R25 Instruments Research Articles

Micro-CT evaluation of different final irrigation protocols on the removal of hard-tissue debris from isthmus-containing mesial root of mandibular molars

This study aimed to compare four final irrigation protocols (passive ultrasonic irrigation [PUI], EndoVac, Self-Adjusting File [SAF] and EasyClean) on the removal of accumulated hard-tissue debris (AHTD) from mesial canals of mandibular molars through microcomputed tomographic (micro-CT) analysis. Forty mesial roots of mandibular molars presenting isthmuses type I or III were scanned in a micro-CT device and instrumented up to Reciproc R40 instrument. After the completion of canal preparations, root canals of each group were submitted to a final rinse using 20mL of solution (16mL of 5.25% NaOCl and 4mL of 17% EDTA) in a total time of 5min according to one of the four final irrigation protocols (n = 10): PUI, EndoVac, SAF and EasyClean operated at reciprocating motion. The sample was scanned again after canal preparation and after the use of the final irrigation protocols, and the registered data sets were examined to evaluate the percentage of AHTD. Data were statistically compared using the Tukey test with a significance level set at 5%. All groups presented a decrease on the accumulation of hard-tissue debris after the use of the final irrigation protocols (P < 0.05). No significant differences in the removal of AHTD were observed among the final irrigation protocols (P > 0.05). All final irrigation protocols showed the same effectiveness in the removal of AHTD. None of them was able to render mesial canals of mandibular molars completely free from packed debris. This study highlighted that all final irrigation protocols (PUI, EndoVac, SAF, and EasyClean) promoted a similar removal of AHTD. However, none of the final irrigation protocols was able to render mesial canals of mandibular molars completely free from packed debris.

The impact of using a pneumatic contra-angle device on the lifespan of M-Wire- and Blue-treated instruments.

To evaluate the cyclic fatigue resistance of Reciproc M-Wire R25 (VDW, Munich, Germany) and Reciproc R25 Blue instruments (VDW) driven by Direct® (VDW) contra-angle connected to an ordinary an air-driven motor or an electric motor and compare the results with those obtained by the Reciproc M-Wire R25 or Reciproc Blue R25 instruments driven by an electric torque-controlled motor using "RECIPROC ALL" preset program. Thirty Reciproc M-Wire R25 (25/0.08v) and 30 Reciproc Blue R25 (25/0.08v) instruments were used. Cyclic fatigue resistance was tested measuring the time to fracture and the number of cycles to fracture in an artificial stainless-steel canal with a 60° angle and a 5-mm radius of curvature. The Reciproc M-Wire and Reciproc Blue instruments were activated with a 6:1 reduction handpiece powered by a torque-controlled motor using "RECIPROC ALL" preset program, with Reciproc Direct® contra-angle powered by an ordinary air-driven motor or with Direct® contra-angle powered by an electric motor (n = 10). The fracture surface of all fragments was examined with a scanning electron microscope. The results were statistically analyzed using Student's t test and one-way ANOVA at a significance level of P < 0.05. Cyclic fatigue life and number of cycles to fracture were significantly higher for Reciproc Blue instruments than for Reciproc M-Wire instruments regardless of the activation mode (P < 0.05). Instruments driven by Direct® contra-angle powered by an electric or by an ordinary air-driven motor revealed significantly longer cyclic fatigue life and number of cycles to fracture than instruments driven by an electric torque-controlled motor using "RECIPROC ALL" preset program (P < 0.05). Reciproc Blue instruments showed improved performance regarding fatigue resistance when compared to Reciproc M-Wire instruments. Instruments driven by Reciproc Direct® contra-angle showed higher cyclic fatigue life and number of cycles to fracture than instruments driven by an electric torque-controlled motor. Recently, Reciproc Direct®, the world's first contra-angle handpiece with integrated reciprocating motion, has been launched in endodontic market. The present study showed improved cyclic fatigue life of endodontic instruments when activated by Reciproc Direct®.

The Effects of Antioxidant Application and Time Factor on Fiber Post Bonding to Root Dentin after Intracoronal Bleaching

Aim: The aim was to evaluate the effects of antioxidant application and delayed cementation on the bond strength of fiber posts after intracoronal bleaching.&#x0D; Methodology: Fifty-five maxillary central incisors were used. Root canals were enlarged using Reciproc system up to R40 instrument. Root canals were irrigated, dried with paper-points, and obturated with gutta-percha and a sealer. In 44 teeth, root canal fillings were removed 2-mm coronally and canal orificies were sealed with glass-ionomer-cement. A 37% CP gel was used to bleach the teeth. Five experimental groups were defined (n=11). G1: No bleaching, G2: Immediate FPC, G3: Immediate FPC after SA application, G4: 14-days delayed FPC, G5: 14-days delayed FPC after SA application. Push-out tests were performed. Statistical interpretations were made (α=0.05).&#x0D; Results: There was no significant difference among the groups in apical thirds (p&gt;0.05). However, significant differences were detected among the groups in middle and coronal thirds (p&lt;0.05).&#x0D; Conclusion: The 14-days delayed cementation seems to be a more reliable method than the SA application before FPC procedure after intracoronal bleaching.

Torsional Fatigue Resistance of Blue-treated Reciprocating Instruments

IntroductionThe aim of the present study was to evaluate the influence of blue thermal treatment on the torsional resistance behavior of M-Wire Reciproc files (VDW, Munich, Germany). MethodsTen M-Wire Reciproc R25 (25/0.08v) and 10 Reciproc Blue R25 (25/0.08v, VDW) instruments were used. The torque and angle of rotation at failure of new instruments (n = 10) were measured according to ISO 3630-1. Three millimeters of each instrument tip was clamped to a small load cell by a lever arm linked to the torsion axis. The fracture surface of all fragments was examined with a scanning electron microscope. Results were statistically analyzed using the Student t test at a significance level of P < .05. ResultsThe maximum torsional strength of M-Wire Reciproc was higher than Reciproc Blue instruments (P < .05). Reciproc Blue instruments showed significantly higher angular rotation to fracture than M-Wire Reciproc instruments (P < .05). Scanning electron microscopy of the fracture surface showed similar and typical features of torsional failure for the 2 types of instruments, including concentric abrasion marks and the fibrous dimple marks at the center of rotation. ConclusionsReciproc Blue instruments showed a higher angle of rotation to fracture but a lower torque to failure than M-Wire Reciproc instruments.

Comparison of the shaping ability of novel thermally treated reciprocating instruments.

ObjectivesThe present study aimed to evaluate the shaping ability of 2 thermally treated nickel-titanium reciprocating systems in simulated curved canals.Materials and MethodsForty simulated canals were prepared to apical size 25 using Reciproc Blue R25 (VDW) and WaveOne Gold Primary (Dentsply Sirona) instruments. Standard pre- and post-preparation images were taken and superimposed. The removal of resin material was measured at 5 standard points: the canal orifice, halfway between the canal orifice and the beginning of the curve, the beginning of the curve, the apex of the curve, and the end-point of the simulated canal. The data were analysed using the independent sample t-test with a 5% significance threshold.ResultsThe canals in which Reciproc Blue R25 was used showed a significantly greater widening than those in which WaveOne Gold was used at 4 of the 5 measurement points (p < 0.05). The Reciproc Blue R25 instrument removed significantly more resin from the inner aspect of the curve at 2 of the 5 points and similar amounts at the remaining 3 points. At the 2 apical points, there was no significant difference between the Reciproc Blue R25 and WaveOne Gold Primary instruments.ConclusionBoth instruments respected the original canal anatomy; however, WaveOne Gold resulted in a more conservative shape with less transportation.

Shaping Ability of Reciproc Blue Reciprocating Instruments with or without Glide Path in Simulated S-shaped Root Canals

Background. The present study aimed to compare the shaping ability of Reciproc Blue instruments with or without the creation of a glide path in simulated S-shaped root canals. Methods. Root canals of thirty #15.02 clear resin S-shaped blocks were dyed using ink and photographed. Then the blocks were randomly divided into 2 groups: group A: Reciproc Blue with glide path created with ProGlider and group B: Reciproc Blue with no glide path preparation (n=15). The blocks were also photographed after preparation. The pre- and post-prepara-tion images were superimposed and evaluated at 9 different measurement points according to the 3 zones, as coronal straight, first curvature, and apical curvature zones. The data were evaluated with independent t-test or Kruskal-Wallis tests with 5% significance interval. Results. Group B removed greater amount of material from the inner aspect of simulated canal at the first curvature and apical curvature zones and from the outer aspect of the canal at apical curvature zone (P<0.05). Both groups exhibited trans-portation and the transportation width in group B was significantly greater in the levels of apical curvature zone (P<0.05). Conclusion. Glide path preparation using ProGlider rotary instrument improved the shaping ability of Reciproc Blue R25 instrument by leading to less transportation and maintaining centering ability.

Cyclic Fatigue Life of Two Single File Engine-Driven Systems in Simulated Curved Canals.

Introduction:This study aimed to evaluate the cyclic fatigue resistance of two single file engine-driven instruments, Reciproc and NeoNiTi, in simulated root canals. Methods and Materials: Two groups of 15 NiTi endodontic instruments with an identical tip size of 0.25 mm were tested: Reciproc R25 (group A) and NeoNiTi A1 (group B). Cyclic fatigue testing was performed in a stainless steel artificial canal. The simulated canals had a 60° angle and 5-mm radius curvature. The Reciproc instruments were operated using the preset program on torque control electric motor specific for the Reciproc instruments, while the NeoNiTi instruments were operated using the manufacturer recommendation. All instruments were rotated until fracture occurred, and the number of cycles to fracture (NCF) and the length of the fractured tip were recorded and registered. Means and standard deviations of NCF and fragment length were calculated for each system and data were subjected to Student’s t test (P<0.05). Results:A statistically significant difference (P<0.05) was noted between Reciproc and NeoNiTi instruments. NeoNiTi A1 instruments were associated with a significantly higher mean NCF as compared to Reciproc R25 instruments (833±176 vs. 318±87 NCF). There was no significant difference (P>0.05) in the mean length of the fractured fragments between the instruments. Conclusion:NeoNiTi instruments were associated with a significantly higher cyclic fatigue resistance than Reciproc instruments.

Comparison of the Cyclic Fatigue Resistance of Reciproc and Reciproc Blue Nickel-Titanium Instruments in Artificial Canals with Single and Double (S-shaped) Curvatures

Objective The aim of this study was to compare the cyclic fatigue resistance of Reciproc (VDW, Munich, Germany) and Reciproc Blue (VDW) in artificial canals with both single and double (s-shaped) curvatures. Methods In total, 80 instruments were tested in this study. Reciproc R40 and Reciproc Blue R40 instruments were selected for the cyclic fatigue resistance test (n=20 in each test). Each instrument was rotated in canals with a single curvature (60° curvature, 5-mm radius) and a double curvature (first coronal curve: 60° curvature and 5-mm radius; second apical curve: 70° and 2-mm radius) until fracture. The time to fracture was calculated, and the length of each fractured fragment was recorded. A one-way analysis of variance (ANOVA) and Tukey's post hoc tests were used to analyse the time to failure. Results All the instruments had significantly higher fatigue resistance in the single simulated curvature canal than in the double curvature canal (P 0.05). Conclusion The Reciproc Blue instruments showed higher cyclic fatigue resistance than the Reciproc instruments in both single and double canal curvatures.

Comparison of the Cyclic Fatigue Resistance of Reciproc and Reciproc Blue Nickel-Titanium Instruments in Artificial Canals with Single and Double (S-shaped) Curvatures.

Objective:The aim of this study was to compare the cyclic fatigue resistance of Reciproc (VDW, Munich, Germany) and Reciproc Blue (VDW) in artificial canals with both single and double (s-shaped) curvatures.Methods:In total, 80 instruments were tested in this study. Reciproc R40 and Reciproc Blue R40 instruments were selected for the cyclic fatigue resistance test (n=20 in each test). Each instrument was rotated in canals with a single curvature (60° curvature, 5-mm radius) and a double curvature (first coronal curve: 60° curvature and 5-mm radius; second apical curve: 70° and 2-mm radius) until fracture. The time to fracture was calculated, and the length of each fractured fragment was recorded. A one-way analysis of variance (ANOVA) and Tukey’s post hoc tests were used to analyse the time to failure.Results:All the instruments had significantly higher fatigue resistance in the single simulated curvature canal than in the double curvature canal (P<0.05). In both curvature groups, the time to fracture of the Reciproc Blue was longer than that of the Reciproc instruments (P<0.05). In the double curvature canal, the instruments tended to fracture more often in the apical curvature than in the coronal curvature. There was no significant difference in the length of the broken fragments between the two groups in either the single or double canal curvatures (P>0.05).Conclusion:The Reciproc Blue instruments showed higher cyclic fatigue resistance than the Reciproc instruments in both single and double canal curvatures.

Dentinal Microcrack Development after Canal Preparation: A Longitudinal in Situ Micro–computed Tomography Study Using a Cadaver Model

IntroductionThe purpose of this study was to evaluate the development of dentinal microcracks after root canal preparation with Reciproc and ProTaper Universal systems using an in situ cadaver model by means of a micro–computed tomography (micro-CT) imaging system. MethodsAt autopsy, 8 maxillary bone blocks having at least the first and second premolar teeth (n = 16) were excised, scanned at a resolution of 13.18 μm, and randomly distributed into 2 groups (n = 8) according to the preparation protocol: Reciproc and ProTaper Universal systems. Root canals were prepared up to R25 and F2 instruments in the Reciproc and ProTaper Universal groups, respectively. After the preparation procedures, the specimens were scanned again, and the registered preoperative and postoperative cross-section images of the roots (n = 19,060) were screened to identify the presence of dentinal defects. ResultsIn the Reciproc group, 9176 cross-section images were analyzed, and no crack was observed. In the ProTaper Universal group, 244 of 9884 cross-section slices (2.46%) had dentinal defects; however, all defects were already present in the corresponding preoperative images, indicating that no new microcrack was created after canal preparation. ConclusionsIn situ root canal preparation of maxillary premolars with Reciproc and ProTaper Universal systems did not induce the formation of dentinal microcracks in a cadaver model as observed by micro–CT.

Cyclic Fatigue Resistance of Reciproc Blue, Reciproc, and WaveOne Gold Reciprocating Instruments

IntroductionThe aim of the present study was to compare the cyclic fatigue resistance of Reciproc Blue R25 (VDW, Munich, Germany) with Reciproc R25 (VDW) and WaveOne Gold Primary (Denstply Maillefer, Ballaigues, Switzerland). MethodsFifteen Reciproc Blue R25, 15 Reciproc R25, and 15 WaveOne Gold Primary instruments were collected and tested in a dynamic cyclic fatigue test device, which has an artificial canal with a 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated until fracture occurred, and time to fracture (TF) and the lengths of the fractured fragments were recorded. The mean and standard deviations of TF and fragment length were calculated for each reciprocating system. TF data were subjected to Kruskal-Wallis 1-way analysis of variance and the Dunn test, whereas fractured fragment length data were subjected to 1-way analysis of variance (P < .05). ResultsReciproc Blue R25 exhibited the highest cyclic fatigue resistance (P < .05). The cyclic fatigue resistance values of WaveOne Gold Primary were significantly higher than those of Reciproc R25 (P < .05). There was no significant difference in the mean length of the fractured fragments among the instruments (P > .05). ConclusionsReciproc Blue R25 instruments had significantly higher cyclic fatigue resistance than WaveOne Gold and Reciproc R25 instruments.

Effectiveness of XP‐endo Finisher and XP‐endo Finisher R in removing root filling remnants: a micro‐CT study

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. 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%. 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). 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.

Mechanical characteristics of counterfeit Reciproc instruments: a call for attention.

To report the main differences seen by direct visual inspection between original and counterfeit Reciproc instruments, together with an evaluation of instrument bending resistance, cyclic fatigue, surface finish, Vickers microhardness and chemical composition. The visual aspects of original Reciproc R25 (VDW, Munich, Germany) and counterfeit Reciproc R25 instruments (claimed to be original, supposedly with dimensions similar to those of Reciproc R25 files, bought at www.mercadolivre.com.br) were evaluated under direct observation, stereomicroscopy and scanning electron microscope. The flexibility of original and counterfeit Reciproc R25 was determined via 45° bending tests according to the ISO 3630-1 specification. Instruments were also subjected to cyclic fatigue resistance, measuring the time to fracture in an artificial stainless steel canal with a 60° angle and 5-mm radius of curvature. The fracture surfaces of all fragments were examined under a scanning electron microscope. Roughness of the instruments was quantified using a profilometer, and the microhardness test was carried out using a Vickers hardness tester. Energy-dispersive X-ray microanalysis (EDX) was also carried out. Results were analysed statistically using the Student's t-test at a significance level of P<0.05. Although the packaging of the original and counterfeit instruments was similar, a number of differences were observed such as ISO colour coding, measurement marks, stopper and morphologic characteristics. Original Reciproc instruments had significantly longer cyclic fatigue life and significantly lower bending resistance than counterfeit Reciproc instruments (P<0.05), as well as significantly lower microhardness and roughness (P<0.05). EDX results revealed differences in the chemical composition of the instruments (P<0.05), indicating that the instruments were manufactured with different raw material. Original Reciproc files outperformed counterfeit instruments in all tests. It is thus important that identification strategies for these counterfeit instruments be developed, thereby preventing their inadvertent use.

Influence of Passive Ultrasonic Irrigation on the Removal of Root Canal Filling Material in Straight Root Canals.

Objective:This study evaluates the efficacy of passive ultrasonic irrigation (PUI) in removing root canal filling material from endodontically treated teeth after using one of two reciprocating systems, Reciproc (VDW, Munich, Germany) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), or one nickel-titanium (NiTi) rotary system, ProTaper Universal Retreatment (Dentsply Maillefer).Methods:One hundred and twenty straight root canals of extracted human maxillary incisors were instrumented and then obturated. The specimens were divided into six groups (n=20) as follows: Group R, Reciproc R25 instrument without PUI; Group W, WaveOne Primary instrument without PUI; Group PT, ProTaper Universal Retreatment system without PUI; Group R-PUI, Reciproc R25 with PUI; Group W-PUI, WaveOne Primary with PUI and Group PT-PUI, ProTaper Universal Retreatment system with PUI. After removing the filling material, the teeth were cleaved longitudinally and photographed. The total canal space and remaining material were quantified with the aid of an imaging software tool. The Kruskal-Wallis test was used to identify significant differences between the groups.Results:No statistically significant differences (P>0.05) in residual filling material were observed between the groups.Conclusion:The use of PUI did not improve the removal of filling material from the root canals, regardless of the previously used instrumentation system.

Effect of solvents on apically extruded debris and irrigant during root canal retreatment using reciprocating instruments.

To evaluate the effect of several solvents on the weight of apically extruded debris and irrigant during retreatment using a novel agar gel model. Orange oil, turpentine oil and chloroform were used as solvents. Eighty single straight-rooted extracted human mandibular premolar teeth with a single root canal were divided into four groups (n=20). All specimens were root canal-filled and weighed prior to their insertion into a prepared 1.5% agar gel model. The mean initial weights were measured by subtracting the weight of the specimen from the weight of the test apparatus and recorded. Following the removal of the coronal 4mm of root filling, the test solvent was applied onto the root filling. No solvent was used in the control group. A Reciproc R25 instrument was used to remove the root filling in all groups. Apically extruded debris and test solvent were collected during retreatment procedures. The mean weights of apically extruded debris and irrigant were calculated by subtracting the mean initial weights from the weights of test apparatus without the Teflon tape and the specimen following the retreatment procedures. Data were statistically analysed using one-way analysis of variance. Use of solvents resulted in significantly less extruded debris and irrigant compared to the control group (P<0.05). Chloroform extruded significantly more debris than orange oil and turpentine oil (P<0.05). Use of solvents during root filling removal was associated with less apically extruded debris and irrigant when compared to no solvent.

Micro-CT assessment of dentinal micro-cracks after root canal filling procedures.

To evaluate the frequency of dentinal micro-cracks after root canal filling procedures with GuttaCore (GC), cold lateral compaction (CLC) and warm vertical compaction (WVC) techniques in mandibular molars using micro-computed tomographic analysis. Thirty mesial roots of mandibular molars, with a type II Vertucci's canal configuration, were prepared to working length with a Reciproc R40 instrument and randomly assigned to one of the three experimental groups (n=10), according to the technique used for root filling: GC, CLC or WVC. The GC group was filled with a size 40 GC obturator, whilst CLC and WVC groups used conventional gutta-percha cones. AH Plus sealer was used in all groups. The specimens were scanned at an isotropic resolution of 14.25μm before and after root canal preparation and after root filling. Then, all pre- and postoperative cross-sectional images of the roots (n=41660) were screened to identify the presence of dentinal defects. Overall, 30.75% (n=12810) of the pre- + post-filling images displayed dentinal defects. In the GC, CLC and WVC groups, dentinal micro-cracks were observed in 18.68% (n=2510), 15.99% (n=2389) and 11.34% (n=1506) of the cross-sectional images, respectively. All micro-cracks identified in the post-filling scans were also observed in the corresponding post-preparation images. Root fillings in all techniques did not induce the development of new dentinal micro-cracks.

Analysis of stress in the walls of simulated artificial root canals during instrumentation with Reciproc system: a pilot study using a photoelastic model

Objective: The aim of this pilot study was to perform in vitro analysis of the stress related to instrumentation of artificial root canals with Reciproc System by using the photoelasticity method. Material and Methods: Photoelastic models consisted of two epoxy resin blocks simulating root canals, which were attached with cyanoacrylate adhesive to a base and placed at the centre of a circular polariscope in a dark-field configuration. The Reciproc R25 instrument was mounted to a VDW motor and used in block 1 up to 12 mm (working length) and then the same instrument was used in block 2. The images were captured by video camera and analysed at the time of the fourth penetration. Isochromatic fringes were observed in the cervical, middle and apical thirds at mesial and distal regions of each block. Therefore, they were divided into cervical-mesial (CM), cervical-distal (CD), middle-mesial (MM), middle-distal (MD), apical-mesial (AM) and apical-distal (AD). Results: In the first instrumentation, it was found that the greatest stress occurred at the middle-distal region (1.38), followed by middle-mesial (1.20), apical-distal (1.20) and apical-mesial regions (1.20). In the second instrumentation, the greatest stress occurred at the middle-mesial (1.20), apical-distal (1.20), apical-mesial (1.20) and middle-distal regions (0.90). Conclusion: The greatest stress occurred in the middle and apical thirds during the first instrumentation. Re-utilization caused less stress. KeywordsDental Stress Analysis; Endodontic; Instrumentation.

Removal of Root Canal Fillings in Curved Canals Using Either Reciprocating Single- or Rotary Multi-instrument Systems and a Supplementary Step with the XP-Endo Finisher

IntroductionThis 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. MethodsForty 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%. ResultsThe 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). ConclusionsThe 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.

Scanning electron microscopy with energy dispersive X-ray spectrophotometry analysis of reciprocating and continuous rotary nickel-titanium instruments following root canal retreatment.

This study aimed to evaluate superficial defects and the composition of Reciproc R25 and ProTaper Retreatment file systems (Dentsply Maillefer, Ballaigues, Switzerland) used for retreatment. A total of 100 maxillary incisor teeth were randomly divided into the following two groups: Reciproc R25 (n = 25) and ProTaper Retreatment instrument (n = 75) groups. The nickel-titanium (Ni-Ti) compositions of the files before and after use were analyzed using energy dispersive X-ray spectrophotometry (EDX). Chi-square, Mann-Whitney U, and Kruskal-Wallis tests were used to analyze the data. ProTaper Retreatment instrument group showed a significantly higher number of defects than the Reciproc group (P < 0.05). No instrument fracture was detected. The presence of debris was observed in both groups before use, although the level was significantly higher in the ProTaper Retreatment group, which consisted of metals (P < 0.05). There was no significant difference between new and used instruments with regard to Ni-Ti composition (P < 0.05). EDX analysis showed that both the Reciproc and ProTaper Retreatment instruments had a Ni-Ti composition that was within the standards specified by the American Society of Testing and Materials. This study confirmed the use of both the Reciproc R25 file and ProTaper Retreatment file system for root canal filling removal in straight root canals as a safe procedure. (J Oral Sci 58, 401-406, 2016).

Negotiability of Second Mesiobuccal Canals in Maxillary Molars Using a Reciprocating System

The aim of this prospective case series report was to assess the frequency in which the Reciproc R25 instrument (VDW, Munich, Germany) is able to scout and reach the full working length (WL) in second mesiobuccal (MB2) canals from maxillary molars. Conventional hand file negotiation was used as the reference technique for comparison. Maxillary molars (270 first molars and 71 second molars) were included in this study. After local anesthesia, the tooth was isolated with a rubber dam, and traditional straight-line access was made. After locating both first mesiobuccal and MB2 canals, patients were randomly assigned to one of the experimental groups (conventional hand filing preparation or R25 Reciproc preparation). All cases in which the hand files (G1) and R25 instrument (G2) were able to reach the fully electronically determined WL were classified as “reaching full WL” (RFWL). All cases in which the hand files (G1) and R25 instrument (G2) were unable to negotiate the full-length canal were classified as “not reaching full WL” (NRFWL). The number of root canals classified as RFWL and NRFWL from both groups were recorded and tabulated on an Excel data sheet (Microsoft, Redmond, WA). The frequency distributions (%) of root canals classified as RFWL and NRFWL were compared with overall-treated canals and for each treatment approach (hand file and R25 instrument) using a Pearson chi-square test. In group 1, the hand file approach reached the full WL in 57.48% of cases, whereas in group 2 the R25 instrument reached the full WL in 85.63% of cases. Three file separations occurred in each group while negotiating the MB2 canal. According to this study, the R25 instrument was 32% more effective when compared with hand files in scouting and negotiating MB2 canals in maxillary first and second molars. There was no difference with regard to file separation when comparing both preparation techniques.