Effectiveness of rotary and hand files in gutta-percha and sealer removal using chloroform or chlorhexidine gel

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

OBJECTIVES

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.

MATERIALS AND METHODS

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).

RESULTS

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.

CONCLUSION

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.

Critical analysis of research methods and experimental models to study removal of root filling materials

Despite enjoying high favourable outcome rates, root canal treatment is not always successful. Root canal retreatment is a widely practised option for managing a non-healing root treated tooth. A basic distinction between retreatment and initial treatment is the requirement to remove the existing root filling material occupying the root canal space. Only then, can the technical deficiencies and possible causes of failure be addressed. Hence, the successful removal of the root filling material is critical to achieving the objectives of retreatment. Many different materials and techniques have been used for root canal filling, which have been documented in a plethora of studies; these are mainly laboratory studies investigating the removal of root filling materials. To help guide future research, which may then better inform clinical practice in relation to retreatment procedures, the focus of this narrative review is on the research methods and experimental models employed to study the removal of root filling materials. The current available literature demonstrates great variation in the research methodologies used to study the removal of root filling material, including direct visualization by splitting tooth samples or clearing, three-dimensional radiographic imaging including using microcomputed tomography or cone-beam computed tomography, and a combination of these techniques. Depending on the research method employed, variation also exists in quantification of root filling material removal; these include measurements of surface area, volume or weight, and criteria-based (semi-quantitative) assessment. Experimental models, using human teeth or resin models, differ with respect to standardization techniques and replication of the clinical scenario including initial sample preparation, canal filling, allocation and technical aspects of retreatment procedures. Future models should replicate, as closely as possible, the clinical scenario. Currently, microcomputed tomography provides a highly detailed, non-invasive and non-destructive method of objectively assessing and quantifying root filling removal.

A Comparative Evaluation of Intracanal Calcium Hydroxide Removal with Hand File, Rotary File, and Passive Ultrasonic Irrigation: An In Vitro Study

Aim

The aim of this study was to compare the effectiveness of hand file (K-file), rotary file (HERO shaper), and passive ultrasonic irrigation (PUI; U-file) in removing Ca(OH)₂ from the root canal.

Materials and Methods

Thirty single-rooted teeth were collected and decoronated to standardize the length to 14 mm. Cleaning and shaping were conducted using HERO shaper rotary files (up to no. 25, 4% taper). Ca(OH)₂ powder was mixed with normal saline and filled into the canals using lentulo spiral and the orifice was sealed with zinc oxide eugenol. After 7 days of incubation, samples were divided into three groups of 10 samples each: Group I (hand files)-no. 20 K-file; Group II (rotary files)-no. 25, 4% HERO shaper; Group III (PUI)-no. 20 U-file. Ca(OH)₂ paste was removed using 2 mL of 3% sodium hypochlorite solution followed by 1-minute activation of the respective file system. All the samples were finally irrigated with 17% ethylenediaminetetraacetic acid and flushed with distilled water.

Results

Ultrasonic group was more effective in removing Ca(OH)₂ followed by HERO shaper and hand file.

Conclusion

It was concluded that PUI had the highest ability to remove Ca(OH)₂ from the root canal walls.

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

Abstract 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.

Efficacy of protaper next and protaper universal retreatment systems in removing gutta-percha in curved root canals during root canal retreatment

Purpose:

The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN), ProTaper Universal Retreatment (PTR) nickel-titanium (NiTi) systems and Hedström hand files in curved mesial canals of mandibular molar teeth and the time required for gutta-percha and sealer removal.

Materials and Methods:

Ninety mandibular molar teeth with curved mesial roots were instrumented up to #35.04 with Mtwo NiTi rotary instruments and obturated using the continuous wave of condensation technique. Removal of gutta-percha and sealer was performed using one of the following: PTN and PTR NiTi systems and Hedström hand files. Samples were placed on the VistaScan phosphor plates in the mesio-distal direction and the radiographs were taken. The digital radiographs were analyzed using AutoCAD software. Also, the total time required for gutta-percha removal was calculated by a chronometer.

Results:

The total retreatment time was significantly shorter in the PTN and PTR groups compared with the manual group (p<0.05). There was a significant difference between the groups according to the total residual gutta-percha and sealer (p<0.05). The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the manual group (p<0.001).

Conclusion:

Within the limitations of this study, the PTN and PTR groups showed less residual gutta-percha and sealer than the manual group. The NiTi rotary systems were significantly faster than the manual group in the time required for gutta-percha and sealer removal.

Cleaning efficacy of reciprocal and rotary systems in the removal of root canal filling material

Aim:

The aim of this study was to compare the efficacy of hand file, nickel titanium rotary instrument, and two reciprocating instruments for removing gutta-percha and sealer from the root canals.

Materials and Methods:

Eighty-eight mandibular premolar teeth were used. The root canals were shaped and filled with gutta-percha and a resin-based sealer. The specimens were divided into four groups according to the technique by which the root filling material was removed: Group 1 — Wave One; Group 2 — Reciproc; Group 3 — ProTaper; and Group 4 — Gates-Glidden burs and stainless steel hand file. Then teeth were split longitudinally and photographed. The images were transferred to a computer. The ratio of remaining filling material to the root canal periphery was calculated with the aid of ImageJ software. Statistical analysis was performed using Kruskal–Wallis and Mann–Whitney tests.

Results:

A significant difference was found among all groups (P < 0.001). The WaveOne group demonstrated significantly less remaining filling material. The greatest amount of filling material was found in specimens where gutta-percha was removed with Gates-Glidden burs and stainless steel hand file.

Conclusion:

The reciprocating files were found to be significantly more effective in removing the filling material from the canal walls compared to the rotational file and hand file.

Efficacy of Combined Use of Different Nickel-Titanium Files on Removing Root Canal Filling Materials

INTRODUCTION

The aim of this study was to estimate the remaining amount of residual filling materials in root canals after retreatment using ProTaper Universal Retreatment (PTUR) files (Dentsply Maillefer, Ballaigues, Switzerland) alone or with the additional use of the Self-Adjusting File (SAF; ReDent-Nova, Ra'anana, Israel), Reciproc (VDW, Munich, Germany), or Hedström-files (H-file; VDW, Antaeos, Munich, Germany) with volumetric estimation using the stereologic method via cone-beam computed tomographic images.

METHODS

Forty-eight mandibular premolars with single canals were used. The canals were instrumented with ProTaper rotary instruments up to F4 and filled with gutta-percha and AH26 sealer (Dentsply De Trey, Johnson City, TN). All the samples were placed into the silicone models. Samples were scanned with cone-beam computed tomographic imaging and assigned into 4 groups (n = 12) according to retreatment files: the PTUR system group, the PTUR system plus SAF group, the PTUR system plus Reciproc group, and the PTUR system plus H-file group. The specimens were rescanned after retreatment procedures, and the volume estimations of the remaining filling materials were performed using the stereologic method. Data were analyzed using Kruskal-Wallis and Dunn tests.

RESULTS

There was no significant difference among the groups regarding mean percentage volumes of the filling materials before retreatment procedures (P > .05). None of the retreatment procedures provided complete removal of the filling materials. The additional use of the SAF did not significantly improve the removal of filling materials when compared with the PTUR system alone (P > .05). However, the additional use of Reciproc or hand H-files significantly improved the removal of filling materials when compared with the PTUR system alone (P < .05).

CONCLUSIONS

The additional use of files with different motion kinetics improved the removal of root canal fillings; however, none of the systems completely removed the root canal filling material from the root canals.

Effectiveness of Sonic, Ultrasonic, and Photon-Induced Photoacoustic Streaming Activation of NaOCl on Filling Material Removal Following Retreatment in Oval Canal Anatomy

OBJECTIVE

This study aimed to assess the effectiveness of sonic, ultrasonic and laser [photon-induced photoacoustic streaming (PIPS)] irrigation activation in removing filling remnants from oval root canals after standard canal retreatment procedures with the ProTaper universal rotary retreatment system.

METHODS

Twenty-eight maxillary first premolars were instrumented with ProTaper NiTi rotary instruments and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. After storage at 37°C and 100% humidity for 1 week, the specimens were retreated with the ProTaper universal retreatment system for the removal of filling material. Teeth were then randomly assigned into four groups (n = 7): group 1, positive control; group 2, retreated with sonic irrigation; group 3, retreated with ultrasonic irrigation; and group 4, retreated with laser irradiation. The specimens were scanned using micro-CT before instrumentation, after obturation and mechanical retreatment, and after additional activation procedures. The percentage volume of the filling remnants was measured. Specimens were split longitudinally after micro-CT scan, canal walls were examined using scanning electron microscopy (SEM), and the amount of residual filling material was scored.

RESULTS

The filling materials' removal efficacy in the three experimental groups was higher than that of the control group (p < 0.05), whereas filling materials ranging from 1.46 ± 0.30 to 2.21 ± 0.46 mm(3) remained in the canal in all three experimental groups. Additionally, there was a significantly greater reduction in the amount of filling remnants in the PIPS group than in the sonic and ultrasonic groups (both p < 0.05), and significantly greater reduction in the ultrasonic group than the sonic group (p < 0.05).

CONCLUSIONS

Activation of NaOCl with PIPS showed significantly better performance than sonic and ultrasonic techniques in removing the filling remnants following mechanical retreatment of oval root canals. The ultrasonic technique also performed better than the sonic technique. However, none of the additional activation procedures was able to completely eliminate the filling remnants.

A comparative evaluation of gutta percha removal and extrusion of apical debris by rotary and hand files

AIM

The aim of this study was to evaluate the efficacy of Protaper retreatment files in comparison with RaCe, K3 and H-files for removal of gutta-percha and apically extruded debris using volumetric analysis.

MATERIALS AND METHODS

Forty extracted single rooted maxillary incisor teeth with straight canals and mature apices were selected for the study. After access cavity preparation, apical patency was confirmed with a size 10 K-file extending 1mm beyond the point at which it was first visible at the apical end. Working lengths were determined with the use of size 15 K-file. The canals were prepared in a step-back technique and the master apical file was size 30 for all teeth. 3% sodium hypochlorite was used as an irrigant after each instrumentation. Before final rinse, size 20 K-file was passed 1mm beyond the apex to remove any dentinal shaving plugs and maintain the apical patency. Then the canals were dried with paper points. The root canal was filled using standard gutta-percha points and zinc oxide eugenol sealer under lateral condensation technique. The teeth were then randomly divided into four groups of ten teeth each based on the instrument used for gutta percha removal. All the rotary instruments used in this study were rotated at 300rpm. The instruments used were: Group 1 - RaCe Files, Group 2 - ProTaper retreatment Files, Group 3 - K3 Files and Group 4 - H Files. The volume of the obturating material was calculated before and after removal using volumetric analysis with spiral CT. The removal efficacy with each instrument was calculated and statistically analysed.

RESULTS

The results of the study show that the ProTaper retreatment files (Group 2) (97.4%) showed the highest efficiency in the removal of obturating material, which was followed by RaCe (95.74%), K3 (92.86%) and H files (90.14%) with the efficiency in the decreasing order. Similarly the mean apical extrusion in H files (0.000 ± 0.002) was significantly lower than all the rotary instruments. However, the difference among the rotary files were not statistically significant (p>0.05).

CONCLUSION

ProTaper retreatment files show significant difference over other groups in removal of obturating material and can be the system of choice in endodontic retreatment procedures.

Confocal microscopy assessment of filling material remaining on root canal walls after retreatment

AIM

The percentage of Endofill remaining on canal walls after retreatment with different techniques was evaluated using confocal microscopy and qualitative analysis of the interface between the filling material/dentine.

METHODOLOGY

Sixty-four root canals of incisors were prepared with ProTaper, filled with gutta-percha and Endofill mixed with 0.1% rhodamine B. The roots were thermocycled and distributed into groups according to the method of evaluation: GI - direct viewing (DV) and GII - operating microscope (OM) and according to the removal technique: A) ProTaper retreatment (PR), B) PR/xylol, C) ultrasound and D) ultrasound/xylol. The root canals were then refilled with gutta-percha and AH Plus with 0.1% fluorescein and sectioned at 2, 4 and 6 mm from the apex. The percentage of remaining Endofill was analysed by confocal microscopy. Additionally, 16 roots were prepared with a ProTaper F5 instrument and were filled with Endofill + 0.1% rhodamine B/gutta-percha (negative control group) (n = 8), and the positive control group (n = 8) were filled with AH Plus with 0.1% fluorescein/gutta-percha.

RESULTS

Three-way anova demonstrated differences in the method of evaluation, removal techniques and their interaction (P < 0.05). OM (26.15 ± 12.16%) had a smaller percentage of remaining sealer than DV (32.77 ± 14.47%). The Tukey's test revealed that ultrasound/xylol (15.77 ± 7.15%) led to lower percentages of remaining sealer, significantly different from the PR group (35.25 ± 13.63%), PR/xylol (33.03 ± 11.64%) and ultrasound (33.79 ± 11.71%), which were similar (P > 0.05). Qualitative analysis detected that ultrasound had lower remaining Endofill than PR, particularly when combined with xylol. Operating microscope resulted in lower residual sealer, regardless of the removal technique.

CONCLUSIONS

None of the protocols was associated with complete removal of the filling material; however, the use of ultrasound/xylol under an OM provided better results.

The efficacy of two rotary NiTi instruments and H-files to remove gutta-percha from root canals

Objective: The aim of this study was to evaluate the efficacy of R-Endo® and K3® rotary nickel-titanium instruments compared with manual instrumentation with H-files, with use of a solvent, for removal of gutta-percha during retreatment. Study design: Forty five freshly extracted human single-rooted teeth, each with one root canal, were instrumented with K-files and filled using cold lateral compaction of gutta-percha and AH 26® sealer. The teeth were randomly divided into three groups of 15 specimens each. Removal of gutta-percha was performed with the following devices and techniques: Group 1 (H-files), Group 2 (R-Endo®), and Group 3 (K3®). The specimens were rendered transparent for the evaluation of the area of remaining gutta-percha/sealer in buccolingual and mesiodistal directions. Statistical analysis as performed by using one-way ANOVA and Kruskal-Wallis tests (p=0.05). Results: All retreatment techniques used in this study left some filling material inside the root canal. Images in buccolingual and mesiodistal directions showed no significant differences between the groups (p>0.05). Conclusions: Under the experimental conditions, the remaining filling material after retreatment was similar for each group.

Key words:Gutta-percha removal, K3®, NiTi, R-Endo®.

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

Objective

The 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 methods

The 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.

Results

ProTaper 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.

Conclusions

ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.

Solvent capacity of different substances on gutta-percha and Resilon

The aim of this study was to evaluate the effectiveness of 3 solvents (eucalyptol, orange oil, and xylol) on 2 types of gutta-percha (conventional and thermoplastic) and Resilon. Specimens (10 mm diameter x 1 mm thick; n=7 per condition) were prepared and maintained at 37ºC for 48 h. Each specimen was weighed on a precision scale every 24 h until its mass was stable, at which time the initial mass was determined. Specimens (n=7) were then immersed in the solvent solutions and, after 48 h at 37ºC, they were reweighed at 24- h intervals, until stabilization (final mass). The difference between the final and the initial mass determined the solvent capacity of each solvent. Data were subjected to analysis of variance and Tukey's test at 5% significance level. The results demonstrated that xylol was the most effective, especially on conventional gutta-percha and Resilon (p<0.05). Eucalyptol and orange oil were more effective on thermoplastic gutta-percha than the other materials (p<0.05). It was concluded that all evaluated substances presented solvent action, but xylol was the most effective on both gutta-percha or Resilon.