study. The canals were prepared using BioRaCe system (FKG Dentaire, Swiss) BR5 40/.04 with sodium hypochlorite irrigation after each instrument. Longitudinal grooves were formed on the proximal root surfaces. All canals (except negative control) were filled with aqueous CH suspension. After seven days of incubation, the teeth were allocated into the four groups (n=7), plus positive and negative control. Four techniques (systems) for CH removal were tested: conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), XP-endo Finisher (FKG Dentaire, Swiss) and Canal Brush (Roeko, Coltene) with irrigation of 5 ml 2% NaOCl and 5 ml 10% citric acid. All the roots were then split into the two halves with chisel and observed under the stereomicroscope (Boeco, Germany) at magnification of 20x. The area with remaining CH on the root canal wall surface was then divided with the total root canal surface area (%). The obtained results were statistically processed using One-way ANOVA and Tukey post-hoc test (p&lt;0.05). Results The most efficient system was XP-endo Finisher with 91.33% of clean surface, followed by PUI 88.36%, Canal Brush 87.83%, and CSI with 66.92%. Conclusion None of the systems completely removed the traces of the medicament from the root canal. For optimal clinical success, it is necessary to combine various systems with copious irrigation.