ProTaper Retreatment Research Articles

An in vitro CT Comparison of Gutta-Percha Removal with Two Rotary Systems and Hedstrom Files.

To evaluate the efficacy of NiTi mechanical rotary instrumentation and Hedstrom file for gutta-percha/sealer removal computed tomography (CT) was utilized in vitro. Thirty extracted human single rooted teeth, each with a single canal were selected. The samples were decoronated with a double faced diamond disk to have 17-mm root; teeth roots were instrumented with K-files up to master apical file #30 using step back technique. Samples were obturated using cold lateral condensation of gutta-percha and AH Plus root canal sealer. The teeth were then randomly divided into three groups of 10 specimens each. After 2 weeks 3-dimensional images of the roots were obtained by CT and the volume of root filling mass was measured. All the canals were then retreated by either the ProTaper retreatment files, Mtwo retreatment files or Hedstrom files. The canals were irrigated with 2 mL of 2.5% sodium hypochlorite irrigating solution during each change of instrument. The volume of remaining filling materials after the retreatment procedures was assessed by CT. Statistical analysis was performed with one-way ANOVA and Tukey's post hoc test. Neither of studied systems completely removed the root filling material. No significant difference was observed between the rotary systems. The volume of remaining filling materials was significantly less in rotary instrumentation than hand files. There was no significant difference for debris extruded from the apical foramen between the groups. Under the experimental conditions, Mtwo and ProTaper retreatment files left less gutta-percha and sealer than H files; however, complete removal of filling materials was not achieved by the three systems investigated.

Comparative Analysis of Efficacy and Cleaning Ability of Hand and Rotary Devices for Gutta-Percha Removal in Root Canal Retreatment: An in vitro Study

To evaluate the efficacy and cleaning ability of Hedstrom files, and ProTaper retreatment instruments in removing gutta-percha from root canals with and without xylene as solvent. Sixty extracted single rooted human teeth were selected and decoronated, straight access established working length determined 1 mm short of canal, chemomechanical preparation done and obturated with guttapercha and AH plus sealer. Samples were stored for 1 week in humidifier divided into four groups of 15 teeth each. • Group I: Hedstrom files without xylene. • Group II: Hedstrom files with xylene. • Group III: ProTaper retreatment instruments without xylene. • Group IV: ProTaper retreatment instruments with xylene. and the following criteria were assessed - Time taken for initial plunge of instrument into guttapercha. - Time taken for complete removal of gutta-percha to reach working length - Ability of H files and ProTaper retreatment files with/ without xylene to remove gutta-percha in coronal, middle and apical 1/3 of canal. The teeth were grooved in labiolingual cross section, observed under a steromicroscope and scored according to gutta-percha debris left in the canal. Results were evaluated using ANOVA test and multiple comparisons done using Scheffe test. The least time to reach working length was found with group IV followed by groups III, II and group I respectively. Also the fastest way to remove maximum gutta-percha was group IV followed by groups III, II, and I respectively with a statistically significant difference among all groups. Apical 1/3 has more amount of remaining gutta-percha debris than middle and coronal 1/3 in all groups. The amount of gutta-percha debris in apical 1/3 was least in group IV followed by groups III, II and I respectively. The better performance of ProTaper rotary instruments has been attributed to their special flute design which tends to pull gutta-percha coronally directing it toward orifice. Also the movements of engine driven instruments produce frictional heat which plasticises gutta-percha and aids in easy removal. Apical third of root canals showed more guttapercha debris compared to coronal and middle 1/3 and has been attributed to the greater anatomic variability and difficulty of instrumentation in the apical area. The existence of deep groves and depressions on dentine walls in this apical 1/3 make them less instrumented areas as it did be difficult to direct the file against the extreme root canal wall. The fastest technique to remove gutta-percha and the shortest time to reach working length was observed with ProTaper retreatment instruments with xylene followed by ProTaper retreatment files without xylene and Hedstrom files without xylene. After instrumentation for removal of gutta-percha, apical third was found to have more debris compared to coronal and middle 1/3 of the root canal.

Effectiveness of ProTaper Retreatment System associated with Organic Solvents in the Removal of Root Canal Filling Material

ABSTRACT Aim To evaluate the effectiveness of ProTaper universal retreatment system in the removal of root canal filling material with thermomechanical compaction, in comparison to manualmechanical technique, associated with orange oil or eucalyptol. Materials and methods Forty extracted lower incisors were filled with thermomechanical compaction technique. After 3 years, the root canal filling was removed by: G1 - manualmechanical technique with orange oil; G2 - manual-mechanical technique with eucalyptol; G3 - ProTaper universal retreatment system with orange oil and G4 - ProTaper universal retreatment system with eucalyptol. In sequence, all root canals were instrumented to F5 instrument. The teeth were longitudinally grooved, images of buccal half were obtained in stereomicroscope and covered area by root canal filling material was measured using image tool software, in cervical, middle and apical radicular thirds. The results were subjected ANOVA and Tukey test (p = 0.05). Results In all thirds, the manual-mechanical technique showed lower presence of root canal filling material on root canal dentin in comparison to ProTaper retreatment universal system, regardless of organic solvent used (p < 0.05). There is no difference between organic solvents in removal root canal filling material (p > 0.05). Conclusion The ProTaper universal retreatment system showed lower effectiveness in removal root canal filling material than manual-mechanical technique, regardless of organic solvents (orange oil or eucalyptol oil) used. Clinical significance Recently rotary instruments have been proposed to removal of root canal filling material. However, there are no studies evaluating its effectiveness in removal root canal filling material in association with orange oil or eucalyptol oil. How to cite this article Guiotti FA, Kuga MC, de Toledo Leonardo R, Chávez-Andrade GM, Magro MG, Cavenago BC, Faria G. Effectiveness of ProTaper Retreatment System associated with Organic Solvents in the Removal of Root Canal Filling Material. World J Dent 2013;4(3):175-179.

Comparison of ProTaper and Mtwo Retreatment Systems for Working Time in the Removal of Resin-based Root Canal Obturation Materials During Retreatment

Objective: The aim of this study is to evaluate the working time of ProTaper and Mtwo retreatment systems for removal of three different resin-based filling materials during simulated retreatment. Methods: 160 extracted maxillary anterior teeth were enlarged using two different rotary systems; ProTaper and Mtwo. The teeth were randomly divided into 8 groups of 20 specimens each. Six groups were filled with 3 different resin-based obturation materials, two groups were filled with an eugenol-based paste as control groups. In groups instrumented by ProTaper files, ProTaper Retreatment files, in groups instrumented by Mtwo files, Mtwo retreatment files were used for removal of root canal fillings. Time for reaching the working length (T1), time for re-preparation (T2) and total time for retreatment (Tt) were measured with a chronometer. Results: Retreatment working time was evaluated for the systems used for preparation of the root canals. There was statistically significant differences between the ProTaper and Mtwo groups. T1, T2 and Tt were significantly higer in Mtwo groups when compared to ProTaper groups. There was statistically significant differences between the groups according to the obturation techniques. Teeth obturated with gutta-percha and AH Plus have shorter working time when compared to all the other obturation techniques. Conclusions: T1,T2 and Tt of the teeth instrumentated with Mtwo were higher than the teeth instrumentated with ProTaper irrespective of the root filling material used. According to the results of our research, ProTaper Retreatment files were faster in removing root filling material from the root canal than Mtwo Retreatment files. Key words: ProTaper, Mtwo, resilon, epiphany, retreatment time

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure.

Comparison of ProTaper and Mtwo retreatment systems in the removal of resin‐based root canal obturation materials during retreatment

AbstractTo evaluate the effectiveness of the ProTaper and Mtwo retreatment systems for removal of resin‐based obturation techniques during retreatment. A total of 160 maxillary anterior teeth were enlarged to size 30 using ProTaper and Mtwo rotary instruments. Teeth were randomly divided into eight groups. Resilon + Epiphany, gutta‐percha + Epiphany, gutta‐percha + AH Plus and gutta‐percha + Kerr Pulp Canal Sealer (PCS) combinations were used for obturation. ProTaper and Mtwo retreatment files were used for removal of root canal treatments. After clearing the roots, the teeth were split vertically into halves, and the cleanliness of the canal walls was determined by scanning electron microscopy. Specimens obturated with gutta‐percha and Kerr PCS displayed significantly more remnant obturation material than did specimens filled with resin‐based obturation materials. Teeth prepared with Mtwo instruments contained significantly more remnant filling material than did teeth prepared with ProTaper. ProTaper files were significantly faster than Mtwo instruments in terms of the mean time of retreatment and time required to reach working length. The Resilon + Epiphany and AH Plus + gutta‐percha obturation materials were removed more easily than were the Epiphany + gutta‐percha and Kerr PCS + gutta‐percha obturation materials. Although ProTaper retreatment files worked faster than did Mtwo retreatment files in terms of removing root canal obturation materials, both retreatment systems are effective, reliable and fast.

Time Required to Remove GuttaCore, Thermafil Plus, and Thermoplasticized Gutta-percha from Moderately Curved Root Canals with ProTaper Files

IntroductionA novel carrier-based obturation system, GuttaCore, was developed to facilitate more efficient nonsurgical retreatments. This ex vivo study evaluated the time required for re-treating GuttaCore and 2 other common obturation materials in moderately curved canals with ProTaper retreatment and ProTaper files. MethodsSixty mesial roots of mandibular molars with the same mean curvature were randomly divided into 3 experimental groups: warm vertical, Thermafil Plus, and GuttaCore. Ten teeth served as positive and negative controls. The mesiobuccal canal in each sample was prepared to ISO size 30 with 0.04 taper. The warm vertical group was obturated by using a continuous-wave technique of gutta-percha compaction, and the Thermafil Plus and GuttaCore groups were obturated according to manufacturers' instructions. After allowing sealer to set, each specimen was sequentially treated with ProTaper Retreatment files D1, D2, and D3 and ProTaper Universal file F3 to the predetermined working length. The time taken to reach working length (T1) and the time required for obturation material removal (T2) were recorded. ResultsOne-way analysis of variance followed by post hoc Tukey-Kramer test indicated that the mean total time to remove filling material for the GuttaCore group was significantly shorter than those observed in the other groups (P < .05). No significant difference was observed between warm vertical and Thermafil Plus groups. ConclusionsGuttaCore is removed in less time from moderately curved canals with ProTaper files than either thermoplasticized gutta-percha or Thermafil Plus materials.

Efficacy of Two Rotary NiTi Instruments in Removal of Resilon/Epiphany Obturants.

The success of endodontic retreatment is related to the complete removal of the obturation material from the root canal system. The aim of this study was to evaluate the efficacy of Mtwo R and ProTaper retreatment files in removing the Resilon/Epiphany system with or without chloroform during retreatment. Sixty distal roots of first mandibular molars were prepared and laterally condensed with Resilon/Epiphany, then divided into four groups (15 each for retreatment): 1) Mtwo R/solvent; 2) Mtwo R; 3) ProTaper D/solvent; and 4) ProTaper D. The cleanliness of the canal walls was evaluated using radiography; a stereomicroscope and SEM. Data were subjected to ANOVA and Student's t-test. Neither rotary system performed better than the other when considering the whole root canal, with or without solvent. In the apical portion, ProTaper/solvent showed the best result (P<0.05). In Resilon/Epiphany retreatment cases, ProTaper/solvent was better in the apical portion; however when considering the whole canal, Mtwo R and the ProTaper D series had the same performance.

Evaluation of Manual and Two-Rotary Niti Retreatment Systems in Removing Gutta-Percha Obturated with Two Root Canal Sealers

Objective. The objective of this study was to evaluate the efficacy of two retreatment NiTi systems (protaper universal retreatment files, R-Endo), when compared to manual technique in removing Gutta-percha obturated with two sealers. Study Design. Sixty extracted single-rooted premolars were instrumented with Protaper rotary files till F3. The specimens were divided into six groups. Groups 1, 2, 3 were obturated with Gutta-percha and zinc oxide eugenol and Groups 4, 5, 6 were obturated with Gutta-percha and AH-plus. The retreatment was carried out in groups 1 and 4 with H-files and GGdrills, groups 2 and 5 with R-endo retreatment files and groups 3 and 6 with Protaper retreatment files. The roots were sectioned and evaluated under optical stereomicroscope. Statistical analysis was performed with one-way ANOVA and Newman-Keul's test at P < 0.05. Results. The manual technique resulted in cleaner canal walls when compared with both rotary retreatment systems. Conclusion. NiTi rotary retreatment files can be used to remove the filling material quickly, but it should be followed by hand instruments to obtain better canal wall cleanliness.

Self-Adjusting Files in Retreatment: A High-resolution Micro–Computed Tomography Study

IntroductionRotary instruments that are used for retreatment are very effective, but most of them leave root filling residue in the canal. The aim of this study was to evaluate the efficacy of removing gutta-percha–based root fillings with ProTaper retreatment files (Dentsply Maillefer, Ballaigues, Switzerland) followed by F1 and F2 ProTaper instruments and to compare these results with those obtained with a #25 .06 ProFile instrument (Dentsply Maillefer) followed by the Self- Adjusting File (SAF; ReDent, Ra’anana, Israel) using high resolution micro–computed tomography (CT) scanning. MethodsTwenty-eight mandibular molar teeth with oval distal root canals were divided into 2 equal groups of 14 teeth each. The distal root canals were instrumented with ProTaper files up to an F2 instrument, the roots were subsequently filled, and the root filling was allowed to set fully. Removal of the root canal filling was performed with D1-D3 ProTaper retreatment files followed by F1 and F2 ProTaper instruments or with a #25 .06 ProFile followed by SAFs. Chloroform was used in both groups to assist in the removal of the root filling material. High-resolution micro-CT scans were used to measure the residual quantities of the root filling material after completion of the procedures. Statistical analysis was performed using the Wilcoxon test and the Student t test. ResultsThe median root filling residue in the ProTaper group was 5.39% (interquartile range [IQR] = 4.71) of the original volume of the root canal filling. In the ProFile and SAF group, the median residue was 0.41% (IQR = 1.64, P < .001). An arbitrarily selected threshold of less than 0.5% residue was defined as “effectively cleaned,” and 57% of the teeth treated with the ProFile and the SAF met this threshold, whereas none of the cases in the ProTaper group did. The ProFile and SAF procedure required less time than the ProTaper protocol. ConclusionsNone of the retreatment methods rendered all of the canals completely free of all root filling residue. Under the conditions of this study, the ProFile and SAF procedure was more effective than the ProTaper procedure and left significantly less root filling residue in the root canal.

Removal of Gutta-percha from Root Canals Using the Self-Adjusting File

IntroductionThe aim of this study was to compare the percentage of the residual gutta-percha–occupied area (PRGPA) in root canals after retreatment using ProTaper retreatment files (Dentsply Maillefer, Ballaigues, Switzerland) with or without the additional use of Self-Adjusting Files (SAFs; ReDent-Nova, Ra'anana, Israel). MethodsRoot canals in 33 curved mesiobuccal roots of the first maxillary molars were cleaned and filled with gutta-percha and AH26 sealer (Dentsply De Trey, Johnson City, TN). Retreatment instrumentation was performed in 28 roots with ProTaper retreatment files and Hedström files. The Additional use of SAF was performed in 14 of the 28 roots. Five roots were not retreated. All roots were sectioned horizontally at 2, 4, and 6 mm from the apex. PRGPA was measured at each section. Scores 1 through 5 were used to represent the increasing extent of PRGPA; score 1 was 0%, and score 5 was >30%. The data were analyzed with nonparametric tests. ResultsScore 5 was recorded in all sections from roots that were not retreated. In retreated roots, the scores for the group using SAF were significantly lower than that without using SAF (P = .045); however, scores were higher at 2 mm than at other levels of the root regardless of whether the SAF had been used (P = .03). ConclusionsThe complete removal of gutta-percha from the apical portion of curved canals remains a challenge. The additional use of SAF removed more gutta-percha than ProTaper alone.

Clinical microscopic analysis of protaper retreatment system efficacy considering root canal thirds using three endodontic sealers

To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty-five palatal root canals of first molars were filled with gutta-percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10×), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal-Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third.

Comparative evaluation of debris extruded apically by using, Protaper retreatment file, K3 file and H-file with solvent in endodontic retreatment

Aim: The aim of this study was to evaluate the apical extrusion of debris comparing 2 engine driven systems and hand instrumentation technique during root canal retreatment. Materials and Methods: Forty five human permanent mandibular premolars were prepared using the step-back technique, obturated with gutta-percha/zinc oxide eugenol sealer and cold lateral condensation technique. The teeth were divided into three groups: Group A: Protaper retreatment file, Group B: K3, file Group C: H-file with tetrachloroethylene. All the canals were irrigated with 20ml distilled water during instrumentation. Debris extruded along with the irrigating solution during retreatment procedure was carefully collected in preweighed Eppendorf tubes. The tubes were stored in an incubator for 5 days, placed in a desiccator and then re-weighed. Weight of dry debris was calculated by subtracting the weight of the tube before instrumentation and from the weight of the tube after instrumentation. Data was analyzed using Two Way ANOVA and Post Hoc test. Results : There was statistically significant difference in the apical extrusion of debris between hand instrumentation and protaper retreatment file and K3 file. The amount of extruded debris caused by protaper retreatment file and K3 file instrumentation technique was not statistically significant. All the three instrumentation techniques produced apically extruded debris and irrigant. Conclusion: The best way to minimize the extrusion of debris is by adapting crown down technique therefore the use of rotary technique (Protaper retreatment file, K3 file) is recommended.

Efficacy of ProTaper Retreatment System in Root Canals Obturated with Gutta-Percha Using Two Different Sealers and GuttaFlow

Objective. To compare the efficacy of ProTaper retreatment files in removing three different obturating materials. Study Design. Forty-five human, single-rooted premolars were divided into three experimental groups. Group 1 was obturated with gutta-percha and AH Plus sealer, Group 2 was obturated with gutta-percha and zinc oxide eugenol sealer, and Group 3 was obturated with GuttaFlow. Retreatment was done using the ProTaper universal rotary retreatment files. Root halves were visualized using magnifying loops at 3X magnification and optical stereomicroscope at 10X magnification. Images were analyzed using AutoCAD 2004 software to calculate area of the remaining debris in the canal. For statistical analysis were used variance test and ANOVA. Results. Total debris/canal area ratio between the three groups showed a statistically significant difference (P < 0.001). Conclusion. ProTaper retreatment system did not produce completely clean canals in any of the groups. However, it had the best efficacy towards removing silicon based obturating material GuttaFlow.

Efficacy of rotary Ni-Ti retreatment systems in root canals filled with a new warm vertical compaction technique

The aim of this study was to compare the efficacy of Mtwo, ProTaper retreatment files and Hedström files for the retreatment of root canals filled with BeeFill 2 in1 and cold lateral compaction techniques. 63 single-rooted human teeth were prepared with Mtwo rotary files to size 35/.04 and assigned into three groups (n=21/group). (1) BeeFill 2 in1/2Seal, (2) BeeFill 2 in1/AH26 and (3) laterally-compacted gutta-percha/AH26. The specimens were subgrouped according to the file system used to remove root fillings (n=7/subgroup): 1. Mtwo retreatment file, 2. ProTaper retreatment file, 3. Hedström file. Roots were split longitudinally and photographed. The time required for removal of root canal fillings and the areas of residual root filling materials were compared statistically (p<0.05). The maximum amount of remnant was observed in the Mtwo group for removal of BeeFill 2 in1/AH26. ProTaper retreatment files required less time to remove root filling material than Mtwo retreatment files and Hedström files (p<0.05). Among the tested removal systems, ProTaper retreatment files may offer the best efficiency-speed combination.

Damage to Root Dentin During Retreatment Procedures

Introduction The aim of this study was to explore the influence of retreatment procedures on the appearance of defects on the root canal walls. Methods Two hundred mandibular premolars were divided into 4 groups. One group was left unprepared. The rest of the teeth were prepared with ProTaper files up to size F4 and filled with gutta-percha and AH26. One group was left filled and received no further treatments. The filling material was removed from the remaining teeth either with ProTaper retreatment files or with Hedström files. Roots were then sectioned and inspected under a microscope. Data were analyzed with the nominal regression test (α = 0.05). Results No defects were observed in the unprepared group. Retreatment groups showed significantly more defects than the initial treatment group ( P < .05).There was no difference between the appearance of defects after retreatment with Hedström files and ProTaper retreatment files. The remaining dentin thickness and level of the root did not significantly influence the appearance of defects. Conclusions Retreatment procedures result in more defects than initial treatment. When assessing the outcomes of endodontic retreatment, the substantial damage to the root canal walls should be considered.

Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

ObjectiveThe aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars. Material and methodsThe amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris. ResultsProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion. ConclusionsProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.

Influence of the Diameter and Taper of Root Canals on the Removal Efficiency of Thermafil Plus Plastic Carriers Using ProTaper Retreatment Files

Introduction This study aimed to investigate the influence of canal shape on the time required for the removal of Thermafil Plus plastic carriers (Dentsply Tulsa Dental, Tulsa, OK) using ProTaper Retreatment Files (Dentsply Maillefer, Ballaigues, Switzerland). Methods Sixty simulated J-shaped canals in resin blocks were divided into six groups prepared differently in terms of apical size (25/04 or 35/06) and coronal enlargement (no coronal enlargement, using a K3 orifice opener [SybronEndo, Orange, CA] 25/08, or using Gates-Glidden drills [Mani, Tochigi, Japan] #1-4) and were filled with a Thermafil Plus of the same carrier size (size 25 or 35). The carriers were removed using ProTaper D1, D2, and D3 in a crown-down sequence, and removal time was measured. A similar experiment was performed using extracted mandibular incisors prepared to 25/04 with or without coronal enlargement using Gates-Glidden drills ( n = 10 each). Results Simulated canals coronally enlarged with Gates-Glidden drills required a significantly longer removal time than other groups of identical apical size ( p < 0.05). When groups with similar coronal enlargement were compared, those apically prepared to 35/06 required a significantly longer removal time than those prepared to 25/04 ( p < 0.05). Coronally enlarged incisors also required a significantly longer removal time than those without coronal enlargement ( p < 0.05). Conclusions Canals with a larger diameter and/or taper required more time for the removal of Thermafil Plus plastic carriers.

Efficacy of three different rotary files to remove gutta‐percha and Resilon from root canals

To evaluate the efficacy of ProTaper Retreatment files, Mtwo Retreatment files and Twisted Files for removal of gutta-percha and Resilon in straight root canals. Ninety single root canals were instrumented and randomly allocated into 6 groups of 15 specimens each with regards to the filling material and instruments used. Group 1: gutta-percha/ProTaper; Group 2: Resilon/ProTaper; Group 3: gutta-percha/Mtwo; Group 4: Resilon/Mtwo; Group 5: gutta-percha/Twisted Files; Group 6: Resilon/Twisted Files. For all roots, the following data were recorded: procedural errors, duration of retreatment, canal wall cleanliness through optical microscope and cone beam computed tomography (CBCT). Data were statistically analysed, and the level of significance was set at P=0.05. No system completely removed the root filling material from root canal walls. No significant differences were observed between the rotary systems in terms of the area of filling material left within the canals (P>0.05). There were statistically significant differences between the filling materials: Resilon/Real Seal had less residual material than gutta-percha/AH plus (CBCT: P=0.01; microscope: P=0.018). Mtwo Retreatment files were more rapid when removing filling material than ProTaper Retreatment files (P=0.19) and Twisted Files (P=0.04). No system removed the root filling materials entirely. Mtwo Retreatment files required less time to remove root filling material than the other instruments. Resilon was removed significantly better from the canal walls than gutta-percha, irrespective of the rotary instruments used.

Comparison of efficiency of gutta percha removal in retreatment using protaper retreatment files, RaCe instruments with and without ‘H’ files - An ex vivo evaluation

Objective: To compare the efficiency of gutta percha removal in retreatment using ProTaper retreatment files, RaCe instruments with and without H files – an ex-vivo evaluation. Study design: Seventy five human premolars with straight and single canal were used. Root Canals were prepared using a crown-down technique and obturated with GP and AH plus sealer using cold lateral compaction. The access cavities were filled and all teeth were stored in an incubator. All samples were randomly divided into 5 groups of 15 specimens each. H files [Gr 1], ProTaper retreatment files [Gr 2], RaCe instruments [Gr 3], ProTaper retreatment files followed by H files [Gr 4] and RaCe followed by H files [Gr 5]; were used group-wise to remove GP and sealer from the canal wall. Endosolv-R solvent was used. Canal wall cleanliness was assessed. Time for retreatment was noted. ANOVA test and Bonferroni multiple comparison tests were used for statistical analysis. Results: Combination of rotary NiTi instruments followed by hand instrumentation was more efficient in removing GP and sealer during retreatment. Gr 5 had least amount of remaining debris. Conclusion: RaCe instruments followed by H files were most efficient in removal of root canal fillings. Rotary instruments with or without H files were faster than combination of GGDs and H files during retreatment.