OBJECTIVES: This study aimed to compare the effectiveness of ultrasound and acoustic and laser cleaning of curved root canals. METHODS: A total of 92 molars with independent root canals with a curvature of 20°-40° were prepared and standardized at 04 25# and stained with gentian violet solution for 72 h. Among them, 52 were randomly divi-ded into four groups for final rinsing (n=13): NI group, PUI group, EDDY group, and PIPS group. Ten samples in each group were cut horizontally along the long axis perpendicular to the root and divided into curved upper, curved, and apical segments. Images were taken with a stereomicroscope and Image J measurements were taken to calculate the depth of rinse penetration. The remaining three samples from each group were split along the long axis of the dentin, photographed by scanning electron microscope to record the dentin tubule exposure and staining layer, and scored for staining layer by double-blind method. SPSS 26.0 software was used to perform statistical analysis and select the best flushing method. An extra 40 samples were randomly divided into four groups for detection of flushing fluid penetration depth (n=10): 10, 20, 30, and 40 s. RESULTS: In the upper part, the mean depth of infiltration was not significantly different between the experimental and control groups (P>0.05). The PIPS group had a significantly lower smear layer score than the control group and the EDDY group (P<0.01). In the curved segment, the mean depth of infiltration was significantly greater in the PUI group than in the control group (P<0.05); the tarnish layer score was lower in each experimental group than in the control group. At the top, the mean depth of infiltration was greater in the PUI and PIPS groups than in the control group (P<0.05), and the smear layer score was lower in the PIPS group than in the other groups (P<0.05). After the time was changed, the depth of infiltration of PUI increased only in the apical segment as the flushing time increased. CONCLUSIONS The PUI and PIPS methods facilitate the penetration of irrigation solution into the dentin canal in curved root canals, especially in the apical segment. The PIPS technique is effective in removing the smear layer in curved root canals.
Humans ; Dental Pulp Cavity ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation/methods* ; Smear Layer ; Sodium Hypochlorite ; Therapeutic Irrigation/methods* ; Double-Blind Method

OBJECTIVE: To construct a model of Enterococcus faecalis (E. faecalis) infection in dentinal tubules by gradient centrifugation and to evaluate the antibacterial effect of low-temperature plasma on E. faecalis in dentinal tubules. METHODS: Standard dentin blocks of 4 mm×4 mm×2 mm size were prepared from single root canal isolated teeth without caries, placed in the E. faecalis bacterial solution, centrifuged in gradient and incubated for 24 h to establish the model of dentinal tubule infection with E. faecalis. The twenty dentin blocks of were divided into five groups, low-temperature plasma jet treatment for 0, 5 and 10 min, calcium hydroxide paste sealing for 7 d and 2% chlorhexidine gel sealing for 7 d. Scanning electron microscopy and confocal laser scanning microscope were used to assess the infection in the dentinal tubules and the antibacterial effect of low-temperature plasma. RESULTS: The results of scanning electron microscopy and confocal laser scanning microscopy showed that after 24 h of incubation by gradient centrifugation, E. faecalis could fully enter the dentinal tubules to a depth of more than 600μm indicating that this method was time-saving and efficient and could successfully construct a model of E. faecalis infection in dentinal tubules. Low-temperature plasma could enter the dentinal tubules and play a role, the structure of E. faecalis was still intact after 5 min of low-temperature plasma treatment, with no obvious damage, and after 10 min of low-temperature plasma treatment, the surface morphology of E. faecalis was crumpled and deformed, the cell wall was seriously collapsed, and the normal physiological morphology was damaged indicating that the majority of E. faecalis was killed in the dentinal tubules. The antibacterial effect of low-temperature plasma treatment for 10 min exceeded that of the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d. These two chemicals had difficulty entering deep into the dentinal tubules, and therefore only had a few of antibacterial effect on the bacterial biofilm on the root canal wall, and there was also no significant damage to the E. faecalis bacterial structure. CONCLUSION Gradient centrifugation could establish the model of E. faecalis dentin infection successfully. Low-temperature plasma treatment for 10 min could kill E. faecalis in dentinal tubules effectively, which is superior to the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d.
Chlorhexidine/pharmacology* ; Calcium Hydroxide/pharmacology* ; Enterococcus faecalis/physiology* ; Temperature ; Dentin ; Biofilms ; Anti-Bacterial Agents/pharmacology* ; Root Canal Irrigants/pharmacology* ; Dental Pulp Cavity

Root canal therapy is the common treatment for endodontic infections. Successful root canal therapy depends on favorable root canal preparation, root canal medication and three-dimensional obturation of the root canal system. The key to successful root canal therapy is to prevent re-infection of the highly complex root canal systems by removing infecious biofilms and bacterial toxins in the root canal system. The present paper reviews the pathogenic mechanism of the Enterococcus faecalis in the harsh environment of root canal system, the inflammation and immunity of refractory periapical periodontitis and the progress of infection control methods.
Dental Pulp Cavity ; Enterococcus faecalis ; Humans ; Periapical Periodontitis/therapy* ; Persistent Infection ; Root Canal Irrigants ; Root Canal Preparation ; Root Canal Therapy

The aim of this study was to compare the efficiency of four final irrigation protocols in smear layer removal and bacterial inhibition in root canal systems. Thirty roots inoculated with Enterococcus faecalis were prepared with ProTaper Universal files. The teeth were disinfected by conventional needle irrigation, sonic agitation using the EndoActivator device, passive ultrasonic irrigation, or an M3 Max file. Teeth with no root canal preparation served as blank controls for the establishment of the infection baseline. Teeth with preparation but no final irrigation served as a post-instrumentation baseline. After the final irrigation, the teeth were sectioned in half. One half of each tooth was examined by scanning electron microscopy (SEM) to assess smear layer removal using a five-point scale. The other half was examined by confocal laser scanning microscopy (CLSM) using the LIVE/DEAD BackLight bacterial viability kit to evaluate the depth of bacterial survival in dentinal tubules. SEM analysis revealed no significant difference in smear layer removal throughout the whole canal among the EA, PUI, and M3 Max groups (P > 0.05). CLSM revealed that PUI achieved the greatest bacterial inhibition depth in the coronal ((174.27 ± 31.63) μm), middle ((160.94 ± 37.77) μm), and apical ((119.53 ± 28.49) μm) thirds of the canal (all P < 0.05 vs. other groups). According to this comprehensive SEM and CLSM evaluation, PUI appears to have the best infection control ability in root canal systems.
Dental Pulp Cavity ; Edetic Acid ; Humans ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation ; Smear Layer ; Sodium Hypochlorite

OBJECTIVE: This work aims to uncover the promoting effect of 17% ethylenediaminetetraacetic acid (EDTA) irrigation on the dentin adhesion of Enterococcus faecalis (E. faecalis). METHODS: Forty-eight half split samples and twelve dentin slices were randomly divided into three experimental groups and one control group. The experimental groups and the control group were soaked with EDTA in different time lengths and with normal saline, respectively. E. faecalis was inoculated, and its dentin adhesion was measured via scanning electron microscopy, confocal laser scanning microscopy (CLSM), colony forming unit counts, and histological Gram staining. RESULTS: According to histological Gram staining, the depth showed no statistically significant differences between 1 min group and the control group, 1 min group and 3 min groups (P>0.05). E. faecalis intruded in the dentine tubules (measured by CLSM), and the thickness of the biofilm on the dentin surface and the colony numbers of experimental groups were greater than those of the control group (P<0.05). The differences between the three experimental groups were statistically signi-ficant (P<0.05). CONCLUSIONS EDTA (17%) irrigation can promote E. faecalis adhesion to dentin. This adhesion would in turn prolong EDTA treatment time.
Biofilms ; Dentin ; Edetic Acid ; Enterococcus faecalis ; Microscopy, Confocal ; Root Canal Irrigants ; Sodium Hypochlorite

OBJECTIVE: This study aimed to evaluate the effectiveness of XP-endo Finisher (XPF) file and passive ultrasonic irrigation (PUI) in the smear layer removal of the root canal. METHODS: A total of 60 human single-rooted premolars were selected and decoronated to standardize their canal length to 16 mm. Tooth samples were prepared using a S3 rotary system to prepare root canal with the file size of 3S and then randomly divided into 6 groups according to the final irrigation protocol, as follows: XPF 3 mL of 3% NaOCl for 1 min (group A); XPF 3 mL of 3% NaOCl for 1 min, followed by 4 mL of 17% ethylene diamine tetraacetic acid (EDTA) for 1 min (group B); PUI of 3 mL of 3% NaOCl for 1 min (group C); PUI of 3 mL of 3% NaOCl for 1 min, followed by 4 mL of 17% EDTA for 1 min (group D); 3 mL of 3% NaOCl for 1 min by using a syringe and a 30 G side-vented needle (group E); and 3 mL of 3% NaOCl for 1 min by using a syringe and a 30 G side-vented needle, followed by 4 mL of 17% EDTA for 1 min (group F). After the completion of the root canal preparation, the teeth were split into two longitudinally. The mean numbers of the visible open dentinal tubules in the apical and middle thirds of the root canals were evaluated via scanning electron microscope. RESULTS: The whole surfaces of the root canals in groups A, C, and E were covered by a smear layer. Groups A and C possessed significantly higher number of visible open dentinal tubules than in group E (P<0.05), with statistically insignificant difference between groups A and C (P>0.05). The apical third of the samples in groups B and D and in the middle thirds of canals in group F exhibited a small amount of smear layer, and the dentinal tubules were open or semi-open. The root canal surfaces in the apical third of the samples in group F were covered by a smear layer, and the dentinal tubules were sealed or semisealed. The smear layers in the middle third of the samples in groups B and D were removed, and the dentinal tubules were more visibly open than those of the four other groups (P<0.05). The difference between groups B and D were statistically insignificant (P>0.05). CONCLUSIONS The difference between XPF and PUI in terms of the smear layer removal of the root canals was insignificant. Hence, XPF, as a new irrigation agitation technique, can aid in improving smear layer removal.
Dental Pulp Cavity ; Edetic Acid ; Humans ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; Root Canal Preparation ; Smear Layer ; Sodium Hypochlorite

OBJECTIVES: To determine the effect of root canal irrigants on the hydrophobicity and adherence of Staphylococcus epidermidis (S. epidermidis) to root canal dentin in vitro. MATERIALS AND METHODS: Root dentin blocks (n = 60) were randomly divided into 4 groups based on the irrigation regimen: group 1, saline; group 2, 5.25% sodium hypochlorite (NaOCl); group 3, 5.25% NaOCl followed by 17% ethylenediaminetetraacetic acid (EDTA); group 4, same as group 3 followed by 2% chlorhexidine (CHX). The hydrophobicity of S. epidermidis to root dentin was calculated by cell surface hydrophobicity while the adherence was observed by fluorescence microscopy, and bacteria were quantified using ImageJ software (National Institutes of Health). Statistical analysis of the data was done using Kruskal-Wallis test and Mann-Whitney U test (p = 0.05). RESULTS: The hydrophobicity and adherence of S. epidermidis to dentin were significantly increased after irrigating with group 3 (NaOCl-EDTA) (p < 0.05), whereas in group 4 (NaOCl-EDTA-CHX) both hydrophobicity and adherence were significantly reduced (p < 0.05). CONCLUSIONS: The adherence of S. epidermidis to dentin was influenced differently by root canal irrigants. Final irrigation with CHX reduces the bacterial adherence and may impact biofilm formation.
Academies and Institutes ; Bacteria ; Biofilms ; Chlorhexidine ; Dental Pulp Cavity ; Dentin ; Edetic Acid ; Hydrophobic and Hydrophilic Interactions ; In Vitro Techniques ; Microscopy, Fluorescence ; Root Canal Irrigants ; Sodium Hypochlorite ; Staphylococcus epidermidis ; Staphylococcus

The essence of pulp and periapical disease is bacterial infection. Thus, satisfactory infection control is the premise and foundation of healing, in which root canal preparation is a critical procedure. Root canal system anatomy, infection degree, physical cutting during root canal preparation, and certain cleaning measures affect the quality of infection control. Appropriate evaluation of the grades of infected root canals before treatment is necessary because different grades of root canal infection demand various disinfection schedules to facilitate tissue healing and guarantee the long-term success rate of endodontic treatment.
Dental Pulp Cavity ; Humans ; Infection Control ; Periapical Diseases ; Periapical Periodontitis ; Root Canal Irrigants ; Root Canal Preparation ; Root Canal Therapy

OBJECTIVE: To investigate the effect of smear layer on apical sealing ability in teeth obturated with mineral trioxide aggregate (MTA) Plus as retrofilling materials. METHODS: Fifty freshly extracted maxillary anterior teeth or premolars with single root canal were used in this study. All teeth were instrumented to master apical point 60# by using the stepback technique, obturated with lateral condensation technique, and then apical resected. A rootend cavity was then instrumented with an ultrasonic diamond-coated tip. Then the selected teeth were randomly and equally divided into two groups (n=25). In the experimental group (smear-), the teeth were irrigated with 0.17 g/L ethylenediaminetetraacetic acid (EDTA) to remove smear layer on the root-end cavity wall; in the control group (smear+), the teeth were irrigated with physiological saline. Five teeth were extracted to evaluate the cleanliness of root end cavity walls under a videomicroscope, respectively. The scanning electron microscope (SEM) evaluation was also performed for the presence of smear layer and open tubule. For the additional 40 teeth, the root-end cavities were filled with MTA Plus. The quantitative apical leakage of each teeth was evaluated by measuring the concentration of leaked sucrose in apical reservoir on 1, 7, 14, 21, 28, 35, 42, 49 and 56 days, respectively. The samples were stored at 37 °C and 100% humidity for 56 days. Statistical analysis was done with ANOVA for repeated measurement design data. RESULTS: Removal of the smear layer did not cause significantly less apical leaked sucrose than that when the smear layer was left intact for 56 days (P>0.05). There were statistically significant differences at the concentration of leaked sucrose among different observation time points (P<0.05). CONCLUSION It may be concluded that removing the smear layer may not be necessary in root-end cavities filled with MTA Plus.
Aluminum Compounds ; Calcium Compounds ; Dental Leakage ; Drug Combinations ; Edetic Acid ; Oxides ; Root Canal Filling Materials ; Root Canal Irrigants ; Root Canal Preparation ; Root Canal Therapy ; Silicates ; Smear Layer ; Sucrose/pharmacokinetics*

OBJECTIVES: The purpose of this study was to compare the antibacterial activity of urushiol against Enterococcus faecalis (E. faecalis) to that of NaOCl. MATERIALS AND METHODS: The canals of thirty two single rooted human teeth were instrumented with Ni-Ti files (ProTaper Next X1, X2, X3, Dentsply). A pure culture of E. faecalis ATCC 19433 was prepared in sterile brain heart infusion (BHI) broth. The teeth were submerged in the suspension of E. faecalis and were incubated at 37℃ for 7 days to allow biofilm formation. The teeth were randomly divided into three experimental groups according to the irrigant used, and a negative control group where no irrigant was used (n = 8). Group 1 used physiologic normal saline, group 2 used 6% NaOCl, and group 3 used 10 wt% urushiol solution. After canal irrigation, each sample was collected by the sequential placement of 2 sterile paper points (ProTaper NEXT paper points, size X3, Dentsply). Ten-fold serial dilutions on each vials, and 100 µL were cultured on a BHI agar plate for 8 hours, and colony forming unit (CFU) analysis was done. The data were statistically analyzed using Kruskal-Wallis and Mann-whitney U tests. RESULTS: Saline group exhibited no difference in the CFU counts with control group, while NaOCl and urushiol groups showed significantly less CFU counts than saline and control groups (p < 0.05). CONCLUSIONS: The result of this study suggests 10% urushiol and 6% NaOCl solution had powerful antibacterial activity against E. faecalis when they were used as root canal irrigants.
Agar ; Biofilms ; Brain ; Dental Pulp Cavity* ; Enterococcus faecalis ; Heart ; Humans ; Root Canal Irrigants ; Sodium Hypochlorite ; Stem Cells ; Tooth