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

Effect of treatment variables on apical extrusion of debris during root canal retreatment: A systematic review and meta-analysis of laboratory studies

Background

This study aimed to systematically and comprehensively review the effect of various treatment variables on apically extruded debris (AED) during non-surgical root canal retreatment (NSRCRT).

Methods

The study protocol is shared in the Open Science Framework database (https://osf.io/kjtdg/?view_only=17060180705745ec9dae9a01614f3880). An electronic search was conducted up to July 2022 to reveal related studies. Two reviewers critically assessed the studies for eligibility against inclusion and exclusion criteria and data extraction. Quantitative data synthesis was performed, and the risk of bias in the studies was also evaluated.

Results

Forty-six studies were included in the systematic review and 14 in the meta-analysis. Conflicting or limited evidence was found for the effect of sealer type, obturation technique, and solvent use. The manual instrumentation increased the amount of AED compared to rotary instrumentation during the removal of filling materials (P<0.001). There was no significant difference in the amount of AED between the use of rotary and reciprocating files during the removal of filling materials (P=0.181).

Conclusion

Rotary instruments can be recommended instead of manual instruments during the removal of filling materials to control the amount of AED. Further studies with a low risk of bias are needed to clarify the effect of other treatment variables on AED during NSRCRT.

Retreatability of NeoSEALER Flo obturated with warm vertical compaction versus single-cone technique using two different retreatment systems

Aim

The aim of this study was to compare the retreatability of NeoSEALER Flo obturated with warm vertical compaction (WVC) and single-cone (SC) techniques using two different retreatment systems.

Materials and Methods

Thirty-two root canals were shaped and obturated with NeoSEALER Flo either in an SC obturation technique or a WVC technique. Samples were retreated using ProTaper retreatment or EdgeFile XR retreatment system. The percentage of remaining debris after retreatment was analyzed under a scanning electron microscope using ImageJ software. The time taken to reach full working length (WL) and induce patency was recorded.

Statistical Analysis

Statistical analysis was performed using an unpaired t-test and a one-way analysis of variance test.

Results

The percentage of remaining debris after retreatment was significantly higher in the SC technique than in the WVC technique, regardless of the retreatment system used. EdgeFile XR system removed more filling material than the ProTaper retreatment system, regardless of the obturation technique. The apical region showed significantly higher remaining debris than other regions in all groups. The WL and patency were achieved faster in the SC group, while in the WVC group, the EdgeFile XR system was faster.

Conclusions

The WVC technique showed better retrieval of the filling material; however, a longer time was taken for retreatment. EdgeFile XR system performed better in removing filling materials from inside the canals.

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.

Evaluation of Apically Extruded Debris Using Positive and Negative Pressure Irrigation Systems in Association with Different Irrigants

This study evaluated the amount of apically extruded debris after chemo-mechanical preparation (CMP) using positive and negative pressure irrigation systems [Conventional irrigation (CI) and EndoVac (EV)] in association with different irrigants [6% Sodium Hypochlorite (NaOCl), 2% Chlorhexidine gel + saline solution (CHXg + SS), 2% Chlorhexidine solution (CHXs) or Saline solution (SS)]. Eighty mandibular premolars with single root canals were selected and randomly assigned into 8 groups (n = 10) according to the irrigation system and the irrigant used during CMP: G1 (EV + NaOCl), G2 (EV + CHXg + SS), G3 (EV + CHXs), G4 (EV + SS), G5 (CI + NaOCl), G6 (CI + CHXg + SS), G7 (CI + CHXs) and G8 (CI + SS). Reciproc® R25 files (25/.08) were used during the CMP and the extruded debris from each tooth was collected in pre-weighted Eppendorf tubes and dried. The average weight of debris was assessed using a microbalance, and the data were statistically analyzed using ANOVA and the post hoc Tukey's test (a = 0.05). All groups were associated with debris extrusion. EV was the irrigation system with less extruded debris (p < 0.05). No differences were observed regarding the irrigant when EV was used. When CI was used, CHXg + SS were associated with lower debris extrusion (p < 0.05). It was concluded that no irrigation protocol succeeded in preventing debris extrusion. EV resulted in lower levels of debris extrusion than CI. The use of CHXg + SS resulted in lower debris extrusion.

Apically extruded debris during the removal of canal filling material from root canals using three techniques

AIM

In the present study, we evaluated the effect of the single-cone technique (SCT), cold lateral compaction (CLC), and wave vertical compaction (WVC) technique performed using two different sealers on the amount of apically extruded debris (AED) produced during the removal of canal filling material.

METHODS

Ninety extracted mandibular premolars were prepared with ProTaper instruments. The teeth were then randomly assigned to six groups (N = 15) for root canal filling: (a) group 1, CLC+AH Plus; (b) group 2, SCT+AH Plus; (c) group 3, WVC+AH Plus; (d) group 4, CLC+MTA Fillapex; (e) group 5, SCT+MTA Fillapex; and (f) group 6, WVC+MTA Fillapex. In all groups, the removal of canal filling material was performed with ProTaper retreatment instruments. The mean weight of the AED was assessed with an analytical balance.

RESULTS

The amount of AED was lowest in groups 2 and 5 (P < .05), with no difference between these groups (P > .05). Groups 3 and 6 produced the greatest amount of extruded debris (P < .05); there was no difference between these groups (P > .05). Additionally, there was no difference between groups 1 and 4 (P > .05). There was no significant difference among the groups regarding sealer type (P > .05).

CONCLUSIONS

The canal filling technique used affected the amount of AED produced during the removal of canal filling material, but not sealer type.

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.

Debris extrusion and foraminal deformation produced by reciprocating instruments made of thermally treated NiTi wires

Objective

To evaluate the amount of apically extruded debris, percentage of foraminal enlargement and apical foramen (AF) deformation that occurred during root canal preparation with different reciprocation systems: Reciproc, WaveOne (M-Wire), and ProDesign R (Shape Memory Technology Wire) at two different working lengths (WLs): 0.0 and 1.0 mm beyond the AF.

Material and methods

The AF of 120 root canals in 60 mesial roots of mandibular molars were photographed with stereomicroscope and randomly assigned into four groups: manual, Reciproc (REC), WaveOne (WO), and ProDesign R (PDR); subsequently, they were further subdivided according to the WL (n=15). Teeth were instrumented, coupled to a dual collecting chamber, and then another photograph of each AF was captured. Extrusion was analysed by determining the weight of extruded debris. Each AF diameter was measured in pre- and post-instrumentation images to determine deformation, which was analysed, and afterwards the final format of AFs was classified (circular/oval/deformed).

Results

We found no significant differences when analysing each system at different WLs. When considering each WL, REC and WO showed highest extrusion values (P<.05); for AF enlargement, differences were observed only for WO, when it was used beyond the AF; differences were observed among M-Wire groups beyond the AF (P<.05). AF deformation was observed in all groups; PDR showed the lowest AF deformation values at both WLs; M-Wire groups showed 50% strain beyond the AF.

Conclusion

Authors concluded that beyond the apical limit, the alloy and taper are important aspects when considering extrusion and deformation.

Efficacy of Different Methods for Removing Root Canal Filling Material in Retreatment - An In-vitro Study

INTRODUCTION

Although success of endodontic therapy has significantly improved in the last few decades due to the introduction of novel materials and techniques, failures of endodontic therapy requiring re-treatment still comprise a significant percentage of patients requiring root canal treatment.

AIM

To evaluate and compare the effective removal of gutta percha and sealer, amount of apical debris extrusion and time required for gutta percha removal using various endodontic files.

MATERIALS AND METHODS

Total 48 extracted mandibular premolars were mounted on acrylic blocks and endodontic procedure was carried out using size 40 K file and obturated using guttapercha and zinc oxide eugenol sealer. After one month storage, samples were decoronated, mounted on screw capped vials and subjected to removal of obturated material by four instruments: H files, safe sided H files, protaper universal retreatment rotary system and ultrasonic retreatment tip, grouped as 1, 2, 3, and 4 respectively. Only 2mm of obturated material from the coronal part was removed using no. 3 Gates Glidden drill, guttapercha was softened with a drop of xylene for 2 mins for each canal and retreatment was performed. The retreatment procedure was said to be complete when no visible debris were observed on the instrument flutes. The samples split into two halves and examined under stereomicroscope, photographed, assessed using AUTOCAD software and percentage of remaining filling material in coronal, middle, apical thirds of the canal was calculated in mm(2). Retreatment time was recorded in seconds and apically extruded debris was assessed by microbalance in grams for each tooth. The data was analyzed by using descriptive statistics, ANOVA and Scheffe's post hoc test through SPSS for windows (v 16.0).

RESULTS

The ultrasonic retreatment tip had less percentage of residual guttapercha/sealer, shorter mean operating time and little apical extrusion with a significant difference (p<0.05) between the other groups.

CONCLUSION

All techniques retained guttapercha/sealer remnants within the root canal. The ultrasonic retreatment tip proved to be an efficient method of removing obturated material. It was fastest with least apical debris extrusion.

Apical extrusion of debris by supplementary files used for retreatment: An ex vivo comparative study

Aim:

This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs) increased the debris extrusion apically.

Materials and Methods:

Eighty mandibular premolars with single root and canal were instrumented with ProTaper Universal rotary system (SX-F3) and obturated. The samples were divided randomly into four groups (n = 20). Group 1 served as a control; only ProTaper Universal RFs D1–D3 were used, and the extruded debris was weighed. Groups 2, 3, and 4 were the experimental groups, receiving a twofold retreatment protocol: Removal of the bulk, followed by the use of supplementary files. The bulk was removed by RFs, followed by the use of ProTaper NEXT (PTN), WaveOne (WO), and Self-Adjusting File (SAF) for removal of the remaining root filling residues. Debris extruded apically were weighed and compared to the control group. Statistical analysis was performed using one-way analysis of variance (ANOVA) and post hoc Tukey's test.

Results:

All the three experimental groups presented significant difference (P < .01). The post hoc Tukey's test confirmed that Group 4 (SAF) exhibited significantly less (P < .01) debris extrusion between the three groups tested.

Conclusion:

SAF results in less extrusion of debris when used as supplementary file to remove root-filling residues, compared to WO and PTN.

Do the Sealer Solvents Used Affect Apically Extruded Debris in Retreatment?

INTRODUCTION

We evaluated apically extruded debris in the retreatment of root canals filled with different root canal sealers and gutta-percha using different solvents.

METHODS

Ninety human mandibular central and lateral teeth were prepared using the Reciproc #25 .08 nickel-titanium system (VDW GmbH, Munich, Germany) and were divided randomly into 6 groups. In groups 1, 2, and 3, root canals were filled with epoxy resin-based sealer and gutta-percha, and in groups 4, 5, and 6, root canals were filled with zinc oxide-eugenol-based sealer and gutta-percha. Each tooth was placed in a glass vial experimental apparatus. All root canal fillings were removed with the ProTaper Retreatment nickel-titanium system (Dentsply Maillefer, Ballaigues, Switzerland). During the retreatment procedure, in group 1, Resosolv (Pierre Rolland, Merignac, France) was used; in group 4, Endosolv E (Septodont, Paris, France) was used; and in groups 2 and 5, Guttasolv (Septodont) was used as the solvent. In the control groups (groups 3 and 6), no solvent was used. Reciproc #40 .06 was used for the final preparation. The times required for retreatments were recorded.

RESULTS

The weight of the extruded debris and the time required for retreatment were decreased significantly in the groups in which a solvent that was intended specifically for the root canal sealer was used (groups 1 and 4). In the Guttasolv groups (groups 2 and 5), the amount of apically extruded debris and the time required decreased for both root canal sealers.

CONCLUSIONS

The amount of apically extruded debris and the duration of retreatment were reduced by the use of a solvent specific to the sealer compared with a gutta-percha solvent or no solvent.

Apical extrusion of debris in flat-oval root canals after using different instrumentation systems

INTRODUCTION

The purpose of this study was to evaluate the amount of apically extruded debris in flat-oval root canal systems during cleaning and shaping with different instrumentation systems.

METHODS

Seventy-two mandibular incisors were randomly assigned to 4 groups (n = 18) according to the instrumentation system to be used: the ProTaper Next rotary system (PTN; Dentsply Tulsa Dental, Tulsa, OK), the WaveOne reciprocating system (WO, Dentsply Tulsa Dental), the Twisted File Adaptive (TFA; SybronEndo, Orange, CA) rotary/reciprocating system, and the Self-Adjusting File (SAF) system (ReDent-Nova, Ra'anana, Israel). Debris extruded during the instrumentation was collected and dried in preweighed Eppendorf tubes. Three consecutive weights were obtained for each tube, and the average was calculated. The data were analyzed using the t test and analysis of variance (Games-Howell test).

RESULTS

The SAF produced significantly more debris compared with the other systems (P < .05). No significant difference was noted amongst the PTN, WO, and TFA (P > .05).

CONCLUSIONS

Regardless of the instrumentation system used, apical extrusion of debris was exhibited at some level, regardless of the instrumentation system used. The SAF was associated with the highest amount of debris extrusion compared with PTN, WO, and TFA.

Influence of Apical Patency and Cleaning of the Apical Foramen on Periapical Extrusion in Retreatment

This study evaluated the influence of apical patency, root filling removal technique and cleaning of the apical foramen, concerning the amount of debris extruded during root canal retreatment. Forty mandibular incisors were randomly assigned to 4 groups - GIM (n=10), GIIM (n=10), GIPT (n=10) and GIIPT (n=10), which were named according to leaving (I) or not (II) apical patency during canal preparation and filling removal technique (manual - M or ProTaper system - PT). After filling material removal, each specimen of each group had the apical foramen cleaned by sizes 15, 20 and 25 instruments, generating 12 subgroups: GIM15, GIM20, GIM25, GIIM15, GIIM20, GIIM25, GIPT15, GIPT20, GIPT25, GIIPT15, GIIPT20 and GIIPT25. Extruded filling debris was collected by a Milipore filtration system, an HV-durapore, 0.45 µm pore filter with a 25 mm diameter. The filters were weighed before and after the collection on an analytical scale (10–5 g), and the difference was calculated. The mean weight of extruded filling debris was analyzed statistically by Kruskal-Wallis and Friedman ANOVA tests (α=0.05). The mean values found in the groups (in mg) were: GIM (0.95±0.94), GIIM (0.47±0.62), GIPT (0.30±0.31) and GIIPT (0.32±0.44). There was no statistically significant difference among any of the groups or subgroups (p>0.05). ProTaper provided the smallest amount of extruded filling material, regardless of presence or absence of apical patency, followed by manual technique, without and with apical patency. Additional amounts of debris were collected during cleaning of the apical foramen, regardless of the instrument, presence/absence of patency or root filling removal technique.