D-RaCe Retreatment Research Articles

In Vitro Cone Beam CT Analysis of the Efficacy of Three Supplementary Steps In the Removal of Obturation Material in Endodontic Retreatment.

To evaluate and compare the efficacy of XP-endo Finisher R (FKG Dentaire, Le Locle, Neuchatel, Switzerland), EDDY (VDW Dental, Munich, Germany), and passive ultrasonic irrigation (PUI) as supplementary steps following the D-RaCe retreatment file system (FKG Dentaire) in the removal of root canal obturation material using cone beam CT. A total of 45 two-rooted permanent maxillary first premolars were selected. Following access preparation, cleaning, and shaping with Hero Shaper (Micro Mega,Besançon, BFC, France)rotary file up to 25/04%, thermoplasticized obturation was performed with TotalFill BC sealer (FKG Dentaire) and gutta-percha. The specimens were subjected to routine retreatment using the D-RaCe retreatment file system. Cone beam computed tomography (CBCT) and volumetric analysis were performed before and after this procedure. The samples were divided into group A (XP-endo Finisher R: n=15), group B (EDDY: n=15), and group C (PUI: n=15). Finally, a third CBCT was taken and a volumetric analysis was done. Statistical analysis was done using SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA). The lowest mean residual volume of obturation material was seen with XP-endo Finisher R (1.6 mm3), followed by PUI (1.7 mm3). The EDDY showed the least efficiency in complete debridement of the root canals (3.6 mm3). This difference in values was statistically significant. The XP-endo Finisher R and PUI showed superior performance than EDDY in the removal of remaining obturation material from the root canal system after retreatment with the D-RaCe retreatment file system. However, none of the systems were able to completely remove the root canal obturation materials.

Retreatability of Bonded and Nonbonded Root Canals Obturation Materials Using D-RaCe Retreatment Files

Retreatability of Bonded and Nonbonded Root Canals Obturation Materials Using D-RaCe Retreatment Files

Efficacy of Endoscope and Periapical Radiography to Detect Residual Root Canal Filling Using Micro-CT as Reference

IntroductionTo evaluate the efficacy of examinations by endoscope of root canals to determine residual root canal filling materials by comparison with microcomputed tomographic (micro-CT) images as reference. MethodsThirty maxillary second premolars with oval canals received root canal treatment. Then D-Race retreatment files were used to remove the root canal fillings supplemented by XP-endo Finisher. Samples were scanned to reconstruct micro-CT reference images. Images were obtained of all samples from the mesiodistal and buccolingual directions by digital radiography. Then the root canals of specimens mounted in manikins were assessed by endoscope. The radiographic and endoscopic results were scored following comparison with the micro-CT images, which served as a reference, by 2 blinded observers. The interexaminer reliability of the assessments was evaluated by kappa test and the accuracy of endoscopic visualization according to the presence of residual root canal filling materials was compared using Kruskal–Wallis H test and Spearman’s rank order correlation with the level of significance set at 5%. ResultsThe efficiency of the periapical radiography and endoscopy to determine residual root canal filling material was similar in every third of the root canal (P > .05). ConclusionsThe endoscope detected residual root canal filling material as efficiently as periapical radiography.

Comparison of the Time Required by Six Different Retreatment Techniques for Retrieval of Gutta-Percha: An In Vitro Study

Abstract Objective A retreatment is a conservative approach than periapical surgery in case of failed root canal treatment. Retreatment techniques that are efficient and faster should be the main concern to treat endodontic failure. This study aimed to compare the time required by various hand and rotary retreatment systems for the retrieval of gutta-percha (GP) from root canals. Materials and Methods A total of 120 extracted single-rooted premolar teeth with straight canals were chosen. Biomechanical preparation was completed using the Step-Back approach keeping the master apical file size 35. Then, teeth were down-packed and back-filled with System B device, along with AH Plus sealer. The teeth were categorized into six groups (n = 20) at random as per techniques applied for retrieval of GP: group I hand instrumentation (Hedstrom files and Gates-Glidden drills); group II ProTaper Universal Retreatment (PTUR) system; group III Mtwo Retreatment (Mtwo R) system; group IV D-RaCe; group V R-Endo; and group VI Mani Gutta Percha Remover (NRT-GPR). A chronometer was used to measure the time required for retrieval of GP. Data were examined by comparative evaluation of one-way analysis of variance and chi-square test. Results Among all the retreatment techniques used, D-RaCe was faster in GP retrieval than other groups. NRT-GPR system also took less time than other groups except for the D-RaCe system. The Mtwo R system was the slowest among all groups. Conclusion D-RaCe retreatment instruments required extensively less time for retrieval of GP than other groups (p < 0.001).

Apical Extrusion Potential of Two Nickel-Titanium Retreatment Systems

The aim of the study was to quantify the amount of apically extruded debris during root canal filling removal with D-Race and Mtwo retreatment systems. Twenty-four extracted single-rooted mandibular incisors with straight oval-shaped root canals were instrumented with XP-Endo Shaper files and filled with gutta-percha and AH Plus sealer using vertical compaction technique. All filled samples were temporarily sealed with Citodur Hard and stored in distilled water for 30 days. The specimens were randomly divided into two groups, according to the nickel-titanium system used for root canal filling removal (n=12). The retreatment procedure was performed with Mtwo Retreatment and D-Race Retreatment. The extruded debris during retreatment procedures, was collected in preweighted Eppendorf tubes. The actual weight of extruded debris was calculated by subtracting the initial weight from the final weight of the Eppendorf tubes. Statistical analysis was performed using IBM SPSS Statistics 23.0 software. The level of significance was set at P<0.05. The investigation results did not find statistically significant differences between the experimental groups. It could be concluded that retreatment with both Mtwo and D-Race cause apical extrusion of debris material with no statistically significant difference between the amounts produced by the two tested systems.

Endodontic Retreatment with D-Race NiTi Instruments Supplemented with XP-Endo Finisher R

The main goal of orthograde root canal retreatment is to completely remove the root canal content and chemically treat the residual infection. Purpose: The aim of this study was to evaluate the effectiveness of D-Race retreatment files supplemented with XP-Endo Finisher R in the removal of root canal filling material from oval-shaped canals. Methodology: Twelve mandibular incisors initially shaped with XP-Endo Shaper and filled by warm vertical compaction were consistently retreated with D-Race files and XP-Endo Finisher R. Micro-CT images were used to evaluate the quality of the root canal filling and the amount of remaining filling material after the two retreatment procedures. Results: The largest amount of root canal filling was removed at full canal length after using each of the retreatment systems. Significant difference was registered between the accumulated effect of the retreatment with D-Race and XP-Endo Finisher R and the volume of the initial filling material at full canal length (p<0.001). Insignificant difference in the amount of remaining filling material was found after using the supplementary retreatment system (p>0.05). The XP-Endo Finisher R file was almost equally efficient in the different portions of the canals but was still most productive apically. Conclusions: The additional application of XP-Endo Finisher R after the D-race retreatment files removed a significant amount of root canal filling. The combined use of the two retreatment systems did not result in completely clean root dentin walls.

An in vitro comparative evaluation of retreatability of a bioceramic and resin sealer using cone-beam computed tomography analysis

Aims: The aim is to evaluate the retreatability of BioRoot RCS (BCS)/Gutta-percha (GP) as compared to AH Plus/GP with and without a solvent using cone-beam computed tomography (CBCT).Materials and Methods: Mesio-buccal canals in 48 first mandibular molars were instrumented using iRace rotary files up to size 25.4% and obturated with GP using one of the following sealers, BCS and AH Plus. Post obturation, the teeth were scanned using a CBCT. All samples were divided into four groups (n = 12). Group 1: GP/BCS was removed using D-Race retreatment files and xylene as a solvent; Group 2: GP/BCS was removed using D-Race retreatment files without xylene; Group 3: GP/AH Plus was removed using D-Race retreatment files with xylene; Group 4: GP/AH Plus was removed using D-Race retreatment files without xylene. Time taken to reach the working length (WL) was recorded. Samples were again scanned using CBCT and the remaining filling material was calculated in the coronal, middle, and apical thirds. Data were tabulated and analyzed via Kruskal–Wallis and Mann–Whitney Post hoc test (P < 0.05).Results: Group 3 exhibited significantly less time to reach WL as compared to Group 1. There was no significant difference between Group 2 and Group 4. In all groups, the apical third had the most remaining filling material (Group 1 – 13.75 ± 4.83, Group 2 – 18.33 ± 3.26, Group 3 – 10.42 ± 3.34, Group 4 – 15.42 ± 3.34). WL and patency were re-established in all the samples.Conclusions: Irrespective of the retreatment technique employed complete removal of both the sealers could not be achieved. However, retreatability of AH Plus with xylene was superior to that of BioRoot RCS.

POSTOPERATIVE PAIN AFTER ENDODONTIC RETREATMENT USING DIFFERENT RETREATMENT SYSTEMS: A RANDOMIZED CLINICAL TRIAL

Aim: This study aimed to compare the effect of various nickel-titanium rotary retreatment systems on intenstiy of postoperative pain after non-surgical endodontic retreatment. Materials and methods: One hundred and eighty patients requiring endodontic retreatment were included in the study. The patients were randomly assigned into three groups of 60 patients, according to the method used to remove old canal filling material. In group 1, canal filling material was removed using ProTaper Universal retreatment (PTUR) instruments. In group 2, the canal filling material was removed with D-Race retreatment instruments. In group 3, Mtwo instruments were used to remove canal filling material. Teeth were then medicated with calcium hydroxide and sealed using temporary filling material. The presence of postoperative pain was assessed after 6, 12, 24, 36 and 72 h, 7 days. Results: Among the three groups, the highest postoperative pain scores were recorded 6 hours after the procedure; the postoperative pain scores decreased over time in all time intervals. In 6 hours, Mtwo group exhibited higher pain score than those of D-RaCe group (P < .05), but there was no difference in the pain scores between D-RaCe and PTUR group; Mtwo and PTUR (P >.05). Conclusions: Retreatment files tested in this study caused similar postoperative pain levels after non-surgical endodontic retreatment, except at 6 hours. Keywords: Endodontics; postoperative pain; retreatment ÖZ Amaç: Bu çalışmada, çeşitli nikel-titanyum döner tedavi sistemlerinin cerrahi olmayan endodontik tedavi sonrası postoperatif ağrının yoğunluğu üzerindeki etkisi karşılaştırıldı. Materyal ve metod: Endodontik tedavi gerektiren 180 hasta çalışmaya dahil edildi. Eski kanal dolgu materyalini çıkarmak için kullanılan yönteme göre hastalar rastgele 60 hastadan oluşan üç gruba ayrıldı. Grup 1'de, kanal dolgu dolgu materyali ProTaper Universal retreatment (PTUR) eğeleri kullanılarak uzaklaştırıldı. Grup 2'de, kanal dolgu materyali D-Race retreatment eğeleri ile uzaklaştırıldı. Grup 3'te, kanal dolgusunu uzaklaştırmak için Mtwo retreatment eğeleri kullanıldı. Daha sonra dişlere kalsiyum hidroksit uygulandı ve geçici dolgu materyali kullanılarak kapatıldı. Postoperatif ağrı varlığı 6, 12, 24, 36 ve 72 saat 7 gün sonra değerlendirildi. Bulgular: Üç grup arasında en yüksek postoperatif ağrı skorları işlemden 6 saat sonra kaydedildi; postoperatif ağrı skorları tüm zaman aralıklarında zamanla azaldı. 6 saat içinde Mtwo grubu D-RaCe grubuna göre daha yüksek ağrı skoru gösterdi (P <.05), ancak D-RaCe ve PTUR grubu arasında ve Mtwo ve PTUR arasında ağrı skorlarında fark yoktu (P> .05). Sonuç: Bu çalışmada test edilen retreatment sistemleri, cerrahi olmayan endodontik retreatment sonrasında 6 saat dışında benzer postoperatif ağrı düzeylerine neden olmuştur. Anahtar Kelimeler: Endodonti; kök kanal yenileme; postoperatif ağrı

Efficacy of reciprocating and rotary retreatment nickel-titanium file systems for removing filling materials with a complementary cleaning method in oval canals.

ObjectivesThis study aimed to evaluate and compare the efficacy of the S1 reciprocating system and the D-Race retreatment rotary system for filling material removal and the apical extrusion of debris.Materials and MethodsSixty-four freshly extracted maxillary canines were shaped with size 10 and size 15 K-files, instrumented using ProTaper Gold under irrigation with 2.5% sodium hypochlorite (NaOCl), obturated according to the principle of thermo-mechanical condensation with gutta-percha and zinc oxide eugenol sealer, and allowed to set for 3 weeks at 37°C. Subsequently, the teeth were divided into a control group (n = 4), the D-Race rotary instrument group (n = 30), and the S1 reciprocating instrument group (n = 30). After classical retreatment, the canals were subjected to a complementary approach with the XP-Endo Shaper. Desocclusol was used as a solvent, and irrigation with 2.5% NaOCl was performed. Each group was divided into subgroups according to the timing of radiographic readings. The images were imported into a software program to measure the remaining filling material, the apical extrusion, and the root canal space. The data were statistically analyzed using the Z-test and JASP graphics software.ResultsNo significant differences were found between the D-Race and S1 groups for primary retreatment; however, using a complementary cleaning method increased the removal of remnant filling (p < 0.05).ConclusionsClassical removal of canal filling material may not be sufficient for root canal disinfection, although a complementary finishing approach improved the results. Nevertheless, all systems left some debris and caused apical extrusion.

Evaluation of apically extruded debris during the removal of canal filling material using three different Ni-Ti systems and hand files in teeth with simulated apical root resorption.

To compare the weight of apically extruded debris produced during the removal of root canal filling material using various files in extracted teeth with simulated apical root resorption. The root canals of one hundred and twenty extracted mandibular premolar teeth were prepared with Revo-S files and filled using a cold lateral compaction technique with gutta-percha and a resin-based sealer (AdSeal; Meta-Biomed, Cheongwon, Korea). Sixty teeth were randomly assigned to four control groups (hand file, ProTaper Universal retreatment file, D-RaCe retreatment file, and Reciproc file) for the removal of root canal filling material. The apical portion of the remaining 60 teeth was modified to simulate apical root resoption, and the teeth were then randomly divided into 4 experimental groups (using thesame techniques as in thecontrol groups) for the removal of root canal filling material. Apically extruded debris was collected into pre-weighed Eppendorf tubes and then dried. The mean weight of the apically extruded debris was assessed with an analytical balance to an accuracy of 10-4 g. Data were analysed using two-way analysis of variance and a Tukey's post hoc test. In the simulated apical root resorption groups, all file systems were associated with significantly more debris extrusion compared to the groups without simulatedresorption (P<0.05). The amount of apically extruded debris was greatest in the hand file groups compared with the other groups (P<0.05). In the groups with simulated apical root resorption, theReciproc systemwas associated with the least weightofapically extruded debris (P<0.05), whereas there was no significant difference between the ProTaper Universal retreatment and D-RaCe files (P>0.05). In the groups without simulated apical root resorption, there was no significant difference between Reciproc, ProTaper Universal retreatment and D-RaCe retreatment files (P>0.05). The time required to remove the root canal filling material was as follows: hand file>ProTaper Universal retreatment=D-RaCe retreatment>Reciproc (P<0.05). The weight of apically extruded debris was significantlygreater in teeth with simulated apical root resorption than in those teeth without simulated apical root resorption. Hand files were associated with significantlymore apically extruded debris in all groups during removal of root canal filling material.

Evaluation of remaining dentin thickness following use of three different rotary nickel-titanium retreatment files: A cone-beam computed tomography study.

Aim:The aim of the study is to measure the amount of remaining dentin thickness (RDT) following retreatment using three different rotary nickel–titanium (NiTi) systems.Methodology:Mesiobuccal roots of 45 extracted maxillary first molars were prepared up to F2 ProTaper File and obturated. After cone-beam computed tomography (CBCT) imaging, to evaluate the obturation, the samples were randomly assigned to three retreatment groups (n = 15). Group I was retreated with ProTaper Universal retreatment kit, Group II and III with MTWO and D-Race retreatment files, respectively. Postoperatively, all samples were subjected to CBCT imaging and evaluated with AutoCAD software (AutoDesk, Inc.) Mill Valley, California, U.S. to calculate the RDT. Data were statistically analyzed using one-way ANOVA and Tukey's post hoc tests, and the level of significance was set at P = 0.05.Results:The amount of RDT was significantly more in D-Race and MTWO groups when compared to ProTaper group.Conclusion:D-Race and MTWO instruments were associated with significantly more RDT than ProTaper.

Apically extruded debris in filling removal of curved canals using 3 NiTi systems and hand files.

The aim of this study was to assess the amount of apically extruded debris during filling removal with WaveOne Gold (WOG), ProTaper Universal Retreatment (PTR), D-RaCe Retreatment (DRR) or hand files (HF), to compare the working time during filling removal, and to describe failures of NiTi instruments. Forty mesiobuccal roots of maxillary first molars were prepared with WOG Primary, obturated and divided into 4 groups (n=10), according to the instruments used: WOG, PTR, DRR or HF. Distilled water was used as irrigant and the extruded debris were collected in Eppendorf tubes and dried. The amount of extruded debris was determined by subtracting the final from the initial weight. The time of filling removal for each canal was recorded and the instruments used were analyzed pre and post-operatively by SEM. Kruskal-Wallis and Dunn's test analyzed extruded debris data and ANOVA, followed by Tukey's test, compared the working time data (a=0.05). Instrument deformation and fracture were described. WOG produced significantly less debris compared with HF and DRR (p<0.05), and similar to PTR (p>0.05). HF, PTR and DRR showed no significant difference (p>0.05). Working time in HF group was significantly higher than others (p<0.05). SEM analyses showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. All instruments tested caused debris extrusion. WOG was associated with less extrusion than DRR and HF. Filling removal with HF was slower than with the other instruments. All NiTi systems presented fracture and deformation.

Effect of retreatment instruments on microcrack formation: a microcomputed tomography study.

The purpose of this study was to compare the occurrence of microcracks in teeth prepared with different retreatment systems using microcomputed tomography (micro-CT). Forty-two freshly extracted mandibular premolar teeth were used. The root canals were instrumented with stainless steel K-files to an apical size of 35/.02 using the balanced-force technique and were obturated using the passive compaction technique. The specimens were divided into 3 experimental groups according to retreatment system used (n = 14): ProTaper Universal retreatment (PTUR), Mtwo retreatment (MTR), or D-RaCe retreatment (D-RC) systems. Each specimen was scanned using a high-resolution micro-CT system before instrumentation, after obturation, and after the removal of the filling material. The images were evaluated, and the presence of microcracks was recorded. The PTUR system demonstrated the highest percentage, while MTR and D-RC retreatment systems resulted in similar numbers of microcracks. Clinicians should be aware that all retreatment systems may cause microcracks.

Evaluation of Apically Extruded Debris from Curved Root Canal Filling Removal Using 5 Nickel-Titanium Systems

IntroductionThis 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. MethodsOne 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. ResultsReciproc 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. ConclusionsIn 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.

Impact of different file systems on the amount of apically extruded debris during endodontic retreatment.

Objective:The goal of present study was to determine the effect of different nickel–titanium file systems on the amount of apically extruded debris during endodontic retreatment: D-RaCe retreatment systems, EdgeFile XR retreatment rotary files, and Reciproc R40.Materials and Methods:Thirty-six single-rooted prepared mandibular premolar teeth were filled with Gutta-percha and AH Plus sealer. The teeth were then randomly assigned into three groups (n = 12) for retreatment. The endodontic retreatment was performed as follows: D-RaCe, EdgeFile XR, Reciproc 40. Debris extruded apically during the retreatment was collected into preweighed Eppendorf tubes. An incubator was used to store tubes at 70° C for 5 days. The initial weight was subtracted from final weight of the Eppendorf tubes to calculate the weight of the dry extruded debris for each group. The data obtained were evaluated using Welch analysis of variance and Games-Howell post-hoc tests (P < 0.05).Results:All files resulted in apical extrusion of debris. Reciproc caused significantly less debris extrusion compared to D-RaCe and EdgeFile XR (P < 0.05).Conclusions:The findings revealed that during endodontic retreatment, number, and taper of files might have an influence on the amount of apically extruded debris during endodontic retreatment.

Cyclic fatigue resistance of D-RaCe, ProTaper, and Mtwo nickel-titanium retreatment instruments after immersion in sodium hypochlorite.

The aim of this study was to investigate the effect of immersion in sodium hypochlorite (NaOCl) on cyclic fatigue resistance of three different rotary nickel-titanium (NiTi) retreatment files. A total of 90 new ProTaper, D-RaCe, and Mtwo retreatment files were tested. Thirty files of the same brand were randomly assigned to two groups (n = 15). Group 1 was no immersion (control group) and 16mm of group 2 instruments were immersed in 5% NaOCl at 37°C for 5min. All instruments were then tested for cyclic fatigue. Resistance to cyclic fatigue was determined by counting the numbers of cycles to failure in a 60° curve with a 5-mm radius, recording the time in seconds to fracture. Data were analyzed by two-way analysis of variance. Resistance to cyclic fatigue decreased significantly for D-RaCe retreatment files after immersion in NaOCl. ProTaper and Mtwo retreatment files were not affected from immersion to NaOCl. D-RaCe retreatment instruments showed better cyclic fatigue resistance than ProTaper and Mtwo retreatment instruments, and the difference was statistically significant (p < 0.05). There was no significant difference between ProTaper and Mtwo retreatment instrument groups (p > 0.05). D-RaCe retreatment instruments had the highest cyclic fatigue resistance among retreatment files tested in this study, but immersion to NaOCl decreased the cyclic fatigue resistance of D-RaCe retreatment instrument. It should be considered that cyclic fatigue resistance of D-RaCe can decrease in contact with NaOCl during the removal of canal filling material.

Comparative Evaluation of the Efficiency of Manual and Rotary Gutta-percha Removal Techniques

IntroductionThis study aimed to evaluate the efficiency of 2 manual and 2 rotary gutta-percha (GP) removal techniques in terms of both the total operating time and GP remnants left in the canal. MethodsGP was removed with manual techniques using H-files and xylene (H + X) and H-files and System B (H + SB) (SybronEndo, Orange, CA) and with rotary techniques using the ProTaper Univeral Retreatment (PTUR) (Dentsply Maillefer, Ballaigues, Switzerland) and D-RaCe Retreatment (D-RR) (FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems. The total operating time was evaluated as the time taken to reach the working length and completely remove GP until no radiopaque remnants were observed in the final radiograph. Any GP remnants left in the canal were evaluated in terms of percentage in the whole canal. ResultsRotary techniques were significantly faster and left lesser GP remnants than manual techniques (P < .05). In rotary techniques, the D-RR system was significantly faster than the PTUR system (P < .05), but there was no significant difference between them regarding GP remnants (P > .05). In manual techniques, H + X was significantly faster and left lesser GP remnants than H + SB (P < .05). ConclusionsRotary techniques were more efficient than manual techniques in GP removal. Overall, the D-RaCe Retreatment system was most efficient, whereas manual use of H-files with System B was least efficient. However, because all the techniques showed GP remnants in the canal and radiographs failed to show these remnants, additional measures would be required to ensure complete GP removal and check for cleaner canals during endodontic retreatment.

Comparing the Efficacy of Mtwo and D-RaCe Retreatment Systems in Removing Residual Gutta-Percha and Sealer in the Root Canal.

Retreatment is performed in teeth with unsuccessful root canal therapy or persistent apical lesion. The most important factor for achieving successful retreatment is thorough cleaning and reshaping. NiTi files and rotary instruments are widely used for the removal of obturatants. This study compared the ability of Mtwo and D-RaCe retreatment systems to remove residual gutta-percha and sealer within the root canal after retreatment. This in vitro experiment was performed on sixty extracted human teeth. The samples were cut at the CEJ level, manually prepared, filled with gutta-percha and AH26 and finally stored at 37ºC for two weeks. Samples were then randomly divided into two groups. Group 1 was retreated with Mtwo and Group 2 with D-RaCe. Both groups were then divided into two subgroups retreated either with or without solvent. Teeth were then vertically sectioned for evaluation of residual filling materials on the canal walls. A microscopic assessment at 16× magnification was performed. T-test statistical analysis was used to compare the data. Comparison between the Mtwo and D-RaCe rotary systems revealed no significant differences in residual gutta-percha or sealer on canal walls (P=0.2). The study revealed a negative effect of solvent on removal of gutta-percha and sealer in both the Mtwo and D-RaCe systems. Mtwo and D-RaCe retreatment files removed residual gutta-percha and sealer similarly; there was no significant difference between them.