Gutta-percha Removal Research Articles

ProTaper retreatment system versus balanced force technique for apical extrusion and gutta-percha removal

Introduction: The aim was to compare root canal wall cleanliness, amounts of apically extruded debris and irrigant during retreatment using the ProTaper Universal Retreatment (PT) system or balanced force technique (BFT).
 Materials and Methods: Root canals of extracted mandibular premolar teeth (n=44) were endodontically prepared and obturated, then the teeth were divided into two groups: BFT and PT. Apically extruded material was collected into preweighed Eppendorf tubes using the Myers and Montgomery method. The root halves were photographed under a stereomicroscope. Area of the remnant filling material (coronal, middle, apical thirds and total canal surface) was measured by software. Data were analyzed by Mann-Whitney U test.
 Results: The BFT and PT system provided similar degrees of canal wall cleanliness (p > 0.05) and amounts of extruded irrigant (p>0.05). The PT system caused less debris extrusion (p<0.05).
 Conclusions: Although the BFT was shown to cause less apical extrusion in primary root canal treatment compared to other manual instrumentation techniques, in the present study, BFT caused more debris extrusion than the PT group.
 
 How to cite this article: Sarıçam E, Altunkaynak B, Kayaoğlu G. ProTaper Retreatment system versus balanced force technique for apical extrusion and gutta-percha removal. Int Dent Res 2019;9(2):63-8.
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

In Vitro Comparison of Efficacy of Neolix and ProTaper Universal Retreatment Rotary Systems in Removal of Gutta-Percha Combined with Two Different Sealers.

The complete removal of filling material is an important step to regain access to the entire canal and facilitate the disinfection of the root canal system. Rotary nickel-titanium (NiTi) instruments systems have been proposed as an effective removal technique for root canal retreatment.The aim of this study was to evaluate the efficacy of Neolix rotary system and ProTaper Universal retreatment system in the removal of gutta-percha combined with two different sealers.In vivo study, eighty extracted human permanent mandibular premolars were prepared using the ProTaper Universal rotary system to an apical size 30 (F3/0.06). The specimens were randomly divided into 4 groups (n=20) and subsequently filled with lateral condensation of gutta-percha and two sealers: AH-26 and Sure-Seal Root. The teeth were stored for 4 weeks at 37°C and 100% humidity and then retreated by one of the following rotary systems: Neolix or ProTaper Universal retreatment system. Teeth were then grooved and monitored under a stereomicroscope with 8× magnification. The images were transferred to the computer and the amount of filling material that remained on the root canal walls was scored using AutoCAD 2017 version 1.1software. Results were analyzed using one-way analysis of variance test and post hoc Tukey-HSD test (p< 0.05).The mean percentage of remaining gutta-percha and sealer was significantly higher in apical third in all groups (p< 0.01). Post hoc Tukey test showed that there is significantly higher residual filling material in the group filled with gutta-percha and Sure-Seal Root sealer and retreated by Neoniti rotary system compared with other groups in both coronal and middle third of the canal.The Neoniti rotary system was as effective as ProTaper Universal retreatment system in retreatment of gutta-percha and AH-26 sealer but was significantly less effective in groups obturated with Sure-Seal Root sealer.

An in vivo comparative evaluation of antimicrobial efficacy of chitosan, chlorhexidine gluconate gel and their combination as an intracanal medicament against Enterococcus faecalis in failed endodontic cases using real time polymerase chain reaction (qPCR)

AimTo evaluate the in vivo antibacterial efficacy of 2% chlorhexidine gel (CHX), 2% chitosan (CS) gel and their combination as an intracanal medicament against Enterococcus faecalis during endodontic retreatment procedure, with the use of qPCR. MethodA total of 45 single rooted permanent teeth were selected from 28 systemically healthy patients (mean age of 43 years). After complete disinfection and access opening as well as gutta-percha (GP) removal, the first microbiological pretreatment sample (S1) was collected. After completion of instrumentation, a post-instrumentation sample (S2) was taken and the teeth were randomly divided into three experimental groups: 2% CHX gel; 2% CS gel; 2% CHX with CS; Fuji IX glass ionomer cement was used to seal the access; after 7 days, the post medication sample (S3) was collected and E. faecalis was quantified using qPCR. ResultsMaximum reduction in bacterial mean CFU (×106) counts was observed between S1 and S2; S2 and S3; S1 and S3 in 2% CHX with chitosan group compared to other groups. Percentage reduction in CFU (×106) counts at different time intervals (S1-S2; S2-S3; S1-S3) was maximum for the 2% CHX with the chitosan group. Comparison of the mean CFU (×106) count within the 2% CHX gel group and the 2% CHX with chitosan group at different time intervals (S1,S2,S3) was found to be highly significant (P = 0.001); whereas in group II, it was significant (P = 0.002). Conclusion2% CHX with chitosan group showed the highest microbial reduction against E. faecalis during retreatment of failed endodontic cases.

Fracture resistance of teeth undergoing postendodontic bleaching: Comparison of four treatment modalities – An in vitro study

Aims: The aims of the study were: (1) to evaluate the fracture resistance of endodontically treated teeth restored with microhybrid composite following combination bleaching and (2) to assess the antioxidizing effect of 10% sodium ascorbate hydrogel. Settings and Design: This was a randomized control trial in a tertiary care setting. Subjects and Methods: Endodontic treatment was performed on 40 freshly extracted human mandibular premolars. Following removal of gutta-percha 2 mm apical to cementoenamel junction and application of resin-modified glass ionomer as cervical barrier, all teeth were embedded in acrylic resin using cylindrical molds. Specimens were divided into five groups: Group 1 (n = 8): Specimens subjected to inside and outside bleaching using 10% hydrogen peroxide followed by composite restoration. Group 2 (n = 8): Specimens subjected to inside-outside bleaching with 10% hydrogen peroxide and sodium perborate followed by composite restoration; Group 3 (n = 8): Specimens subjected to conditioning with 10% sodium ascorbate after inside-outside bleaching using 10% hydrogen peroxide followed by composite restoration; Group 4 (n = 8): Specimens subjected to conditioning with 10% sodium ascorbate after inside-outside bleaching with 10% hydrogen peroxide and sodium perborate followed by composite restoration; and Group 5 (negative control) (n = 8): After endodontic treatment specimens were restored with composite. Finally, all the specimens were subjected to fracture resistance test using Universal Testing Machine. Statistical Analysis Used: ANOVA test followed by post hoc comparison of groups taken together by Tukey's analysis was performed. Results: Statistically significant difference in fracture resistance was present between Group 5 and Group 1 and also between Group 5 and Group 2. Unpaired t-test showed statistically significant difference between Group 1 and Group 3 and also between Group 2 and Group 4. Conclusion: The use of 10% sodium ascorbate antioxidant gel was effective in compensating for the decreased fracture resistance following combination bleaching.

Comparative evaluation of removal of gutta-percha from root canals with laser using different solvents: An in vitro study

Aim: The aim of this study is to evaluate the gutta-percha removal from root canals with diode laser using chloroform and Endosolv E solvents. Materials and Methods: Thirty freshly extracted permanent human maxillary central incisors with single and straight root canals were selected for the study. Teeth were biomechanically prepared and then obturated. Teeth were then stored in 100% humidity at 37°C for 7 days. Then teeth were randomly divided into three groups based on retreatment method used: Group 1-Only diode laser; Group 2-Diode laser along with chloroform as solvent; Group 3-Diode laser along with Endosolv E (Tetrachloroethylene) as solvent. After completion of retreatment, roots were sectioned longitudinally and viewed under stereomicroscope at 10x magnification. The area of the remaining filling material in each half was measured using Image tool for Windows v. 3.00 software. Data were analyzed by using analysis of variance test followed by post hoc test. Results: The results showed that all the laser groups left some filling material inside the root canal. However, the specimens retreated with diode laser along with chloroform (Group 2) left less filling material inside the root canals as compared to other groups. Conclusion: The present study revealed that the diode laser with solvents (Chloroform and Endosolv E) were significantly more effective than only diode laser group in removing gutta-percha during retreatment of the root canal system. Out of these, Group 2 (diode laser along with chloroform as solvent) was more effective than other groups.

Evaluation of Efficacy of Different Instrumentation for Removal of Gutta-percha and Sealers in Endodontic Retreatment: An In Vitro Study

The aim of the present study was to evaluate the efficacy of different instrumentation for removal of gutta-percha and sealers in endodontic retreatment. A total of single-rooted mandibular premolars were collected. Access opening was performed in all specimens. The working length was determined by reducing 1 mm from the length of instruments that were seen reaching the apex. All the canals were dried with paper points. Lateral condensation technique was used to obturate the canals with gutta-percha and zinc oxide eugenol was used as a sealer. The specimens were randomly segregated into three experimental groups. Group I: ultrasonic retreatment tip, group II: R-Endo retreatment files, group III: Mtwo retreatment files. Roots were grooved into two halves with a diamond disc in a longitudinal, buccolingual direction. A stereomicroscope with ×40 magnification was used to image the quantity of gutta-percha and sealer on canal walls. With ultrasonic retreatment tip, least amount (1.96 ± 0.32) of gutta-percha and sealer remained, followed by Mtwo retreatment files (2.84 ± 0.24) and R-Endo retreatment files (3.18 ± 0.63). A statistically significant inter-group difference among different instrumentation groups was demonstrated by ANCOVA analysis. In the present study, ultrasonic retreatment tip file systems was found to be more effective in the removal of root canal filling material, followed subsequently by Mtwo retreatment file system and R-Endo retreatment file system. Thorough removal of filling material from the root canals is essential during root canal retreatment for probable cleaning and shaping of canal morphology. Thus, clinicians should be aware of the suitable and better instrumentation system that provides a clean and sterile root canal system without any debris. How to cite this article: Agrawal P, Ramanna PK, Arora S, et al. Evaluation of Efficacy of Different Instrumentation for Removal of Gutta-percha and Sealers in Endodontic Retreatment: An In Vitro Study. J Contemp Dent Pract 2019;20(11):1269-1273.

Comparative Efficacy of Three Different Retreatment Rotary Instrument Systems for Removal of Gutta-Percha from Root Canals: A Comparative in Vitro Study

Comparative Efficacy of Three Different Retreatment Rotary Instrument Systems for Removal of Gutta-Percha from Root Canals: A Comparative in Vitro Study

Ex Vivo Evaluation of Endodontic Retreatment Using Four Rotary File Systems and Hand Hedstrom Files in the Removal of Gutta-percha and MTA-based Salicylate Resin Sealer

Ex Vivo Evaluation of Endodontic Retreatment Using Four Rotary File Systems and Hand Hedstrom Files in the Removal of Gutta-percha and MTA-based Salicylate Resin Sealer

Comparison between Three Different Root Canal Rotary Instruments in retreatment: An in vitro study

Aim: The aim of this study was to compare Protaper Universal retreatment files, M-Pro, andTwisted files in retreatment.Methodology: Experimental groups were divided into three group; Group I: Protaper UniversalRetreatment (PTU; Dentsply Maillefer, Ballaigues, Switzerland), Group II: M-Pro (InnovativeMaterial and Devices, ShangHai, China), and Group III: Twisted File (TF; SybronEndo, Orange,CA). Each group was evaluated for time to reach the working length, amount of debris extrudedduring retreatment. Data were then collected, tabulated and statistically analyzed.Results: Statistical analysis showed that TF recorded the least time to reach the working length,while M-Pro showed the highest amount of debris extruded.Conclusion: Under the condition of the current study, TF was faster than M-Pro and PTU toperform gutta-percha removal in the retreatment of teeth. The use of M-Pro in retreatment increasedthe amount of apically extruded debris.

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

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

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

To compare the Reciproc Blue, Reciproc and ProTaper Universal Retreatment systems with regard to the effective removal of epoxy resin-based sealer and gutta-percha during the retreatment of oval, straight root canals. Forty-five extracted, human mandibular first premolars with single straight oval canals were selected on the basis of cone beam computed tomography evaluations. The root canals were instrumented with the ProTaper Next system up to the X2 file, and filled with gutta-percha and epoxy resin-based sealer using the cold lateral condensation technique. After 1month, the samples were randomly divided into three groups (n=15) according to the retreatment system used: Reciproc Blue R40, Reciproc R40 and ProTaper Universal. The specimens were scanned at the resolution of 1.2μm by a microcomputed tomography device after the root filling and retreatment procedures, and the decrease in the volume of filling material after each retreatment protocol was measured. The results were analysed using the Kruskal-Wallis test and additional box-and-whisker plots. Although the volume of the filling material decreased significantly in all three groups (P<0.05), none of the systems removed the material completely. The Reciproc system removed significantly more material than the ProTaper Universal (P<0.001) and Reciproc Blue (P=0.005) systems, with the latter two exhibiting equal volumes of remaining material (P=0.068). The Reciproc system was more effective than the Reciproc Blue and ProTaper Universal Retreatment systems during the removal of filling material from oval, straight canals, although none of the systems completely removed the filling material.

Efficacy of ProTaper rotary instruments in removing filling materials during root canal retreatment

The aim of the this study was to investigate the efficacy of ProTaper rotaryinstruments compared to hand instrumentation with Hedstrom files, with and withoutthe use of a solvent (eucalyptol) in the retreatment of gutta-percha filled root canals.Roots of forty extracted single-rooted maxillary anterior teeth with straight root canalswere utilized in this study. The root canals were prepared using step-back techniqueand obturated with laterally condensed gutta-percha and sealer cement. The rootsrandomly divided into four groups with ten specimens each. Removal of gutta-perchawas performed using ProTaper and Hedstrom files, both were used with and withoutthe solvent eucalyptol. Both, time taken to reach the working length and time taken tocomplete removal of gutta-percha were recorded. Statistical analysis of the collecteddata revealed a highly significant decrease in the working time when ProTaper wasused to remove gutta-percha compared with Hedstrom files. A highly significantdecrease in the working time was found when eucalyptol was used with ProTaper. Nosignificant difference existed between the treatments using Hedstrom with or withoutthe use of eucalyptol.

Bacterial Reduction after Gutta-Percha Removal with Single vs. Multiple Instrument Systems.

Introduction:The aim of this study was to evaluate the effectiveness of a reciprocating single-instrument system (Reciproc-REC) compared with combined continuously rotating multiple-instrument systems [D-Race (DR) and BioRace (BR)] in reducing Enterococcus faecalis (E.f.) after gutta-percha removal. Methods and Materials:Forty-six extracted human maxillary incisors were prepared and contaminated with E.f. strain (ATCC 29212) for 30 days. The samples were obturated and randomly divided into two experimental groups for gutta-percha removal (n=23): a REC group (R50) and a DR/BR group (DR1, DR2 and BR6). A standardized irrigation with 0.9% saline solution was performed. Root canal samples were taken with paper points before (S1) and after (S2) the removal of gutta-percha to establish bacterial quantification by culture. The time required for gutta-percha removal was also recorded. Positive and negative control groups (n=6) were used to test bacterial viability and control asepsis, respectively. Data were analysed using t-Student and one-way ANOVA tests (5% margin of error). Results:The mean percentage of bacterial reduction was significantly higher in DR/BR group (84.2%) than in REC group (72.3%) (P<0.05). The mean time for obturation removal was 74.00 sec in REC group and 107.53 sec in DR/BR group (P<0.05). Conclusion: The combined continuously rotating multiple-instrument system was more effective in reducing bacteria after the removal of gutta-percha than the single-instrument system. None of the tested systems was able to completely eliminate root canal infection after gutta-percha removal. Thus, additional techniques should be considered.

Effect of root canal preparation, obturation, and retreatment on the induction of dentinal microcracks: A microcomputed tomography study.

Introduction:This study evaluated the effect of root canal preparation, obturation, and different techniques of retreatment on the percentage increase in the number of dentinal microcracks using microcomputed tomography (CT) analysis.Materials and Methods:Forty-five mandibular premolars after micro-CT scanning were prepared using Protaper universal files up to F4 and obturated. After the second micro-CT scanning again, the samples were randomly divided into three groups (n = 15) for retreatment procedure. In Group 1, retreatment was done with Protaper universal D1, D2, and D3 retreatment files followed by Protaper universal file till F4. In Group 2, retreatment was performed with R-Endo reciprocating motion, Re, R1, R2, R3, and Rs followed by Hero Shaper size #40. In Group 3, retreatment was performed with H-files and xylene till size #40. After gutta percha removal, the samples were again scanned for micro-CT for the evaluation of percentage increase in dentinal microcracks. Data were analyzed using “Kruskal–Wallis test ANOVA” and “student t-test” at 5% level of significance.Results:Few unprepared samples showed preexisting microcracks. There were statistically significant percentage increase dentinal cracks after root canal preparation and obturation as well as after retreatment procedure with statistically significant percentage increase in the number of dentinal microcracks between all three groups.Conclusion:Intraradicular procedures such as shaping and cleaning and obturation as well as the use of retreatment file lead to the induction and propagation of dentinal microcracks. In the present study, the maximum microcracks were produced with Protaper universal retreatment file system followed by R-Endo system. H-files produced minimum cracks during retreatment procedures.

Evaluation of apically extruded debris during removal of gutta-percha and ResilonTM using different instrumentation techniques

Background/Aim. Apical extrusion of material is considered as one of the very important factor for endodontic treatment success. Microorganisms, necrotic tissue, filling material and irrigants, which can be extruded apically during endodontic retreatment, may jeopardize the success of the therapy. The aim of this in vitro study was to quantitatively evaluate the amount of apically extruded debris during endodontic retreatment of teeth obturated with two different materials, using one hand and three rotary instrumentation techniques. Methods. Ninety-six extracted single-rooted teeth were endodontically treated and enlarged to size 40 using BioRaCe system, and then randomly divided into 8 groups of 12 specimens each. Half of the specimens were obturated with gutta-percha and AH Plus? sealer and another half with RealSeal SE system, using lateral condensation technique. Retreatment was performed using: Hedstr?m files; ProFile rotary files; ProTaper Retreatment system and D-RaCe system. Apically extruded debris was collected in pre-weighed Eppendorf tubes and evaluated using an electronic microbalance. Data were analyzed statistically using t-test and analysis of variance. Results. In the AH Plus/gutta-percha group, all tested rotary instruments gave significantly less extruded debris compared with Hedstr?m files (p &lt; 0.05). In theRealSeal group, there was significant difference between DRaCe and Hedstr?m instruments (p &lt; 0.05). Conclusion. All retreatment techniques resulted in apical extrusion. DRaCe system produced significantly less extruded debris compared to hand files. No significant difference was found when comparing two instruments specially designed for retreatment: D-RaCe and ProTaper systems.

Evaluation of Effectiveness of Two Different Endodontic Retreatment Systems in Removal of Gutta-percha: Anin vitroStudy

To determine the effectiveness of two different endodontic retreatment systems for the removal of laterally compacted gutta-percha (GP). Sixty-three freshly extracted human maxillary central incisors were used for the study. The teeth were instrumented with K-flex files and obturated using lateral condensation technique with GP and AH Plus sealer. The teeth were divided into three retreatment groups, each group consisting of 21 teeth. Group I: D-RaCe desobturation files (D-RaCe); group II: ProTaper Universal retreatment files (PTUR); group III: Hedstrom files (H-file). After removal of GP, the teeth were split longitudinally and divided into three equal parts: Cervical, middle, and apical third. The middle and apical thirds of all root halves were examined using scanning electron microscope (SEM). The total surface area covered by the residual debris was evaluated using Motic Image plus 2.0 software. Statistical analysis was done by one-way analysis of variance (ANOVA) test with a p-value <0.05 used to determine significance and Tukey's multiple post hoc tests used for comparison between the groups, and 't' test was done for comparison between the thirds within the same group. The PTUR retreatment files showed overall better performance compared with D-RaCe files and H-files. The PTUR files performed better at middle third compared with others. The PTUR files and D-RaCe files performed equally at apical third better than H-files. ProTaper retreatment files are better compared with D-RaCe files and H-files for the retreatment of the previously endodontically treated teeth. Highest efficacy for the removal of GP was shown by ProTaper Universal System followed by D-RaCe and H-file.

Efficacy of novel thermomechanically treated reciprocating systems for gutta-percha removal from root canals obturated with warm vertical compaction.

Background. The present study aimed to test the efficacy of novel reciprocating systems in terms of gutta-percha removal of roots obturated with warm vertical compaction technique. Methods. Ninety straight rooted maxillary incisors were enlarged with hand files up to a # 50/02 apical size and obturated using warm vertical compaction technique. The specimens were divided into four groups according to system used for filling removal, as Reciproc Blue, Reciproc, WaveOne Gold and hand-instrumentation. The residual filling materials and time required for root canal removal were calculated. Statistical analyses were performed using one-way analysis of variance and Tukey tests with 5% significance threshold. Results. There were no significant differences among Reciproc, Reciproc Blue and WaveOne Gold (P > 0.05). Hand-instrumentation group left significantly greater root canal filling material (P < 0.05). The time required for root canal filling removal was significantly shorter in the Reciproc group followed by WaveOne Gold, Reciproc Blue and hand-instrumentation groups (P< 0.05). Conclusion. Efficacy of Reciproc Blue, WaveOne Gold and Reciproc instruments for root canal filling removal were similar and superior to hand-instrumentation.

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

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

Micro-CT Evaluation of Gutta-Percha Removal by Two Retreatment Systems.

Introduction:The aim of the present ex vivo research was to compare the remaining filling material and the volumes of dentine removed after retreatment of curved canals with two rotary systems naming ProTaper Universal Retreatment and Mani NRT-GPR using micro-computed tomography (micro-CT). Methods and Material: Forty mandibular molars containing two completely separated canals, with curvature angle of 25-35° and a curvature radius <10 mm were prepared to the Mtwo instrument 35/0.04 and filled with warm gutta-percha and AH-Plus sealer. The teeth were randomly divided into 2 groups (n=20), according to the retreatment system evaluated: ProTaper Universal Retreatment (PR group) or Mani NRT-GPR (MR group). Retreatment was considered complete when the working length was reached and when smooth dentinal walls were observed, with no evidence of filling material adhered to instruments or in the irrigating solution. Preoperative and postoperative micro-CT images were obtained with an isotropic voxel size of 11.88 µm to observe the volume of residual filling material in the canals and dentine removed after retreatment. Statistical analysis was performed by Student’s t-test (P<0.05). Results:The mean percentage of remaining filling material was 12.96% for PR group and 24.26% for MR group (P=0.0056). The percentage of dentin removal was greater in the PR group (5.02%) than MR group (1.36%) (P=0.0028). Both systems failed to completely remove the filling material from the canals. Conclusion: ProTaper Universal Retreatment system was more effective than Mani NRT-GPR system regarding removal of root filling material and also removed significantly more dentine after retreatment of curved mesial root canals of mandibular molars.

Efficacy of rotary and reciprocating single-file systems on different access outlines for gutta-percha removal in retreatment: An in vitro study.

Introduction:The aim of this study is to compare the effectiveness of reciprocating and continuous rotary nickel-titanium instruments during retreatment performed through two different access outlines.Methodology:A total of 48 freshly extracted mandibular first and second premolars with single root and canal were selected. Initial root canal treatment was completed through a contracted endodontic cavity (CEC) design. Canals were instrumented with F2 ProTaper instrument, obturated with warm lateral condensation of gutta-percha with AH Plus sealer, and allowed to set for 30 days at 37°C and 100% humidity. For retreatment, specimens were divided into two groups (n = 24) on the basis of access outline, CEC or traditional endodontic cavity. Retreatment was initiated using ProTaper Retreatment instruments (D1–D3). Specimens were further divided (n = 12) and reinstrumented up to Neoniti 25/0.08 or WaveOne 25/0.08. Irrigation was performed using 3% sodium hypochlorite and 17% ethylene diamine tetraacetic acid. Retreatment time was recorded. Teeth were sectioned and photographed, and the percentage of remaining obturation material was measured.Results:Data were collected, and statistical analysis was performed using one-way analysis of variance and Tukey honestly significant difference multiple post hoc procedures (P < 0.05).Conclusion:None of the systems completely removed the root filling material from root canals. However, ProTaper/Neoniti instruments removed more GP when compared to Protaper/WaveOne instruments with both the access outlines. Both the instruments with traditional access outline required less time for removal of obturating material when compared to CEC.