Comparison of the effectiveness of various rotary and reciprocating systems with different surface treatments to remove gutta-percha and an epoxy resin-based sealer from straight root canals.

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.

ÖGRO survey on radiotherapy capacity in Austria : Status quo and estimation of future demands.

BACKGROUND: A comprehensive evaluation of the current national and regional radiotherapy capacity in Austria with an estimation of demands for 2020 and 2030 was performed by the Austrian Society for Radiation Oncology, Radiobiology and Medical Radiophysics (ÖGRO). MATERIALS AND METHODS: All Austrian centers provided data on the number of megavoltage (MV) units, treatment series, fractions, percentage of retreatments and complex treatment techniques as well as the daily operating hours for the year 2014. In addition, waiting times until the beginning of radiotherapy were prospectively recorded over the first quarter of 2015. National and international epidemiological prediction data were used to estimate future demands. RESULTS: For a population of 8.51 million, 43 MV units were at disposal. In 14 radiooncological centers, a total of 19,940 series with a mean number of 464 patients per MV unit/year and a mean fraction number of 20 (range 16-24) per case were recorded. The average re-irradiation ratio was 14%. The survey on waiting times until start of treatment showed provision shortages in 40% of centers with a mean waiting time of 13.6 days (range 0.5-29.3 days) and a mean maximum waiting time of 98.2 days. Of all centers, 21% had no or only a limited ability to deliver complex treatment techniques. Predictions for 2020 and 2030 indicate an increased need in the overall number of MV units to a total of 63 and 71, respectively. CONCLUSION: This ÖGRO survey revealed major regional differences in radiooncological capacity. Considering epidemiological developments, an aggravation of the situation can be expected shortly. This analysis serves as a basis for improved public regional health care planning.

Hemodialysis reinitiation using a resurrected mummy fistula: a case report.

BACKGROUND: Kidney allograft loss becomes an important cause of end-stage kidney disease and requires dialysis reinitiation. We report a case of a patient who restarted hemodialysis after his second kidney graft failure using a long-discarded autologous arteriovenous fistula. CASE PRESENTATION: A 62-year-old man was diagnosed with end-stage renal disease 20 year ago, and a native arteriovenous fistula was created for hemodialysis. After the patient received his first kidney transplantation, the hemodialysis fistula was discarded and chronically thrombosed for 13 years. When the patient experienced his second kidney graft loss and presented with uremia again, dialysis restart was needed. Under vascular ultrasound, but not x-ray, guidance, we successfully revascularized the patient's chronically occluded, long-discarded arteriovenous fistula access and used it for hemodialysis. The resurrected fistula remained patent and clinically useable for hemodialysis up to 18 months. CONCLUSIONS: This report provides the feasibility of ultrasound-guided transluminal angioplasty for the treatment of a mummy hemodialysis fistula, which could be considered when managing patients who need dialysis reinitiation.

Efficacy of Rotary and Hand Instrument in removing Gutta-percha and Sealer from Root Canals of Endodontically Treated Teeth.

AIM: One of the common dental procedures employed these days in patients with irreversible pulpitis is root canal therapy. In retreatment cases, it is necessary for complete removal of obturate gutta-percha (GP) from obturate root canal system. Various methods and techniques are available these days for this purpose. This study was aimed to assess the efficacy of D-RaCe files, ProTaper retreatment files, Mtwo retreatment files, and manual Hedstrom files (H-files) in removing filling materials from the root canals of the endodontically treated teeth. MATERIALS AND METHODS: The present study included comparative evaluation of efficacy of nickel-titanium (NiTi) retreatment instruments and H-files in removing GP and sealer from root canals. All the samples were randomly and broadly divided into four study groups based on the instrumentation technique for removing the root canal fillings. Evaluation of the results was done based on operating time and remaining root canal filling material. Stereomicroscopic evaluation of the samples was done at 8* magnification. RESULTS: All the results were assessed and analyzed by Statistical Package for the Social Sciences (SPSS) software. Least quantity of filling material was left by ProTaper retreatment files. When put together in decreasing order, the efficacy of different study groups, in terms of mean time taken for retreatment, was found to be as follows: D-RaCe > ProTaper Retreatment > Mtwo Retreatment > H-file. CONCLUSION: No single technique can completely remove obturating fillings from the root canals of endodontically treated teeth. However, rotary instruments are better in comparison with hand instruments for removing the GP from obturate root canals. CLINICAL SIGNIFICANCE: ProTaper retreatment files and D-RaCe files are recommended over other instrument systems in terms of quality for managing retreatment root canal cases.

Healing of apical periodontitis through modern endodontic retreatment techniques.

The presence of apical periodontitis in teeth which have undergone initial root canal treatment is largely attributed to bacteria residing in or invading from the apical root canal space. Bacteria-associated apical periodontitis will not heal spontaneously, nor will systemic antibiotics eradicate the infection. Only endodontic retreatment, endodontic surgery, or extraction will control the bacterial etiology. Modern retreatment is an effective means of addressing apical periodontitis. A mandibular premolar with apical periodontitis, apical root resorption, and overfilled gutta percha was retreated with post removal, retrieval of gutta percha from beyond the apex, ultrasonic irrigation and disinfection, and placement of a collagen internal matrix to facilitate a well-controlled MTA apical fill. The magnification and illumination imparted by the operating microscope was integral to achievement of treatment objectives. The patient's symptoms were resolved and complete osseous healing occurred. During treatment planning, clinicians should consider the capability of modern endodontic techniques to overcome technical challenges, often allowing the natural dentition to be preserved and restored to function days after retreatment.

Effectiveness of ProTaper, D-RaCe, and Mtwo retreatment files with and without supplementary instruments in the removal of root canal filling material.

AIM: To assess the efficacy of different retreatment rotary files in removing gutta-percha and endodontic sealer from canals. METHODOLOGY: Ninety straight single-rooted premolars were prepared up to a size 30 and filled with gutta-percha and sealer and then randomly assigned to six retreatment groups (n = 15). Groups I, III, and V were retreated using rotary systems ProTaper Universal Retreatment (PTUR), D-RaCe, and Mtwo Retreatment, respectively. Groups II, IV, and VI were retreated using the additional instruments F4, size 40, .04 taper RaCe, and size 40, .04 taper Mtwo, respectively. The roots were split vertically, and images of the halves were obtained using a high-resolution scanner and evaluated with AutoCAD software to calculate the percentage of residual material. Data were analyzed with Kruskal-Wallis and Student-Newman-Keuls tests using a 5% significance cutoff (P < 0.05). RESULTS: There were no statistically significant differences (P > 0.05) between groups when additional instruments were used. The percentage of residual material was lowest in the PTUR group and was statistically significant only when compared to the D-RaCe system (P = 0.0038). CONCLUSIONS: All root canals had residual filling material after retreatment even when additional instruments were used.

The efficacy of R-Endo rotary NiTi and stainless-steel hand instruments to remove gutta-percha and Resilon.

AIM: To evaluate the efficacy of the R-Endo rotary nickel titanium instrumentation system and hand instrumentation to remove gutta-percha or Resilon from root canals. METHODOLOGY: Eighty single-rooted teeth with straight canals were selected, the pulp chamber was opened, and the canals prepared to a size 30, 0.04 taper. The teeth were divided randomly into two groups of 40 each for root filling with gutta-percha + MMSeal sealer or Resilon + RealSeal sealer. After storage, each group was divided into two subgroups, and material was removed with Hedström files or with R-Endo instrumentation. Times to reach the working length and to eliminate filling material were recorded. Root canal walls were examined using scanning electron microscope to evaluate material remnants on each third. The presence of material was measured according to a score scale. The Student's t-test was used to determine significant differences between mean values of time and remaining material (P < 0.05). RESULTS: No significant differences occurred between thirds, material or removal technique regarding remaining filling debris (P > 0.05). However, times to reach the working length and for removal of filling were lower with R-Endo than with Hedström files (P < 0.0001). CONCLUSIONS: Both instrumentation techniques left filling material inside the root canal and mainly in the apical third. There was no difference between the instrumentation techniques.

Retreatability of Bioceramic Endodontic Sealers: a Review.

In 2009 a new type of endodontic sealers was introduced to the market. The so called "bioceramic" sealers are a promising alternative to the present golden standard of root canal fillings. Now a decade later, still very little is known about the ability to remove these sealers in cases of non-surgical endodontic retreatment (NSER). There are only a limited number of articles that provide such information. The commonly used hand files are not efficient in removing thoroughly the sealer from the main canal walls. Machine driven files are much easier and faster alternative to the hand ones, but are still not able to ensure complete removal. Although ultrasonics can be applied only in the straight portion of the main canal, they raise the efficacy of sealer removal. Photon-initiated photoacoustic streaming (PIPS) is another way to enhance the removal of bioceramics. Solvents like chloroform and orange oil are effective in softening gutta-percha, but not the bioceramics. This article reviews the available scientific data concerning removal of bioceramic materials in the context of a NSER.

Secondary colonic stent insertion in acute large bowel obstruction following primary stent failure.

INTRODUCTION: Colonic stent insertion has been shown to be an effective treatment for patients with acute large bowel obstruction, either as a bridge to surgery or as definitive treatment. However, little is known of the role of secondary stent insertion following primary stent failure in patients considered inappropriate or high risk for emergency surgery. METHODS: Fourteen patients presenting with acute large bowel obstruction who had previously been treated with colonic stent insertion were studied. All underwent attempted placement of a secondary stent. RESULTS: Technical deployment of the stent was accomplished in 12 patients (86%) but only 9 (64%) achieved clinical decompression. Successful deployment and clinical decompression of a secondary stent was associated with older age (p=0.038). Sex, pathology, site of obstruction, duration of efficacy of initial stent and cause of primary failure were unrelated to outcome. No procedure related morbidity or mortality was noted following repeated intervention. CONCLUSIONS: Secondary colonic stent insertion appears an effective, safe treatment in the majority of patients presenting with acute large bowel obstruction following failure of a primary stent.

Treatment of Wide-Necked Bifurcation Aneurysms : Initial Results with the pCANvas Neck Bridging Device.

BACKGROUND: Recently, numerous devices dedicated to the treatment of wide-necked aneurysms have become available. We present our initial experience with the pCANvas device and present the technical success rate, clinical outcome and immediate angiographic occlusion rates. OBJECTIVE: We sought to determine the efficacy of flow with the pCANvas for the treatment of unruptured intracranial aneurysms. METHODS: We performed a retrospective review of our prospectively collected data to identify patients treated with the pCANvas device between February 2015 and February 2017. The patient demographics, aneurysm characteristics, immediate and delayed clinical and radiographic follow-up data were recorded. RESULTS: We identified 17 patients (13 female) treated only with the pCANvas device. The average age of the patients was 60.5 ± 13.3 years (range 25-75 years). The average dome width was 7.6 ± 3.2 mm (range 3-15.8 mm), dome height 7.1 ± 3.2 mm (range 3-12.9 mm) and neck width 5.4 ± 3.2 (range 3-16.3 mm). The average aspect ratio was 1.5 ± 0.8 (range 0.6-3.7). At the end of the procedure 15 aneurysms continued complete filling of the aneurysm (Raymond Roy Classification[RRC] 3) with 2 aneurysms showing only filling of the neck of the aneurysm (RRC 2). Early follow-up angiography was available for 16 patients and at this stage 11 aneurysms showed persistent and complete filling of the aneurysm (RRC 3), 5 aneurysms showed complete occlusion of the aneurysm (RRC 1) and 7 aneurysms underwent repeat treatment with coiling. CONCLUSION: The early results on the use of the pCANvas are promising; however, longer term follow-up and larger studies are required.

Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals.

AIM: To evaluate the efficacy of the ProTaper Universal rotary retreatment system for gutta-percha (GP) removal from root canals. METHODOLOGY: Root canals of 60 extracted human maxillary anterior teeth were prepared and filled with laterally condensed GP and AH Plus sealer. Teeth were divided into three groups: group A--GP removal completed with the ProTaper Universal rotary retreatment system and with further canal repreparation accomplished with ProTaper Universal rotary instruments; group B--GP removal was completed using Gates Glidden drills and Hedström files with chloroform as a solvent, followed with further canal repreparation with ProTaper Universal rotary instruments; group C--the same as group B for GP removal with further canal preparation with stainless steel K-flex files (Kerr). The operating time was recorded. Teeth were rendered transparent for the evaluation of the area of remaining GP/sealer in bucco-lingual and mesial-distal directions. Statistical analysis was performed by using repeated measures analysis of variance and anova. Results The ProTaper Universal technique (group A) resulted in a smaller percentage of canal area covered by residual GP/sealer than in groups B and C, with a significant difference between groups A and C (P < 0.05). Mean operating time for group A was 6.73 min, which was significantly shorter (P < 0.05) than group B (10.86 min) and group C (13.52 min). CONCLUSIONS: In this laboratory study all test techniques left GP/sealer remnants within the root canal. The ProTaper Universal rotary retreatment system proved to be an efficient method of removing GP and sealer from maxillary anterior teeth.

Life-threatening DBS withdrawal syndrome in Parkinson's disease can be treated with early reimplantation.

INTRODUCTION: The deep brain stimulation (DBS) withdrawal syndrome (DBS-WDS) is a rare, life-threatening complication in Parkinson's disease (PD) patients with long disease duration and stimulation when stimulation is terminated for extended periods mostly due to infection of the DBS-hardware. METHODS, RESULTS: In five patients explantation became necessary because of infection after a mean of 11.4 years (range 4-15 years) of DBS and a mean disease duration of 24.6 years (range 3-22 years). Mean UPDRS motor-score pre-explantation was 38 points (range 24-55 points) which increased to a mean of 78.4 points (range 58-90 points) after explantation, despite optimal Levodopa dosing. Reimplantation of the hardware after 23 days (range 3-45 days) under antibiotic treatment led to an improvement to a mean of 40 points (range 25-73 points) and a complication free survival. CONCLUSION: Early reimplantation of the DBS-hardware is a treatment option of the DBS-WDS when the life-threatening urgency overrides surgical standards. Observation of the syndrome indicates pharmacological unresponsiveness of the dopaminergic system in advanced PD and long-term DBS.

Comparison between Single-file Rotary Systems: Part 1-Efficiency, Effectiveness, and Adverse Effects in Endodontic Retreatment.

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.

Meta-analysis of treatment outcomes of posterior circulation non-saccular aneurysms by flow diverters.

INTRODUCTION: Non-saccular aneurysms of the posterior circulation are uncommon but highly dangerous lesions. Flow diverter stents have been demonstrated to be effective treatments of various anterior circulation aneurysms, particularly large and giant proximal internal carotid artery aneurysms. However, evidence regarding the treatment of non-saccular posterior circulation aneurysms with flow diverters is lacking. METHODS: A systematic literature review of the English language literature since 2007 was conducted using PubMed, MEDLINE, and Embase. Keywords and MeSH terms included flow diversion, flow diverter, pipeline, surpass, intracranial aneurysm, vertebrobasilar, and non-saccular. Case reports were excluded. Angiographic and clinical outcomes were pooled using a random effects meta-analysis. RESULTS: 13 retrospective non-comparative studies reporting 129 patients and 131 aneurysm treatments were included. The average number of flow diverters per aneurysm was 4.33. Immediate complete or near complete occlusion of the aneurysm occurred in 25% (95% CI 1% to 60%), and long term occlusion in 52% (29-76%). Periprocedural stroke occurred in 23% of cases. Good long term neurologic outcome (modified Rankin Scale score ≤2) was achieved in 51% (95% CI 31% to 71%). Overall mortality was 21% (95% CI 7% to 38%) and morbidity was 26% (12%-42%). Retreatment was required in 5% (95% CI 0% to 14%). Good neurologic outcome rate was higher in vertebral artery aneurysms (83%) than other locations (18-33%). CONCLUSIONS: Flow diversion is a feasible and efficacious treatment for non-saccular aneurysms in the posterior circulation. However, the intervention carries a significant risk of periprocedural stroke, and is still associated with high overall mortality. Further studies are needed to identify significant treatment risk factors and optimize patient selection.

Pipeline-assisted coiling versus pipeline in flow diversion treatment of intracranial aneurysms.

BACKGROUND AND PURPOSE: Flow-diversion therapy (FDT) for large and complex intracranial aneurysms is effective and considered superior to primary coil embolization. Data evaluating common treatment with both FDT and coiling continues to emerge, but information on outcomes remains scarce. This study aims to examine further the efficiency and outcomes correlated with joint FDT using pipeline embolization device (PED) and coiling compared to PED-alone in treating intracranial aneurysms. MATERIALS AND METHODS: Comparative review and analysis of aneurysm treatment with PED in 416 subjects were conducted. Joint modality, PED, and coiling were compared to PED-alone for aneurysm occlusion, recurrence, retreatment, thromboembolic or hemorrhagic events, and functional outcome using the modified Rankin Scale. Data on patient demographics, aneurysm characteristics, clinical and angiographic follow up, were also collected. Both univariate analysis and multivariate logistic regression modeling using mixed-effects were performed. RESULTS: Total of 437 aneurysms were treated using PED of which 74 were managed with both PED and coiling. Average patient-age was 56 years, the majority were men (85%), an average aneurysm size was 9 mm, and the majority were saccular aneurysms (84%). Larger aneurysm size was associated with a poor outcome in patients with unruptured aneurysms (OR = 1.06). Adjusted regression analyses revealed no differences between treatment groups in thromboembolic or hemorrhagic events, aneurysm occlusion rate, residual flow on follow up angiography, or functional outcome. CONCLUSIONS: Treatment of intracranial aneurysms with joint PED and coiling was safe with no increase in complications when compared to PED alone. Aneurysm occlusion rates and functional outcome with PED and coiling stays comparable to treatment with PED-alone.

Impact of the global outflow angle on recanalization after endovascular treatment of middle cerebral artery bifurcation aneurysms.

BACKGROUND AND PURPOSE: Intracranial aneurysm recanalization after endovascular treatment (EVT) remains a major problem. The goal of this study was to find new predictive factors of recanalization after EVT of middle cerebral artery (MCA) bifurcation aneurysms. METHODS: 96 MCA bifurcationaneurysms, ruptured or unruptured, treated by EVT between Septembre 2009 and December 2014, were retrospectively included. Clinical parameters and aneurysm characteristics were recorded. From the initial three-dimensional DSA, spatial coordinates found on parent and daughter arteries of MCA bifurcations gave four different flow angle values; inflow, outflows 1 and 2, and the global outflow angle (the sum of the two outflow angles). Inter- and intra-observer reproducibilities of three-dimensional angle value measurements were performed. RESULTS: Recanalization occurred in 25 cases (26%) and retreatment was performed in 11 cases (11%). Only 1 patient (1%) had rebleeding. Univariate analysis established the following as predictive factors of recanalization: high blood pressure (P=0.014), aneurysm height (P<0.001), aneurysm width (P<0.001), neck size (P<0.001), postoperative occlusion class (P=0.040), percentage of packing volume (P<0.001), as well as the two outflow angles (P=0.006 and 0.045), and the global outflow angle (P<0.001). Multivariate analysis revealed two independent risk factors for recanalization: the global outflow angle (OR=1.05; 95% CI 1.02 to 1.08; P<0.002) and aneurysm width (OR=0.67; 95% CI 0.46 to 0.96; P=0.031). A global outflow angle threshold <192° was found to be a risk factor for recanalization (OR=13.75; 95% CI 4.46 to 42.44), with a sensitivity of 80% and specificity of 77%. CONCLUSIONS: This study emphasizes that a new parameter, the global outflow angle, can be predictive of recanalization for MCA bifurcation aneurysms treated by EVT.

Efficacy of two rotary NiTi instruments in the removal of Gutta-Percha during root canal retreatment.

The aim of this study was to evaluate the efficacy of ProTaper and K3 in the removal of gutta-percha during root canal retreatment in comparison with hand Hedstrom files. Time of gutta-percha removal and amount of apically extruded debris were also evaluated. Sixty extracted single-rooted anterior teeth and premolars were instrumented and obturated with laterally condensed gutta-percha technique. The teeth were cleared and randomly divided into three groups of 20 teeth each. The roots were split longitudinally, digital images were created using a scanner, and the areas of remaining filling material were traced using Ulead Photoimpact7 then calculated using SigmaScan software. The results indicated that the two rotary nickel-titanium instruments left significantly less remaining filling material than hand instruments (p < 0.001). The ProTaper and K3 required significantly less time for filling material removal than hand instruments (p < 0.001). There was no statistically significant difference among the three techniques regarding the amount of apically extruded debris (p = 0.159). In conclusion, ProTaper and K3 were found to be effective and faster in removing gutta-percha.

Quantitative evaluation of debris extruded apically by using ProTaper Universal Tulsa rotary system in endodontic retreatment.

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.

The Efficacy of the WaveOne Reciprocating File System versus the ProTaper Retreatment System in Endodontic Retreatment of Two Different Obturating Techniques.

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 (F1,76 = 15.32, P = .0002) and the type of retreatments (F1,76 = 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.