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BACKGROUND This systematic review of the literature aimed to identify published studies and evaluate them on the quality of root canal fillings (RCF) and procedural errors with rotary systems for in vivo studies prepared for different clinical settings. MATERIAL AND METHODS A full literature exploration was conducted in Clarivate Analytics' Web of Science, Elsevier's Scopus, Embase, and PubMed for studies published between January 2020 and March 2024. A manual search was also performed by reviewing the references of selected papers. The following keywords were used: quality of root canal filling(s) OR quality of root canal obturation, root canal obturation OR endodontic treatment, clinical setting (academic, private, governmental), AND/OR procedural errors and rotary instrumentation. RESULTS Sixteen clinical studies were included in this review. The acceptance percentages for obturation length, density, and taper were 76.3%, 74.7%, and 82.5%, respectively, indicating significantly high, good ratios. The overall RCF recorded showed that 68.2% of root canal obturations were considered acceptable. Acceptable rates remained higher than unacceptable rates in academic, hospital, and private settings, and percentages ranged from 65.2% to 93.0%. Only 5 studies reported procedural errors, namely, ledge formation, separated instruments, apical perforation, transportation, lateral perforation, and root/foramen perforation. CONCLUSIONS Using rotary instruments for different root canal treatment steps as instrumentation and obturations is highly recommended. Among different clinical setting and practice, these instruments resulted in a good and acceptable RCF, overall quality performed by those instruments, and few procedural errors.

Objective: The aim of this study was to evaluate the use of Self-adjusting file (SAF) system and Hedström (H) file for removing remaining filling material (RFM) from C-shaped canals., Methods: 20 C-shaped mandibular second molars with C1 configurations were instrumented, filled with tagger´s hybrid technique. Samples were divided into 2 groups (n=10). Reciproc R25 and a Mtwo 35/04 file were used for retreatment in both groups. Then, a 2.0 SAF file (group I) and a #35 H file (group II) were used as supplementary steps for RFM removal. Micro-CT scanning was performed after every procedure. Total volumes were calculated and converted into percentages. Also, the minimum wall thickness at 3, 5, 7 mm from apex was calculated. The Prism 7.0 software was used as the analytical tool with a significance of 5%., Results: Initial obturation removal was approximately 64% in group I and 67% in Group II. The apical third had the highest values of RFM. The use of a H file significantly reduced the RFM compared to SAF in the total canal length respectively (30% vs 18%) and at 1-3 mm and 3-6 mm when compared to the use of SAF. A statistically significant decrease of RFM and minimum wall thickness were observed in both groups (P<0.05)., Conclusion: None of the retreatment techniques completely removed RFM. The apical region was the more unaffected area. Also, the SAF file was less effective than the H file in removing the RFM. Although C-shaped canals possesses thinner dentinal wall thickness, no excessive dentine removal was observed after each instrument use., Competing Interests: Conflict of interest: The authors deny any conflicts of interest related to this study., (Copyright: © 2020 European Endodontic Journal.)

Objective: The aim of this study was to compare the efficacy of HyFlex EDM (Coltene/Whaledent, Altstätten, Switzerland) and ProTaper Universal Retreatment Nickel-Titanium (NiTi) Systems [The ProTaper Universal Retreatment (PTR), Dentsply Maillefer, Ballaigues, Switzerland] in the removal of the root canal filling materials with or without laser activated irrigation. Materials and methods: The root canals of 60 human mandibular premolars were instrumented with K files up to size 35 at a working length; the step-back procedure was performed in 1 mm increments up to size 50. Next, the teeth were obturated using the lateral compaction technique with gutta-percha and resin-based sealer, and they were randomly divided into two groups ( n  = 30) according to the retreatment systems: PTR and HyFlex EDM NiTi rotary files. Then, each group was divided into two subgroups ( n  = 15), laser [photon-induced photo-acoustic streaming (PIPS); Fotona, Ljubljana, Slovenia] activated irrigation and conventional needle irrigation group. Following these procedures, the specimens were evaluated using micro-computed tomography. Results: There was no significant difference between the instrumentation systems regarding the cleaning efficacy (χ 2  = 0.754; p  = 0.86). Additionally, PIPS method did not have a significant effect on the removal of the filling material compared to conventional needle irrigation. Conclusions: Both instrumentation systems were effective in removing the filling material, but neither was able to remove the filling material completely. PIPS method did not show a significant additional effect regarding the removal of filling material.

Objectives: To evaluate and compare the obturation quality of mineral trioxide aggregate (MTA) and Biodentine placed with hand condensation or indirect ultrasonic activation technique in teeth models simulating perforating internal root resorption (IRR) using micro-computed tomographic (micro-CT) imaging., Materials and Methods: Standardized models with perforating IRR cavities were created using 40 extracted single-rooted human teeth and randomly divided into four groups (n = 10). The specimens were obturated with either MTA or Biodentine and the placement technique applied was either hand condensation or indirect ultrasonic activation. Micro-CT scans were performed for the volumetric analysis of voids and filling materials in the resorption cavities and apical portion of the specimens. Data were analyzed using one-way analysis of variance and paired t test., Results: No significant difference was observed between the groups in terms of the percentage volume of filling materials (p > 0.05). The apical portion of the specimens significantly presented less percentage volume of filling materials than the resorption cavities in each group (p < 0.05)., Conclusions: No placement technique produced void-free fillings in teeth with perforating IRR. There was no significant difference between the obturation quality of Biodentine and MTA. The obturation quality in the apical portion of the root canals was inferior than that in the resorption cavities., Clinical Relevance: The obturation of the apical region of teeth with perforating IRR is challenging irrespective of the material type and placement technique.

Aim: To compare the efficiency of M-Wire Reciproc and Reciproc Blue instruments in the removal of root filling material and in their ability to regain apical patency through micro-computed tomographic (micro-CT) analysis., Methodology: Ten anatomically matched pairs of teeth, with a single oval-shaped straight canal, were selected and scanned in a micro-CT device. The root canals were prepared with M-Wire Reciproc R25 instruments and filled with gutta-percha and AH Plus sealer. The root canals were then randomly allocated into two groups (n = 10), according to the instrument used: M-Wire Reciproc and Reciproc Blue. The canals were retreated up to instrument sizes 25 and then 40 in both groups. The surface area and volume of residual filling material were assessed using micro-CT imaging after the retreatment procedures. The time required to remove the root fillings was recorded. Data were analysed statistically using t-test with a significance level of 5%., Results: No significant difference (P > 0.05) was observed between the instruments in terms of the volume of residual root filling material. Apical enlargement from size 25 to 40 significantly improved the removal of filling materials (P < 0.05). It was possible to regain apical patency in all specimens from both M-Wire Reciproc and Reciproc Blue groups. No difference was observed in the time required to perform the retreatment between the instruments., Conclusions: Both M-Wire Reciproc and Reciproc Blue instruments were effective in removing filling materials from oval-shaped straight canals. Apical patency was reestablished in all specimens., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Objectives: Successful pulpectomy in primary teeth depends on quality of obturation. It can be evaluated using digital intra-oral receptor (D.I.O.R) and cone beam computed tomography (C.B.C.T). The purposes of this study were to compare 3 different obturation techniques such as lentulospiral, insulin syringe, and endodontic plugger in primary incisors and to evaluate its quality of obturation using D.I.O.R and C.B.C.T technique., Materials and Methods: Thirty-three extracted primary incisors were biomechanically prepared and obturated with zinc oxide eugenol cement by 3 different obturation techniques. The obturation was evaluated for length of obturation and voids using D.I.O.R and C.B.C.T methods., Results: There was a statistically significant difference between all the groups in length of obturation (P = 0.02) in both D.I.O.R and C.B.C.T. Significant differences (P = 0.03) were present in number of voids among 3 obturation techniques in C.B.C.T. Statistically more voids were observed with D.I.O.R in lentulospiral (P = 0.04) group and in insulin syringe (P = 0.02) group., Conclusions: Acceptable result was obtained with lentulospiral in length of obturation compared to insulin syringe and endodontic plugger technique. Insulin syringe technique resulted in increased underfilling with least number of voids. More number of voids were seen in middle one-third and least number of voids were observed at apical one third of the root among all the 3 techniques of obturation. The study concluded that void identification is improved with D.I.O.R compared to C.B.C.T., Clinical Relevance: Lentulospiral reported effective length of obturation, while insulin syringe with least number of voids. D.I.O.R (2-Dimensional) is efficient in detecting voids compared to C.B.C.T (3-Dimensional) in obturated primary teeth.

Introduction: Pulpectomy has been a treatment of choice in all necrotic primary teeth. Advancing technology has brought the rotary system to reduce the manual dexterity and improve the quality of treatment for pulpectomy. Advancing technology in pediatric dentistry should be used for the better treatment protocol., Aim: The aim of this study is to compare the obturation quality and instrumentation time after root canal instrumentation with rotary Kedo-S files, hand K-files, and H-files in primary molars., Materials and Methods: A randomized control trial where pulpectomy was performed on 75 primary molars equally distributed for instrumentation with K-file, H-files rotary Kedo-S files, respectively. The instrumentation time and obturation quality were noted., Results: Kedo-S files showed the least instrumentation time with better obturation quality as compared to other two groups (P < 0.001)., Conclusion: Pediatric rotary files Kedo-S has better obturation quality in minimum instrumentation time., Competing Interests: None

Aim: To compare the Reciproc Blue, Reciproc and ProTaper Universal Retreatment systems with regard to the effective removal of epoxy resin-based sealer and gutta-percha during the retreatment of oval, straight root canals., Methodology: Forty-five extracted, human mandibular first premolars with single straight oval canals were selected on the basis of cone beam computed tomography evaluations. The root canals were instrumented with the ProTaper Next system up to the X2 file, and filled with gutta-percha and epoxy resin-based sealer using the cold lateral condensation technique. After 1 month, the samples were randomly divided into three groups (n = 15) according to the retreatment system used: Reciproc Blue R40, Reciproc R40 and ProTaper Universal. The specimens were scanned at the resolution of 1.2 μm by a microcomputed tomography device after the root filling and retreatment procedures, and the decrease in the volume of filling material after each retreatment protocol was measured. The results were analysed using the Kruskal-Wallis test and additional box-and-whisker plots., Results: Although the volume of the filling material decreased significantly in all three groups (P < 0.05), none of the systems removed the material completely. The Reciproc system removed significantly more material than the ProTaper Universal (P < 0.001) and Reciproc Blue (P = 0.005) systems, with the latter two exhibiting equal volumes of remaining material (P = 0.068)., Conclusion: The Reciproc system was more effective than the Reciproc Blue and ProTaper Universal Retreatment systems during the removal of filling material from oval, straight canals, although none of the systems completely removed the filling material., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Objective: The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the sealing ability of two root canal obturation techniques by using micro-computed tomography imaging and a push-out test., Methods: The root canals of 40 human maxillary premolar teeth were instrumented and divided into four groups: (A) single cone (SC) followed by immediate post space preparation, (B) continuous wave of condensation (CWC) followed by immediate post space preparation, (C) SC followed by delayed post space preparation, and (D) CWC followed by delayed post space preparation. Micro-CT scans were performed for volumetric analysis of voids and filling materials in the apical 4-mm portion. A push-out test was performed, and failure modes (adhesive, cohesive, or mixed) were assessed. Data were analyzed using the Kruskal-Wallis test and one-way analysis of variance., Results: No significant differences were observed among the four groups in terms of the percentage volume of voids of the apical 4 mm or the bond strength of apical gutta-percha., Conclusions: The percentage volume of voids and bond strength of apical gutta-percha were similar and were not significantly influenced by the timing of post space preparation or the obturation technique.

The circumferential strains created in the radicular dentin by nickel-titanium (NiTi) and stainless steel (SS) finger spreaders (FSs) during a simulated clinical procedure of lateral compaction were compared after minimal (size 50) and extensive (size 100) canal preparations. Nineteen maxillary central incisors underwent minimal preparation, while 10 underwent an extra phase of extensive preparation. Four miniature strain gauges were bonded circumferentially in the apical third of the root (buccal, lingual, mesial, and distal). Lateral compaction was performed using either NiTi-FSs or SS-FSs. Force and strains were continuously recorded. The maximal strains (with and without normalization according to force) were recorded. The SS-FSs generated higher maximal strains normalized according to force compared with the NiTi-FSs. The maximal normalized strains were higher by 37%-43% for the mesial and distal aspects and by 6%-14% for the buccal and lingual aspects after the minimal preparation and by 24%-28% for the mesial and distal aspects and by 19%-20% for the buccal and lingual aspects after extensive preparation. The maximal normalized strains increased by 30%-70% from minimal to extensive preparations, with two teeth exhibiting vertical root fracture while compaction with SS-FS. The NiTi-FSs induce less strain in root dentin than the SS-FSs and thus may contribute less to the risk of vertical root fracture., (© 2018 Eur J Oral Sci.)

Aim: To evaluate the effectiveness of NaOCl, NaOCl-EDTA and NaOCl + HEBP activated by ultrasonics and XP-endo Finisher on organic tissue removal from simulated internal root resorption cavities., Methodology: The root canals of 144 single-rooted teeth were instrumented. The teeth were split longitudinally, and semicircular cavities were prepared in the canal walls on each half of the roots. Samples obtained from ground bovine muscle tissue were weighed and adapted into the semicircular cavities. The root fragments were reassembled and cemented to create a circular simulated resorption cavity within the canal. Teeth were divided into twelve groups (n = 12) according to the irrigation protocols: group 1: NaOCl, no activation; group 2: NaOCl, passive ultrasonic irrigation (PUI); group 3: NaOCl, XP-endo Finisher; group 4: NaOCl-EDTA, no activation; group 5: NaOCl-EDTA, PUI; group 6: NaOCl-EDTA, XP-endo Finisher; group 7: NaOCl + HEBP, no activation; group 8: NaOCl + HEBP, PUI; group 9: NaOCl + HEBP, XP-endo Finisher; group 10: distilled water, no activation; group 11: distilled water, PUI; and group 12: distilled water, XP-endo Finisher. The teeth were disassembled, and the tissue remaining inside the resorption cavities were weighed. The data were analysed statistically using two-way anova and Fisher's LSD tests with a significance level of 0.05., Results: The use of XP-endo Finisher with the experimental solutions resulted in the greatest tissue weight loss compared to the other activation protocols (P < 0.001). There was no significant difference between NaOCl and NaOCl + HEBP in terms of tissue removal., Conclusion: The use of a NaOCl + HEBP mixture activated with XP-endo Finisher was an effective irrigation regimen for removing simulated organic tissues from artificial internal root resorption cavities in the straight root canals of single-rooted teeth., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Introduction: This study compared the cyclic fatigue and the canal transportation promoted by Twisted File (TF) Adaptive and Navigator EVO systems when used with 2 different motions., Methods: Forty mesiobuccal roots of maxillary molars were scanned by using micro-computed tomography imaging before and after root canal preparation with the 2 instrument systems used with 2 motions (adaptive and continuous rotation). Samples were divided into 4 groups: TFA, TF Adaptive instruments under adaptive motion; TFC, TF Adaptive instruments under continuous motion; NA, Navigator instruments under adaptive motion; and NC, Navigator instruments under continuous motion. Root canals were prepared until 35.04 instruments. Apical transportation was analyzed by using micro-computed tomography at 3 levels: 3, 6, and 9 mm from the apex. The cyclic fatigue tests were performed by using a custom-made device. Ten instruments of each brand were activated by using a 6:1 reduction handpiece powered by a torque-controlled motor using the preset programs "custom mode" and "TF Adaptive" to activate 25.06 and 35.04 instruments. Kruskal-Wallis and Dunn tests were used to assess canal transportation, centering ability, and canal volume. The Student t test was used to evaluate cyclic fatigue (P = .05)., Results: At 3 and 9 mm, the canal transportation and centering ability were similar in all groups (P > .05). At 6 mm, TFC presented higher canal transportation toward furcal region than NA and NC (P < .05). After canal preparation, TFA promoted great dentinal excision, presenting higher canal volume than NA and NC (P < .05). Higher cyclic fatigue resistance was observed under continuous than adaptive motion regardless of system or tip/diameter of the instrument (P < .05)., Conclusions: Both systems can be used under adaptive or continuous rotation. However, the life span of the instruments was higher when used under continuous rotation. Small canal transportation occurred when mesiobuccal root canals from maxillary molars were prepared until 35.04 instruments., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to compare centering ability and transportation values of the Primary WaveOne Gold (PWOG; Dentsply Sirona, Ballaigues, Switzerland) instrument with or without different glide path techniques. Centering ability and transportation were also compared between the 3 different glide path preparation groups., Methods: The mesiobuccal canals of 60 extracted human mandibular molars (curvature angles between 25° and 35° and radii ≤10 mm) were selected and randomly divided into 4 groups with 15 canals each. Canals were negotiated to patency with a #8 K-file. Canal preparations were performed by a single operator using precurved #10, 15, and 20 stainless steel manual K-files (group KF); a #10 stainless steel manual K-file followed by PathFiles #1-3 (Dentsply Sirona) (group PF); a #10 stainless steel manual K-file followed by the WaveOne Gold Glider (Dentsply Sirona) (group WOGG); and no further glide path preparation (group NG). Micro-computed tomographic imaging was used to scan teeth before and after glide path preparation. The final canal preparation was performed with PWOG; after which, all 60 specimens were scanned again using micro-computed tomographic imaging. Canal transportation and centering ratio values were determined over levels 3 mm, 5 mm, and 7 mm from the root apex after glide path preparation and again after final preparation with PWOG. One-way analysis of variance was used to statistically compare groups. The significance level was set at P < .05., Results: No statistically significant difference in the mean centering ratios was found after glide path preparation when the KF, PF, and WOGG groups were compared (P > .05). The mean combined transportation values after glide path preparation were statistically significantly higher in the KF group compared with the PF and WOGG groups (P > .05). There was no statistically significant difference in the mean combined centering ratios or transportation values of the NG and 3 glide path groups in combination with PWOG over the 3 levels (P > .05)., Conclusion: KF group showed the highest mean transportation values during glide path preparation. However, the PWOG instrument's performance regarding centering ability and transportation was not influenced by the different glide path/no glide path preparation groups., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Manufacturers offer single-file instrumentation systems with matching gutta-percha (GP) cones to simplify root canal preparation and obturation. The purpose of this study was to determine whether file diameters and tapers match with corresponding cone diameters and tapers (precision) as well as industry standards (accuracy)., Methods: Twenty files and corresponding GP cones from each size of F360 (#25, #35, #45, #55 with .04 taper) and Reciproc (#25, #40, #50 with variable tapers) instruments were examined by using optical microscopy (×32) to determine their diameter and taper. Precision was evaluated by using one-way analysis of variance (α = 0.05) with Scheffé post hoc tests and t tests with Bonferroni correction. Accuracy was calculated by subtracting the nominal values from the measured values of all files and GP cones, and mean diameter and taper differences were compared by using one-way analysis of variance (α = 0.05) and Scheffé post hoc test for pairwise comparison., Results: For F360, the majority of file and cone diameters were within the tolerance levels, but most of the file diameters were significantly larger than GP cone diameters (P < .05), but the majority of all measured values were within the tolerance levels. For Reciproc, file and cone diameters at D1 and D3 mostly approached the nominal values. At the coronal end, file diameters #25 and #50 were significantly smaller than cone diameters (P < .05). For both instrumentation systems, almost all file and cone tapers matched with the preset tolerance ranges. For Reciproc, significant differences between file and GP cone demonstrated either smaller cone or smaller file diameters and tapers, depending on the size. Most of the measured values were within the acceptable range, but diameters at the coronal end exhibited the highest percent difference from the nominal values., Conclusions: Despite the call for standardization, variability in diameter and taper dimensions between single-file instrumentation systems and their corresponding GP cones can be expected., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To compare the cyclic fatigue resistance of R-PILOT and WaveOne Gold Glider files in curved artificial canals., Methodology: A total of 60 new R-PILOT and WaveOne Gold Glider files were tested in artificial canals with 45° and 60° angles of curvature. Fifteen new files of each brand were tested in both canals. Cyclic fatigue resistance was determined by recording the time to file fracture in the artificial canals. The length of each fractured fragment was also recorded. An independent sample t-test was used to analyse the data., Results: In the canal with a 45° angle of curvature, no significant differences were observed between the R-PILOT and WaveOne Gold Glider files (P > 0.05). In the canal with a 60° angle of curvature, WaveOne Gold Glider files had greater cyclic fatigue resistance than R-PILOT files (P < 0.05). There was no difference between the files in terms of the lengths of fractured fragments in canals with 45° and 60° angles of curvature (P > 0.05)., Conclusions: WaveOne Gold Glider files exhibited greater cyclic fatigue resistance than R-PILOT files in artificial canals with a 60° angle of curvature., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Objectives: The aim of this clinical study was to evaluate and compare the incidence and intensity of postoperative pain following removal of gutta-percha from root canals using rotary and reciprocating instruments., Materials and Methods: One hundred and sixty patients scheduled for a non-surgical endodontic retreatment were included for evaluation. Preoperative pain was recorded with using a questionnaire with a 10-cm visual analogical scale (VAS). Endodontic filling material was removed with Reciproc (VDW, Munich, Germany) or ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK) instruments. Patients then recorded their postoperative pain in a VAS pain scale at 4, 8, 16, 24, 48, and 72 h post-treatment. Results were analyzed using the Mann-Whitney U, Kruskal-Wallis, and Chi-square tests. Multivariate logistic and a multiple regression analysis were used to detect the effect of confounding factors., Results: Results showed a direct relation between the intensity of pre-operative pain and that of postoperative pain (P < .05). No significant differences were observed between the two groups regarding postoperative pain (P > .05) as a qualitative variable. As numerical values, statistically significant differences were found regarding sex and the system used (P < .05)., Conclusions: The method for pain evaluation was determinant in postoperative pain findings. Endodontic retreatment preparation with Reciproc results in lower values of postoperative pain compared with ProFile. Women are more susceptible to postoperative pain than are men., Clinical Relevance: One of the most significant contributions of this research is the importance given to the method used for pain evaluation. The present study analyzed postoperative pain resulting from the use of reciprocating or continuous rotary instruments during removal of gutta-percha in retreatment procedures.

Aim: To compare the cyclic fatigue resistance and bending properties of R-Pilot and WaveOne Gold (WOG) Glider files, at intracanal temperature (35°C)., Methodology: Forty R-Pilot and 40 WOG Glider files were subjected to a cyclic fatigue resistance test (n = 20), calculating the time to fracture (TTF) in an artificial stainless steel canal. The length of the fractured file tips (FL) was also measured. The fracture surface of fragments was examined with a scanning electron microscope, and the cross-sectional area of the fractured surfaces was measured. Flexibility of the tested files (n = 20) was determined using 45° bending test. Data were analysed statistically using the Mann-Whitney U-test at 5% significance level., Results: Time to fracture was significantly higher in the R-Pilot group compared to the WOG Glider (P < 0.05). There was no significant difference between groups for fracture length. The bending resistance of R-Pilot files was significantly greater than WOG Glider files (P < 0.05)., Conclusions: A significant greater cyclic fatigue resistance was observed for R-Pilot files compared to WOG Glider instruments, although the bending resistance of WOG Glider files was lower., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: In the present study, we evaluated the effect of the single-cone technique (SCT), cold lateral compaction (CLC), and wave vertical compaction (WVC) technique performed using two different sealers on the amount of apically extruded debris (AED) produced during the removal of canal filling material., Methods: Ninety extracted mandibular premolars were prepared with ProTaper instruments. The teeth were then randomly assigned to six groups (N = 15) for root canal filling: (a) group 1, CLC+AH Plus; (b) group 2, SCT+AH Plus; (c) group 3, WVC+AH Plus; (d) group 4, CLC+MTA Fillapex; (e) group 5, SCT+MTA Fillapex; and (f) group 6, WVC+MTA Fillapex. In all groups, the removal of canal filling material was performed with ProTaper retreatment instruments. The mean weight of the AED was assessed with an analytical balance., Results: The amount of AED was lowest in groups 2 and 5 (P < .05), with no difference between these groups (P > .05). Groups 3 and 6 produced the greatest amount of extruded debris (P < .05); there was no difference between these groups (P > .05). Additionally, there was no difference between groups 1 and 4 (P > .05). There was no significant difference among the groups regarding sealer type (P > .05)., Conclusions: The canal filling technique used affected the amount of AED produced during the removal of canal filling material, but not sealer type., (© 2018 John Wiley & Sons Australia, Ltd.)

Aim: To determine the effectiveness of two different endodontic retreatment systems for the removal of laterally compacted gutta-percha (GP)., Materials and Methods: Sixty-three freshly extracted human maxillary central incisors were used for the study. The teeth were instrumented with K-flex files and obturated using lateral condensation technique with GP and AH Plus sealer. The teeth were divided into three retreatment groups, each group consisting of 21 teeth. Group I: D-RaCe desobturation files (D-RaCe); group II: ProTaper Universal retreatment files (PTUR); group III: Hedstrom files (H-file). After removal of GP, the teeth were split longitudinally and divided into three equal parts: Cervical, middle, and apical third. The middle and apical thirds of all root halves were examined using scanning electron microscope (SEM). The total surface area covered by the residual debris was evaluated using Motic Image plus 2.0 software. Statistical analysis was done by one-way analysis of variance (ANOVA) test with a p-value <0.05 used to determine significance and Tukey's multiple post hoc tests used for comparison between the groups, and 't' test was done for comparison between the thirds within the same group., Results: The PTUR retreatment files showed overall better performance compared with D-RaCe files and H-files. The PTUR files performed better at middle third compared with others. The PTUR files and D-RaCe files performed equally at apical third better than H-files., Conclusion: ProTaper retreatment files are better compared with D-RaCe files and H-files for the retreatment of the previously endodontically treated teeth., Clinical Significance: Highest efficacy for the removal of GP was shown by ProTaper Universal System followed by D-RaCe and H-file.

Aim: To compare the shaping ability of four root canal instrumentation systems in oval-shaped canals using micro-computed tomographic analysis., Methodology: Forty anatomically matched mandibular incisors were scanned and assigned to four groups (n = 10), according to the canal preparation protocol: BioRace, Reciproc, Self-Adjusting File (SAF) and TRUShape systems. After canal instrumentation, the specimens were rescanned, and the registered pre- and postoperative datasets were examined to evaluate the percentages of accumulated hard-tissue debris, untouched canal walls and dentine removed. Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction were used to compare the variables in the groups (α = 5%)., Results: The preparation techniques did not affect the percentage of accumulated hard-tissue debris (P = 0.126). The percentage of untouched canal areas was significantly higher for BioRace (32.38%)compared to Reciproc (18.95%) and SAF (16.08%) systems (P < 0.05). Reciproc removed significantly more dentine (4.18%) than BioRace (2.21%) and SAF (2.56%) (P < 0.05). The TRUShape system had intermediate results for both untouched canal walls (19.20%) and dentine removed (3.77%), with no significant difference compared to BioRace, Reciproc and SAF systems., Conclusions: The preparation techniques resulted in the same level of accumulated hard-tissue debris. Compared to the other tested systems, BioRace was associated with more untouched canal walls and Reciproc produced the greatest amount of removed dentine. Although it touched more of the root canal walls, the SAF system removed less dentine, whereas TRUShape had intermediate results for these same parameters. None of the systems tested were able to provide optimal shaping ability in oval-shaped canals., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: To compare the torsional resistance of XP-endo Shaper (XPS; size 30, .01 taper, FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments at body temperature with TRUShape (TRS; size 30, .06 taper, Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), ProFile Vortex (PV; size 30, .04 taper, Dentsply Tulsa Dental Specialties) and FlexMaster (FM; size 30, .04 taper, VDW GmbH, Munich, Germany) nickel-titanium rotary instruments., Methodology: A metal block with a square-shaped mould (5 mm × 5 mm × 5 mm) was positioned inside a glass container. Five millimetres of the tip of each instrument was held inside the metal block by filling the mould with a resin composite. The instruments were tested for torsional resistance in saline solution at 37 °C. Data were analysed using one-way analysis of variance (anova) and Tukey post hoc tests. The significance level was set at P < 0.05., Results: FM had the greatest torsional resistance amongst the instruments tested (P < 0.001). There was no significant difference between FM and PV instruments (P = 0.211). The ranking for torsional resistance values was: FM > PV > TRS > XPS., Conclusions: FlexMaster and ProFile Vortex instruments were more resistant to torsional stress compared with TRUShape and XP-endo Shaper instruments. The manufacturing process used to produce XP-endo Shaper instruments did not enhance their resistance to torsional stress as compared with the other instruments., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: To isolate the effect of metallurgy in lateral and axial cutting efficacy against plastic and bovine dentine substrates by comparing two rotary systems with identical design but manufactured with either conventional nickel-titanium or heat-treated gold alloy., Methodology: A total of 258 ProTaper Universal (PTU) and ProTaper Gold (PTG) Shaping instruments were used. Bending behaviour was assessed to determine the appropriate displacement associated with a 2 N force in lateral cutting. Ten instruments of each type were used in lateral action for 60 s against bovine dentine or plastic substrates four consecutive times producing four notches in each specimen. Ten further instruments of each type were used in on axial action in four standardized simulated root canals fabricated from 4-mm thick plastic or dentine discs. Both tests were performed at 300 rpm in a computer-controlled testing platform. Notch area and torsional load were compared with Student's t-tests. Repeated measures ANOVA was used to compare cutting efficiency across the four different time-points. Pearson correlation coefficients between substrates were also determined., Results: For lateral action, all three PTG instruments cut significantly more effectively (P < 0.05) than PTU on the plastic substrate. S1 and S2 PTG cut significantly more after 120 and 180 s (P < 0.05) on bovine dentine substrate. For axial action, S1 and S2 PTG were significantly more efficient in cutting at 180 s on plastic and 120 s on bovine dentine (P < 0.05)., Conclusion: Instruments made from heat-treated nickel-titanium gold alloy had equal or greater cutting efficiency when compared to those made from conventional nickel-titanium., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: To compare the cyclic fatigue resistance (CFR) of PathFile, ProGlider and ScoutRaCe nickel-titanium (NiTi) rotary instruments used in an S-shaped artificial canal., Methodology: A total of 90 instruments were tested in an S-shaped artificial canal (n = 30 for each group: PathFile (size 16, 2% constant taper), ProGlider (size 16, variable taper between 2% and 8% along the shaft) and ScoutRaCe (size 15, 2% constant taper). All files were rotated until fracture. The number of cycles to failure was counted to determine CFR. The length of each fractured fragment was measured in millimetres. The CFR was analysed statistically with the Kruskal-Wallis test. The fragment length was analysed using one-way analysis of variance and Tukey's post hoc tests., Results: The ProGlider instruments were associated with significantly greater CFR than the PathFile and ScoutRaCe files in the apical curvature (P < 0.05). There was no significant difference between the CFR of the PathFile and ScoutRaCe files in the apical curvature (P > 0.05). ProGlider, PathFile and ScoutRaCe instruments exhibited similar CFR in the coronal curvature (P > 0.05)., Conclusions: The ProGlider files had greater cyclic fatigue resistance than the PathFile and ScoutRaCe files in the apical curvature of an artificial S-shaped canal., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: To examine the cyclic fatigue resistances of R-Pilot, HyFlex EDM and PathFile NiTi glide path files in S-shaped artificial canals., Methodology: Twenty R-Pilot (12.5/.04), 20 HyFlex EDM (10/.05) and 20 PathFile (19/.02) single-file glide path files were included. Sixty files (n: 20/each) were subjected to static cyclic fatigue testing using double-curved canals until fracture occurred (TF). The number of cycles to fracture (NCF) was calculated by multiplying the rpm value by the TF. The length of the fractured fragment (FL) was determined by a digital microcaliper. Six samples of fractured files (n: 2/each) were examined by SEM to determine the fracture mode. The NCF and the FL data were analysed using one-way anova, post hoc Tamhane and Kruskal-Wallis tests using SPPS 21 software. The significance level was set at 5%., Results: In the double-curved canal, all the files fractured first in the apical curvature and then in the coronal curvature. The NCF values revealed that the R-Pilot had the greatest cyclic fatigue resistance, followed by the HyFlex EDM and PathFile in both the apical and coronal curvatures (P < 0.05)., Conclusions: R-Pilot NiTi glide path files, used in a reciprocating motion, had the greatest cyclic fatigue resistance amongst the tested NiTi glide path files in an artificial S-shaped canal., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Objectives: The objective of the study was to compare the retreatability of three calcium silicate-containing sealers (BioRoot RCS, MTA Fillapex, Endo C.P.M.) and an epoxy resin-based sealer (AH Plus) with different root canal instruments (Hedström files, Reciproc R40, Mtwo retreatment file R 25/.05 + Mtwo 40/.06, and F6 SkyTaper) concerning sealer remnants and retreatment time., Materials and Methods: Root canals of 192 teeth were instrumented with Reciproc R40. All root canals were obturated using the single-cone technique with Reciproc R40 gutta-percha and one of the sealers (n = 48 per sealer). Two months later, retreatment was performed using one of the mentioned instruments (n = 12 per instrument and sealer). The roots were split longitudinally, and both halves were investigated using light microscopy. The percentage of sealer remnants covering the root canal wall was evaluated using the software ImageJ. The time required for retreatment was recorded. Statistical analysis was performed using two-way ANOVA and Student-Newman-Keuls post hoc test., Results: Regarding the percentage of root canal filling remnants as well as retreatment time, two-way ANOVA indicated that the results were significantly affected by the sealer (p < 0.001) and by the instrument used (p < 0.05). Overall, the use of AH Plus was associated with significantly more remnants compared to all other sealers (p < 0.001) and F6 SkyTaper instruments allowed significantly faster retreatment than the other instruments (p < 0.05)., Conclusion: The retreatability of calcium silicate-containing sealers was better compared to AH Plus as less sealer remnants and shorter retreatment times were observed. Retreatment with engine-driven NiTi instruments was superior compared to hand instrumentation., Clinical Relevance: Engine-driven NiTi instruments are better suited to remove root canal fillings than stainless steel Hedström files.

Aim: To evaluate the efficacy of filling material removal from oval-shaped canals after the use of supplementary files (XP-endo Finisher and XP-endo Finisher R) through microcomputed tomographic (micro-CT) analysis., Methodology: The root canals of twenty maxillary single-rooted teeth were prepared with Reciproc R25 files and filled with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. The root canals were then retreated using Reciproc R25 and R40 instruments. After this, the specimens were assigned to two groups according to the supplementary cleaning approach, using XP-endo Finisher and XP-endo Finisher R. The surface area and volume of removed filling material was assessed using micro-CT imaging before and after the use of the XP-endo instruments. Data were analysed statistically with a significance level of 5%., Results: Removal of filling material at 66.8% and 59.4% in volume and 67.3% and 61.4% in surface area was seen for the XP-endo Finisher and the XP-endo Finisher R files, respectively. The amount of filling material removed by both supplementary files was highly significant (P = 0.000). No significant difference in the percentage of removed filling material was detected for the XP-endo instruments (P = 0.636 for volume and P = 0.667 for surface area)., Conclusions: Both XP-endo files were equally effective in the removal of remaining filling material from straight oval-shaped canals. None of the instruments were able to remove all the residual filling material., (© 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

The aim of this study was to compare two irrigation techniques and four devices for endodontic sealer placement into the dentinal tubules. Ninety-nine single-rooted human teeth were instrumented and allocated to either the control (CO) (n=11) or experimental groups according to the irrigation method: syringe and NaveTip needle (NT) (n=44), and EndoActivator (EA) (n=44). These groups were subdivided according to sealer placement into K-File (KF), lentulo spiral (LS), Easy Clean (EC), and EndoActivator (EA) subgroups. Moreover, the distances of 5 mm and 2 mm from the apex were analyzed. The teeth were obturated with AH Plus and GuttaCore X3. Analyses were performed by scanning electron microscopy associated to cathodoluminescence. The percentage and maximum depth of sealer penetration were measured. Data were evaluated by three-way analysis of variance (ANOVA) and Games-Howell test (p<0.05). EA was superior to NT in percentage of sealer penetration. EC was significantly superior to EA (subgroup) for sealer penetration, and both improved the percentage of sealer penetration when compared to LS. Better sealer penetration was observed at the distance of 5 mm from the apex. Sealer penetration into the dentinal tubules was significantly improved by sonic irrigant activation.

Introduction: The objective of this study was to examine the temperature rise on the plugger surface of 2 commercially available gutta-percha heating devices: the System B (Kerr Dental, Amersfoort, The Netherlands) and the System B Cordless Pack Unit (Kerr Dental)., Methods: Temperature changes were recorded by a Thermocouple Data Logger device (Pico Technology Ltd, St Neots, UK) and 2 thermocouples: the first to record the temperature on the plugger surface in an isolated polytetrafluoroethylene system and the second to record the base temperature of the environment. The gutta-percha heating devices studied were System B with F, FM, M, and ML pluggers set at the "use" position, "touch" mode, temperature of 200°C, and a power setting of 10 and the System B Cordless Pack Unit with the FM plugger set at low power. Two variables were extracted from the collected temperature data: the temperature on the plugger surface 10 seconds after activating each gutta-percha heating device (θ 10 ) and the time required to reach 60°C (t 60 ). The differences between the pluggers over those 2 variables were investigated using analysis of variance and the Tukey B test for post hoc comparisons (P < .05)., Results: The mean θ 10 for all pluggers ranged between 73°C and 87°C. The mean t 60 for all pluggers ranged between 1.3 and 3.3 seconds. No clinically significant differences between the pluggers were observed., Conclusions: The gutta-percha heating devices tested achieve maximum temperatures lower than 94°C and are capable of gutta-percha phase transformation within approximately 4 seconds of activation., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to evaluate the thermal stability of 23 commercially-available endodontic obturation materials., Materials and Methods: Specimens (n = 10) were sealed in aluminum differential scanning calorimetry (DSC) crucibles and subjected to thermal scan series consisting of a 25 to 70 °C at 5 °C/min followed by a rapid increase to 230 °C, followed by a second scan from 25 to 70 °C at 5 °C/min. The first scan evaluated the materials as-received followed by a worse-case-scenario thermal challenge simulating temperatures involved with warm vertical condensation obturation techniques. The second thermal scan observed any phase changes from the high temperature challenge. This two-scan process was repeated twice to observe changes encountered by repeat high heat exposure during obturation. Mean thermal enthalpies were analyzed with Kruskal-Wallis and Games-Howell post-hoc test. (p = 0.05)., Results: Thermal behavior was material dependent. During the first thermal scan, materials typically demonstrated broad endothermic enthalpy curves suggesting either a gutta-percha phase mixture and/or an alpha crystalline phase. The first high-heat challenge produced definitive alpha/beta thermal phase signatures usually associated with gutta-percha. Changes in beta-phase enthalpies were noted with Therarmafil Plus and UltraFil Firmset while increase in alpha-phases was observed with GuttaCore, K3, Lexicon, and Schein Accessory Points., Conclusions: Commercial endodontic gutta-percha obturation materials displayed thermal characteristics that were material dependent. However, all demonstrated stability at temperatures in excess to that experienced during warm vertical condensation techniques., Clinical Relevance: The gutta-percha obturation materials evaluated in this evaluation can be used successfully in warm vertical condensation techniques without fear of degradation.

Introduction: The purpose of this study was to evaluate in vitro the efficacy of both the electronic apex locator (EAL) and auto apical reverse (AAR) functions of the endodontic motor MM Control (Micro-Mega, Besançon Cedex, France) compared with Root ZX II (J Morita, Tokyo, Japan)., Methods: After cervical preflaring, the actual lengths (ALs) of 36 single-rooted teeth were obtained up to the apical foramen. The EAL measurements at the marks "APEX" and "0.5" of both devices were obtained using an alginate model. The teeth were divided randomly into 2 groups (n = 18), and root canal preparation was performed with rotary instruments using the AAR function (0.5 mark) of each motor. The length provided by the AAR was compared with the visual length after preparation (AL2). The differences between the electronic lengths and the respective visual measurements were assigned as negative for lower or positive when higher. The means of the absolute values and the percentages of distribution of the electronic measurements between devices were compared., Results: There was no difference between the devices in terms of the means of the EAL measurements or AAR length (analysis of variance, P > .05). However, the EAL function of MM Control presented a greater percentage of measurements >1.01 mm longer than AL (chi-square, P < .01). The AAR function provided an acceptable apical limit in 83.3% of the cases for Root ZX and 77.8% of the cases for MM Control., Conclusions: The AAR function of both MM Control and Root ZX II provided an adequate apical limit of preparation in vitro. However, the use of only the EAL function of MM Control resulted in significantly more cases of overextended readings., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: The aim of this study was to compare and evaluate the efficiency of five different obturation methods in delivering the filling material into the canals of primary teeth using cone beam computerized tomography (CBCT) scan., Method: A total of fifty prepared canals of primary teeth which further divided into five groups with ten canals in each group were obturated with zinc oxide-eugenol cement using five different obturation methods such as endodontic plugger, lentulo spiral (handheld), lentulo spiral mounted on slow speed handpiece, local anesthetic syringe, and tuberculin syringe. Using CBCT scan, the pre- and post-obturation volume and the percentage of obturated volume (POV) were calculated for each group. The results obtained were statistically analyzed using one-way analysis of variance and Tukey's post hoc test., Results: Following CBCT scan, the method obturated with lentulo spiral mounted to handpiece showed the highest POV value followed by the method of lentulo spiral mounted to handpiece, hand plugger, and tuberculin syringe. Local anesthetic syringe gave the least POV (P < 0.05)., Conclusion: Lentulo spiral mounted to handpiece showed the best technique of obturation using CBCT evaluation among the five groups evaluated in primary teeth. However, more studies are highly essential to prove it a boon for estimating obturation quality in primary teeth.

Objective: To compare the efficacy of manual and mechanical instrumentation techniques, including ProTaper Universal retreatment system, Mtwo retreatment system, Reciproc system, and Hedström files, regarding removal of overextended root canal filling material., Materials and Methods: Eighty extracted human mandibular premolar teeth were prepared at the apical foramen level using Revo-S rotary files and subsequently obturated. The root canal filling material was deliberately extruded from the apex. Samples were transferred to glass vials that simulated the periapical area. Eighty samples of overfilled teeth were randomly assigned to four equal groups (n = 20) for removal of the root filling material with ProTaper Universal retreatment files (Group 1), Mtwo retreatment files (Group 2), Reciproc system (Group 3), and hand files (Group 4). Removal of the root canal filling material and additional preparation were performed by individual instruments from each different system up to a #40 size. The external apical surface of the teeth and the surrounding glass vials were checked using a dental operation microscope with ×12.5 magnification. Samples were divided into two groups based on whether removal of the overextended root canal filling material was successful or not. The Fisher's exact test was used to detect any significant difference between the groups (α = 0.05)., Results: The success rate for removal of overextended gutta-percha was greater for the Mtwo (30%) and hand files (30%) compared with the ProTaper (20%) and Reciproc (10%). However, no significant statistical differences existed among the experimental groups (P > 0.05)., Conclusions: This study demonstrated that all tested systems had similar efficacy in removing overextended root canal filling material.

Introduction: This ex vivo study aimed to evaluate the efficacy of retreating GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) and warm vertically condensed gutta-percha in moderately curved canals with 2 different systems: ProTaper Universal Retreatment (Dentsply Tulsa Dental) and WaveOne (Dentsply Tulsa Dental)., Methods: Eighty mesial roots of mandibular molars were used in this study. The mesiobuccal canals in each sample were prepared to length with the WaveOne Primary file (Dentsply Tulsa Dental). The canals were obturated with either a warm vertical approach or with GuttaCore and divided into 4 retreatment groups with the same mean root curvature: warm vertical retreated with ProTaper, warm vertical retreated with WaveOne, GuttaCore retreated with ProTaper, and GuttaCore retreated with WaveOne. The warm vertical groups were obturated using a continuous-wave technique of gutta-percha compaction, and the GuttaCore groups were obturated according to the manufacturer's instructions. After allowing sealer to set, each specimen was retreated with either the ProTaper Universal Retreatment files D1, D2, or D3 or with the WaveOne Primary file to the predetermined working length. The time taken to reach the working length was recorded. Instrument fatigue and failure were also evaluated., Results: The post hoc 2-sample t tests showed that the overall mean total time taken to reach the working length for the warm vertical groups was significantly greater than that observed for the GuttaCore groups (mean = 87.11 vs 60.16 seconds, respectively), and the overall mean total time taken to reach the working length for WaveOne was significantly greater than that observed for ProTaper (99.09 vs 48.18 seconds, respectively). Two-way analysis of variance showed a significant main effect for both the type of experiment groups (F 1,76  = 15.32, P = .0002) and the type of retreatments (F 1,76  = 54.67, P < .0001). Also, the WaveOne Primary file underwent more separations than the ProTaper files., Conclusions: The WaveOne Primary file underwent more separations and was unable to remove gutta-percha as efficiently as the ProTaper Universal Retreatment files. Also, canals obturated with GuttaCore were retreated more efficiently and with fewer file separations than the canals obturated using continuous wave of warm gutta-percha., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

This study evaluated the influence of different instrumentation techniques on the adaptation of gutta percha cones in oval-shaped root canals. A total of 90 human single-rooted teeth were divided into groups according to the instrumentation technique that was used: group M, manual; group OM, hybrid: oscillatory plus manual; group PT, rotary (ProTaper Universal); group OPT, hybrid: oscillatory plus rotary (ProTaper Universal); group MT, rotary (Mtwo); and group OMT, hybrid: oscillatory plus rotary (Mtwo). After a single gutta percha cone was adapted to the canal, cone beam computed tomography was utilized to perform assessments at areas of greater contact of gutta percha to root canal walls. The adaptation was rated as ideal, satisfactory, minimally acceptable, or unsatisfactory. The frequency of ideal adaptation of the cone to the 4 canal walls varied from 26.67% (groups OMT and PT) to 73.33% (group MT); the differences between group MT and groups PT and OMT were statistically significant (P < 0.05). The mean area of the canal preparation without adaptation (contact) of the cone varied from 0.06 mm² (group MT) to 0.41 mm² (group OMT). The results showed that an instrumentation technique using the Mtwo system provided the best adaptation of the .04 gutta percha cones to anatomically oval root canals., Competing Interests: Disclaimer: The authors have no financial, economic, commercial, or professional interests related to topics presented in this article.

Purpose: To compare the volume of root canals of primary teeth filled by four different obturating techniques: (1) lentulospiral (LS); (2) insulin syringe (IS); (3) endodontic pressure syringe (EPS); and (4) the NaviTip system (NS) using cone beam computed tomography (CBCT)., Methods: 76 root canals of primary posterior teeth were selected and divided into four groups, according to the obturation technique. Biomechanical preparation of each root canal was completed with a number 30 K-file, and the volumes of the canals were then measured using CBCT. Each canal was obturated with zinc oxide eugenol paste using the respective technique for that group. A second CBCT scan was performed to measure the filled volume in each canal, and the percentage of obturated volume (POV) was calculated., Results: A statistically significant difference was seen between the pre- and post-mean values (P<.001) and in the mean POV values (P< .001) among the four groups. NS (93.5 percent) and EPS (91.5 percent) showed the highest POV compared to LS (75.5 percent) and IS (64 percent)., Conclusion: The NaviTip system and endodontic pressure syringe showed the best root canal obturation, with the nearest to complete filling of the volumes of prepared root canals, while the insulin syringe was least effective.

Aim: The aim of the present study is volumetric analysis of root canal filling with cold lateral compaction, Obtura II, Thermafil, and Calamus using spiral computerized tomography (SCT)., Materials and Methods: Root canals of eighty mandibular premolars were instrumented using rotary ProTaper, and the volume of the canal space was measured using spiral computerized tomography (SCT). The teeth were divided into four groups of twenty teeth each, and root canals filled by lateral compaction technique, Thermafil carriers, Obtura II, and Calamus techniques, respectively. AH Plus was used as a sealer with all techniques. The filled volume in each canal was measured using SCT, and the percentage of obturated volume (POV) was calculated. The data were statistically analyzed using ANOVA, Kruskal-Wallis test, and Mann-Whitney U-test., Results: The four groups were comparable in canal volume. The overall POV was 78.11%, 85.72%, 82.50%, and 87.89% for lateral compaction, Thermafil, Obtura II, and Calamus, respectively (P Conclusion: The greatest POV was obtained with Calamus and Thermafil. Voids were seen in all root fillings.

Objectives: The objectives of the study were to evaluate the radiographic technical quality of root canal treatment before and after the implementation of a nickel-titanium rotary (NiTiR) preparation followed by a matching-taper single-cone (mSC) obturation and to detect the procedural errors associated with this technique., Materials and Methods: A random sample of 535 patients received root canal treatment at the Department of Conservative Dentistry and Periodontology at the University of Würzburg: 254 teeth were treated in 2002-2003 by using stainless steel instruments (SSI) for preparation and a lateral compaction (LC) technique (classic group (CG)). Two hundred eighty-one teeth were root filled in 2012-2013 employing NiTiR instruments for the root canal shaping and a mSC technique (advanced group (AG)). The quality assessments were based on the radiographic criteria of the European Society of Endodontology. The presence of voids was recorded separately for the apical, central and cervical thirds of the root canals. Procedural errors, such as ledges, apical transportations, perforations and fractured instruments, were detected. The root canal fillings in the CG and AG were compared using chi-squared and Fisher's exact tests. Multivariable logistic regression was performed to investigate the association between the independent variables (patient age, tooth type and type of treatment) and the dependent variables (density and length)., Results: Adequate length was achieved significantly more often in the AG compared to the CG for molars (p = 0.017), mandibular teeth (p = 0.013) and primary root canal treatments (p = 0.024). No significant difference was detected between the AG and CG regarding adequate length in general (p = 0.051) or adequate overall quality of root canal filling (p = 0.1). In the AG, a significant decrease in procedural errors was evident (p = 0.019) and decreases in the densities of the root canal fillings in the cervical (p = 0.01) and central (p = 0.01) thirds of the root canals were also observed. Moreover, root canals in elderly patients exhibited fewer voids (p = 0.009)., Conclusions: Rotary root canal preparation followed by a matching-taper single-cone filling technique provides a reliable shaping of the root canal, with fewer procedural errors and a more acceptable filling quality in terms of length and homogeneity in the apical third. Less favourable results were achieved in the central and cervical parts of the root canals., Clinical Relevance: The matching-taper single-cone technique seems to effectively obturate well-tapered root canals after adequate rotary instrumentation. Irregularly shaped canals require additional lateral or warm vertical condensation to avoid voids.

Endodontic retreatment can be a challenging task that can result in many complications if not approached cautiously. Many of these difficulties revolve around regaining access to the pulp chamber through extensive coronal restorations and removing residual root filling material, the commonest being gutta-percha (GP), from within obturated canals. This can often be an untidy, time consuming process that places teeth at a greater risk of iatrogenic injury and inhibits the operator achieving the necessary chemical disinfection required to eliminate the persistent apical disease. Therefore the following article aims to aid practitioners, particularly those who are unfamiliar, with accessing and removing GP from endodontically treated teeth. The outlined systematic approach is accessible in general practice, where the vast majority of endodontic treatment is conducted, requires basic equipment and with the correct experience can be applied to both straight and curved canals. By overcoming this initial stage of retreatment, subsequent chemical disinfection, which is critical to success, can be carried out to a higher standard reducing risks of re-infection.

Background: Debris extrusion from the apical foramen can be problematic in severely curved canals. This study aimed to assess the use of Twisted Files (TF) at different rotational speeds during retreatment, compared with manual technique using Triple-Flex Files (TFF)., Methods: Forty-eight mesiobuccal root canals were randomized to four groups (n = 12 per group). In groups A, B, and C, gutta-percha was removed using TF at 500, 1000, and 1500 rpm, respectively, while it was removed using TFF in group D. Apical debris was collected in a pre-weighed centrifuge tube. The weight of dry debris was assessed by comparing the pre- and post-instrumentation weight for each group., Results: Instrumentation in group D (0.69 ± 0.04 mg) extruded significantly more debris than any of the TF groups (A: 0.54 ± 0.05 mg; B: 0.48 ± 0.04 mg; C: 0.42 ± 0.03 mg; all P < 0.001). In addition, increasing the rotational speed of TF decreased the amount of extruded debris (A vs. B: P = 0.006; B vs. C: P < 0.001; A vs. C: P < 0.001)., Conclusions: TF at 1500 rpm produced less apical extrusion debris than other TF operating speeds and TFF.

The aim of this study was to evaluate the sealing ability of three different canal filling techniques. Sixty-four roots of extracted human maxillary anterior teeth were prepared using ProTaper® rotary instruments. The specimens were then randomly divided into 3 experimental groups ( n = 16) and 2 control groups ( n = 8). The root canals were filled using cold lateral compaction (CLC group), continuous wave condensation technique using the Elements Obturation Unit® (EOU group), and ProTaper obturators (PT group). For the negative control group, 8 roots were filled using lateral compaction as in the CLC group, and the teeth were covered twice with a layer of nail varnish (NCG group). Another 8 roots were filled using lateral compaction, but without sealer, and these were used as the positive control (PCG group). A glucose leakage model was used for quantitative evaluation of microleakage for 24 hours and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 weeks. No significant difference in the cumulative amount of leakage was found between the three experimental groups at all observation times. The lateral condensation of cold gutta-percha can guarantee a similar seal of canal fillings as can be achieved by using thermal methods, in the round canals.

Objectives: The aim was to evaluate ex vivo apical debris extrusion associated with WaveOne and Self-Adjusting File instruments when used in oval canals., Methods: Twenty-four extracted human mandibular premolars with oval-shaped canals were assigned in two equal groups. Following coronal cavity preparation, a glide path was created. Group A was subjected to canal preparation using a WaveOne primary file, which was used along with syringe and needle irrigation and 10 mL of 2.4 % NaOCl solution, followed by flushing with 10 mL of 17 % EDTA solution, activation with EndoActivator for 1 min and final flushing with 10 mL of 2.4 % NaOCl solution, and activation for 30 s. Group B, the SAF system was used with continuous simultaneous irrigation, provided by the system's pump. The irrigant was supplied at 5 mL/min, alternating every minute between 2.4 % NaOCl solution and 17 % EDTA solution, over a total of 4 min followed by final flushing with 10 mL of 2.4 % NaOCl solution. Extruded apical debris from each root canal was collected into a preweighed glass vial and dried. The mean weight of the debris from each group was assessed and analyzed statistically. Both systems resulted in apical debris extrusion., Results: The WaveOne system was associated with a statistically significant greater mean mass of apically extruded debris (2.18 ± 0.44 mg) than the SAF system (0.49 ± 0.33 mg, permutation-based Wilcoxon test, p < 0.001)., Conclusion: Both WaveOne and the SAF systems were associated with apical debris extrusion. The amount of debris extruded by the WaveOne system was 4.4 times greater than that extruded by the SAF system., Clinical Relevance: The results of the present ex vivo comparative study cannot be directly applied to the clinical situation. Difference between both groups remains completely unclear; maybe the amount of extrusion is harmless in both groups or similarly deleterious for the periradicular tissues in both groups or may be dose-related to the amount of the extruded material.

Objectives: The aim of this study was to evaluate the efficacy of sonic and ultrasonic activation of epoxy-amine resin-based root canal sealer (2Seal; VDW GmbH, München, Germany) on penetration of the sealer into lateral canals compared to non-activated filling., Materials and Methods: Thirty-six single-rooted human anterior teeth were decoronated and prepared, using the ProTaper rotary system (Dentsply Maillefer, Ballaigues, Switzerland) to F4. After the completion of the clearing procedures, lateral canals were created at 2, 4, and 6 mm from the working length. The specimens were randomly divided into a control group (non-activated sealer application) and two experimental groups that received a sealer application with either sonic or ultrasonic activation. The root canals were filled using cold lateral compaction and images were obtained from each lateral canals at 40× magnification using a stereomicroscope. The sealer penetration was evaluated using a four-grade scoring system. The data were evaluated statistically using the Kruskal-Wallis and Mann-Whitney U tests with a 95 % confidence level (P = 0.05)., Results: The ultrasonic activation resulted in a better sealer penetration compared with the non-activated and sonically activated groups (P < 0.001). Sonic activation also resulted in better sealer penetration compared to the non-activated group (P < 0.001)., Conclusions: The use of the ultrasonic activation of an epoxy-amine resin-based sealer promoted greater sealer penetration into the lateral canals. Sonic activation was not effective as ultrasonic activation, but was more effective than the non-activated group., Clinical Relevance: The ultrasonic activation of an epoxy-amine resin-based sealer could be beneficial in filling procedures.

Objectives: The aim of this study was to compare the efficacy of rotary and reciprocating techniques for removing filling material from root canals, using micro-computed tomography (micro-CT) imaging., Materials and Methods: The distal root canals of 42 human mandibular molars were instrumented with hand files up to size 40 according to a step-down technique and obturated with gutta-percha and an epoxy resin-based sealer using Tagger's hybrid technique. Teeth were divided into six groups (n = 7) according to the instruments used for removal of filling material: group PTUR (Protaper Universal Retreatment), group W40 (WaveOne 40.08), group R40 (Reciproc 40.06), group R50 (Reciproc 50.05), group W25/W40 (WaveOne 25.08/40.08), and group R25/R40/R50 (Reciproc 25.08/40.06/50.05). Teeth were scanned with a micro-CT device before and after use of the instruments to calculate the percentage of remaining filling material. Data were compared using one-way ANOVA and Fisher's LSD test at 5 % significance level., Results: The mean percentage of remaining filling material was significantly lower when canals were retreated with the set of instruments R25/R40/R50 and single instruments W40 and R50 compared with the set of instruments W25/W40 (P < 0.05), which promoted material compaction in the apical region., Conclusion: None of the retreatment techniques removed the root fillings completely. PTUR instruments performed equally effective regarding filling removal compared with W40, R40, R50, W25/W40, and R25/R40/R50. For WaveOne, the use of a single instrument (size 40, taper 0.08) was more effective in removing filling material, while for Reciproc showed similar cleaning ability using single instrument or combination of instruments., Clinical Relevance: The results of this in vitro study provide consistent information on filling material removal capacity of mechanized systems during retreatment at the different root canal thirds.

Introduction: The aim of this study was to compare the effectiveness of TRUShape (TS) instruments with ProFile Vortex Blue (VB) instruments for the removal of obturation materials during retreatment of single-canal mandibular premolars performed through 2 access outlines., Methods: Initial root canal treatment was completed through a contracted endodontic cavity (CEC) design. Canals were instrumented to an F2 ProTaper instrument, obturated with warm lateral condensation of gutta-percha with AH Plus sealer, and allowed to set for 30 days at 37°C and 100% humidity. For retreatment, specimens were divided into 2 groups (n = 24) on the basis of access outline, CEC or traditional endodontic cavity (TEC). Retreatment was initiated by using ProTaper Retreatment instruments (D1-D3). Specimens were then stratified, further divided (n = 12), and reinstrumented up to TS 40 .06v or 40 .06 VB. Irrigation was performed by using 8.25% NaOCl and QMix 2in1. Retreatment time was recorded. Teeth were sectioned and photographed, and the percentage of remaining obturation materials was measured. Data were analyzed with Kruskal-Wallis analysis of variance for two-factor tests (α < 0.05)., Results: The interaction between access design and instrument type showed that the combination of CEC-VB presented significantly higher amounts of remaining obturation materials on the canal surface when compared with TEC-VB, CEC-TS, and TEC-TS (P ≤ .05). None of these other combinations were different from each other (P > .05). Significantly more time was required for retreatment with CEC-TS (27.68 ± 1.4 minutes) than the other groups (P < .05)., Conclusions: Neither retreatment protocol was able to completely eliminate all obturation materials from the root canal surface of mandibular premolars. However, in the presence of a CEC access design, using TS instruments removed more obturating material in single-rooted, oval-shaped canals., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objectives: In this in vitro study, we assessed filling characteristics (adaptation, homogeneity, sealer percentage, position of the carrier) of warm and cold obturation methods in curved root canals., Materials and Methods: A reciprocating method was used to prepare 90 curved roots (25 ° average curvature) to an apical size of 25.08. They were then obturated with either (A) Guttafusion (VDW, Munich, Germany), (B) Thermafil (Maillefer, Ballaigues, Switzerland) or (C) single cone technique using 25.08 gutta-percha (VDW) and sealer (2Seal easymix) (n = 30 each group). Five sections in 1-mm steps were obtained from each root, beginning 1 mm short of the apex. The percentage of voids in contact with root canal walls (PVO), the proportion of voids per area (PVA) and the percentage of sealer per area (PSA) were measured., Results: Little to no differences between Guttafusion and Thermafil were seen in curved root canals with respect to adaptation and homogeneity in the apical region. Both methods showed significantly better adaptation and homogeneity than the single cone technique. The proportion of sealer was significantly greater when roots were obturated with Guttafusion than with Thermafil, but both warm obturation techniques had significantly smaller sealer areas than the single cone technique., Conclusions: Compared to the single cone technique, a more favourable root canal filling with less sealer could be expected from both warm obturation techniques in curved root canals., Clinical Relevance: The easier-to-handle Guttafusion leads to comparable results as Thermafil in curved root canals.

Introduction: This study evaluated the amount of apically extruded debris in the retreatment of curved root canals using different nickel-titanium (NiTi) systems: the ProTaper Universal Retreatment (Dentsply Maillefer, Ballaigues, Switzerland), Mtwo Retreatment (VDW, Munich, Germany), D-Race Retreatment (FKG Dentaire, La Chaux-de-Fonds, Switzerland), R-Endo Retreatment (Micro-Mega, Besançon, France), and Reciproc (VDW) systems., Methods: One hundred human mandibular premolars with curved root canals were prepared with the Reciproc #25 .08 NiTi system filled with AH Plus Jet (Dentsply DeTrey, Konstanz, Germany) sealer and gutta-percha and divided into 5 groups (n = 20). The canal filling was removed with the ProTaper, Mtwo, D-Race, and R-Endo retreatment systems and Reciproc instruments. Final preparation was done with the Reciproc #40 .06 NiTi system. Extruded debris was collected in preweighed Eppendorf tubes. The times required for retreatment were recorded., Results: Reciproc produced significantly (P < .001) more debris than the other systems. ProTaper R and Mtwo R produced significantly (P < .001) more debris than D-Race and R-Endo. The Reciproc group required significantly (P < .001) less preparation time than the other groups., Conclusions: In the retreatment of curved root canals, the Reciproc system extruded significantly more debris than the rotary retreatment NiTi systems. In addition, the ProTaper and Mtwo retreatment systems extruded significantly more debris than the R-Endo and D-Race systems. The Reciproc system was significantly faster than the rotary retreatment systems., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study compared the efficacy of a reciprocating single-instrument system and a rotary multi-instrument system followed by a supplementary approach with a finishing instrument in removing the filling material from curved canals during retreatment., Methods: Forty mesial canals from extracted mandibular molars were instrumented and filled. Then, each mesial canal was retreated by using either Reciproc (VDW, Munich, Germany) or Mtwo (VDW) instruments, alternating the technique used per canal from root to root. The working time was recorded, and the percentage of removed filling volume was assessed by means of micro-computed tomography imaging before and after retreatment. Canals still showing filling material remnants were subjected to an adjunctive approach with the XP-Endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland), and another microCT scan was taken. Data were statistically analyzed with a significance level of 5%., Results: The percentage of filling material removed with Mtwo instruments (96%) was significantly higher than Reciproc (89%) (P < .05), both used up to a final instrument size of 40. Mtwo required less time to remove the filling material than Reciproc (P < .05). Intragroup analysis in the Reciproc group showed that the R40 instrument removed significantly more filling material than R25 (P < .05). The supplementary approach with the XP-Endo Finisher was effective in significantly enhancing the removal of filling material (P < .05)., Conclusions: The rotary multiple-instrument system was more effective and faster than the reciprocating single-instrument approach in removing previous root canal fillings. As for the Reciproc group, it was observed that the larger instrument promoted significantly better results. The adjunctive finishing instrument XP-Endo Finisher significantly improved filling material removal., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

The aim of the present study was to evaluate the bond strength (BS) of root canal fillings to root dentin using the reciprocating file-matched single-cone or lateral compaction techniques with resin-based and calcium-silicate-based sealers. Maxillary canine roots were prepared and filled using one of the following approaches: Reciproc R40 file and R40 single cone, WaveOne Large file and Large single cone, or ProTaper up to F4 file with lateral compaction. The root filling was performed using AH Plus, Epiphany SE or MTA Fillapex (n = 10). Three 1-mm-thick slices were obtained from each third of each root. Two slices were subjected to a push-out test, and the other slices were prepared for scanning electron microscopy (SEM) to examine the dentin-sealer interface. Data (in MPa) from the push-out tests were analyzed using a two-way ANOVA and Tukey's test (p < 0.05). Failure modes (adhesive, cohesive or mixed) were evaluated at ×25 magnification. The single-cone techniques resulted in lower BS values than the lateral compaction technique. For lateral compaction, AH Plus and Epiphany SE showed the highest and lowest BS values, respectively. Slight differences were observed between sealers when the single-cone techniques were used. A tendency to reduce the BS toward the apical third was observed. Adhesive failures were predominant for all experimental conditions. A closer adaption of the filling material on the root dentin was observed for the AH Plus and lateral compaction techniques. The Reciproc and WaveOne techniques were associated with lower BS values than the lateral compaction technique. However, the effect of the root canal filling technique appears to be sealer-dependent.

Introduction: This study evaluated filling material removal from distal oval-shaped canals of mandibular molars with rotary, reciprocating, and adaptive motion systems by using micro-computed tomography., Methods: After cone-beam computed tomography scanning, 21 teeth were selected, prepared up to a size 40 file, root filled, and divided into 3 groups (n = 7) according to the filling material removal technique: group PTUR, ProTaper Universal Retreatment combined with ProTaper Universal F2, F3, F4, and F5 files; group RP, Reciproc R50 file; and group TFA: TF Adaptive 50.04 files. The specimens were scanned preoperatively and postoperatively to assess filling material removal by using micro-computed tomography imaging, and the percent volume of residual filling material was calculated., Results: The statistical analysis showed the lowest percent volume of residual filling material at the coronal third in all groups (P < .05). There was no significant difference among the systems in the coronal third (P > .05). In the middle third, group TFA (31.2 ± 10.1) showed lower volume of residual filling material than group RP (52.4 ± 14.1) (P < .05). In the apical third, groups TFA (44.8 ± 20.6) and PTUR (48.6 ± 16.8) presented a lower percent volume of filling material than group RP (70.6 ± 7.2) (P < .05), as confirmed by the qualitative analysis., Conclusions: The use of the adaptive motion increased the amount of root filling removed in the middle and apical thirds compared with the reciprocating motion. However, no technique was able to completely remove the filling material from the canals., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)