Final Irrigation Regimen Research Articles

Effect of advanced irrigation protocols on self-expanding Smart-Seal obturation system: A scanning electron microscopic push-out bond strength study.

Introduction:The aim of this study was to evaluate the effect of different final irrigation activation techniques affect the bond strength of self-expanding Smart-Seal obturation at the different thirds of root canal space.Materials and Methods:One hundred single-rooted human teeth were prepared using the Pro-Taper system to size F3, and a final irrigation regimen using 3% sodium hypochlorite and 17% EDTA was performed. The specimens were randomly divided into five groups (n = 20) according to the final irrigation activation technique used as follows: No activation (control), manual dynamic activation (MDA), CanalBrush activation, ultrasonic activation (UA) and EndoActivator. Five specimens from each group were subjected to scanning electron microscopic observation for assessment of the smear layer removal after the final irrigation procedures. All remaining roots were then obturated with Smart-Seal obturation system. A push-out test was used to measure the bond strength between the root canal dentin and Smart-Seal paste. The data obtained from the push-out test were analyzed using two-way analysis of variance and Tukey post-hoc tests.Conclusions:It was observed that UA improved the bond strength of Smart-Seal obturation in the coronal and middle third and MDA/EndoActivator in the apical third of the root canal space.

Effect of three different irrigation solutions applied by passive ultrasonic irrigation.

ObjectivesThis study evaluated the maximum depth and percentage of irrigant penetration into dentinal tubules by passive ultrasonic irrigation (PUI).Materials and MethodsThirty extracted human teeth were instrumented and divided into three groups. According to final irrigation regimen, 5.25% sodium hypochlorite (Group A, NaOCl), 2% chlorhexidine (Group B, CHX) and saline solution (Group C, control group) were applied with Irrisafe 20 tips (Acteon) and PUI. Irrigant was mixed with 0.1% rhodamine B. Sections at 2 mm, 5 mm, and 8 mm from the apex were examined with confocal laser scanning microscopy (CLSM). The percentage and maximum depth of irrigant penetration were measured. Kruskal-Wallis test and Mann-Whitney test were performed for overall comparison between groups at each level and for pairwise comparison, respectively. Within a group, Wilcoxon test was performed among different levels. p values less than 0.05 were considered significant.ResultsIn all groups, highest penetration depth and percentage of penetration were observed at the 8 mm level. At 2 mm level, Groups A and B had significantly greater depths and percentages in penetration than Group C (p < 0.05), but there were no significant differences between Groups A and B. At 5 mm level, penetration depths and percentage of penetration was not significantly different among the groups.ConclusionsNaOCl and CHX applied by PUI showed similar depth and percentage of penetration at all evaluated levels.

Effect of QMix 2in1 on Sealer Penetration into the Dentinal Tubules

IntroductionThe purpose of this study was to evaluate the effect of final irrigation with a new endodontic irrigant, QMix 2in1 (Dentsply Tulsa Dental, Tulsa, OK), on sealer penetration into dentinal tubules using confocal laser scanning microscopy. MethodsThirty recently extracted human maxillary incisors were used in the present study. The teeth were instrumented with sodium hypochlorite (NaOCl) irrigation and then divided into 3 groups according to the final irrigation regimen used: (1) control group, 2.5% NaOCl; (2) EDTA + CHX group, 17% (EDTA) followed by 2% chlorhexidine (CHX); and (3) QMix group, QMix 2in1. All teeth were dried and then obturated with gutta-percha and rhodamine B–labeled AH26 sealer (Dentsply DeTrey, Konstanz, Germany). After setting, the roots were sectioned horizontally 3, 5, and 8 mm from the root apex. Sealer penetration into the dentinal tubules was examined by confocal laser scanning microscopy. ResultsIn the apical sections of the roots, no significant difference was detected in the percentage of sealer penetration between any of the final irrigation groups (P > .05). Both the EDTA + CHX and QMix groups showed significantly more sealer penetration than the control group in the middle and coronal sections. However, no difference was found between the EDTA + CHX and QMix groups in either of these areas (P > .05) ConclusionsUse of EDTA + CHX or QMix during final irrigation significantly improved sealer penetration when compared with the control group in the middle and coronal sections of the roots; however, no effect was observed in the apical sections.

Cleaning efficacy of different root canal preparation systems and irrigation regimens

PurposeTo compare the cleaning efficacy of root canal walls after using two Nickel–Titanium (Ni–Ti) rotary files (Flexmaster and Mtwo) and one hand Ni–Ti file (Ni–Ti flex-K) when associated with different final irrigation regimens (SmearClear, 17% ethylene diamine tetra acetic acid (EDTA) and sodium hypochlorite). Materials and methodsNinety extracted human premolars with similar range of canal curvature (21–39°) were selected. After crown removal and working length determination, roots were divided into three equal groups according to root canal instrumentation: Group I and Group II were prepared using Flexmaster, Mtwo Ni–Ti rotary systems respectively where Group III was prepared using hand NiTi flex-K files. Each group was further subdivided into three equal subgroups according to root canal final irrigation; subgroup A: SmearClear, subgroup B: 17% EDTA and subgroup C: NaOCl. Roots were then splitted longitudinally and processed for scanning electron microscopic (SEM) examination to evaluate and score the root canal cleanliness. ResultsFinal root canal irrigation using either SmearClear or 17% EDTA had significantly better cleaning efficiency than that of NaOCl in all tested groups. Ni–Ti hand files had significantly less cleaning efficacy than that of rotary systems except in subgroup C using NaOCl.

Efficacy Of Different Final Irrigation Techniques On The Removal Of Smear Layer From The Root Canal – A Scanning Electron Microscopic Analysis

Aim The purpose of this study was to compare the efficacy of the F-file in removing the smear layer from the instrumented root canal and compare it to passive ultrasonic irrigation and conventional needle syringe irrigation.Materials amp Method Sixty freshly extracted intact caries free human teeth with straight single canal and mature apices were collected. Access cavities were prepared followed by working length determination and rotary instrumentation of the canal with ProTaper system up to size F3. The teeth were divided in to three groups of 20 teeth each depending upon the final irrigation regimen it received Group Andashneedle irrigation with 17 Ethylene Di amine tetra acetic acidEDTA 5.25 Sodium Hypochlorite NaOCl Group B ndash Passive ultrasonic agitation of 5.25 NaOCl and Group C ndash 5.25 NaOCl F-File. The teeth were decoronated the roots were split longitudinally and the sections examined under scanning electron microscope for the presence of smear layer at the coronal middle and apical thirds of root canals and scored.Results Mean scores for smear layer were calculated and statistically analyzed p lt 0.05. F-file scored least for smear layer and the difference among the three groups was statistically significant. All the groups recorded highest score for smear layer at the apical third. Conclusion F-file can be a time and cost efficient alternative to passive ultrasonic irrigation as a final irrigation regimen in straight root canals.

The effect of different irrigating solutions on the push out bond strength of endodontic sealer to dentin and assessing the fracture modes: An In-vitro study

Aim: To evaluate the effect of smear clear, 7% maleic acid, 10% citric acid, and 17% EDTA on the push-out bond strength of epoxy resin-based endodontic sealer to dentin. Materials and Methodos: Fifty extracted mandibular premolars were collected. After decoronation using a diamond disc and water spray to obtain approximately 14 mm long root segments, canal patency and working length were established by inserting K file #15 (Mani). The root canals were enlarged using Protaper nickel-titanium rotary instruments to size #F3 at the working length irrigating with 3 mL of 2.6% sodium hypochlorite between each file size. The roots were then randomly divided into four groups (n = 10) according to the final irrigation regimen Group1: Saline (control). Group 2: 17% EDTA, Group 3: 7% maleic acid, Group 4: 10% citric acid, Group 5: Smear clear. Obturation was done using gutta-percha with AH Plus sealer. Each root section was then subjected to a compressive load via a universal testing machine, to measure the push out bond strength followed by assessment of fracture pattern under stereomicroscope. Results: The data was collected and submitted to statistical analysis by one-way analysis of variance (ANOVA) test. Group 3: NaOCl/maleic acid/distilled water showed greater bond strength (2.2+/-0.278 MPa) as compared to other groups. Mixed type of bond failure was predominant. Conclusion: Removal of smear layer with maleic acid as a final rinse enhanced the adhesive ability of AH plus sealer, followed by EDTA and smear clear.

Residual activity of cetrimide and chlorhexidine on Enterococcus faecalis-infected root canals

Effective final irrigation regimen is an important step in order to achieve better disinfection and ensure residual antimicrobial effects after root canal preparation. The aim of this study was to compare the residual antimicrobial activity of 0.2% cetrimide, and 0.2% and 2% chlorhexidine in root canals infected with Enterococcus faecalis. Biofilms of E. faecalis were grown on uniradicular roots for 4 weeks. After root canal preparation, root canals were irrigated with 17% ethylenediaminetetraacetic acid (EDTA) to remove the smear layer. The roots were randomly divided into three experimental groups (n=26) according to the final irrigating solution: Group I, 5 mL 0.2% cetrimide; Group II, 5 mL 0.2% chlorhexidine; and Group III, 5 mL 2% chlorhexidine. Samples were collected for 50 days to denote the presence of bacterial growth. The proportion of ungrown specimens over 50 days was evaluated using the nonparametric Kaplan–Meier survival analysis. Differences among groups were tested using the log-rank test and the level of statistical significance was set at P<0.05. The highest survival value was found with 2% chlorhexidine, showing statistically significant differences from the other two groups. At 50 days, E. faecalis growth was detected in 69.23% specimens in Groups I and II, and in 34.61% specimens of Group III. There were no significant differences between 0.2% cetrimide and 0.2% chlorhexidine. Final irrigation with 2% chlorhexidine showed greater residual activity than 0.2% chlorhexidine and 0.2% cetrimide in root canals infected with E. faecalis.

Effectiveness of a Canal Brush on Removing Smear Layer: A Scanning Electron Microscopic Study

This study evaluated the effectiveness of a highly flexible endodontic brush made of polypropylene canal brush (CanalBrush; Coltène) on smear layer removal from the canal walls when used according to the manufacturer's recommendations. Forty-four single-rooted mandibular incisors were prepared to apical size 30/0.06 and randomly divided into three groups A, B and C, where the final irrigation regimen was 10 mL 17% EDTA and 10 mL 2.5% NaOCl for group A, 10 mL EDTA, 5 mL NaOCl, CanalBrush for 20 s at 450 rpm and 5 mL NaOCl for group B, 10 mL NaOCl, CanalBrush and 10 mL NaOCl for group C. One medium-sized CanalBrush was used for each root canal and all brushes were examined under the optical microscope after application to evaluate bristle deformation. Afterwards, roots were split longitudinally and the presence of smear layer was evaluated under a scanning electron microscope. Used brushes invariably exhibited bristle deformation. Group C exhibited the highest means of smear layer in all thirds. Comparing the apical thirds in all groups, there was no statistical difference between groups A and B (3.64 ± 0.48 and 3.68 ± 0.62 respectively), while group C exhibited significantly higher scores (3.9 ± 0.28) than the other two groups. In conclusion, the CanalBrush proved unable to remove smear layer from the instrumented root canals, when used according to the manufacturers' instructions.

The Effect of Different Final Irrigant Activation Techniques on the Bond Strength of an Epoxy Resin–based Endodontic Sealer: A Preliminary Study

IntroductionThe aim of this study was to evaluate whether or not different final irrigation activation techniques affect the bond strength of an epoxy resin–based endodontic sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany) to the root canal walls of different root thirds. MethodsEighty single-rooted human mandibular premolars were prepared by using the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) to size F4, and a final irrigation regimen using 3% sodium hypochlorite and 17% EDTA was performed. The specimens were randomly divided into 4 groups (n = 20) according to the final irrigation activation technique used as follows: no activation (control), manual dynamic activation (MDA), CanalBrush (Coltene Whaledent, Altststten, Switzerland) activation, and ultrasonic activation. Five specimens from each group were prepared for scanning electron microscopic observation to assess the smear layer removal after the final irrigation procedures. All remaining roots were then obturated with gutta-percha and AH Plus sealer. A push-out test was used to measure the bond strength between the root canal dentin and AH Plus sealer. The data obtained from the push-out test were analyzed using 2-way analysis of variance and Tukey post hoc tests. ResultsThe bond strength values mostly decreased in the coronoapical direction (P < .001). In the coronal and middle thirds, ultrasonic activiation showed a higher bond strength than other groups (P < .05). In the apical third, MDA displayed the highest bond strength to root dentin (P < .05). The majority of specimens exhibited cohesive failures. ConclusionsThe bond strength of AH Plus sealer to root canal dentin may improve with ultrasonic activation in the coronal and middle thirds and MDA in the apical third.

Effect of Photoactivated Disinfection on Bond Strength of Root Canal Filling

IntroductionThe aim of this in vitro study was to assess and compare the effect of photoactivated disinfection (PAD) on the bond strength of root canal sealers to human root canal dentin using the push-out test. MethodsFifteen extracted human mandibular premolar teeth with single and straight roots were used. After the clinical crowns were removed from the cementoenamel junction, root canals were prepared with the ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) rotary system to the size of the F3 file. The smear layer of the roots was removed using 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl) and distillate water. The roots were then randomly divided into 3 groups (n = 5) according to the final irrigation regimen. In group 1, PAD (FotoSan; CMS Dental, Copenhagen, Denmark) was applied to the root canals and light cured for 20 seconds. Group 2 was finally irrigated with a 2% solution of chlorhexidine gluconate, and group 3 served as the control group (NaOCl + EDTA). All the canals were then obturated with the lateral condensation technique using gutta-percha and AH Plus sealer (Dentsply Maillefer) sealer. One-millimeter-thick horizontal sections from the coronal and midthirds of each root (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. The data were converted to megapascals and statistically analyzed using 1-way analysis of variance and the post hoc Tukey test. ResultsThere was no significant difference among the bond strength of PAD, chlorhexidine gluconate, and NaOCl (P > .05). ConclusionsWe conclude that PAD does not adversely affect the bond strength of the AH Plus sealer to root canal dentin and that it can be used for the final disinfection of root canals.

Ex vivo microbial leakage after using different final irrigation regimens with chlorhexidine

Objective:To assess the influence of final irrigation protocols with chlorhexidine in the coronal leakage of Enterococcus faecalis in filled root canals.Material and Methods:Seventy single-root canals from extracted teeth were prepared using ProTaper instruments. The irrigation protocol accomplished an alternating irrigation with 5 mL of 2.5% sodium hypochlorite (NaOCl) and 17% EDTA between each file. The teeth were randomly divided into four experimental groups (n=15) according to the final irrigation regimen: group 1, without final irrigation; group 2, irrigation with 10 mL 2.0% chlorhexidine (CHX); group 3, with a final application of EC40TM; and group 4, irrigation with the combination (1:1) of 0.2% CHX + 0.1% cetrimide (CTR). All the teeth were mounted in a two-chamber apparatus and the coronal access was exposed to E. faecalis. The presence of turbidity in the BHI broth over a period of 180 days was observed. The Friedman test was used for statistical analysis.Results:EC40TM varnish showed the least leakage at 180 days, and was statistically similar to 2% CHX. No significant differences were observed between the group without final irrigation and the 2% CHX group or 0.2% CHX + 0.1% CTR.Conclusions:In this ex vivo study, EC40TM showed the longest delayed coronal leakage of E. faecalis, although without significant differences from 2% CHX.

Multivariate analysis of the cleaning efficacy of different final irrigation techniques in the canal and isthmus of mandibular posterior teeth

ObjectivesThe aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems.Materials and MethodsMesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant) affecting the cleaning efficacy of the experimental groups.ResultsGroup SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05), and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05). Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances.ConclusionsBoth VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

Residual Activity of Chelating Agents and their Combinations with Cetrimide on Root Canals Infected with Enterococcus faecalis

IntroductionThe use of chelating agents in endodontic treatment is required to remove the smear layer and to achieve better disinfection within the root canal system. The aim of this study was to evaluate the residual antimicrobial activity of 17% ethylenediaminetetraacetic acid (EDTA), 7% maleic acid (MA), and 10% lactic acid (LA) alone and combined with 0.2% cetrimide (CTR) on infected root canals with Enterococcus faecalis. MethodsBiofilms of E. faecalis were grown in uniradicular roots for 4 weeks. After preparation the roots were randomly divided into 6 groups (n = 15) according to the final irrigation regimen as follows: 5 mL of 17% EDTA; 5 mL of 17% EDTA + 0.2% CTR; 5 mL of 7% MA; 5 mL of 7% MA + 0.2% CTR; 5 mL of 10% LA; and 5 mL of 10% LA + 0.2% CTR. Samples were collected for 60 days to denote the presence of bacterial growth. Fisher and Pearson χ2 tests were applied to compare the percentages of specimens without E. faecalis regrowth at all the time periods. ResultsThere were significant differences in bacterial regrowth between the groups with and without CTR. There were not significant differences over time among the 3 groups with CTR or among the 3 without CTR. ConclusionsThe residual activity against E. faecalis of 7% MA + 0.2% CTR, 17% EDTA + 0.2% CTR, and 10% LA + 0.2% CTR was greater than the use of chelating agents alone.

Residual Effectiveness of Final Irrigation Regimens on Enteroccus faecalis–infected Root Canals

Introduction The application of a final irrigating solution that remains active over a fairly long period of time stands as one strategy for preventing bacterial recolonization or eliminating the bacteria that persist after root canal treatment. The aim of this study was to evaluate the residual antimicrobial activity of four final irrigation regimens in root canals contaminated with Enterococcus faecalis. Methods Biofilms of E. faecalis were grown in uniradicular roots for 4 weeks. After preparing the roots chemomechanically, four final irrigation regimens were applied: (1) group EDTA-NaOCl, 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl); (2) group MA-NaOCl, 7% maleic acid (MA) followed by 5.25% NaOCl; (3) group EDTA-CHX + CTR, 17% EDTA followed by 2% chlorhexidine (CHX) + 0.2% cetrimide (CTR); and (4) group MA-CHX + CTR, 7% MA followed by 2% CHX + 0.2% CTR. Samples were collected for 60 days to denote the presence of bacterial growth. The Fisher exact test was used to compare the percentages of specimens without E. faecalis regrowth. Results All root canals in which the final irrigant was 5.25% NaOCl yielded positive cultures on the fifth day. Groups EDTA-CHX + CTR and MA-CHX + CTR with a final irrigation of 2% CHX + 0.2% CTR showed respective percentages of samples without regrowth of 72.1% and 66.8% at 60 days. There were no statistically significant differences between these groups. Conclusions The combination of 2% CHX + 0.2% CTR would be an effective alternative final irrigation regimen given its antimicrobial action over time.

Comparison of Debris Removal with Three Different Irrigation Techniques

Introduction The purpose of this study was to compare the effectiveness of debris removal between EndoVac, PiezoFlow, or needle irrigation (Max-i-Probe) in mandibular molars. Methods The mesial roots of 30 extracted mandibular molars were mounted in resin by using the K-Kube and then sectioned at 2 and 4 mm from the apex. The specimens were reassembled and instrumented to size 40/0.04. A standard irrigation protocol was used during instrumentation in the PiezoFlow and Max-i-Probe groups. During instrumentation of teeth in the EndoVac group, the manufacturer’s recommendations for irrigation were followed. Images of the canals and isthmuses were taken before final irrigation. The percentage of cleanliness for each canal and isthmus was calculated by using interactive software. The specimens were reassembled for final irrigation with EndoVac, PiezoFlow, and Max-i-Probe by using similar volumes of irrigants. Images were again used to calculate cleanliness. Comparisons of canal and isthmus cleanliness before and after final irrigation were made by using paired t tests, and the groups were compared with repeated-measures analysis of variance ( P < .05). Results There were no statistically significant differences in canal and isthmus cleanliness among all 3 groups at 2 and 4 mm from working length before or after final irrigation. Canal and isthmus cleanliness significantly improved at all levels after the final irrigation regimen in each group. Conclusions Final irrigation by using EndoVac, the PiezoFlow, or Max-i-Probe with similar volumes of irrigants significantly improved canal and isthmus cleanliness.

Effect of ultrasonication with EDTA or MTAD on smear layer, debris and erosion scores

The purpose of this study was to compare the effects of ultrasonication with ethylenediaminetetraacetic acid (EDTA) and a mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final canal irrigants on the smear layer, debris and erosion scores. Fifty-eight extracted single-rooted human teeth were instrumented with ProTaper rotary files up to size F3. According to the final irrigation regimen, the samples were distributed into the following groups: EDTA, MTAD, EDTA ultrasonicated for 1 min, and MTAD ultrasonicated for 1 min. The smear layer, debris and erosion scores were recorded at the apical, middle, and coronal third of each canal using a scanning electron microscope. Data were subjected to statistical evaluation using the Kruskal-Wallis and Mann-Whitney tests (P < 0.05). There were no significant differences in smear layer or debris removal between the experimental groups. EDTA caused significantly more erosion at the middle level than MTAD. Also EDTA resulted in more erosion at the coronal level than MTAD when subjected to ultrasonication. Ultrasonic activation of EDTA significantly increased its erosive effects at the middle and coronal levels. Based on the present findings, MTAD appears to cause less dentinal erosion while allowing proper removal of the smear layer and debris.

Ex vivo assessment of irrigant penetration and renewal during the final irrigation regimen

To assess irrigant penetration in curved canals after shaping procedures ex vivo. Thirty extracted mandibular molars with moderate to severe root canal curvature were included. A special aiming device was used to guarantee that each successive radiograph was taken with the same positioning. The mesiolingual canal of each tooth was instrumented with ProTaper rotary files. Apical third preparation was completed with an F1 instrument before additional step-back enlargement using F2 then F3 instruments. For each apical taper, the teeth were submitted successively to active irrigation (AI) then to passive irrigation (PI). AI consisted of a 0.5 mL flush of sodium diatrizoate (Hypaque 50%) immediately followed by manual mechanical activation with a gutta-percha point. PI consisted in flushing the canals with sodium hypochlorite passively delivered with a syringe. A digital radiograph was taken after each modality. The influence of needle tip design, needle tip insertion level, irrigant volume, root canal taper and solution activation was assessed by using digital subtraction radiography and measures of the depths of irrigant penetration. Comparisons were performed within an analysis of variance framework in a repeated-measures approach. For PI, all the four explanatory variables 'apical taper', 'volume of irrigant used', 'corono-apical level of needle tip placement', 'needle tip design' had a significant (P < 0.005) influence on outcome of irrigation penetration. Only active irrigation allowed complete penetration and exchange of irrigating solution. For syringe irrigation alone, the level of needle tip placement in the canal was the most dominating factor.

Effectiveness of Different Final Irrigant Activation Protocols on Smear Layer Removal in Curved Canals

Introduction A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. The improvement of these protocols is possible by using specific delivery and agitation techniques. This study examined the effect of different final irrigation regimens and methods of activation on smear layer removal in curved canals after root canal instrumentation. Methodology Mesial root canals of 50 extracted mandibular molars were prepared using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland) and 3% NaOCl. Teeth were then allocated to two control groups and four experimental groups ( n = 10) for final irrigation as follows: no-activation group (final rinse with a 27-gauge needle and 17% EDTA/3% NaOCl), manual-dynamic activation group (final rinse 17% EDTA/3% NaOCl + gutta-percha agitation), automated-dynamic activation group (final rinse 17% EDTA/3% NaOCl + RinsEndo [Dürr Dental GmbH & Co KG, Bietigheim-Bissingen, Germany]), and sonic-activation group (final rinse 17% EDTA/3% NaOCl + Endoactivator [Advanced Endodontics, Santa Barbara, CA]). All mesial roots were split with a new approach to allow visualization of every third of the canal, particularly the apical third. The samples were prepared for scanning electron microscopic observation to assess the smear layer removal. Blind scoring was performed by two calibrated observers using a five-score scale. The differences in smear layer scores between the experimental groups were analyzed with the Kruskal-Wallis test and the Mann-Whitney U test. The level of significance was set at p = 0.05. Results Very high levels of root canal cleanliness (≤score 3) were found for each test group with activation. For the middle and apical third, the no-activation group was significantly less effective than the three other activation groups (p < 0.05). The manual-dynamic activation group (final rinse 17%EDTA/3%NaOCl + gutta-percha agitation) and the sonic-activation group (final rinse 17%EDTA/3%NaOCl + Endoactivator) showed significantly better smear layer removal (p < 0.05) in comparison with the other test groups in the apical third. Conclusion Root canal cleanliness benefits from solutions activation (especially sonic activation and manual-dynamic activation) in comparison with no activation during the final irrigation regimen.

Effect of Final Irrigation Regimen on Sealer Penetration in Curved Root Canals

IntroductionThe purpose of this study was to evaluate the effect of different final irrigation regimens on the sealer penetration into dentinal tubules of curved root canals. MethodsThe mesiobuccal canals from 45 extracted maxillary and mandibular molars were instrumented with sodium hypochlorite (NaOCl) irrigation. The samples were divided into 3 groups according to the final irrigation used: group N (control), 3.5% NaOCl; group E, 17% ethylenediaminetetraacetic acid (EDTA); and group EN, 17% EDTA followed by 3.5% NaOCl. All teeth were obturated with gutta-percha and AH Plus sealer labeled with fluorescent dye. Transverse sections at 2 mm (apical) and 5 mm (coronal) from root apex were examined by using confocal laser scanning microscopy. Then, total percentage and maximum depth of sealer penetration were measured. ResultsThe apical sections in each group showed significantly lower percentage and maximum depth of sealer penetration than the coronal sections (P < .05). In apical levels, group E and EN resulted in a higher percentage of sealer penetration than the control group (P < .05), but there was no significant difference of maximum depth between group E and the control group (P > .05). ConclusionsIn curved canal, final rinse with NaOCl after the use of EDTA had no additional effect on sealer penetration. Complete debridement with a 1-minute application of EDTA remains a challenge in the apical area of curved canals.

The Effect of Different Irrigating Solutions on Bond Strength of Two Root Canal–filling Systems

The bond strength of ActiV GP root canal filling system and gutta-percha/AH plus sealer when used after final rinse with different irrigation protocols was evaluated in this study. Forty roots were randomly divided into four groups ( n = 10) according to the final irrigation regimen: group 1, 5 mL 17% EDTA; group 2, 5 mL 17% EDTA followed by 5 mL 2% chlorhexidine gluconate (CHX); group 3, 5 mL MTAD; and group 4, 5 mL MTAD followed by 5 mL 2% CHX. Each group was further subdivided into two subgroups ( n = 5): in subgroup a, the root canals were filled using warm gutta-percha and AH plus sealer, and in subgroup b, the root canals were filled using the ActiV GP obturation system. Two-millimeter thick horizontal sections from the coronal and midthirds of each root were sliced for the push-out bond strength measurement. EDTA/CHX/ActiV GP (2.46 ± 1.02 MPa ) yielded significantly the highest mean bond strength value. The significantly lowest bond strength was recorded for EDTA/ActiV GP (1.12 ± 0.72 MPa). It was concluded that the bond strength of ActiV GP was improved by using 2% CHX in the final irrigation after 17% EDTA, whereas CHX did not enhance the effect of MTAD on the bond strength of the material. The bond strength of gutta-percha/AH plus was adversely affected by MTAD and MTAD/CHX.