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The aim of this study was to evaluate the effectiveness of the XP-endo Finisher R (XPFR; FKG Dentaire, La Chaux-de-Fonds, Switzerland) or the Flatsonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, SP, Brazil) in removing remaining filling material after the retreatment of flattened root canals using micro–computed tomographic imaging. Twenty-four flattened distal root canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were prepared with Reciproc Blue (RB) R40 (VDW GmbH, Munich, Germany) and filled using the Tagger hybrid technique. All canals were retreated with RB R40, and apical enlargement was performed with RB R50 (VDW GmbH). The specimens were randomly distributed into 2 groups: XPFR or Flatsonic (n = 12). The percentage of remaining filling material after retreatment and centralization ability was evaluated. Data were submitted to Mann-Whitney, Wilcoxon, and unpaired t tests (α = 5%). Greater capacity to remove remaining filling material in the entire canal and the cervical and middle thirds was observed for the Flatsonic compared with the XPFR (P <.05). However, both supplementary cleaning techniques showed a similar percentage of residual filling material in the apical third (P >.05). No difference was observed in the centralization ability between the techniques (P >.05). The Flatsonic promotes greater removal of remaining filling material than the XPFR in the retreatment of flattened root canals. However, both supplementary cleaning approaches were similar in the apical third. The XPFR and Flatsonic were able to maintain root canal centralization. [ABSTRACT FROM AUTHOR]

The aim of this study was to conduct a micro–computed tomographic assessment of the effectiveness of 3 supplementary cleaning techniques in reducing the residual volume of gutta-percha and a bioceramic sealer after performing endodontic retreatment procedures in teeth with oval canals. Thirty-six mandibular premolars were instrumented with the ProTaper Next system (instruments X1–X3; Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and Bio-C Sealer (Angelus, Londrina, PR, Brazil) using the single-cone technique. The teeth were reinstrumented with the Reciproc R40 instrument (VDW, Munich, Germany) and divided into 3 groups according to the supplementary cleaning technique used (n = 12): ultrasonic-assisted irrigation (UAI), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) irrigation (EAI), or the XP-endo Finisher R system (XPR; FKG Dentaire, La Chaux-de-Fonds, Switzerland). Micro–computed tomographic imaging was used to quantify the residual volume of filling material. One-way analysis of variance complemented by the Tukey test was used to perform the statistical analysis (P <.05). Significant reductions were obtained in the residual filling material after supplementary cleaning (P <.05). XPR (47.5%) led to significantly greater (P <.05) filling material removal than UAI (16.6%) or EAI (22.6%). The removal values of the 2 latter systems were not significantly different. XPR was more effective than UAI and EAI in removing filling material in mandibular premolars with oval canals. None of the tested supplementary cleaning techniques completely removed the residual filling material. [ABSTRACT FROM AUTHOR]

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

The goal of regenerative endodontic treatment (RET) is to regenerate the pulp-dentin complex in immature teeth with pulp necrosis. There is no consensus in using RET in previously treated teeth. This article reports on long-term outcomes of RET in previously treated immature teeth. Previously treated immature teeth with signs/symptoms of failure were included. After local anesthesia and rubber dam isolation, the root canal filling material was removed without the use of chemical solvents. The root canals were irrigated with 6% sodium hypochlorite using an EndoVac (Kerr Endodontics, Culver City, CA), and a creamy mix of metronidazole and ciprofloxacin was placed in the canals for 4 weeks. At the second visit, the antibiotic dressing was removed using 17% EDTA. Bleeding was induced into the root canal space, and SynOss Putty (Collagen Matrix Inc, Oakland, NJ) was placed. Bioceramic putty was placed over the SynOss Putty, and the teeth were restored at a subsequent visit. Five teeth in 4 patients were included. The patients' ages ranged from 14–46 years. Recall examinations were performed from 20 to 72 months with an average of 54.4 months. The apical openings of the teeth ranged from 1–3.7 mm. All teeth were functional and asymptomatic at the recall visits. All periapical lesions resolved with partial or complete mineralization of the root canals, and all teeth showed partial to complete apical closure at the follow-up visits. RET can be a viable option for nonsurgical retreatment of immature teeth. This article adds a new perspective to the field of regenerative endodontics. [ABSTRACT FROM AUTHOR]

Abstract Introduction The aim of this study was to evaluate in vitro the performance of 3 single-file systems: WaveOne Gold Primary (WOG; Dentsply Sirona, Ballaigues, Switzerland), Hyflex EDM "one file" (EDM; Coltene/Whaledent, Alstatten, Switzerland), and XP Shaper (XP; FKG, La Chaux de Fonds, Switzerland), for nonsurgical endodontic retreatment on mandibular anterior teeth in regard to the amount of remaining filling material inside the canal, debris extrusion, and operation time. Methods Sixty extracted standardized mandibular incisors presenting with a single oval canal were prepared to size 30.04 and obturated using warm vertical condensation. After 30 days (37°C, 100% humidity), teeth were randomly divided into 3 groups (n = 20) according to the file used for retreatment (WOG, EDM, or XP operated at 3000 rpm). During the retreatment procedures, preweighed vials were used to collect apically extruded debris, and the time required to remove the filling material was recorded in seconds. Cone-beam computed tomographic scans were taken before and after the retreatment to determine the amount of remaining filling material inside the root canal space. Statistical analysis was performed using the Kruskal-Wallis test, 1-way analysis of variance, and the Pearson test at a 5% significance level. Results There was a statistically significant difference among the groups regarding the instrumentation time (P <.05). XP was the fastest to remove gutta-percha from the canals (40.54 ± 28.03 seconds) followed by EDM (55.77 ± 19.76 seconds) and WOG (105.92 ± 53.92 seconds). The percentage of remaining filling was significantly greater for WOG (26.65% ± 14.63%) (P <.05). No difference was found between EDM (13.51% ± 9.53%) and XP (8.60% ± 7.28%). No difference was found regarding the amount of extruded debris among the 3 groups (P >.05). Conclusions XP was the most efficient in gutta-percha removal from the canals when operated at a higher speed (3000 rpm) followed by EDM and WOG. Highlights • In this study, we investigated the effectiveness of 3 different single-file systems for endodontic retreatment in regard to the remaining root canal filling material, the amount of apically extruded debris, and operation time. • Within the limitations of the study, the XP Shaper was the most efficient in gutta-percha removal from the canals followed by Hyflex EDM and WaveOne Gold. • The percentage of remaining filling was significantly greater for WaveOne Gold compared with the other 2 rotary systems. • No difference was found in regard to the amount of extruded debris among the 3 groups. [ABSTRACT FROM AUTHOR]

Abstract Introduction The aim of the study was to determine long-term tooth survival after endodontic retreatment and whether the presence of intraradicular posts influences the outcome. Methods Ninety-five teeth were randomly assigned to surgical or nonsurgical endodontic retreatment. Forty-seven teeth in 45 patients were treated by conventional endodontic surgery and 48 teeth (47 patients) by nonsurgical retreatment, including the removal of intraradicular posts in 37 (77%). The outcome was tooth survival; follow-up continued until the tooth had been extracted, at least 10 years had elapsed since retreatment, the patient declined further follow-up, or the patient died. The Fisher exact test was used to analyze differences between the groups. Results The median follow-up time was 10.1 years (range, 0.0–15.6 years). The overall survival rate was 76%, with no significant differences in long-term tooth survival between retreatment methods or the presence of an intraradicular post. The reasons for tooth extraction were related to the retreatment method. Vertical root fractures were significantly more frequent in the nonsurgical group when retreatment included post removal (P =.036). Conclusions There was no significant difference in long-term tooth survival after surgical or nonsurgical retreatment. The presence of intraradicular posts did not affect long-term tooth survival, but for teeth with posts, those retreated nonsurgically were more frequently extracted because of vertical root fractures than those retreated surgically (P =.036). The major limitations of the study were a smaller sample size and the use of outmoded retreatment techniques. [ABSTRACT FROM AUTHOR]

Introduction Low-level laser therapy (LLLT) is a practical, nonpharmacologic technique for reducing pain. This study evaluated the effect of LLLT on postoperative pain after root canal retreatment (RCR). Methods This study enrolled patients ( N = 36) who required root canal retreatment (RCR) on mandibular molar teeth, presented with periapical lesions with periapical index scores of 2 or 3, and had a pain visual analog scale (VAS) <50 and a percussion pain VAS <50. The participants were divided into 2 groups: (1) patients scheduled for RCR followed by LLLT ( n = 18) and (2) patients scheduled for RCR followed by a mock LLLT (placebo) ( n = 18). Postoperative pain was assessed using the VAS. Data were collected and statistically analyzed with the chi-square test, the independent sample t test, and the Mann-Whitney U test ( P = .05). Results On the first 4 days, postoperative pain significantly reduced in the LLLT group compared with the placebo group ( P < .05). However, no statistically significant differences in postoperative pain were found between the 2 groups after 5 and 7 days ( P > .05). The number of patients who needed analgesics was lower in the LLLT group than in the placebo group ( P < .05). No patient reported pain during LLLT application. Conclusions LLLT may reduce postoperative pain after RCR of mandibular molars. [ABSTRACT FROM AUTHOR]

Introduction This clinical study evaluated the influence of the apical preparation size using nickel-titanium rotary instrumentation and the effect of a disinfectant on bacterial reduction in root canal–treated teeth with apical periodontitis. Methods Forty-three teeth with posttreatment apical periodontitis were selected for retreatment. Teeth were randomly divided into 2 groups according to the irrigant used (2.5% sodium hypochlorite [NaOCl], n = 22; saline, n = 21). Canals were prepared with the Twisted File Adaptive (TFA) system (SybronEndo, Orange, CA). Bacteriological samples were taken before preparation (S1), after using the first instrument (S2), and then after the third instrument of the TFA system (S3). In the saline group, an additional sample was taken after final irrigation with 1% NaOCl (S4). DNA was extracted from the clinical samples and subjected to quantitative real-time polymerase chain reaction to evaluate the levels of total bacteria and streptococci. Results S1 from all teeth were positive for bacteria. Preparation to the first and third instruments from the TFA system showed a highly significant intracanal bacterial reduction regardless of the irrigant ( P < .01). Apical enlargement to the third instrument caused a significantly higher decrease in bacterial counts than the first instrument ( P < .01). Intergroup comparison revealed no significant difference between NaOCl and saline after the first instrument ( P > .05). NaOCl was significantly better than saline after using the largest instrument in the series ( P < .01). Conclusions Irrespective of the type of irrigant, an increase in the apical preparation size significantly enhanced root canal disinfection. The disinfecting benefit of NaOCl over saline was significant at large apical preparation sizes. [ABSTRACT FROM AUTHOR]

Introduction The aim of this randomized clinical trial was to evaluate the influence of rotary or reciprocating retreatment techniques on the incidence, intensity, duration of postoperative pain, and medication intake. Methods After power analysis calculations, 65 patients who needed endodontic retreatment were randomly assigned to 1 of 2 groups according to the instrumentation system used: Mtwo (VDW, Munich, Germany) or Reciproc (VDW). Retreatments were performed in a single visit by an endodontic specialist. Participants were asked to rate the incidence and intensity of the postoperative pain on a verbal rating scale 24, 48, and 72 hours after treatment. Patients were also asked to record the number of prescribed analgesic medication tablets (ibuprofen 400 mg) taken. A logistic regression analysis was used to assess both the incidence and duration of pain. Differences in the intensity of pain were analyzed using the ordinal (linear) chi-square test, and the Mann-Whitney U test was used to assess differences in the intake of analgesic medication between groups. Results No statistically significant difference was found among the 2 groups in relation to postoperative pain or analgesic medication intake at the 3 time points assessed ( P > .05). Multivariate analysis showed a significantly higher incidence of pain after 24 hours when preoperative pain was present and a significantly longer duration of pain for men than women independently of the retreatment technique used. Conclusions The reciprocating system and the continuous rotary system were found to be equivalent regarding the incidence, intensity, duration of postoperative pain, and intake of analgesic medication. [ABSTRACT FROM AUTHOR]

Introduction The aim of this systematic review was to answer the following clinical question: Which is the best treatment option for a pulpally involved tooth? Methods An electronic search was conducted in the Cochrane, PubMed (MEDLINE), and ScienceDirect databases between December 2015 and February 2016. A manual search was also performed. The inclusion criteria were randomized clinical trials, prospective or retrospective cohort studies, and cross-sectional studies performed on humans with at least 1 year of follow-up and published within the last 10 years. Two researchers independently screened the title and abstract of every article identified in the search in order to establish its eligibility. The selected articles were classified into different levels of evidence by means of the Strength of Recommendation Taxonomy criteria. Results Sixty articles met the inclusion criteria for this systematic review. The survival rate of single-tooth implants was greater than the success rate of the distinct conservative treatments. However, among comparative studies, no important differences between both treatments were observed until at least 8 years later. Conclusions The endodontic treatment and the implant placement are both valid and complementary options for planning oral rehabilitation. Although a level B recommendation can be stated, these results come from retrospective comparative studies because there is a lack of randomized clinical studies comparing both types of therapeutic options. [ABSTRACT FROM AUTHOR]

Introduction This study compared the antibacterial effects of 1% sodium hypochlorite (NaOCl) and 2% chlorhexidine digluconate (CHX) during retreatment of teeth with apical periodontitis. Methods Root canal–treated teeth with apical periodontitis were randomly distributed into 2 groups. Bacteriological samples were taken from the canals before (S1) and after (S2) preparation using either NaOCl or CHX irrigation and after calcium hydroxide medication (S3); 16S ribosomal RNA gene-based real-time quantitative polymerase chain reaction was performed to quantify total bacteria, streptococci, and Enterococcus faecalis . Results Forty-nine teeth were available for analysis (NaOCl, n = 20; CHX, n = 29). Bacterial DNA occurred in all S1 samples, streptococci in 57% and E. faecalis in 6%. The total bacterial counts decreased from S1 to S2 in both groups ( P < .01) but were higher in S3 than S2 ( P < .01). Thirty-five percent of the teeth in the NaOCl group were positive in S2, decreasing to 20% in S3. In the CHX group, 41% were positive in S2, decreasing to 31% in S3. The bacterial load in S1 influenced the incidence of bacteria in S2 ( P < .01). Streptococci were significantly reduced in both groups, and E. faecalis was found in only 1 S2 sample and not in S3. No significant difference between NaOCl and CHX was found. Conclusions NaOCl and CHX both reduced bacterial counts and the number of infected canals. Intracanal medication with calcium hydroxide reduced the number of canals with persistent infection but resulted in overall larger bacterial counts in the cases positive for bacteria. The effectiveness of antimicrobial treatment can be influenced by the initial bacterial load. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction This in vivo study compared the antibacterial effects of 2 instrumentation systems in root canal–treated teeth with apical periodontitis. Methods Forty-eight teeth with a single root and a single canal showing post-treatment apical periodontitis were selected for this study. For retreatment, teeth were randomly divided into 2 groups according to the instrumentation system used: Self-Adjusting File (SAF; ReDent-Nova, Ra'anana, Israel) and Twisted File Adaptive (TFA; SybronEndo, Orange, CA). In both groups, 2.5% sodium hypochlorite was the irrigant. Bacteriological samples were taken before (S1) and after chemomechanical preparation (S2). In the TFA group, passive ultrasonic irrigation (PUI) was performed after instrumentation, and samples were also taken after this supplementary step (S2b). DNA was extracted from the clinical samples and subjected to quantitative real-time polymerase chain reaction to evaluate the levels of total bacteria, streptococci, and Enterococcus faecalis . Statistical analyses from quantitative real-time polymerase chain reaction data were performed within groups using the Wilcoxon matched pairs test and between groups using the Mann-Whitney U test and the Fisher exact test with the significance level set at P < .05. Results Bacteria were detected in S1 samples from 43 teeth, which were then included in the antibacterial experiment. Both SAF and TFA instrumentation protocols showed a highly significant intracanal bacterial reduction ( P < .001). Intergroup quantitative comparisons disclosed no significant differences between TFA with or without PUI and SAF ( P > .05). PUI did not result in significant improvement in disinfection ( P > .05). Conclusions Both instrumentation systems/treatment protocols were highly effective in significantly reducing the intracanal bacterial counts. No significant difference was observed between the 2 systems in disinfecting the canals of teeth with post-treatment apical periodontitis. [ABSTRACT FROM AUTHOR]

Introduction This article describes 3 cases that presented persistent symptoms after appropriate endodontic treatment. Histopathologic and histobacteriologic investigation were conducted for determination of the cause. Methods Three cases are reported that presented with persistent symptoms after endodontic retreatment (cases 1 and 2) or treatment (case 3). Periapical surgery was indicated and performed in these cases. The biopsy specimens, consisting of root apices and the apical periodontitis lesions, were subjected to histopathologic and histobacteriologic analyses. Results Case 1 was an apical cyst with necrotic debris, heavily colonized by ramifying bacteria, in the lumen. No bacteria were found in the apical root canal system. Case 2 was a granuloma displaying numerous bacterial aggregations through the inflammatory tissue. Infection was also present in the dentinal tubules at the apical root canal. Case 3 was a cyst with bacterial colonies floating in its lumen; bacterial biofilms were also seen on the external apical root surface, filling a large lateral canal and other apical ramifications, and between layers of cementum detached from the root surface. No bacteria were detected in the main root canal. Conclusions Different forms of extraradicular infection were associated with symptoms in these cases, leading to short-term endodontic failure only solved by periapical surgery. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: This article describes a case of recurrent post-treatment apical periodontitis and late failure after endodontic retreatment performed in a single visit. Methods: The patient presented with a tooth exhibiting inadequate endodontic treatment and a large periradicular lesion that extended laterally to the root. Retreatment was performed in a single visit and involved chemomechanical preparation using 5.25% NaOCl as the irrigant and root canal obturation by Schilder’s vertical compaction technique. A large lateral canal was radiographically revealed after obturation. After 2 years, the lesion was no longer radiographically discernible, a condition that was confirmed 9 years after retreatment procedures. Nonetheless, after 12 years, radiographs revealed recurrent disease. Apical surgery was performed, and the root apex, including the area of the large lateral canal, was resected with care to maintain the lesion attached to it. The biopsy specimen was subjected to histopathologic and histobacteriologic analyses. Results: Longitudinal sections of the apical root specimen revealed a heavy dentinal tubule infection surrounding the area of the lateral canal. Bacteria were not found in any other area of the specimen. No other possible reason for the inflammatory periradicular lesion, such as root fracture, coronal leakage, or foreign-body reaction, was evident. Conclusions: A persistent intraradicular infection caused by bacteria located within dentinal tubules is the most reasonable explanation for resurgence of the apical periodontitis lesion. This case report stresses the importance of attaining proper disinfection of the root canal system for a predictable long-term outcome of the treatment. [Copyright &y& Elsevier]

Abstract: Introduction: Failure in endodontic treatment is often caused by the persistence of microorganisms in the root canal after therapy. When treatment fails, an immune response develops that is characterized by an extensive network of immunologic mechanisms that lead to the production of cytokines and chemokines. Methods: The objective of this study was to determine the relative messenger RNA (mRNA) expression of IFN-γ, TNF-α, IL-1β, IL-17A, IL-10, and MCP-1 in periapical dental lesions refractory to treatment. Clinical samples were taken from teeth presenting periapical lesions refractory to endodontic treatment (the experimental group) or from healthy teeth with pulp vitality (the control group). Three paper points passing through the root apex (2 mm) were used to collect the samples. The total RNA was extracted from each sample, complementary DNA was synthesized, and quantitative polymerase chain reaction analysis was performed. The Mann-Whitney U test was used to determine the statistical significance of our findings (P < .05). Results: Significant differences in the levels of IFN-γ, TNF-α, IL-17A, and MCP-1 mRNA expression were observed in cases refractory to endodontic treatment as compared with the control group. The expression of IL-1β mRNA was not significantly different between the groups. The expression of IL-10 mRNA was insignificant in both the experimental and control groups. Conclusions: A significantly increased expression of TNF-α, IFN-γ, IL-17A, and MCP-1 mRNA was observed in the periapical immune response in cases of endodontic failure. These results suggest that a proinflammatory cytokine profile predominates in these types of dental lesions. [Copyright &y& Elsevier]

Abstract: Introduction: This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment. Methods: Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy. Results: The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type. Conclusions: The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results. [Copyright &y& Elsevier]

Abstract: Introduction: The objective of this article was to show an alternative clinical approach to retreating teeth having had prior combined nonsurgical and surgical endodontic treatment with retrograde amalgam fillings. Nonsurgical retreatment performed alone has historically presented numerous challenges for the clinician and an uncertain outcome for the patient. Surgical retreatment has the potential disadvantages of additional root shortening, bone loss, and scarring. Methods: Four cases are presented with recalls up to 5.5 years. Results: The procedure was shown to be predictable and successful in this series. Root length was preserved, and surgery was avoided. Conclusions: Nonsurgical amalgam removal from the root end may provide a desirable alternative to the more common and complicated option of combined nonsurgical and surgical endodontic retreatment. [Copyright &y& Elsevier]

Abstract: Introduction: This ex vivo study evaluated the heat release, time required, and cleaning efficacy of MTwo (VDW, Munich, Germany) and ProTaper Universal Retreatment systems (Dentsply/Maillefer, Ballaigues, Switzerland) and hand instrumentation in the removal of filling material. Methods: Sixty single-rooted human teeth with a single straight canal were obturated with gutta-percha and zinc oxide and eugenol-based cement and randomly allocated to 3 groups (n = 20). After 30-day storage at 37°C and 100% humidity, the root fillings were removed using ProTaper UR, MTwo R, or hand files. Heat release, time required, and cleaning efficacy data were analyzed statistically (analysis of variance and the Tukey test, α = 0.05). Results: None of the techniques removed the root fillings completely. Filling material removal with ProTaper UR was faster but caused more heat release. Mtwo R produced less heat release than the other techniques but was the least efficient in removing gutta-percha/sealer. Conclusions: ProTaper UR and MTwo R caused the greatest and lowest temperature increase on root surface, respectively; regardless of the type of instrument, more heat was released in the cervical third. Pro Taper UR needed less time to remove fillings than MTwo R. All techniques left filling debris in the root canals. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of this in vitro evaluation was to study the accuracy of Root ZX and ProPex system during retreatment of canals obturated with different obturating materials (gutta-percha + zinc oxide–eugenol sealer, gutta-percha + AH plus sealer, and Resilon + Epiphany sealer). Methods: Sixty human mandibular premolar roots were instrumented with Rotary ProTaper until size F4 under copious irrigation. After instrumentation, actual working length was directly measured by using #15 FlexoFile. Electronic working length was taken with the help of Root ZX and ProPex. Teeth were divided into 3 groups and obturated by using lateral condensation of gutta-percha + zinc oxide–eugenol sealer (group I), gutta-percha + AH plus sealer (group II), and Resilon + Epiphany sealer (group III). After 7 days, the obturating materials were removed by using Gates-Glidden burs and K-files. A new electronic working length was taken. Original and post-treatment electronic working lengths were compared with actual working length. Accuracy of both electronic root canal length measurement devices was calculated for tolerance limits of ±0.5 mm and ±1.0 mm. Accuracy was compared by using χ2 tests, and difference between actual working length and original and post-treatment electronic working lengths was compared by using Student t test. Results: The accuracy of electronic root canal length measurement devices before root canal obturation was 83.3% and 93.3% for Root ZX and ProPex, respectively, for a tolerance limit of ±0.5 mm and 100% for a tolerance limit of ±1.0 mm. There was no statistically significant effect of different obturating materials tested in this study on the accuracy of Root ZX and ProPex for tolerance limits of ±0.5 mm and ±1.0 mm. Student t test revealed insignificant differences between the mean of actual working length and original and post-treatment electronic working lengths. Conclusions: Root ZX and ProPex can be a useful adjunct with a high accuracy rate during root canal preparation and retreatment. [Copyright &y& Elsevier]

Abstract: A light and electron microscope examination of the resected root tip of a failing endodontically re-treated lower molar was examined. The tooth had been initially treated 10 years ago and then re-treated 2 years ago. The resected root tip was sectioned axially, and thin sections were examined through the entire length of the specimen. Thin sections were examined with a transmission electron microscope. The thin sections were randomly chosen along the isthmus areas between the mesiobuccal and mesiolingual canals. Our findings suggest that a complex, variable, multispecies biofilm was present the entire length of the specimen. [Copyright &y& Elsevier]

Abstract: The aim of this study was to isolate and detect microorganisms of root-filled teeth associated with periradicular lesions. Specimens were sampled from patients undergoing root canal retreatment. The bacteria were characterized by morphologic and biochemical analysis and by 16S rRNA gene sequencing. Microorganisms were detected in 10 of 18 teeth. The majority of positive samples revealed a mixed culture of 2–8 species. In 2 teeth Enterococcus faecalis was the only detected species. For the first time Vagococcus fluvialis was detected in root canals. Solobacterium moorei and Fusobacterium nucleatum were the most prevalent species. Presence of F. nucleatum was associated with the presence of S. moorei in 5 of 7 cases. In all teeth with Parvimonas micra and Dialister invisus, F. nucleatum and S. moorei were found. Moreover, members of additional different genera were detected delivering bacterial compositions that have been not described yet. [Copyright &y& Elsevier]

Abstract: This study evaluated the amount of apical debris during endodontic retreatment by using the ProTaper Universal Tulsa rotary files. Forty-five extracted human anterior teeth were root filled before randomly assigned to 3 groups. In group A, gutta-percha was removed by using the ProTaper Universal Tulsa retreatment system, and canals were re-prepared with ProTaper rotary files. In group B, gutta-percha was removed by using Hedström files with chloroform, and canals were reshaped with ProTaper rotary files. In group C, the same method as that in group B was used for gutta-percha removal, and canals were reshaped with K-flex files. Apical debris was collected and compared among 3 groups. Although all retreatment techniques resulted in apical extrusion, the ProTaper Universal Tulsa rotary technique in group A produced significantly less amount of apical extrusion than other 2 methods (P < .001). The ProTaper Universal Tulsa rotary technique proves to be a viable alternative method in endodontic retreatment. [Copyright &y& Elsevier]

Abstract: This study determined the presence of microorganisms by culture and polymerase chain reaction in asymptomatic root-filled teeth with periradicular lesions. Furthermore, a disinfecting regimen using sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine digluconate (CHX) irrigation, and calcium hydroxide (Ca(OH)2) dressing was assessed. After removal of the root-filling material, specimens of 20 cases undergoing retreatment were sampled. Moreover, the canals were sampled after each step of the disinfecting regimen. Prevalence of microorganisms was 60% by culture and 65% by polymerase chain reaction. In four of those samples (31%), DNA of Enterococcus faecalis was found. After further root canal preparation and irrigation using NaOCl and EDTA, microorganisms could be detected in none of the teeth. Thus, CHX and Ca(OH)2 could not show further disinfection. In contrast, microorganisms were found in two teeth after the interappointment dressing. It may be concluded that proper root canal preparation and irrigation using NaOCl and EDTA are sufficient for decontamination of the root canal system during endodontic retreatment. [Copyright &y& Elsevier]

Abstract: Enterococcus faecalis is the most commonly found species in root-filled teeth evincing recalcitrant periradicular lesions and as a consequence, a role in causation of endodontic treatment failure has been suggested. The purpose of this study was to evaluate the prevalence of this bacterial species in root-filled teeth with or without periradicular lesions. Identification of E. faecalis was carried out by polymerase chain reaction (PCR) or conventional culture procedures. Overall, E. faecalis was detected by species-specific 16S rRNA gene-based PCR in 40/50 teeth (80%), while culture revealed the occurrence of this species in 8/50 teeth (16%). PCR was significantly more effective than culture in detecting this bacterial species (p < 0.001). Of 27 root-filled teeth with no periradicular lesions, E. faecalis was found in 22 cases (81.5%) by PCR and in five cases (18.5%) by culture. Of 23 root-filled teeth with periradicular lesions, E. faecalis was identified in 18 cases (78%) by PCR and in three cases (13%) by culture. Regardless of the identification technique used, no significant difference was observed when comparing the occurrence of E. faecalis in root-filled teeth with and without periradicular lesions (p > 0.05). Although these findings apparently put into question the status of E. faecalis as the main species causing endodontic treatment failure, other related factors still need to be clarified before this assumption turns into certainty. [Copyright &y& Elsevier]

Abstract: Enterococcus faecalis is a microorganism commonly detected in asymptomatic, persistent endodontic infections. Its prevalence in such infections ranges from 24% to 77%. This finding can be explained by various survival and virulence factors possessed by E. faecalis, including its ability to compete with other microorganisms, invade dentinal tubules, and resist nutritional deprivation. Use of good aseptic technique, increased apical preparation sizes, and inclusion of 2% chlorhexidine in combination with sodium hypochlorite are currently the most effective methods to combat E. faecalis within the root canal systems of teeth. In the changing face of dental care, continued research on E. faecalis and its elimination from the dental apparatus may well define the future of the endodontic specialty. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to determine if Enterococcus spp. are more prevalent in endodontically treated teeth with periradicular lesions compared with teeth that require retreatment but have no periradicular rarefaction. Fifty-eight teeth that had received root canal therapy more than 1 yr previously and required retreatment were included. Designation of lesion versus no lesion was determined by two experienced endodontists. DNA extraction and PCR amplification were performed using ubiquitous 16S rDNA bacterial primers, as well as Enterococcus spp.-specific primers. The results showed that the overall prevalence of bacteria was 90% and Enterococcus spp. was 12%. χ2 analysis revealed a statistically significant relationship between the presence of a lesion and the presence of bacteria, as detected by the universal primers (p = 0.032). Using logistic regression, a statistically significant relationship was found between teeth with normal periapex and the presence of Enterococcus spp. (p = 0.023). This study revealed that bacteria are significantly associated with endodontic treatment failure but enterococci are not associated with disease. [Copyright &y& Elsevier]