Identification of Culturable and Nonculturable Microorganisms,Lipopolysaccharides, and Lipoteichoic Acids From Root Canals of Teeth With Endodontic Failure

AimTo elucidate the presence of apical periodontitis in the root canal of teeth with secondary/persistent infection, including composition of microbiota, levels of endotoxins and lipoteichoic acid (LTA), and clinical implications of these findings.MethodSamples were collected from root canals of 50 patients who needed endodontic retreatment and had radiographic evidence of apical periodontitis. Microorganisms were identified by using the culture technique and biochemical tests. Nested–polymerase chain reaction (nested-PCR) was used to identify 17 species of specific bacteria. Lipopolysaccharides (LPS) and LTAs were quantified by using, respectively, limulus amebocyte lysate and enzyme-linked immunosorbent assay tests.ResultsBacteria were detected in all samples by culture and molecular methods. A total of 154 gram-positive strains, of 188 strains isolated, were found in the root canals by culture. Enterococcus faecalis and Gemella morbillorum were the most prevalent species identified by the biochemical tests, whereas molecular analyses (nested-PCR) showed a high frequency of P. gingivalis, E. faecalis, and Fusobacterium nucleatum. LPS and LTA were detected in all samples, with mean values being 3.52 EU/mL and 597.83 pg/mL, respectively. Significant statistical correlations were found between levels of LTA and clinical features.ConclusionDespite the prevalence of gram-positives, the microbiota present in secondary/persistent infections showed a large variety of species. Within this diversity, associations were found between specific bacteria and clinical features. In addition, higher levels of LTA were statistically associated with larger periapical radiolucent areas, but no correlation between this feature and LPS was found.     

Efficacy of 6% Sodium Hypochlorite on Infectious Content of Teeth with Symptomatic Irreversible Pulpitis

IntroductionThe objective of this study was to monitor the effects of chemomechanical preparation (CMP) performed with 6% sodium hypochlorite and calcium hydroxide–based intracanal medication (ICM) on the levels and diversity of bacteria, endotoxins (lipopolysaccharides [LPS]), and lipoteichoic acid (LTA) in root canals of teeth with symptomatic irreversible pulpitis.MethodsSamples were collected from 10 teeth with symptomatic irreversible pulpitis before CMP (S1), after CMP (S2), and after ICM (S3). The levels of bacteria, LPS, and LTA were assessed by using checkerboard DNA-DNA hybridization, LAL Pyrogent 5000, and enzyme-linked immunosorbent assay, respectively. Wilcoxon test, repeated-measures analysis of variance, and Tukey post hoc test were used for statistical analysis at a significance level of 5%.ResultsForty species were detected at S1. Two species were eliminated after CMP and 5 after ICM. Resistant and pain-related species were detected in the root canals. Higher levels of culturable bacteria were detected at S1. However, CMP and ICM effectively reduced the microbial load in the root canals. Higher levels of LPS and LTA were detected at S1. CMP was effective in reducing both LPS and LTA (P < .05). ICM produced additional reduction in the levels of LPS (P > .05) and LTA (P < .05).ConclusionsChemomechanical preparation using 6% sodium hypochlorite and calcium hydroxide–based intracanal medication were effective in reducing the levels of bacteria, LPS, and LTA in teeth with vital pulp and irreversibly inflamed pulp.     

Root Canal Preparation and Enlargement Using Thermally Treated Nickel-Titanium Rotary Systems in Curved Canals

IntroductionThe purpose of this study was to evaluate root canal preparation and apical enlargement of curved canals using rotary heat-treated and heat/surface-treated systems by micro–computed tomographic imaging.MethodsCurved mesial root canals (n = 48) of mandibular molars (20°–40°) were prepared using ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 25/.01 and 25/.06 or HyFlex EDM (HFEDM) 10/.05, HyFlex CM 20/.04, and HFEDM 25/.08. Apical enlargement was performed using PDL 40/.05 or HFEDM 40/.04. Scanning (9 μm) was performed before and after preparation and after apical enlargement using micro–computed tomographic imaging. Volume, percentage of volume increase, debris, untouched root canal surface, and centering ability were analyzed. Statistical analysis was performed using Mann-Whitney, Wilcoxon, and unpaired t tests (α = .05).ResultsHFEDM promoted a higher volume increase of the root canals than PDL after preparation and after apical enlargement (P < .05). The apical enlargement promoted a significant decrease in debris and untouched surface in both groups (P < .05). The percentage of debris and untouched surface were similar between HFEDM and PDL after preparation and after apical enlargement (P > .05). Both systems promoted centered canals (P > .05).ConclusionsHFEDM instruments promoted greater volume of the root canal than PDL. However, the cleaning ability of the instruments was similar. The apical increase up to size 40 with both instruments provided less debris and untouched surfaces and allowed centralization of the curved root canals.     

The Effects of Different Endodontic Access Cavity Design and Using XP-endo Finisher on the Reduction of Enterococcus faecalis in the Root Canal System

IntroductionThe aim of this study was to evaluate the effect of using the XP-endo Finisher (XPF; FKG Dentaire, La Chaux de Fonds, Switzerland) in teeth that have a traditional access cavity (TEC) and a contracted access cavity (CEC) design on the amount of decrease in the number of Enterococcus faecalis bacteria within the root canal system.MethodsEighty mandibular first molar teeth were selected and randomly divided into 2 groups: TEC and CEC (n = 40/group). After access cavity preparation in the 2 groups, 80 mesiobuccal root canals were contaminated with Enterococcus faecalis for 4 weeks. After the first sampling (S1), in order to perform root canal instrumentation, the TEC and CEC groups were further divided into 4 subgroups (10 teeth/group): Reciproc (VDW GmbH, Munich, Germany) and ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) with or without XPF. Bacterial sampling from the root canals was performed with sterile paper points before (S1) and after (S2) instrumentation to determine the bacterial load. The bacterial reduction was counted as colony-forming units/mL and analyzed statistically by 3-factor repeated measures analysis of variance. Multiple comparisons of the main factor effect were performed using the Bonferroni correction (α < .05), all at 5% significance.ResultsThe number of E. faecalis bacteria in all the samples with different cavity designs were significantly reduced after instrumentation. The lowest value of bacterial decrease percentage was observed in the CEC-Reciproc-XPF (82.8%) group.ConclusionsThe bacterial reduction counts of E. faecalis were a similar level in the TEC and CEC cavities, and the use of XPF did not show significant differences between groups.     

Evaluation of Passive Ultrasonic Irrigation and GentleWave System as Adjuvants in Endodontic Retreatment

IntroductionNonsurgical endodontic retreatment continues to be a challenge in endodontics, particularly when dealing with a complex tooth anatomy. This study evaluated the efficacy of passive ultrasonic irrigation (PUI) and the GentleWave system as supplementary techniques to remove remaining filling materials from oval-shaped root canals.MethodsTwenty distal roots of human mandibular molars with single and oval-shaped canals were shaped with R40 (40.06) instrument and filled with gutta-percha and AH Plus sealer using warm vertical obturation. Initial filling material removal was performed with R50 (50.05) instrument, followed by the use of PUI (n = 10) or GentleWave system (n = 10). Micro-computed tomographic images were obtained after obturation, initial material removal, and after the use of PUI and GentleWave. The volume of remaining filling material was calculated for the entire canal as well as for the coronal, middle, and apical thirds. Statistical analyses were performed by using analysis of variance, Kruskal-Wallis and Mann-Whitney tests. P ≤ .05 was considered significant.ResultsThe use of PUI and GentleWave as supplementary techniques significantly reduced the volume of remaining filling material after initial instrumentation (P < .05). However, none of these techniques was able to render canals free from filling materials. PUI showed better performance by removing 18% of the remaining filling material, whereas the GentleWave system was able to remove approximately 10% (P = .02).ConclusionsThe use of supplementary techniques optimized filling material removal after initial instrumentation. PUI enhanced the overall cleaning of the root canal system during endodontic retreatment in oval-shaped canals.     

Removal of Calcium Hydroxide from Artificial Grooves in Straight Root Canals: Sonic Activation Using EDDY Versus Passive Ultrasonic Irrigation and XPendo Finisher

Introduction

The aim of the present study was to compare sonic activation using EDDY (VDW, Munich, Germany), passive ultrasonic irrigation (PUI), and mechanical activation using the XPendo Finisher (FKG Dentaire, La Chaux-des-Fonds, Switzerland) for the removal of calcium hydroxide from artificial grooves in straight root canals.

Ex Vivo Evaluation of the Efficacy of Photodynamic Therapy in Eliminating Enterococcus faecalis from Dentinal Tubules by Confocal Laser Scanning Microscopy

IntroductionThe aim of the present study was to investigate ex vivo by confocal laser scanning microscopy the antibacterial effect of photodynamic therapy (PDT) on dentinal tubules in the apical 5 mm of human mandibular premolars contaminated with Enterococcus faecalis.MethodsThirty-four teeth were standardized to 20 mm and foraminal anatomic diameters using a #20 K-file (Dentsply Maillefer). Samples were contaminated for 21 days and divided into the following 3 experimental groups (n = 10): the PDT group (instrumented canals and PDT), the passive ultrasonic irrigation (PUI) group (instrumented canals and PUI), and the PUI-PDT group (instrumented canals, PUI, and PDT), along with a control group (n = 4) (noninstrumented canals). The canals in the experimental groups were instrumented with ProTaper Next (Dentsply Maillefer) up to X3 and rinsed with EDTA and sodium hypochlorite. The photosensitizer used was 0.01% methylene blue with a preirradiation time of 5 minutes and a diode laser with 4 J energy and a 660-nm wavelength. Cross sections were made 5 mm from the apex of all samples, which were analyzed using confocal laser scanning microscopy. The results were analyzed using the Shapiro-Wilk and Kruskal-Wallis (Dunn) tests.ResultsThere was a lower percentage of live bacteria in the PUI-PDT group, with a statistical difference compared with the control and PDT groups (P < .05). There was no statistical difference in the percentage of live bacteria between PUI-PDT and PUI (P > .05).ConclusionsIt was concluded that the PUI-PDT association was most effective in disinfecting root canals compared with the control group and PDT.     

Antimicrobial efficacy of 0.5% peracetic acid and EDTA with passive ultrasonic or manual agitation in an Enterococcus faecalis biofilm model

We compared the antimicrobial efficacy of EDTA and 0.5% peracetic acid (PAA), with manual agitation (MA) or passive ultrasonic irrigation (PUI) in an Enterococcus faecalis biofilm model. Fifty‐five single‐rooted human premolar teeth were chemo‐mechanically prepared and inoculated with E. faecalis for biofilm formation. These were divided into five groups (n = 11): saline solution, PAA+MA, PAA+PUI, EDTA+MA and EDTA+PUI. Root canal sampling and scanning electron microscopy of the canal lumen and dentinal tubule areas at the different root thirds were performed. The images were ranked based on contamination level. Only the PAA groups presented with no bacterial growth, with the remaining groups not presenting significant differences among them. PAA+PUI presented with the highest median position rankings in every third and location, whereas EDTA+MA performed similarly to the saline control. No differences were found when comparing MA and PUI within the same solution, however, PUI was associated with lower contamination levels mean rankings.     

Disinfecting oval-shaped root canals: effectiveness of different supplementary approaches

Introduction

This study compared the ability of different approaches to supplement the antibacterial effects of chemomechanical preparation in oval-shaped root canals.

Methods

Long oval canals from extracted teeth infected with Enterococcus faecalis (ATCC 29212) were chemomechanically prepared up to a 40/04 rotary BioRaCe instrument using 2.5% NaOCl irrigation and then subjected to two supplementary protocols. In the passive ultrasonic irrigation (PUI)/chlorhexidine (CHX) group, canals were subjected to PUI for the activation of NaOCl followed by a final rinse with 0.2% CHX digluconate solution. In the Hedström group, canals received additional Hedström filing directed towards the buccal and lingual canal recesses. Bacteriological samples were taken before and after preparation, after PUI or Hedström instrumentation, and after CHX final rinsing.

Results

Chemomechanical preparation and the supplementary steps promoted a highly significant bacterial reduction (P < .001). Quantitative (reduction in levels) and qualitative (frequency of negative cultures) analyses showed that PUI alone or Hedström filing did not significantly increase bacterial reduction (P > .05). Further rinsing with CHX also failed to significantly increase bacterial elimination when compared with post-PUI samples. However, the cumulative antibacterial effects of PUI and CHX final rinse were effective in significantly reducing bacterial counts to levels below those achieved after preparation (P = .03). This combined PUI/CHX approach also resulted in a significant increase in the incidence of negative cultures (P = .04).

Conclusions

Findings suggest that there may be a benefit of using the PUI for the activation of NaOCl followed by a final rinse with CHX as supplementary steps in the treatment of infected oval-shaped root canals.     

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.     

Smear Layer Removal Using Passive Ultrasonic Irrigation and Different Concentrations of Sodium Hypochlorite

IntroductionThe present study evaluated the effect of passive ultrasonic activation (PUI) of EDTA solution followed by conventional irrigation with 2 concentrations of sodium hypochlorite (NaOCl) on smear layer removal.MethodsFifty single-root mandibular premolars were chemomechanically prepared with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments and 1% NaOCl. The roots were cleaved, and the dentin surfaces were analyzed with scanning electron microscopy operated at a low vacuum. Images were obtained from previously demarcated areas in each root canal third. The teeth were reassembled and distributed into 5 groups according to the final irrigation protocols (n = 10): group 1, EDTA/PUI + 1% NaOCl; group 2, EDTA/PUI + 5% NaOCl; group 3, EDTA/CI + 1% NaOCl; group 4, EDTA/CI + 5% NaOCl; and group 5 (negative control), saline solution/PUI. After irrigation, the teeth were reseparated and prepared for conventional high-vacuum scanning electron microscopy of the same dentin surface that was previously analyzed. The amount of debris was classified using a 4-point scoring system. Data were analyzed with Kruskal-Wallis and Dunn tests at α = 0.05.ResultsGroups 1 and 2, which used PUI and different concentrations of NaOCl, were not significantly different; however, they differed significantly from group 3 (P < .05). With respect to canal cleanliness at different root thirds, all groups showed the worst cleaning at the apical third.ConclusionsPUI activation of the EDTA irrigant is required when canal debridement is performed with EDTA and a lower concentration of NaOCl.     

Relationship of biofilm formation and gelE gene expression in Enterococcus faecalis recovered from root canals in patients requiring endodontic retreatment

Introduction

Enterococcus faecalis is known to be the most frequently detected species in root canals with failed endodontic treatment. Many studies are available on biofilm formation and the expression of virulence factors such as gelatinase (gelE) in E. faecalis. However, the relationship of biofilm formation and the expression of gelE in E. faecalis recovered from root canals undergoing orthograde retreatment is not well understood.

Methods

E. faecalis was isolated from clinical samples of root canal retreatment, and the expression of gelE in E. faecalis was assessed. Automatic microplate reader and scanning electron microscopy were used to investigate the biofilm formation ability of E. faecalis isolates. Real-time quantitative polymerase chain reaction was used for detecting the expression of gelE in biofilm-positive and biofilm-negative E. faecalis isolates.

Results

The detection rate of E. faecalis in the root canal retreatment cases was 39.26%. An automatic microplate reader showed that most isolates were able to form biofilms, and the biofilm formation ability of strains isolated from the teeth without a sinus tract was better than that with a sinus tract (P < .05). The expression of gelE was stronger in the cases of apical radiolucency than in those without the symptom (P < .05). The expression of gelE was higher in the biofilm-positive than in biofilm-negative strains (P < .05).

Conclusions

Biofilm formation in E. faecalis was facilitated in the cases without a sinus tract. In the cases of apical radiolucency and in the biofilm-positive strains, the expression of gelE was higher.     

Influence of the apical enlargement size on the endotoxin level reduction of dental root canals

Gram-negative bacteria play an essential role in endodontic infections because they have virulence factors such as endotoxin. Due to its potential cytotoxic activity, special attention has been given to the removal/neutralization of this endotoxin in the root canal system.

Objective

The aim of this study was to evaluate the influence of the apical enlargement size (AES) by using rotary instruments on the endotoxin level reduction of dental root canals.

Material and Methods

Forty root canals of the mandibular premolar teeth were used. Escherichia coli endotoxin (055: B55) was inoculated into thirty root canals. Ten teeth served as the negative control group. After the incubation period, the first endotoxin samples were collected from the root canals with a sterile/apyrogenic paper point for the analysis of the endotoxin units (EU/mL) present before instrumentation (S1). Specimen instrumentation was performed with the Mtwo^® rotary system in the sequence 10/.04, 15/.05, 20/.06, 25/.06, 30/.05, 35/.04 and 40/.04. To monitor the effectiveness of increasing apical enlargement on endotoxin removal, the second endotoxin samples were collected from all the root canals after instrumentation with the following instruments: #25/.06- (S2); #30/.05- (S3); # 35/.04- (S4); and #40/.04- (S5). Limulus amebocyte lysate (LAL) was used to quantify the levels of endotoxin. The results were statistically compared by using repeated measures of ANOVA with post hoc Tukey testing.

Results

Increasing levels of endotoxin removal was achieved by large sized apical enlargement: S2 (AES #25/.06)- 89.2%, S3 (AES #30/.05)- 95.9%, S4 (AES #35/.04)- 97.8% and S5 (AES #40/.04)- 98.2%. Substantial reduction of endotoxin content was obtained in S4 and S5 compared to S2 (p<0.05), however, the root canal preparation was not able to eliminate the endotoxin.

Conclusions

Under the conditions of this study, it was concluded that the reduction of endotoxin levels of the dental root canals could be predicted by increasing the apical enlargement size.     

Comparison of the Effects of Intraradicular Materials on the Incidence of Fatal Root Fracture in Immature Teeth Treated with Mineral Trioxide Aggregate Apexification: A Retrospective Study

IntroductionThis study aimed to compare the incidence of root fractures that led to extraction in immature teeth endodontically treated by mineral trioxide aggregate (MTA) apexification and were restored with either reinforced (resin composite or fiber post) or nonreinforced (gutta percha or MTA) intraradicular materials.MethodsNecrotic immature teeth treated with MTA apexification from 1996 to 2017 were selected according to the inclusion and exclusion criteria. Intraradicular materials and preoperative and treatment factors were obtained from dental charts and radiographs. The incidence of fatal root facture was identified. Kaplan-Meier survival analysis and the Cox proportional hazard model were used to show the survival rate and predisposing factors at a significance level of .05.ResultsThe average recall period was 30 months. The incidence of root fracture in the teeth restored with the reinforced materials was 5.5%, which was not significantly different from the nonreinforced materials (8.3%). Furthermore, the fracture rates between the fiber post and resin composite groups were not significantly different. Two significant predisposing factors influencing the incidence of root fracture were detected: preoperative external inflammatory root resorption (hazard ratio = 26.86; P < .05) and patient age > 15 years (hazard ratio = 8.60, P < .05).ConclusionsImmature teeth treated with MTA apexification and restored with the reinforced or nonreinforced intraradicular materials exhibited a similar rate of root fracture. Preoperative external inflammatory root resorption and patient age > 15 years were found to be the predisposing factors that significantly increased the incidence of root fracture.     

Effectiveness of various irrigant activation techniques on the penetration of sodium hypochlorite into lateral canals of mature permanent teeth: A systematic review and meta-analysis

ObjectiveThis review aimed to systematically review the effectiveness of various irrigant activation techniques (IATs) on the penetration of sodium hypochlorite (NaOCl) into the lateral canals of mature permanent teeth.MethodsElectronic databases including MEDLINE (via PubMed), Scopus, ProQuest, and Cochrane Library were searched to identify laboratory studies evaluating the penetration of NaOCl into lateral canals following the use of apical negative pressure irrigation (ANP), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and/or manual dynamic activation (MDA) techniques. Meta-analysis was performed for individual IATs in comparison with CNI into the lateral canals of both straight and curved root canals. On the basis of the previous literature and parameters, the risk of bias of the selected studies was evaluated with the help of a customized tool.ResultsOf the 983 records screened, 12 studies were selected to include in the systematic review, and 10 studies were selected for the meta-analysis. The total quality assessment across the included studies indicated a high quality (83.3%). Overall, the meta-analysis demonstrated IATs had significant improvement in the penetration of NaOCl into the lateral canals of straight canals (34.3%) over CNI. The subgroup analysis of individual IATs demonstrated PUI (60.9%) to be superior in the penetration into lateral canals of straight canals.ConclusionsIATs improved the irrigant penetration into lateral canals and therefore their use during routine endodontic practice is recommended. In straight canals, PUI is the most effective IAT followed by ANP, SI, and MDA techniques.     

New Ultrasonic Tip Decreases Uninstrumented Surface and Debris in Flattened Canals: A Micro–computed Tomographic Study

IntroductionThe preparation of flattened root canals using reciprocating or rotary nickel-titanium instruments associated with the Flatsonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, SP, Brazil) was evaluated by micro–computed tomographic imaging.MethodsTwenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were randomly divided into 2 experimental groups for preparation: a Reciproc Blue (RB; VDW GmbH, Munich, Germany) 40/.06 file in reciprocating motion or ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 40/.01 and 40/.05 files in rotary motion (n = 12). A complementary preparation was performed with the Flatsonic ultrasonic tip for both preparations. Micro–computed tomographic scanning at a resolution of 8.74 μm was performed before and after preparation with the nickel-titanium instruments and after the use of the Flatsonic tip. The percentages of increase in volume, debris, and uninstrumented surface were analyzed. The data obtained were submitted to the paired and unpaired t test, analysis of variance, and the Tukey test (α = 5%).ResultsThe percentage increase in volume, debris, and uninstrumented surface was similar between RB and PDL in the entire root canal (P > .05). The PDL promoted a lower percentage of debris in the cervical third and a lower percentage of increase in volume in the apical third in comparison with RB (P < .05). The Flatsonic decreased debris and uninstrumented surface after PDL preparation in all thirds (P < .05). After preparation with RB, the Flatsonic decreases the debris in the cervical third and the uninstrumented surface in the cervical and middle thirds (P < .05).ConclusionsThe preparation of flattened root canals using RB or PDL produced a high percentage of debris and uninstrumented surface. The Flatsonic ultrasonic tip significantly improved the cleaning of flattened root canals.     

In Vivo Quantitative Evaluation of Live and Dead Bacteria in Root Canal Infection by Using Propidium Monoazide with Real-Time PCR

IntroductionFor selective detection of viable bacteria with molecular methods, propidium monoazide (PMA) treatment has been successfully applied to a wide range of bacteria. The purpose of this study was to compare the quantity of live cells with the total amounts of both live and dead cells before and after chemomechanical preparation by using PMA in combination with real-time polymerase chain reaction (qPCR).MethodsTwenty-one teeth with pulp necrosis and a periapical lesion were included. Bacterial sampling of the root canals was performed before (S1) and after (S2) chemomechanical root canal treatment. Each sample was separated into 2 different tubes. PMA was added to one of the tubes, and the other was left untreated. Then, DNA extraction and qPCR were performed. To evaluate the validity of the PMA treatment, the defined mixtures containing different ratios of live and dead cell suspensions of Enterococcus faecalis were either subjected to PMA treatment or not subjected to PMA treatment, followed by qPCR quantification.ResultsA paired t test showed a highly significant difference in the mean threshold cycle values between S1 with and without PMA (P = .0002), and this difference (0.89) was similar to that (0.96) obtained from the samples consisting of 80% live cell suspension and 20% dead cell suspension of E. faecalis. The threshold cycle values between the S2 samples with and without PMA were also significantly different (P = .0134), and this difference (0.37) was similar to that obtained from the 100% live cell suspension of E. faecalis (0.42).ConclusionsPMA in conjunction with qPCR appeared to be useful in analyzing the primary infections of root canals because there were significant amounts of dead bacteria in the root canals. Although the use of PMA treatment in post-preparation samples significantly reduced the detection of dead bacteria, this difference was still small, so further studies should be carried out to confirm the necessity of PMA treatment.     

ANTIMICROBIAL ACTIVITY OF SODIUM HYPOCHLORITE ASSOCIATED WITH INTRACANAL MEDICATION FOR Candida albicans AND Enterococcus faecalis INOCULATED IN ROOT CANALS

Objective:

The purpose of this study was to evaluate the action of sodium hypochlorite (NaOCl) associated with an intracanal medication against Candida albicans and Enterococcus faecalis inoculated in root canals.

Material and Methods:

Thirty-six human single-rooted teeth with single root canals were used. The canals were contaminated with C. albicans and E. faecalis for 21 days and were then instrumented with 1% NaOCl. The roots were divided into 3 groups (n=12) according to the intracanal medication applied: calcium hydroxide paste, 2% chlorhexidine (CHX) gel, and 2% CHX gel associated with calcium hydroxide. The following collections were made from the root canals: a) initial sample (IS): 21 days after contamination (control), b) S1: after instrumentation, c) S2: 14 days after intracanal medication placement; S3: 7 days after intracanal medication removal. The results were analyzed statistically by the Kruskal-Wallis test at 5% significance level.

Results and Conclusions:

Both 1% NaOCl irrigation and the intracanal medications were effective in eliminating E. faecalis and C. albicans inoculated in root canals.     

Improving the microbial sampling and analysis of secondary infected root canals by passive ultrasonic irrigation

Objective

The persistence of pathogenic microorganisms in root canals is the most common reason for the failure of root canal treatment and the necessity of a root filling treatment, which results in an uncertain prognosis due to technical complexity and the variety of highly adaptable microorganisms.

This study evaluated the effect of passive ultrasonic irrigation (PUI) on the outcome of the microbial analysis of root canal-treated teeth with persistent or recurrent apical inflammation in vivo.

Materials and methods

Sample collection was performed after root filling removal (sample S1, control group) and after PUI with NaCl (sample S2) using sterile paper points. In total, 19 samples were obtained. Quantification was performed by means of serial dilution of the samples. Subcultivated pure cultures were identified using MALDI-TOF MS complemented by the Vitek-2-System or PCR, followed by sequencing of the 16S rRNA gene. The results of the samples (S1 and S2) were evaluated regarding their bacterial count and composition.

Results

The total count of bacteria and the number of aerobic/facultative anaerobic microorganisms significantly increased in the S2-samples after application of PUI. The number of obligate anaerobic microorganisms showed an increase after PUI, although it was not significant. We detected 12 different aerobic/facultative anaerobic microorganisms before PUI, and in 21 cases after PUI. Two different obligate anaerobic microorganisms were found in S1 samples compared to nine different species in S2 samples.

Conclusions

PUI is a powerful method for detaching bacteria in infected root canals and enables a more precise analysis of the etiology of persistent endodontic infections.

Clinical relevance

This study indicates that PUI exerts a positive cleansing effect and adds to the accessibility of microorganisms during the application of bactericidal rinsing solution in root canal treatments.

     

Efficacy of XP-endo Finisher File in Removing Calcium Hydroxide from Simulated Internal Resorption Cavity

Introduction

The aim of this study was to evaluate the effect of supplementary use of XP-endo Finisher file, passive ultrasonic activation (PUI), EndoActivator (EA), and CanalBrush (CB) on the removal of calcium hydroxide (CH) paste from simulated internal resorption cavities.